GENERAL BODY SYSYTEM (WESTERN CONCEPT) AND QI-SYSTEM (EASTERN CONCEPT) AND THEIR INTERACTION TOWARDS MAINTAINING HEALTH AND LIFE IN THE HUMAN BODY


	GENERAL BODY SYSYTEM (WESTERN CONCEPT) AND QI-SYSTEM (EASTERN CONCEPT) AND THEIR INTERACTION TOWARDS MAINTAINING HEALTH AND LIFE IN THE HUMAN BODY

HUMAN BODY AND ITS SYSTEMS

Philosophers and scientists have observed that human beings are made up of the same elements found in ordinary soil and water. But when these 20 or so basic elements combine in thousands of different ways to form a human body, the result is one of the most complex organism on this earth and it is both wonderful and mysterious to behold.

About 75 to 80 percent of an adult’s human body is made up of slightly salty water, while the rest is of chemical compounds, many of which are unique to human beings. Cells are the smallest and the most basic life units and there are hundreds of different kinds of cells from these chemical ompounds. The human body contains 80 to 100 trillion cells of which similar types of cells join together to form specific types of tissue - nerves, muscles and bones etc. These collections of related tissues join to form different body organs - heart, liver, prostrate etc. dependent on each other in function with the exception of blood cells. Then, organs are grouped into different systems in the human body recognized by WESTERN MEDICAL SCIENCE as follows :-

WESTERN CONCEPT (FINDINGS)

The Outer Protective System - The Skin
The skin is the largest organ of the body, weighing about seven pounds in an average adult and is about 5% of body weight covering eighteen square feet of the human body. It is water- proof, helps the regulation of body temperature and acts as a protective barrier against bacteria, dirt and other substances which are harmful. It also provides us with a sense of touch. It consists of 3 layers - the epidermis, the dermis and the subcutaneous layer.

1. Epidermis is the outer most layer. It contains pigment cells and specialized cells that manufacture kiratin - a tough substance found also in hair and nails.

2. Dermis : - This layer contains, blood vessels, nerve endings, hair follicles, sweat glands and sebaceous (oil) glands.

3. Subcutaneous layer is the lowest layer and it is where the sweat glands originated, and fat is stored. This layer also supports the blood vessels and nerves that supply the outer layers of the skin. The skin acts as a sensory organ because the dermis and the subcutaneous layer are rich with nerve - endings acting as nerve receptors. These nerves transmit all types of perceptions or “feelings” to the brain.

THE MUSCULOSKELETAL SYSTEM

The Human Skeleton (Bone and Joints)
It gives the body, the needed support and protective framework for the internal organs and also provides levers for locomotion and other movements. It gives us the shape that we have or we would be just a blob of blood and flesh on the floor. Bones are hardened masses of living tissues that have several functions, they collect and store calcium up to 99% of it. Within some bones is a substance called marrow, which produces red and white blood cells and platelets. We had 350 bones in our skeleton when we were born. By the time we are an adult, we only have 206 bones because some of the bones fused together to become one bone. The place where 2 or more bones meet is called a joint which allows movement of the bones that are involved. Ligaments (bands of fibrous tissues) connect one bone to another and cartilage (elastic tissues) covering the ends of the bones cushions and protect bones with the aid of various joint fluids and bursac (small sacs containing lubrication fluid that encompass the joints). Tendons attached bones to muscles. The coordination of ligaments, tendons and muscles is necessary for the movement of the body.

Of the 206 bones in your skeleton, 80 bones form the Axial Skeleton - the cranium, spine, ribs, sacrum and sternum. The balance of the 126 bones form the Appendicular Skeleton - the arms / elbows / hands / legs / knees / ankles / shoulders and pelvis. These are further classified as follows:-

1. The Skull 4. The Hands

i) Parietal - on top i) Carpal - wrist bone

ii) Frontal - in front ii) Metacarpals - hand bones

iii) Temporal - at the side iii) Phalanges - finger bones

iv) Occipital - at the back

v) Maxilla - upper jaw 5. The Leg

vi) Mandible - upper jaw i) Femur - upper bone

vii) Others - other head bones ii) Patella - knee cap

iii) Tibia - larger lower bone

2. The Vertebrae iv) Fibula - small lower bone

i) Cervical - first 7 units

ii) Thoraxic - the following 12 - units 6. The Foot

iii) Lumbar - the next 5 units i) Tarsus - ankle bones

iv) Sacrum - the next 5 units fused at hips ii) Metatarsus - foot

v) Coccyx - the last 4 units fused - tail ones iii) Phalanges - toes

3. The Arms 7. The Chest

i) Humerus - upper arm i) Clavicle - collar bone

ii) Radius - thumb side lower ii) Scapula - shoulder bone

iii) Ulna - finger side lower iii) Sternum - breast bone

iv) Ribs - rib bones in front of chest

There are several types of joints that our body make use of to coordinate movements or make connections, and they are as follows - The skull make use of fixed joints. The ribs and the vertebrae are semi-movable joints. The others are movable but different in nature such as the elbow making use of hinge joints, the hip - ball and socket joint, base of skull - pivot joint, hand - gliding joint.

The Muscles
There are more than 600 muscles in the human body and the three types of muscles are as follows :-

1. The skeletal muscles which are attached to bones and make voluntary movements possible. This type of muscles are striated or striped and consists of layers of tissues divided into bundles of interwoven fibres that run parallel to one another. Skeletal muscles constitute approximately 40 percent of the total body weight.

2. The smooth, organic muscle is present in several of the internal organs, including the intestines, in the larger blood vessels and the bladder. Smooth muscle contains elongated, spindly cells arranged parallel to one another and are often merged into bundles. The autonomic nervous system controls this type of muscle.

3. Cardiac muscle is striated and is controlled by the autonomic nervous system. It is only found in the heart. Muscle tissue has the specialized function of contraction (i.e. the ability to shorten and thicken) and thus produce movement of the different parts of the body. It is also elastic and after stretching, it can revert back to its original length.

THE BRAIN AND THE NERVOUS SYSTEM

The Nervous System
The nervous system is divided into the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and the spinal cord which are immersed in the cerebrospinal fluid. The peripheral nervous system which includes the cranial nerves and the spinal nerves convey nerve impulses to and fro, from the central nervous system to different parts of the body. The autonomic nervous system, part of the peripheral nervous system control all involuntary activities of the body.

The Brain
The human brain weighs about 3 pounds, the largest brain of any living creature on Earth and is the control centre for the entire body. It has more than 10 billion inter-linked brain cells which control all the functions of the body systems all the time. Different area of the brain is in charge of different functions of the body. Basically, it is divided into three main sections, firstly, the cerebrum which is divided into the left and right cerebral hemisphere and make up of the largest part of the brain. The cerebrum interprets impulses from the senses, stores memory, and controls voluntary muscles. The second largest part of the brain is the cerebellum and is behind the brain stem. The cerebellum controls muscle tone and muscle movements and responsible for the body’s balancing. At the lowest section of the brain is the brain stem under the cerebellum and is linked up to the spinal cord. It is make up of three sections - the pons, the middle brain and the medulla. All parts of the brain stem contain collections of greymatter, which are the nuclei of the cranial nerves, and the grey and white matter of the reticular formation.

The Spinal Cord
The spinal cord is an extension from the brain stem and form part of the central nervous system. It runs 2/3 of the way down the dorsal side of the body and protected by the vertebrae. Between the vertebra are the spinal cartilage discs which act as shock absorbers. In the adult, it is about 45 cm (18 in) long and tapers into the conus medullaris to end at the lower level of the first lumbar vertebra. The spinal cord has 31 pairs of nerves that branch out from each side of the vertebral column by two roots, ventral and dorsal. The spinal cord contains many neurons and sensory nerve fibres that transmit impulses from the brain to every part of the body.

