HUMAN ORGAN SYSTEMS
• The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages (including hair, scales, feathers, and nails).
• Functions: Serve to waterproof, cushion, and protect the deeper tissues; Excrete wastes, and regulate temperature; is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature; Vitamin D synthesis.
• The human skin is composed of a minimum of 3 major layers of tissue:
Epidermis: Thin, tough, outer layer made up of epithelial cells & it does not contain blood vessels.
• Stratum corneum is the outermost portion of the epidermis, prevents most bacteria, viruses, and other foreign substances from entering the body
• Melanocytes produce the pigment melanin, function is to filter out ultraviolet radiation from sunlight
• Langerhans cells are part of the skin’s immune system which helps detect foreign substances and defend the body against infection.
• Dermis: Thick layer of fibrous and elastic that gives the skin its flexibility and strength. Contains nerve endings, sweat glands and oil (sebaceous) glands, hair follicles, and blood vessels
• Sweat glands produce sweat in response to heat and stress.
• The sebaceous glands secrete sebum into hair follicles. Sebum is oil that keeps the skin moist and soft and acts as a barrier against foreign substances.
• The blood vessels of the dermis provide nutrients to the skin and help regulate body temperature.
• Hypodermis: Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves.
• Fat Layer helps insulate the body from heat and cold, provides protective padding, and serves as an energy storage area.
• Botox treatment: It targets Epidermis layer of skin. Botox is a toxin produced by the bacterium Clostridium Botulinum.
• Small, diluted amounts can be directly injected into specific muscles causing controlled weakening of the muscles. Botox blocks signals from the nerves to the muscles. The injected muscles can no longer contract, which causes the wrinkles to relax and soften.
THE DIGESTIVE SYSTEM
• Steps in Digestion: Ingestion, Digestion (Mechanical and Chemical), Absorption, Elimination.
• Parts of Digestive system: The digestive system consists of the alimentary canal (Salivary glands, Pharynx, Esophagus, stomach, small intestine, large intestine ending in the rectum and anus) and accessory digestive organs (liver, gallbladder, and pancreas).
• Food moves from one organ to the next through muscle action called peristalsis
• The Salivary glands in the mouth produces Saliva which contains an enzyme amylase that digest the starch from food into smaller molecules
• The Stomach has three mechanical tasks. To store the swallowed food, to mix up the food, liquid, and digestive juice produced by the stomach and to empty its contents slowly into the small intestine.
• The liver is the largest gland of the body. It secretes bile which helps the body absorb fat.
• The pancreas produces enzymes that help digest proteins, fats, and carbohydrates. It also makes a substance that neutralizes stomach acid.
• Small intestine has 3 divisions such as duodenum, jejunum and ileum. The inner wall of the small intestine is covered with millions of microscopic, finger-like projections called villi. The villi are the vehicles through which nutrients can be absorbed into the body.
• The large intestine secretes no enzyme and plays only a minor role in the absorption of nutrients. The three divisions of large intestine are Caecum, Colon and Rectum. The rectum is where feces are stored until they leave the digestive system through the anus as a bowel movement.
• Disorders and Diseases of Digestive System: Gastrointestinal infections can be caused by viruses, by bacteria such as Salmonella, Shigella, Campylobacter, or E. coli, Hepatitis, a condition with many different causes, is when the liver becomes inflamed and may lose its ability to function.
THE RESPIRATORY SYSTEM
• The Respiratory system is the anatomical system of an organism used for respiration.
• Parts of the Upper Respiratory Tract: Mouth, nose & nasal cavity: The nostrils (also called nares) act as the air intake; called cilia protect the nasal passageways and other parts of the respiratory tract.
• Pharynx: Pharynx is part of the digestive system as well as the respiratory system because it carries both food and air. Larynx: This is also known as the voice box as it is where sound is generated. It also helps protect the trachea by producing a strong cough reflex if any solid objects pass the epiglottis
• Trachea (Wind Pipe): It carries air from the throat into the lungs. The inner membrane of the trachea is covered with cilia
• Bronchi: The trachea divides into two tubes called bronchi, one entering the left and one entering the right lung.