The Nerves
Nerves are bundles of grey fibrous cord connecting the brain and spinal cord to the tongue, eyes, ears, glands and other parts of the body. They are under the peripheral nervous system control and carry impulses affecting mostly of senses and motion.

The Neurons
Neurons are nerve cells with outgrowths and composed the structural units of the nervous system. A neuron is divided into firstly the cell body which is responsible for making proteins and to grow, control impulses, and to handle maintenance. Branching out from the cell body are the dendrites whose function is to convey impulses to the cell body and the efferent processes are the axons whose function is to convey impulses out of the cell body. The axon, of which is normally one per cell, branches near its termination into several fine axon terminals. When these end in close proximity to another neuron, the gap or junction is called a synapse and when the other cell is a muscle cell, a neuromuscular junction is formed. Tranmission of information from one neuron to another at a synapse is in most cases, neurochemical although there are also electrically acting synapses similar to the electrical junctions in cardiac and unstiated muscle. Neurochemical transmission depends on the ability of axon terminals to synthesize, store and let go the chemical transmitter. Many substances were discovered to be neurotransmitter. Some of the important ones are acetycholine, the catecholamines, noradrenaline and dopamin, serotonin and the amino acid, gamma aminobutyric acid (GABA).

THE FIVE BASIC SENSES

The five basic senses - sight, hearing, taste, smell and touch are perception of everything that is happening about our surroundings through - the eyes, ears, tongue, nose and the hands. All our sensory organs are complex nervous systems with a direct pathway to the brain which process the information instantly and respond accordingly to the stimuli.
The structures involved in the production of a sensation are :-

1. An end - organ or sensory receptor .ie. the tongue situated in the peripheral at the terminations of the sensory nerves.

2. The afferent nerve fibres in the peripheral nerve and spinal cord.

3. The thalamus, which is a cell station relaying sensations to the cerebral cortex.

4. The sensory reception areas in the brain which are connected with various psychic areas where the impulse is interpreted and may be stored as memory.

Although the brain receives and determines the sensation, it returns it back to the place or end organ where it originated and is actually felt by the person concerned as being in the peripheral region.

The Sense of Touch - The Skin
The sense of touch are sensations from the skin in response to pain, temperature (cold or hot) and light touch. The concentration of “touch feelings” are in the hands or rather the finger tips of an individual. Minute sensory areas, are scattered all over the skin in different concentration at different spots, which correspond with the nerve-endings. Different types of sensation activate different types of nerve-endings.

The Sense of Smell - The Nose
The way sense of smell works depends on :-

1. The end-organ or receptor ie. the endings of the 1st cranial or olfactory nerve in the mucous membrane of the upper part of the nasal cavity.

2. The olfactory bulb and tract which convey the impulses to the brain.

3. The limbic lobe situated in the medial surface of the cerebral hemisphere.

To trigger the sense of smell, the factor must be either in the form of a gas or minute particles which can dissolve in the secretions of the nasal mucous membrane and the sensation produced are mostly classified either pleasant or unpleasant. The sense of smell is closely associated with the sense of taste.

The Sense of Taste - The Tongue
The tongue consists of muscles some of which arise from the hyoid bone and the lower jaw. The tongue is covered by mucous membrane and the taste buds which are the end-organs for the sense of taste are concentrated mostly at the tip, the sides and the base of the tongue. These taste buds recognize four basic tastes ie. bitter, sour, sweet and salty. The tongue also contains nerve-endings that respond to the sensations of pain and touch.

The Sense of Hearing - The Ears
The ears consist of the external ear, the middle ear, the cochlea of the internal ear and the cochlear nerve and acoustic zone in the temporal lobe of the brain. The external ear is meant to collect sound waves and conduct them through the external acoustic meatus into the middle ear or tympanic cavity. The sound waves are further transmitted by a chain of small bones or ossicles when they impinged onto the Tympanic membrane, onto the membrane covering the fenestra vestibuli and from there they are further passed on to the internal ear. The sound nerves eventually end up on the organ of Corti which is the true end-organ of the sense of hearing and of course, up to the VIIIth cranial nerve to the brain stem and thereby to the temporal lobe of the brain (of opposite side). The sense of hearing is affected by three factors of vibration in the air, namely the pitch, which depends on the frequency of the vibrations, the intensity or loudness which depends on the amplitude of the vibrations, and lastly the quality which is due to the combination of various vibrations.

The Sense of Sight - The Eyes
The organ of sight is the eye and is located in the orbital cavity of the skull. The essential organs of the visual apparatus are, the eyeball, the optic nerve and lastly the visual centres in the brain. The eye is comparable to a camera with the eye lids functioning as a shutter, the cornea acting as the opening for the light rays, the iris acting as the aperture regulator, the choroid acting as a darkened interior and the retina acting as the image receiver. When light rays or electromagnetic waves impinged onto the retina, certain chemical changes occur which activates the endings of the optic nerve. The stimili are conveyed by the optic nerve to the optic chiasma and finally to the cortex of the occipital lobe where they are interpreted into consciousness.

THE LUNGS AND THE RESPIRATORY SYSTEM

The Lungs
The lungs are a pair of conical shaped organs, surrounded by the pleura, a serous membrane. The lungs are separated from each other by the mediastinum. The lungs are divided into lobes by deep fissures and the right lung has three lobes, upper, middle and lower while the left has two - the upper and lower. Each lobe of the lung contains many small lobules made up of the aveoli and their bronchioles, which join with one another to form the larger bronchi. The venous blood from the right ventricle of the heart goes to the lungs by way of the pulmonary artery while the pulmonary veins supply the left atrium with oxygenated blood.

The Respiratory System
The respiratory system consists of the lungs and the air passages formed by the nose, mouth, pharynx, larynx and upper trachea (extra thoracic parts) and the lower trachea, bronchi, bronchioles and alveoli (intrathoracic parts or tracheobronchial tree). The main points, of respiration are the exchange of (O2) oxygen from the air to the body tissues and replacing with (CO2) carbon dioxide from the tissues back to the air. The actual interchange of the gases take place in the aveoli or air sacs which number about 700 million units in an adult human. Basically there are two stages in the gases exchange as follows :-

1. External respiration - takes place in the lungs where oxygen is extracted into the blood and carbon dioxide is released into the air.

2. Internal respiration - where the oxygen in the blood is exchanged for carbon dioxide in the tissues of the body.

In addition of the above main function of the respiratory system, it also supplies air to the larynx for the purpose of voice production.

THE HEART AND CIRCULATORY SYSTEM

THE CIRCULATORY SYSTEM

It is a transportation system within the body carrying blood containing oxygen, nutrients, hormones and other substances to the tissues and convey carbon dioxide to the lungs and other waste products to the kidneys. The blood is the vehicle or transporter and the blood vessels are the channels along which it travels. The heart which is a muscular pump is the driving force which moves the blood through the blood vessels. Other forces assisting the movement of the blood would be skeletal muscle activity squeezing the veins, the inspiratory phase of breathing, which sucks blood towards the thorax and also gravity, assisting the venous return of blood to the heart for those parts which are higher than the heart. The circulatory system is specially constructed to meet the following conditions :-

1. To keep a constant blood supply to the brain and vital centres, all the time. An interruption of blood supply to the brain can cause unconsciousness and if prolonged lack of oxygen, can cause permanent brain damage or even death.

2. To regulate the blood supply to other organs according to their immediate needs eg.
1) More blood supply to the muscles during increased activities such as running, swimming etc.
2) More blood to the stomach organs when food is being ingested.