• Bronchioles: Tertiary bronchi continue to divide and become bronchioles, very narrow tubes, less than 1 millimeter in diameter.
• Alveoli: Individual hollow cavities contained within alveolar sacs. Alveoli have very thin walls which permit the exchange of gases Oxygen and Carbon Dioxide. Thorax or the chest cavity is the airtight box that houses the bronchial tree, lungs, heart, and other structures.
• Diaphragm: located below the lungs. It is a large, dome-shaped muscle that contracts rhythmically and continually, and most of the time, involuntarily. The tidal volume is the volume of air that is inhaled or exhaled in a single such breath.
• Breathing is a constant process where you breathe in and out constantly throughout the day. Respiration is a process where the body breaks down the oxygen, so that the cells in the body can use it.
• The process of Respiration: In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels) lining the alveolar walls. Blood contains Haemoglobin – a specialized protein that binds to oxygen in the lungs so that the oxygen can be transported to the rest of the body.
• Carbon dioxide, which is produced during the process of diffusion, moves out of these cells into the capillaries, where most of it is dissolved in the plasma of the blood.
• Asthma: Asthma is a chronic inflammatory lung disease that causes airways to contract, tighten and narrow. Often triggered by irritants in the air such as cigarette smoke, asthma flares.
• Smoking has two fold effects on respiration; it may irritate the cells lining the respiratory tract. Long term effects include diseases like emphysema [over inflation of air sacs/alveoli] or fibrosis [excess of fibrous connective tissue] of which the earlier is much common.
THE CIRCULATORY SYSTEM
• The circulatory system is responsible for the transport of water and dissolved materials throughout the body, including oxygen, carbon dioxide, nutrients, and waste.
• The structure of Circulatory System, The heart has four chambers: Right Atrium, Left Atrium, Right Ventricle, and Left Ventricle.
• The bottom part of the heart is divided into two chambers called the right and left ventricles, which pump blood out of the heart.
• The upper part of the heart is made up of the other two chambers of the heart, the right and left atria.
• Arteries carry blood away from the heart. They are the thickest blood vessels, with muscular walls that contract to keep the blood moving away from the heart and through the body.
• Two coronary arteries provide oxygen and nourishment to the muscles of the heart.
• Veins carry blood back to the heart; waste products such as carbon dioxide are also removed by the capillaries.
• The working of Circulatory system: One complete heartbeat makes up a cardiac cycle, which consists of two phases: In the first phase, the ventricles contract sending blood into the pulmonary and systemic circulation then the ventricles relax and fill with blood from the atria, which makes up the second phase of the cardiac cycle.
• The normal heart beat is 70-72 per minute in males and 78-82 per minute in females. The heartbeat of a child is more than that of an adult. i.e. 140/min.
• The sinoatrial or SA node, a small area of tissue in the wall of the right atrium, sends out an electrical signal to start the contracting of the heart muscle.
• These electrical impulses cause the atria to contract first, and then travel down to the atrioventricular or AV node. In the systemic circulation, blood travels out of the left ventricle, to the aorta, to every organ and tissue in the body, and then back to the right atrium.
• In the pulmonary circulation, blood low in oxygen but high in carbon dioxide is pumped out the right ventricle into the pulmonary artery, which branches off in two directions.
• Coronary Circulation: The coronary arteries supply blood to the heart muscle.
• Blood: The blood transports life-supporting food and oxygen to every cell of the body and removes their waste products
• Blood has two main constituents. The cells, or corpuscles, comprise about 45 percent, and the liquid portion, or plasma, in which the cells are suspended, comprises 55 percent
• The blood cells comprise three main types: Red blood cells, or Erythrocytes, White blood cells, or leukocytes, Platelets, or thrombocytes
Diseases of the Blood
• Anaemia: Anaemia is a deficiency of haemoglobin in the blood. It can be caused by blood loss, abnormal destruction of the red cells, and inadequate red cell formation by the bone marrow.
• Leukaemia: A great increase in abnormal leukocytes may occur for unknown reasons, resulting in the diseases known as the leukaemia’s
• Atherosclerosis is a disorder of large and medium-sized arteries, such as the large coronary arteries that supply the heart muscle with oxygen. The disorder is characterized by a buildup of fatty deposits, called plaques, on the inner walls of arteries.
• Vein Diseases: The most important peripheral vascular disease of the veins is thrombophlebitis or phlebitis. This disorder involves the formation of a blood clot (or clots) in large veins, usually in the leg or pelvis.
• Hypertension: High blood pressure is often secondary to hardening of the arteries. As the arteries lose their elasticity, the heart has to beat harder to force the blood through. The result is high blood pressure.
THE NERVOUS SYSTEM
• The nervous system is a network of specialized cells called neurons that coordinate the actions and transmit signals between different parts of its body.
• The central nervous system of vertebrates contains the brain, spinal cord, and retina.
• The peripheral nervous system consists of sensory neurons, clusters of neurons called ganglia, and nerves connecting them to each other and to the central nervous system.
• Neuron: The neuron is the functional unit of the nervous system.
• All neurons have three parts: Dendrites receive information from another cell and transmit the message to the cell body. The axon conducts messages away from the cell body.
• Three types of neurons occur: Sensory neurons carry messages from sensory receptors to the central nervous system. Motor neurons transmit messages from the central nervous system to the muscles (or to glands). Inter neurons are found only in the central nervous system where they connect neuron to neuron. Schwann cells serve as supportive, nutritive, and service facilities for neurons
• Node of Ranvier: serves as points along the neuron for generating a signal.
• The junction between a nerve cell and another cell is called a synapse.
• Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse
• The Forebrain: The forebrain is the largest and most complex part of the brain. It consists of the cerebrum. The cerebrum contains the information that essentially makes us who we are: our intelligence, memory, speech, ability to feel etc.
• The outer layer of the cerebrum is called the cortex in the inner part of the forebrain sits the thalamus, hypothalamus, and pituitary gland.
• The thalamus carries messages from the sensory organs like the eyes, ears, nose, and fingers to the cortex. The hypothalamus controls the pulse, thirst, appetite, sleep patterns, and other processes in our bodies that happen automatically.
• The Midbrain: The midbrain, located underneath the middle of the forebrain, acts as a master coordinator for all the messages going in and out of the brain to the spinal cord.
• The Hindbrain: The hindbrain sits underneath the back end of the cerebrum, and it consists of the cerebellum, Pons, and medulla.
• The brainstem takes in, sends out, and coordinates all of the brain’s messages. It also controls many of the body’s automatic functions, like breathing, heart rate, blood pressure, swallowing, digestion, and blinking. The sympathetic nervous system prepares the body for sudden stress.
• The parasympathetic nervous system helps the digestive tract move along so our bodies can efficiently take in nutrients from the food we eat.
• Huntington’s disease is due to imbalances of neurotransmitters.
• Parkinson’s disease is due to a dopamine deficiency.
• Alzheimer’s disease is associated with protein plaques in the brain.
Problems of Nervous System:
• Brain tumours: Benign tumours usually grow in one place and may be curable through surgery.
• A malignant tumour is cancerous and more likely to grow rapidly and spread.
• Meningitis and encephalitis: These are infections of the brain and spinal cord that are usually caused by bacteria or viruses. Meningitis is an inflammation of the coverings of the brain and spinal cord, and encephalitis is an inflammation of the brain tissue.
THE MUSCULAR SYSTEM
Based on their location, three types of muscles are identified:
(i) Skeletal (ii) Visceral (iii) Cardiac
• Muscle is a specialized tissue of mesodermal origin. About 40-50 per cent of the body weight of a human adult is contributed by muscles.
• Each myofibril has alternate dark and light bands on it. A detailed study of the myofibril has established that the striated appearance is due to the distribution pattern of two important proteins – Actin and Myosin.
• Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.
• The myosin, releasing the ADP and Pi goes back to its relaxed state. A new ATP binds and the cross-bridge is broken. The ATP is again hydrolyzed by the myosin head and the cycle of cross bridge formation and breakage is repeated causing further sliding.
Disorders of muscular system:
• It is an auto-immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.