The Heart
The heart is a hollow muscular organ, enclosed within a fibroserous sac called the pericardium, and lies obliquely in the thorax, in the middle mediastinum between the lungs and above the diaphragm. It is shaped like a upside down pear. Its average weight is 300 gms in adult human males and 250 gms in adult human female. Clinically the heart is partitioned into right and left halves. Each of the halves contains two chambers, namely the upper atrium and the lower ventricle. The septum separates the right and left sides of the heart. The mitral valve connects the left atrium with the left ventricle and the tricuspid valve connects the right atrium with the right ventricle. The heart, therefore, is actually made up of two pumps, one for each of its own circulation, but anatomically combined into one organ. Blood leaves the right ventricle into the pulmonary artery into the lungs and after oxygenated, it returned by the pulmonary veins into the left atrium. The left atrium pumps its blood into the left ventricle and out through the aorta, the main artery. The heart itself is served by its own supply system called the right coronary artery and left coronary artery and drains back into the heart by the coronary sinus, the anterior cardiac veins and the Thebesian veins. The function of the heart is to pump day and night continuously in moving the blood through the circulatory system. Although we assume that the heart does not rest but it does rest between every beat during the resting period called the diastole and the period of contraction is called the systole. The resting heart beat in a healthy adult is about 62 beats per minute but in athletes, it may be much lower. The contraction of the heart ie. the atria and ventricles are controlled by electrical impulses generated spontaneously within the heart but the autonomic nervous system exercises control over the rate of the heart beat. All these electrical events can be recorded on the electrocardiogram.

The Blood Vessels
The blood vessels form the network of passage ways that transport blood throughout the human body. There are about 60,000 miles of blood vessels in an adult human body. Basically they are divided into two main types of vessels, namely the arteries and the veins. The arteries transport oxygenated blood from the heart to all the tissues of the body including the heart itself. The arteries are thick walled tubes consisting of three layers, namely, the outer fibrous tunica adventitia, the middle tunica media consisting of smooth (unstriated) muscle fibres with some yellow elastic fibres and the inner tunica intima, consisting of a layer of flattened endothelial cells. Most of the arteries of the body are directly under the control of the autonomic nervous system. The veins transport deoxygenated blood back to the heart. Although the prime force that is responsible for the venous return of the blood to the heart is the pumping action of the heart, it is also helped by a) the thoraxic pump b) the skeletal pump c) the heart beat. The veins also have three layers, similar to those of the arteries but they are much thinner than the arteries. Many veins of the limbs and abdomen have valves in their interior, so that they allow blood to flow only towards the heart and prevent back- flow.

The Blood
Blood is the fluid that runs through the circulatory system of the body. It is made up of plasma, red blood cells, white blood cells and platelets. It also contains oxygen and carbon dioxide molecules “dissolved” in the haemoglobin of the red blood cells. Also present in the blood are nutrients eg. vitamins, proteins, mineral salts for the usage of the tissue cells, and toxins, produced by the tissue cells in their constant living activities eg. the dying and destruction of cells materials, the result of muscular activities - lactic acid and also uric acid - all for excretion through the excretory organs. Plasma is a straw-coloured clear fluid that is composed of 90% water and dissolved mineral salts and is the actual transportation medium of the blood. The red colour of the red blood cells is due to the protein chemical called haemoglobin. The average life span of a red blood cell is about 120 days. The white blood cells have a shorter life of about a few days to a few weeks and are responsible for the defense of the body against germs and bacteria. The platelets are responsible for closing of a “wound” or “opening” in our bodies due to various reasons such as injuries due to a cut or a fall. When bleeding from a wound occurs, the platelets gather at the site and react with the fibrinogen to form tiny fibrin threads. The fibrin threads then form a web-like mesh that “traps” the red blood cells from leaking out. This mixture of fibrin threads and red blood cells hardens as they dry to form a clot called a scab. Our blood is classified into type A, type B, type AB and type O. Blood types have to be compatible for blood transfusion or a fatal situation may occur.

Type A person can donate blood to a type A or AB person

Type B person can donate blood to type B or AB person

Type A person can receive blood from type A or O person

Type B person can receive blood from type B or O person

Type O person can receive blood from type O person only

So, type AB person is called a universal receiver and type O is called a universal donor. Our blood is again further classified into positive or negative. If your blood contains a certain blood protein, you are said to be Rh positive (Rh+) and if you do not have it, then your blood is Rh negative (Rh-). This Rh factor is another important factor for blood transfusion. When we talked about “blood pressure”, we meant the force or pressure which blood exerts on the walls of the artery, which it is contained. Blood pressure is dependent on several factors such as - the force of the heart beat, the resistance to blood flow in the arterioles ie. the peripheral resistance, and the volume of circulating blood, and is measurable by an instrument called the sphygmomanometer.

THE DIGESTIVE SYSTEM

Digestion is the process by which the body converts food into simple constituents that can be absorbed into the blood and utilized by the various tissues for heat, energy, growth and replacement or repair. The digestive tract which is about 30 meters long extending from the mouth to the anus and is lined with mucous membrane which includes several hollow organs - the mouth, esophagus, stomach, small intestine, big intestine (colon), each of which has a specific job in the digestion of food. Digestion happens in the alimentary canal or digestive tract and is assisted by the accessory pancreas which secrete their juices into the alimentary canal to assist digestion. Two types of processes of digestion take place, namely the mechanical and the chemical to break down the complex composition of food. The mechanical process of digestion involves mastication, swallowing and the peristaltic movements of the alimentary tract, which helps to mix the food with the digestive juices and move it along the canal. The chemical process of digestion involves all the changes due to the enzymes of the digestive juices secreted by the accessory organs of digestion. Basically, what really happens are the following :-

1. Ingestion - the in taking of food through the mouth.

2. Digestion - starts at the mouth and is primarily done in the stomach and small intestine. Both mechanical and chemical processes of digestion occur at this section.

3. Absorption - this process occurred when the digested food has been reduced into simple constituents and absorbed through the mucosa of the gastro-intestinal tract into the blood and lymph of the body.

4. Egestion - takes place when food substances which cannot be digested (have no food value) are excreted (Excretion) as faeces.

The Mouth
The mouth, or buccal cavity is the upper expanded portion of the alimentary tract. It consists of two portions - the outer part or vestibule, is the recess between the teeth and the inner face of the cheeks. The inner central part contains the tongue, and communicates with the oro-pharynx. The tongue is made up of voluntary muscle and is used for mastication, swallowing, taste and speech. The teeth in the mouth are also used in the cutting, biting, chewing - reducing into smaller pieces for easier digestion. The three pairs of salivary glands - the parotid, submandibular and sublingual glands secrete saliva, consisting 90% water and contains the enzyme ptyalin (salivary amylase) which begins the digestion of carbohydrates.

The Pharynx
The pharynx, or throat is an expanded muscular tube about 13 cm long and stretches from the base of the skull to the level of the cricoid cartilage. The pharynx is anatomically divided into three sections, namely the nasopharynx, the oropharynx and the laryngopharynx. The walls of the pharynx are made up of constrictor muscle which contracts - in the act of swallowing.

The Oesophagus
The gullet or oesophagus is a collapsible muscular tube running from the pharynx to the cardiac opening of the stomach. It is about 25 cm long and runs downwards through the neck, the thorax and ending in the abdominal cavity at the cardia. The circular muscle fibres of the oesophagus are thickened to form sphincter muscles at its upper (cricopharyngeal) and lower (cardiac sphincter) ends, which relax when swallowing takes place. The cardiac sphincter prevents regurgitation of stomach contents into the oesophagus.

The Stomach
The stomach is an inflated part of the alimentary canal, located between the oesophagus and the begining of the small intestine. It is a muscular, elastic organ and its shape and size varies according to the stomach’s content, amount and type and also to the pressure exerted on it by surrounding organs. Digestion occurs in the stomach when the gastric glands of the mucosal lining secrete large volumes of digestive juices and mixed up with the stored food. Rippling waves of peristalis called tonus or mixing waves move the food towards the antral part of the stomach where vigorous peristolic movements break down, as well as churn the food and gastric secretions into a milky-white sludge, called chyme. When the chyme is fluid enough, the pyloric spincter opens and the chyme is released into the duodenum. The gastric juice is a clear watery fluid containing hydrochloric acid, mineral salts, mucuos and three enzymes called pepsin, renin and gastric lipase to aid in the digestion process.