SKELETAL SYSTEM AND ITS FUNCTIONS, JOINTS
• Skeletal system consists of a framework of bones and a few cartilages. This system has a significant role in movement shown by the body. Bone and cartilage are specialized connective tissues.
• Axial skeleton comprises 80 bones distributed along the main axis of the body. The skull, vertebral column, sternum and ribs constitute axial skeleton.
• Skull: The skull is composed of two sets of bones – cranial and facial, that totals to 22 bones. Cranial bones are 8 in number.
• Vertebral Column: Our vertebral column is formed by 26 serially arranged units called vertebrae and is dorsally placed. It extends from the base of the skull and constitutes the main framework of the trunk.
• Rib Cage: There are 12 pairs of ribs. Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end and is hence called bicephalic.
• Appendicular Skeleton: The bones of the limbs along with their girdles constitute the appendicular skeleton. Each limb is made of 30 bones. The bones of the hand (fore limb) are humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number).
• Joints: Joints are essential for all types of movements involving the bony parts of the body. Locomotory movements are no exception to this. Joints are points of contact between bones, or between bones and cartilages.
• Fibrous Joints: Fibrous joints do not allow any movement.
• This type of joint is shown by the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures, to form the cranium.
• Synovial Joints: Synovial joints are characterized by the presence of a fluid filled synovial cavity between the articulating surfaces of the two bones. Such an arrangement allows considerable movement.
• Cartilaginous Joints: In cartilaginous joints, the bones involved are joined together with the help of cartilages.
• Arthritis: Inflammation of joints.
• Osteoporosis: Age-related disorder characterized by decreased bone mass and increased chances of fractures. Decreased level of estrogen is a common cause.
• Gout: Inflammation of joints due to accumulation of uric acid crystals.
THE ENDOCRINE SYSTEM
• Glands & Hormones: Our body produces its own chemicals and uses them to control certain functions, and the main system that coordinates these chemicals is called the endocrine system
• A gland is a group of cells that produces and secretes, or gives off, chemicals. A gland selects and removes materials from the blood, processes them, and secretes the finished chemical product for use somewhere in the body
• Exocrine glands, such as the sweat and salivary glands, release secretions in the skin or inside of the mouth. Endocrine glands, on the other hand, release more than 20 major hormones directly into the bloodstream where they can be transported to cells in other parts of the body
• Diabetes: Diabetes mellitus is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced.
- Type 1 diabetes: results from the body’s failure to produce insulin, and requires the person to inject insulin.
- Type 2 diabetes: results from insulin resistance, a condition in which cells fail to use insulin properly, sometimes combined with an absolute insulin deficiency.
• Growth Disorders: If the body produces too much growth hormone (GH), gigantism or acromegaly (gigantism in adults) can occur; too little growth hormone results a condition called growth hormone deficiency,
• Osteoporosis: is a condition in which bones become fragile and more likely to break.
Polycystic Ovary Syndrome (PCOS): PCOS is a condition associated with symptoms of infrequent or irregular menstruation
• Thyroid Disorders: Thyroid hormones, hormones produced by the thyroid gland, influence nearly all of the body’s symptoms. Thyroid problems include hyperthyroidism (too much thyroid hormone), hypothyroidism
• Cushing’s syndrome: Cortisol is a hormone that helps the body perform a number of important functions including converting fat into energy, maintaining immune system function, and responding to stress
• Addison’s disease: Addison’s disease occurs when the adrenal glands, which are located at the top of each kidney, produce an insufficient amount of steroid hormones despite the presence of an adequate amount of ACTH, the hormone that triggers the adrenal glands to release steroids.
THE REPRODUCTIVE SYSTEM
• Animals’ reproductive systems can be divided into the internal reproductive organs and the external genitalia
• Gametes are reproductive cells that unite during sexual reproduction to form a new cell called a zygote. When the haploid male and female gametes unite in a process called fertilization, they form what is called a zygote
• In the male, testes produce sperm, and in the female, ovaries make eggs.
• Hermaphroditism is when one organism has both sexes. Earthworms and garden snails always have both male and female organs
• Parthenogenesis is the ability of an unfertilized egg to develop and hatch.