The Small Intestine
The small intestine is a carvoluted tube, running from pylorus of the ileocaecal valve, where it links up with the large intestine. It is about 5 meters in length and made up of three sections ie. the duodenum, the jejunum and the ileum. The functions of the small intestines are, to finish the job of digestion of food, to absorb the final products of digestion and to transport the chyme towards the large intestines. Along the duodenum, the mucosa in the intestinal walls secrete mucus and intestinal juice (succus entericus) which contains the enzyme enterokinaze. Simultaneously, the mucosa secrets the hormones secretin and cholecytokinin into the blood to reach the pancreas to induce it to secrete large amount of sodium bicarbonate liquid. The sodium bicarbonate neutralizes the acid in the chyme. At the same time, the pancreas also secrete the digestive enzymes, amylase for digestion of carbohydrates to disaccharides and sucrase, maltase and lactase for converting disaccharides to monosaccharides, trypsinogen and chyrnotrypsinogen for digestion of proteins and lipase for the digestion of fats. Meanwhile, the gallbladder secretes bile, containing bile salt which will emulsify the fats in the chyme. Finally the digested food is absorbed through the epithelial surface of the villi (minute finger-like processes on the surface of the mucus membrane). Along with it, are the fluid, digestion juices, mineral salts, vitamins etc. Eventually, the propulsive peristaltic movements pushed the chyme to the end of the small intestine at the ileocaecal valve at the entrance of the large intestine.

The Large Intestine
The colon or large intestine is 1.5 meter in length and runs from the ileocaecal valve to the anus. It is made up of the following section ie. the caecum and verniform appendix, the ascending colon, the transverse colon, descending colon, pelvic or sigmoid colon, anal canal and rectum. By the time, when the digested balance of the small intestine reached the caecum (the beginning of the large intestine), the digestive process is completed and most of the products of digestion have been absorbed. What remains, is a liquid residue and the process of re-absorption continues. The first half of the large intestine would have removed most of the water and electrolytes, remaining only the faecal residue. There are a number of bacteria living in symbiosis in the large intestine and they synthesize vitamins B and K which are absorbed into the blood stream through the mucosa. Any excess of mineral salts such as calcium, iron and drugs of the heavy metal types such as bismuth will be excreted by the walls of the large intestine through the peristaltic movements of the large intestine.
Defaecation is the expulsion of faeces from the anal canal through the rectum. The faeces are normally a semi-solid, paste-like mass, coloured brown by stercobilin, a pigment taken from the bilirubin and biliverdin of the bile.

THE KIDNEYS AND URINARY SYSTEM

The Kidneys
The kidneys area pair of bean shaped organs, each of which is about 11 cm. in length and 6 cm. in width, located at the back of the abdomen and embedded in the perirenal or perinephric fat. The average weight of the adult kidney is about 150 gms. in the human male and 135 gms. in the human female. They are dark red in colour. Each kidney is wrapped in a thin smooth fibrous capsule and consists of two layers, an outer cortex and an inner medulla. The kidney substances, under a microscope is seen to be composed of a) Renal corpuscles (Malpighian bodies) b) renal tubules c) blood vessels and supporting tissues. The foremost job of the kidneys, is keeping the composition of the blood constant by the excretion of abnormal constituents and of excess normal constituents through the following ways :- a) The excretion of water b) The excretion of ions and regulation of the acid-base balance and PH of the blood c) The excretion of drugs, toxins and chemical substances which can be detrimental to the health of the human body d) The excretion of the end products of protein metabolism. The kidneys using the nephrons to process the blood in the kidney by filtration, re-absorption, secretion and the end result is urine. Normal urine is usually a clear yellow or amber coloured liquid having a specific gravity (S.G.) of between 1015-1025 and slightly acidic (pH 6).

The Urinary System
The job of the urinary system is the creation and excretion of urine, a waste product containing toxic substances, which may be harmful to the human body and also excess water. The urinary system consists of the following :- a) the kidneys - the excretory organs b) the ureters - the duct draining the kidneys c) the urinary bladder - the urinary reservoir d) the urethra, the channel to the exterior. The ureter is the duct that conveys the urine from the kidney to the bladder. The ureter is a tube about 20 cm. long. The urinary bladder is the reservoir for the urine collected from the kidneys via the ureters. The muscular layer of the bladder is known as the detrusor muscle and is primary responsible for emptying the bladder during micturition and may be assisted in this by a rise in intra- abdominal pressure brought about by contraction of muscles of the abdominal wall. The neck is the lowest part of the bladder and in the male, it rests on the base of the prostrate, with which it fuses. The neck of the bladder opens into the urethra. The urethra is the tube conveying the urine from the bladder to the exterior. It is different in the male and female and in the male, its chief function is for reproduction. The male urethra is a small channel about 20 cm in length leading from the bladder to its external orific, the meatus of the urethra at the end of the penis and compose of three sections - a) the prostatic section, b) the perineal or membranous section and c) the penile or spongy section. Micturition is the act of emptying the bladder or passing urine and is primarily a reflex action which after infancy, can be consciously controlled by impulses from the higher centres of the brain which either enhance or inhibit it.

THE ENDOCRINE SYSTEM

The endocrine system comprises of endocrine or ductless glands which produce special chemical substances called hormones which are secreted directly into the blood stream. A hormone is also known as chemical messenger, secreted by a ductless gland, which is transported by blood circulation to the organ of its influence. In some cases, an organ such as the pancreas is both endocrine and exocrine because it secretes insulin and glucagon into the blood stream and pancreatic juice into the duodenum via the pancreatic duct. The major endocrine glands may be classified in two groups :-

1. the anterior pituitary gland, the adrenal cortex, the thyroid gland, the gonards or sex glands.

2. the posterior pituitary gland, the pancreas, the adrenal medulla, the parathyroid glands.

The glands of the first group are controlled by the anterior pituitary gland via the intermediary of trophic hormones eg. ACTH or corticotrophin which it secretes. The anterior pituitary gland is itself being controlled by the hypothalamus which secretes releasing and inhibiting hormones eg. corticotrophin – releasing factor. The glands of the second group are controlled by other types of stimili, both neural and chemical. The gastrointestinal tract also produces some internal secretions, all of them are peptides and some are gastrin and secretin. Some are even present in both the gastrointestinal tract and within the nervous system where they appear to act as neurotransmitter. These are called the “ brain-gut peptides” and include somastatin, enkephalins and vasoactive intestinal peptide.

The Thyroid Gland
The thyroid gland is located in the lower part of the neck and consists of two lobes, one on either side of the trachea, joined together by an isthmus which passes in front of the trachea just below the cricoid cartilage. The lobes are conical in shape and have upper and lower poles. The thyroid contains two types of hormones producing cell a) the follicular cells that produce thyroid hormones b) the C (clear) cells that produce calcitonin. The thyroid gland stores large amounts of thyroid hormones in an inactive form, called colloid which consists of thyroglobulin produced by the follicular cells and then converting it into thyroid hormones, trio-iodothyronine (T3) and thyroxine (T4) before releasing them into the blood stream. Both thyroid hormones contain a high amount of iodine obtained from foods especially sea foods and drinking water.

The Parathyroid Glands
These are small oval shaped glands, smaller than peas which are situated on the posterior surface of the thyroid gland. Usually there are two pairs of thyroid glands, a superior and an inferior pair. The main cells of the parathyroid glands secrete a hormone called parathormone which controls serum calcium levels.

The Suprarenal Glands
The adrenal or suprarenal glands are two small flattened, yellowish objects squatting on the upper pole of each kidney. Each is about 5 cm in height, 3 cm in width and 1 cm in thickness. The outer part of the gland, the cortex is yellow in colour as it is rich in lipids, whereas the medulla is the dark interior. The hormones of the suprarenal cortex are derived from cholesterol and are from a type of fatty or wax-like substances called steroids. They are divided into three main groups according to their main effects.

1. The mineralocorticoids - aldosterone and corticosterone, control the body sodium and potassium ion levels and maintain the fluid and electrolyte balance of the body.

2. The glucocorticoids - cortisol (hydrocortisol), corticosterone and 11 - deoxycortisol controls a lot of functions - among them are - enhancement of water diuresis, immunosuppression, suppression of growth hormone release and activity etc.

3. Sex hormones - androgens and aestrogens influence sexual development and growth. In females, the suprarenal glands are the principal source of androgens, which are required by both sexes for normal puberty and skeletal development.

The hormones of the suprarenal medulla are adrenaline and noradrenalin and these catecholamines are not controlled by the anterior pituitary gland but by the sympathetic nervous system. They control blood pressure, the rate and force of the heartbeat, relax the involuntary muscle of the bronchi and stimulate the liver to convert glycogen into glucose. Adrenal secretion of catecholamines is a reserve mechanism in the human body that is activated in times of fear or anger - to fight or to run by increasing blood pressure and circulation in the muscle and brain and at the same time convert glycogen into glucose for increased activity.

The Pituitary Gland (Hypophysis)
This gland is about 1 cm in diameter and located at the base of the brain in the depression in the sphenoid bone known as the sella trucica and attached to the brain by a short stalk just behind the optic chiasma. The pituitary gland is made up of two parts, the anterior and posterior lobes - both are under the control of the hypothalamus but by different mechanism. The anterior pituitary (Adenohypophysis) produced six hormones as follows :-

1. Tyroid - stimulating hormone (TSH) which stimultaes the growth and activity of the thyroid gland.

2. Corticotrophin or adrenocorticotrophic hormone (ACTH) which promotes the production of steroid hormones, especially cortisol, in the suprarenal cortex.

3. Growth hormone (GH) (Somatotrophin) influences the synthesis, of a group of proteins called somatomedins, by the liver - affects the growth of the body.

4. Gonadotrophins (FSH and LH) - FSH induce the maturing of ovarian follicles and oestrogen production in the female and activates spermatogenesis in the male. LH induces ovulation and formation of the corpus luteum, which secretes progesterone, in women, and stimulates the testis to produce testerone in men.

5. Prolactin promotes lactation in female especially during lactation.

6. The posterior pituitary (neurohypophysis) hormones are of two types and are synthesized in the hypothalamus and reached the posterior pituitary where they are stored, prior to usage as follows :- i) Vasopressin (antidiuretic hormone ADH) controls the re-absorption of water into the blood from the collecting ducts of the kidneys. The function of the vasopressin is to maintain a normal plasma osmolality (270-290 m OSM / kg) and plasma volume.
ii) Oxytocin causes contraction of the smooth muscles of the uterus and breast (induces ejection of milk from lactating breasts).

The Pineal Gland
The pineal gland is a small reddish-grey body, about the size of a pea, located in the midline of the brain, just behind the third ventricle and under the posterior end of the corpus callosum. It is believed that it has a regulatory role in modulating the activity of the pituitary and other glands.

The Sex Glands or Gonards
The sex glands or gonards of both sexes are responsible primarily for the propagation of the human species and also to give the characteristic traits of the respective sex.

The Male Gonards
Testes are small oval shaped glands suspended in the scrotum, they are the male gonards or reproductive glands. They secrete the following items :-

i) Spermatozoa - for fertilizing an ovum of the females sex.

ii) Androgens hormones - which consist mainly of testosterone - a steroid compound, dehydroepiandrosterone and androstenedione in lesser amount. Testosterone promotes maturing of the male reproductive organs and induces the appearance of secondary sexual characteristics such as growth of hair over the chest, abdomen and pubis and also on the face. It is also responsible for the enlargement of the larynx which caused the deepening of the voice of an adult male. Testosterone also plays a part in the maturing of the spermatozoa. It also has a powerful anabolic role in stimulating protein synthesis and growth of bones.

iii) Oestrogen - only a small amount is secreted but its function in the male is unknown.

The Female Gonards
The two female ovaries or gonards are oval shaped bodies, of about 3-4 cm in length, 2 cm in width and 1 cm in thickness, lying one on each side of the uterus. Each ovary is hung from below the cornu of the uterus by an ovarian ligament. The secretions of the ovary are as follows :-

i) Ovum or the egg produced, are meant for fertilization by spermatozoa to create new life.

ii) Oestrogen is a group of steroid compounds - oestradiol, oestriol and oestrone. Oestrogen is responsible for the commencement of secondary sexual characteristics of the female sex at puberty and for the growth and development of the female reproductive tract and mammary glands.

iii) Progesterone is a steroid compound whose main function is to initiate secretory changes in the endometrium in preparation for pregnancy. It acts together with oestrogen to promote the proliferation and enlargement of the alveolar cells of the female breast.

iv) Androgens are also secreted but in smaller amounts in a normal female.

The Pancreas
It is a gland that has both exocrine and endocrine functions. Is exocrine function is the secretion of digestive enzymes and its endocrine function is the secretion of three hormones - insulin, glucagon and somatostatin. It is greyish-pink in colour and is situated behind the stomach and consists of a number of lobules, supported by fine loose connective tissues. Embedded between the acinar cells of the pancreas are islets of Langerhans which secrete the hormones directly into the blood stream.

i) Insulin is vital in the metabolism of carbohydrates, fats and proteins.

ii) Glucagon is associated with the breakdown of liver glycogen (glycogenolysis) and with increased gluconeogenesis. It also lipolytic (breaks down fats) and has other numerous actions.

iii) Somatostatin inhibit the secretion of many hormones and other substances and is one of the brain-gut peptides which acts as neurotransmitters.

THE REPRODUCTIVE SYSTEM

Reproduction of the human species is a complicated process involving the activity of two sexes, the female and the male, each contributing a gamete (mature sex cell) for the interaction and formation of a new individual. Sexual reproduction results from the merger of an ovum and a sperm. The reproductive organs of the male and female differ in anatomical structure and arrangements, each being suited to the functional activities they are required to perform. The function of the male organ is the formation of spermatozoa and place them within the female so that they can fertilize the ova. The female organs are created to produce ova to be fertilized by the spermatozoa. After fertilization, an embryo will form and remain in the uterus and will grow into a fetus, and eventually grow into a baby.

THE MALE REPRODUCTIVE SYSTEM

The Scrotum
It is a pouch consisting of pigmented skin, located below the root of the penis and is joined with the skin of the perineum and groin. The scrotal raphe marked the surface and shows the division of two portion by a midline fibrous septum. Each half of the scrotum contains a testis, an epidermis and the lower end of the spermatic cord.

The Testes
They are small oval shaped glands hanging inside the scrotum. These are the male gonards. They are responsible for the production of spermatozoa and also the secretion of hormones such as the androgens which consists mainly of testosterone, a steroid compound and oestrogen. The testosterone is responsible for the maturing of the male productive organs and the appearance of secondary sexual characteristics such as growth of hair over the chest, abdomen and pubis and the face. It is also responsible for the voice changes of a male from a boy to a man.

The Epididymis and Vas deferens
The epididymis is a tightly coiled tubule surrounded by connective tissue. The epithelial cells of the convoluted tubule secrets hormones, enzymes and nutrients essential in the maturing of spermatozoa. The vas deferens is a thick walled fibro muscular tube about 45 cm long and form an ampulla at its end. Mature spermatozoa are stored in the vas deferens and ampulla.

The Spermatic Cord
The spermatic cords contain the testicular artery, the pampiniform plexus of veins, lymphatic vessels, nerves and the vas deferens.