• There are two major mechanisms of fertilization. In external fertilization, used by many aquatic invertebrates, eggs and sperm are simultaneously shed into the water, and the sperm swim through the water to fertilize the egg.
• In internal fertilization, the eggs are fertilized within the reproductive tract of the female, and then are covered with eggshells and/or remain within the body of the female during their development.
• Oviparous organisms: like chickens and turtles, lay eggs that continue to develop after being laid, and hatch later.
• Viviparous organisms like humans and kangaroos, are live-bearing. The developing young spend proportionately more time within the female’s reproductive tract,
• Ovoviviparous organisms like guppies, garter snakes, and Madagascar hissing roaches, have eggs (with shells) that hatch as they are laid, making it look like live birth.
• Male Reproductive System: Sperm are produced in the testes located in the scrotum. From there, sperm are transferred to the epididymis, coiled tubules also found within the scrotum that store sperm and are the site of their final maturation.
• The ends of the vasa deferentia, behind and slightly under the bladder, are called the ejaculatory ducts. The seminal vesicles are also located behind the bladder.
• Their secretions are about 60% of the total volume of the semen and contain mucus, amino acids, fructose as the main energy source for the sperm, and prostaglandins to stimulate female uterine contractions to move the semen up into the uterus
• The prostate is the largest of the accessory glands and puts its secretions directly into the urethra secretions are alkaline to buffer any residual urine, which tends to be acidic, and the acidity of the woman’s vagina.
• The bulbourethral glands or Cowper’s glands: this fluid may serve as a lubricant for inserting the penis into the vagina.
• Female Reproductive System: Eggs are produced in the ovaries. Within the ovary, a follicle consists of one precursor egg cell surrounded by special cells to nourish and protect it. Due to the stimulation of follicle- stimulating hormone (FSH) one egg per cycle matures and is released from its ovary.
Ovulation is the release of a mature egg due to the stimulation of Luteinizing Hormone (LH), • which then stimulates the remaining follicle cells to turn into a corpus luteum which then secretes progesterone to prepare the uterus for possible implantation
• Each egg is released into the abdominal cavity near the opening of one of the oviducts or Fallopian tubes.
• The vagina is a relatively-thin-walled chamber. It serves as a repository for sperm (it is where the penis is inserted), and also serves as the birth canal.
• The cervix secretes mucus, the consistency of which varies with the stages in her menstrual cycle.
• Cervical cancer: It is one of the most common cancers in women is caused due to Human Pappiloma Virus (HPV). Pap smear test is a common and quick method to check cervical cancer.
Problems with Reproduction System:
• Testicular cancer: It occurs when cells in the testicle divide abnormally and form a tumor.
• Inguinal hernia: When a portion of the intestines pushes through an abnormal opening or weakening of the abdominal wall and into the groin or scrotum, it is known as an inguinal hernia.
• Syphilis is a sexually transmitted disease caused by the bacteria Treponema pallidum. Antibiotics, usually penicillin, are used to treat Syphilis.
FOOD AND NUTRITION
• Carbohydrates: Carbohydrates are the organic compounds containing carbon, hydrogen and oxygen which constitute sugars (Starch, cellulose, glucose etc).
• Simple Carbohydrates are made up of a single basic sugar & provide the sweet taste in our food
• Complex carbohydrates are a combination of different types of sugars. Based on the number of sugars they are classified as disaccharide, Oligosaccharides, Polysaccharides.
• Proteins: Proteins are polymer chains made of amino acids linked together by peptide bonds
• Protein is found in all cells of the body and is the major structural component of all cells in the body.
• Hormones and enzymes are also formed from amino acids
• Protein deficiency causes Kwashiorkor – a severe under-nourishment condition.
• Fats: Fat molecules are a rich source of energy for the body. Proteins and carbohydrates contain 4 kCal per gram as opposed to fats which contain 9 kcal per gram.
- Saturated fats: Solid at room temperature. Saturated fats directly raise total and LDL (bad) cholesterol levels hence are advised to avoid
- Unsaturated fat: Liquid at room temperature.