The Seminal Vesicles
There are two small convoluted pouches located behind the bladder and above the prostrate gland. Each vesicle is about 5 cm long and consists of three layers i) An outer layer of connective tissues containing elastic fibres ii) A middle layer of smooth muscle fibres iii) An inner layer of secretory columnar epithelium. Testosterone will influence the epithelium to secrete a viscid liquid containing fructose and other nutrients, which is stored within the seminal vesicles until the occurrence of ejaculation. Just before ejaculation, the seminal vesicles will empty their contents into the ejaculatory ducts to join the spermatozoa from the vas deferens.

The Ejaculatory Ducts
Each ejaculatory duct is formed by the merger of the vas deferens with the seminal vesicle duct. The length is about 2 cm and enters the prostatic urethra through the prostrate gland.

The Prostate Gland
It is about the size of a chestnut and is located below the bottom of the bladder surrounding the uretha. The false capsule, a sheath of fibro-elastic tissue enclosed it. The true capsule consisting of dense fibrous tissue lies beneath the prostate gland. The prostate secretes a thin, milky, mildly alkaline liquid which contains calcium, acid phosphate and citric acid. In many elderly men, the prostate glands have become enlarged and pressed onto the urethra, causing obstruction on the flow of urine from the bladder thus resulting in the retention of urine. In this case prostatectomy may be performed to remove the prostate surgically.

The Bulbourethral Glands
They are located one on each side, in the connective tissue, behind the membranous urethra just below the prostate gland. Each gland is about the size of a pea and secretes a clear, viscid alkaline fluid.

The Penis
It is made up mainly of three cylindral columns of erectile tissue. The corpora cavernosa penis are the two larger dorsal columns, and the single inferior column is the corpus spongiosum. Numerous trabeculae divide each column of tissue into cavernous spaces (sinuses) and give the entire formation, a spongy look. The penis has a fixed root arising from the perineum and a free shaft. The corpora cavernosa are surrounded by thick fibrous sheaths and the corpus spongiosum is surrounded by a thin fibrous sheath. The end of the corpus spongiosum expanded to form a cap called the glans penis. The three columns of erectile tissues are surrounded by a small quantity of subcutaneous tissue containing numerous smooth muscle fibres and covered by a thin, delicate skin, which forms a double fold over the glans penis called the prepuce (foreskin). The urethra is utilized for urine and semen dispersion. Semen (seminal fluid) is a mucoid, milky white liquid, made up of spermatozoa suspended in the mixed secretions from the vas deferens, seminal vesicles, prostate gland and the bulbourethral glands. The average PH value of semen is about 7.5. The erect penis is basically used for penetration during sexual intercourse (coitus) into the female vagina and the introduction of semen by ejaculation, for the purpose of reproduction of the human species.

THE FEMALE REPRODUCTIVE SYSTEM

The External Organs
The external genitalia of the female gender are collectively called the vulva and are enclosed in an area surrounded in front by the mons veneris and the labia majora on both sides. The mon veneris is a pad of fat located on top of the symphysis pubis. The labia majora are two folds of skin extending backwards from the mons veneris to unite posteriorly in the skin of the perineum. They contain numerous sebaceous and apocrine glands. The labia minora are two gentle folds of skin between the labia majora. They also contain numerous sebaceous glands. The labia minora surrounds a triangular patch called the vestibule within are the openings of the vagina and the urethra. The labia minora unite at the anterior end to surround the clitoris with the prepuce at above and the frenulum below. At the posterior end, the labia minora unite in a snall fold called the fourchette. The clitoris is the most sensitive part of the vulva and is composed of erectile tissue and richly supplied with nerves. The hymen is a thin membranous diaphragm covering the vagina entrance. The greater vestibular gland (Bartholin’s glands) are located one on both side of the vaginal orific. The glands secrete a transparent mucoid fluid for lubricating the vulva especially during sexual excitement. The lesser vestibular glands (skene’s glands) are a group of small mucous glands on the posterior wall of the urethal meatus.

The Perineum
It is the area between the anus and the fourchette. The perineal body lies in the perineum and provides a central attachment for the muscles and fascia of the pelvic floor.

The Internal Organs
The internal organs of the female sex lies internal to those of the external organs and consists of the following structures as below.

The Vagina
It is a fibromuscular canal which runs backwards and upwards from the vulva. The posterior wall of the vagina is about 8 cm in length while the anterior wall is shorter because of the cervix of the uterus. The vault is the upper blind end and is divided into four parts or fornices by the projections of the cervix (the posterior, the anterior and the lateral fornices). The walls of the vagina are composed of three layers as follows :-

1. An inner lining of thick stratified squamous epithelium, with transverse folds or rugae. The epithelium is kept moist by the secretion of the mucous gland present in the cervix.

2. A middle layer of smooth muscle fibres arranged in circular and longitudinal bundles.

3. An outer layer of dense connective tissue.

The Uterus
It is a hollow, pear-shaped organ located in the pelvic cavity. It is a small central cavity, surrounded by thick muscular walls. In an adult female, it is about 7.5 cm long, 5 cm width and 2.5 cm thick. It is made up of the fundus, the body and the cervix. The fundus is the upper part of the uterus located between the uterine tubes. The body or corpus forms the greater part of the uterus. The cervix or neck is the lowest part, part of which protrude into the vault of the vagina like an inverted cone. The walls of the uterus consist of three layers :-

1. The perimetrium, an outer layer of peritoneum which covers the uterus except at the sides.

2. The myometrium which is the thick middle layer of smooth muscle fibres arranged in three coats, an inner coat of circular fibres, middle coat of oblique fibres and an outer coat of longitudinal fibres.

3. The endometrium is a specialized type of mucous membrane which varies in thickness according to the menstrual period. It is covered by a layer of partially ciliated columnar epithelium which contains glands.

During the productive years, the female will have regular menstrual cycles which the body prepares the uterus to receive a fertilized ovum, to retain and to nourish the developing fetus during pregnancy and at the end, contraction of the uterus walls to expel the fetus.

The Uterine Tubes (Fallopian Tubes)
They are about 10 cm in length each and extends from the cornu of the uterus to curve round the ovary. The uterine tube is divided into four sections :-

1. The intersitial section passes obliquely through the uterine wall and has a very narrow lumen.

2. The isthmus is the narrow and straight section extending from the uterus.

3. The ampulla is wide and tortuous.

4. The infundibulum is the expanded funnel shaped section which opens into the peritoneal cavity.

The fimbriae, fringe-like processes surrounds the margin of the infundibulum The fimbria ovarica is one of the longer fimbriae and lies in contact with the ovary. The uterine tube function is to convey the ovum from the ovary to the uterus by peristaltic contractions of the smooth muscles.

The Ovary
The two ovaries, lying one on each side of the uterus are oval in shape and about 3-4 cm long, 2 cm wide and about 1 cm thick. They are attached by the mesovarium, a peritoneum fold to the posterior surface of the broad ligament. Each is hanging from below the cornu of the uterus by an ovarian ligament. The ovary is made up of 2 parts merged together, the first part is the medulla, composed of loose connective tissue containing numerous blood vessels, lymphatics, nerves and contains small groups of hilus cells, and the second part is the cortex consisting of compact connective tissue stroma containing ovarian follicles in all stages of development. Surrounding the cortex is a layer of dense connective tissue called the tunica albuginea. The germinal epithelium covers the outer surface of the ovary. At birth, the ovaries of a human female contain about 2 million primodial follicles. During childhood, many of the follicles die, so by the time puberty arrives, only about 400,000 remain. Only about 500 of the follicles will ever mature and expel their ova into the uterus. The mature ovary has a cycle of activity of about 28 days. Ovulation occurs about 14 days before the next ovarian cycle commences. Normally, only a single ovum is released from the ovaries in each cycle, multiple ovulation may sometimes happen.

The Breasts (Mammary Glands)
They are the accessory glands of the female reproductive system. The breast consists of 15 to 20 lobes separated by fibrous tissue, which also acts as a supporting framework of suspensory ligaments. Each lobe is sectioned into numerous lobules by connective tissue containing fat cells. There are clusters of alveoli, the sensory cells of the gland contained in the lobules. The nipple is made of erectile tissue covered by pigmented epithelium, which when stimulated, contracts, hardens and elevate the nipple. The lactiferous ducts open onto the surface of the nipple. The pigmented area of skin, surrounding the nipple is called the areola and contains a number of specialized sebaceous glands (the glands of Montgomery). When stimulated by pregnancy, the mammary glands secrete milk for a newborn baby. After being conceived, the breasts become larger and the hardening of it. The veins on the surface become dilated and dark brown pigment is deposited in the areola. A few days before delivery of the baby, the breasts will secrete a watery fluid called colostrum. Milk production starts 3-4days after childbirth.

REPRODUCTION OF THE HUMAN SPECIES

This comes about during coitus of the male and female gender, resulting in the introduction of sperm by the male penis into the womb of the female gender. The resultant fertilization of the egg produced by the female with the sperm of the male is the natural process of procreation of life in the human species.

THE IMMUNE SYSTEM

The immune system is similar to the defense system of a country keeping out foreign invaders. Basically in the human species, we have two main types of immunity ie. Innate Immunity and Acquired Immunity.

Innate Immunity
There are a number of ways in innate immunity used by the body to defend itself against foreign invaders. Starting at the basic, the skin in its intact form, especially the outer horny layer is an effective mechanical barrier to the entry of microorganisms into the body. Even the mucous membranes, not having a horny layer, but have mechanical mechanism eg. a high flow rate of secretions as in the urinary and biliary tracts, discourages bacterial proliferation. Chemical factors such as the fatty acids on the surface of the skin have an antiseptic action. Lysozyme, an enzyme secreted by macrophages prevents bacterial conjunctivis in human tears. It disables or destroys many Gram-positive bacteria by chemically attacking their cell walls, break them up by a process called lysis. Damaged cells released basic polypeptides to destroy certain bacteria. Complement is made up of a complex group of proteins, all of large molecular size, form a series of enzymes which help in the first-line host defense against microorganism, destroying them by lyse. When attacked by a virus, many cells produce interferon which interferes with the synthesis of new virus by the cells of the host.

Phagocytes
There are two types of phagocytic cells which have the power of engulfing bacteria and other foreign materials. The first type is called the circulatory polymorphonuclear leukocytes of the blood and the mononuclear phagotic cells known as macrophages. Macrophages are of two types, the first are those which circulate in the blood (monocytes) and those which are fixed in the tissue e.g. histocytes in the connective tissues). These active phagocytic cells are referred to as the mononuclear phagocytic system. The phagocytes either digest material which they devour or store it somewhere else so that it does not irritate the tissue, and quickly and effectively clean out the blood of bacteria and other irritants. The phagocytes have the ability to recognize, bind and ingest microorganisms and other particles.

Acquired Immunity
Humans have recognition mechanisms that enable them to discriminate between their own cells and the cells of other individual. We have protein molecules called antibodies which recognize and bind with one particular type of antigen and is called antibody specificity. These antigens are important in the rejection of tissues and organs transplanted from another individual and are known as histocompatibility antigens or transplantation antigens. The recognition mechanisms are concerned with maintaining the intergrity of the individual. If a substance is recognized by its surface antigens as being foreign, it can be destroyed or inactivated. Lack of immunity or immunological deficiency is a failure of this process, but immune tolerance means the individual’s own cells will not be attacked. Acquired immunity is the second line of defense against microorganisms which have penetrated through the first line of defense ie. the innate immunity. The immune response to an antigen is of two types - humoral and cell mediated.

Humoral Immunity
Antibody (immunoglobulin) is synthesized mainly in the plasma cells and eventually secreted into the blood stream. There are five main types of immunoglobulin (Ig) and can be known by the laboratory testing called immuno-electrophoresis. They are known as Ig G,. Ig M, Ig E, Ig D, and Ig A - of which seventy five percent of the immunoglobulin in serum is Ig G. Ig M is a very efficient agglutinating antibody of bacteria. Ig A specialise with surface protection ie. defence at mucosal surfaces. Ig E are reaginic antibodies and have a strong affinity for tissues to which they attach themselves. Apart from antibodies for the destruction of micro organisms, antibodies are formed which are able to neutralize toxins created by bacteria eg. the exotoxins of diptheria, cholera and tetanus. Macrophages are also important in the battle against diseases and their functions are as follows :-

i) Secret enzymes, complement components and prostaglandins.

ii) Process antigens and present them in a form which either stimulates lymphocytes or induces tolerance.

iii) Later acts as phygocytic cells, swallowing particular antigens and immune complexes.

Cell Mediated Immunity
Contact with an antigen cause the development of a cell-mediated response, which activates lymphocytes besides production of circulating antibody through humoral immunity for the same particular antigen. The cell-mediated immune system is under the control of the thymus and the cells involved are known as thymus-dependent lymphocytes or T-cells. The precursors of T cells mature in the thymus where they are programmed in two ways :-

1. To recognize the “self markers or histocompatibility antigens which they will encounter in the tissues.

2. They have the ability to kill cells which bear foreign (non-self ) antigens - they are cytotoxic T-lymphocytes. They do not attack the body’s own normal cell as they have been programmed to recognize “self”.

The lymphoid immune system responds to a wide spectrum of antigens which are the markers of foreign molecules and perform the following function :-

1. Activates the body’s non-specific defence mechanism of inflammation.

2. Creates a reserve of “memory cells” (T-lymphocytes).

3. Recruit cells wherever they are needed.

The destruction of antigen depends on the immune response which is a highly complicated process involving many cells of different types.

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1.	Epidermis is the outer most layer. It contains pigment cells and specialized cells that manufacture kiratin - a tough substance found also in hair and nails.
2.	Dermis : - This layer contains, blood vessels, nerve endings, hair follicles, sweat glands and sebaceous (oil) glands.
3.	Subcutaneous layer is the lowest layer and it is where the sweat glands originated, and fat is stored. This layer also supports the blood vessels and nerves that supply the outer layers of the skin. The skin acts as a sensory organ because the dermis and the subcutaneous layer are rich with nerve - endings acting as nerve receptors. These nerves transmit all types of perceptions or “feelings” to the brain.

1. The Skull			4. The Hands
i)	Parietal	- on top	i)	Carpal	- wrist bone
ii)	Frontal	- in front	ii)	Metacarpals	- hand bones
iii)	Temporal	- at the side	iii)	Phalanges	- finger bones
iv)	Occipital	- at the back
v)	Maxilla	- upper jaw	5. The Leg
vi)	Mandible	- upper jaw	i)	Femur	- upper bone
vii)	Others	- other head bones	ii)	Patella	- knee cap
			iii)	Tibia	- larger lower bone
2. The Vertebrae			iv)	Fibula	- small lower bone
i)	Cervical	- first 7 units
ii)	Thoraxic	- the following 12 - units	6. The Foot
iii)	Lumbar	- the next 5 units	i)	Tarsus	- ankle bones
iv)	Sacrum	- the next 5 units fused at hips	ii)	Metatarsus	- foot
v)	Coccyx	- the last 4 units fused - tail ones	iii)	Phalanges	- toes

3. The Arms			7. The Chest
i)	Humerus	- upper arm	i)	Clavicle	- collar bone
ii)	Radius	- thumb side lower	ii)	Scapula	- shoulder bone
iii)	Ulna	- finger side lower	iii)	Sternum	- breast bone
			iv)	Ribs	- rib bones in front of chest

1.	The skeletal muscles which are attached to bones and make voluntary movements possible. This type of muscles are striated or striped and consists of layers of tissues divided into bundles of interwoven fibres that run parallel to one another. Skeletal muscles constitute approximately 40 percent of the total body weight.
2.	The smooth, organic muscle is present in several of the internal organs, including the intestines, in the larger blood vessels and the bladder. Smooth muscle contains elongated, spindly cells arranged parallel to one another and are often merged into bundles. The autonomic nervous system controls this type of muscle.
3.	Cardiac muscle is striated and is controlled by the autonomic nervous system. It is only found in the heart. Muscle tissue has the specialized function of contraction (i.e. the ability to shorten and thicken) and thus produce movement of the different parts of the body. It is also elastic and after stretching, it can revert back to its original length.

1.	An end - organ or sensory receptor .ie. the tongue situated in the peripheral at the terminations of the sensory nerves.
2.	The afferent nerve fibres in the peripheral nerve and spinal cord.
3.	The thalamus, which is a cell station relaying sensations to the cerebral cortex.
4.	The sensory reception areas in the brain which are connected with various psychic areas where the impulse is interpreted and may be stored as memory.

1.	The end-organ or receptor ie. the endings of the 1st cranial or olfactory nerve in the mucous membrane of the upper part of the nasal cavity.
2.	The olfactory bulb and tract which convey the impulses to the brain.
3.	The limbic lobe situated in the medial surface of the cerebral hemisphere.

1.	External respiration - takes place in the lungs where oxygen is extracted into the blood and carbon dioxide is released into the air.
2.	Internal respiration - where the oxygen in the blood is exchanged for carbon dioxide in the tissues of the body.

1.	To keep a constant blood supply to the brain and vital centres, all the time. An interruption of blood supply to the brain can cause unconsciousness and if prolonged lack of oxygen, can cause permanent brain damage or even death.
2.	To regulate the blood supply to other organs according to their immediate needs eg. 1) More blood supply to the muscles during increased activities such as running, swimming etc. 2) More blood to the stomach organs when food is being ingested.

1.	Ingestion - the in taking of food through the mouth.
2.	Digestion - starts at the mouth and is primarily done in the stomach and small intestine. Both mechanical and chemical processes of digestion occur at this section.
3.	Absorption - this process occurred when the digested food has been reduced into simple constituents and absorbed through the mucosa of the gastro-intestinal tract into the blood and lymph of the body.
4.	Egestion - takes place when food substances which cannot be digested (have no food value) are excreted (Excretion) as faeces.

1.	the anterior pituitary gland, the adrenal cortex, the thyroid gland, the gonards or sex glands.
2.	the posterior pituitary gland, the pancreas, the adrenal medulla, the parathyroid glands.

1.	The mineralocorticoids - aldosterone and corticosterone, control the body sodium and potassium ion levels and maintain the fluid and electrolyte balance of the body.
2.	The glucocorticoids - cortisol (hydrocortisol), corticosterone and 11 - deoxycortisol controls a lot of functions - among them are - enhancement of water diuresis, immunosuppression, suppression of growth hormone release and activity etc.
3.	Sex hormones - androgens and aestrogens influence sexual development and growth. In females, the suprarenal glands are the principal source of androgens, which are required by both sexes for normal puberty and skeletal development.

1.	Tyroid - stimulating hormone (TSH) which stimultaes the growth and activity of the thyroid gland.
2.	Corticotrophin or adrenocorticotrophic hormone (ACTH) which promotes the production of steroid hormones, especially cortisol, in the suprarenal cortex.
3.	Growth hormone (GH) (Somatotrophin) influences the synthesis, of a group of proteins called somatomedins, by the liver - affects the growth of the body.
4.	Gonadotrophins (FSH and LH) - FSH induce the maturing of ovarian follicles and oestrogen production in the female and activates spermatogenesis in the male. LH induces ovulation and formation of the corpus luteum, which secretes progesterone, in women, and stimulates the testis to produce testerone in men.
5.	Prolactin promotes lactation in female especially during lactation.
6.	The posterior pituitary (neurohypophysis) hormones are of two types and are synthesized in the hypothalamus and reached the posterior pituitary where they are stored, prior to usage as follows :- i) Vasopressin (antidiuretic hormone ADH) controls the re-absorption of water into the blood from the collecting ducts of the kidneys. The function of the vasopressin is to maintain a normal plasma osmolality (270-290 m OSM / kg) and plasma volume. ii) Oxytocin causes contraction of the smooth muscles of the uterus and breast (induces ejection of milk from lactating breasts).

i)	Spermatozoa - for fertilizing an ovum of the females sex.
ii)	Androgens hormones - which consist mainly of testosterone - a steroid compound, dehydroepiandrosterone and androstenedione in lesser amount. Testosterone promotes maturing of the male reproductive organs and induces the appearance of secondary sexual characteristics such as growth of hair over the chest, abdomen and pubis and also on the face. It is also responsible for the enlargement of the larynx which caused the deepening of the voice of an adult male. Testosterone also plays a part in the maturing of the spermatozoa. It also has a powerful anabolic role in stimulating protein synthesis and growth of bones.
iii)	Oestrogen - only a small amount is secreted but its function in the male is unknown.

i)	Ovum or the egg produced, are meant for fertilization by spermatozoa to create new life.
ii)	Oestrogen is a group of steroid compounds - oestradiol, oestriol and oestrone. Oestrogen is responsible for the commencement of secondary sexual characteristics of the female sex at puberty and for the growth and development of the female reproductive tract and mammary glands.
iii)	Progesterone is a steroid compound whose main function is to initiate secretory changes in the endometrium in preparation for pregnancy. It acts together with oestrogen to promote the proliferation and enlargement of the alveolar cells of the female breast.
iv)	Androgens are also secreted but in smaller amounts in a normal female.

i)	Insulin is vital in the metabolism of carbohydrates, fats and proteins.
ii)	Glucagon is associated with the breakdown of liver glycogen (glycogenolysis) and with increased gluconeogenesis. It also lipolytic (breaks down fats) and has other numerous actions.
iii)	Somatostatin inhibit the secretion of many hormones and other substances and is one of the brain-gut peptides which acts as neurotransmitters.

1.	An inner lining of thick stratified squamous epithelium, with transverse folds or rugae. The epithelium is kept moist by the secretion of the mucous gland present in the cervix.
2.	A middle layer of smooth muscle fibres arranged in circular and longitudinal bundles.
3.	An outer layer of dense connective tissue.

1.	The perimetrium, an outer layer of peritoneum which covers the uterus except at the sides.
2.	The myometrium which is the thick middle layer of smooth muscle fibres arranged in three coats, an inner coat of circular fibres, middle coat of oblique fibres and an outer coat of longitudinal fibres.
3.	The endometrium is a specialized type of mucous membrane which varies in thickness according to the menstrual period. It is covered by a layer of partially ciliated columnar epithelium which contains glands.

1.	The intersitial section passes obliquely through the uterine wall and has a very narrow lumen.
2.	The isthmus is the narrow and straight section extending from the uterus.
3.	The ampulla is wide and tortuous.
4.	The infundibulum is the expanded funnel shaped section which opens into the peritoneal cavity.

i)	Secret enzymes, complement components and prostaglandins.
ii)	Process antigens and present them in a form which either stimulates lymphocytes or induces tolerance.
iii)	Later acts as phygocytic cells, swallowing particular antigens and immune complexes.

1.	To recognize the “self markers or histocompatibility antigens which they will encounter in the tissues.
2.	They have the ability to kill cells which bear foreign (non-self ) antigens - they are cytotoxic T-lymphocytes. They do not attack the body’s own normal cell as they have been programmed to recognize “self”.

1.	Activates the body’s non-specific defence mechanism of inflammation.
2.	Creates a reserve of “memory cells” (T-lymphocytes).
3.	Recruit cells wherever they are needed.