• They are of 2 types – Monounsaturated fats which are found in olives, olive oil, nuts, peanut oil, canola oil and avocados.
• Trans Fats or Hydrogenated Fats: actually unsaturated fats, but they can raise total and LDL (bad) cholesterol levels while also lowering HDL (good) cholesterol levels
• Low-density lipoprotein (LDL) is one of the five major groups of lipoproteins, which enable transport of cholesterol within the water- based bloodstream.
• Vitamins: A vitamin is an organic compound required as a nutrient in tiny amounts by an organism.
• The two types of vitamins are: water-soluble vitamins (all the B vitamins and vitamin C) and fat- soluble vitamins (vitamins A, D, E, and K). Fat- soluble vitamins are stored in the liver and fatty tissue of the body, whereas water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine.
• Essential Minerals: Calcium: Healthy bones and teeth, muscle contraction, assists in blood clotting, oxygen transport, cellular secretion of fluids and enzyme activity.
• Copper: Acts as a catalyst to store and release iron to help form hemoglobin.
• Iodine: Needed by the thyroid hormone and influences nutrient metabolism, nerve and muscle function, nail, hair, skin and tooth condition, and physical and mental development
• Iron: Necessary for red blood cell formation and required for transport of oxygen throughout the body
• Phosphorous: Works with calcium to develop and maintain strong bones and teeth.
• Balanced Diet: Food is anything solid or liquid that has a chemical composition which enables it, when swallowed to do one or more of the following:
• Provide the body with the material from which it can produce heat, or any form of energy.
• Provide material to allow growth, maintenance, repair or reproduction to proceed.
• Supply substances, which normally regulate the production of energy or the process of growth, repair or reproduction.
• The body mass index (BMI), or Quetelet index, is a tool that helps one to measure the amount of body fat one has based on height and weight. BMI does not actually measure the percentage of body fat.
• Malnutrition: Malnutrition essentially means “bad nourishment”. Malnutrition is characterized by inadequate or excess intake of protein, energy, and micronutrients such as vitamins, and the frequent infections and disorders that result.
• Severe forms of malnutrition include marasmus, cretinism and irreversible brain damage due to iodine deficiency; and blindness and increased risk of infection and death from vitamin A deficiency.
BLOOD GROUPS AND TRANSFUSION
- It transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.
- Blood is a liquid, which has cells of various kinds suspended in it. The fluid part of the blood is called plasma.
- One type of cells are the red blood cells (RBC) which contain a red pigment called haemoglobin.
- Haemoglobin bind with oxygen and transports it to all the parts of the body and ultimately to all the cells. The presence of haemoglobin makes blood appear red.
- The blood also has white blood cells (WBC) which fight against germs that may enter our body.
- The clot is formed because of the presence of another type of cells in the blood, called platelets.
- They are two types of blood vessels namely arteries and veins.
- Veins are the blood vessels that carry carbon dioxide-rich blood [impure blood] from all parts of the body back to the heart. Pulmonary vein is an exception as it carries oxygen-rich blood [pure blood] from lungs to heart. The veins have thin walls.
- Arteries are the blood vessels that carry oxygen-rich blood from heart to all parts of the body. Pulmonary artery is an exception as it carries carbon dioxide-rich blood from heart to lungs. The arteries have thick walls as the pressure acting on then is high.
- Blood From Heart → Artery
- Blood To Heart → Vein
- Arteries divide into smaller vessels. On reaching the tissues, they divide further into extremely thin tubes called capillaries. The capillaries join up to form veins which empty into the heart.
Body Fluids and Circulation
- Blood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.
- Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood.
- 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it.
- Fibrinogen, globulins and albumins are the major proteins.
- Fibrinogens are needed for clotting or coagulation of blood.
- Globulins primarily are involved in defense mechanisms of the body
- Albumins help in osmotic balance.
- Plasma also contains small amounts of minerals like Na+, Ca++, Mg++, HCO3-, Cl-, etc. Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body.
- Factors for coagulation or clotting of blood are also present in the plasma in an inactive form. Plasma without the clotting factors is called serum.
Red Blood Cells (RBC)
- Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in blood.
- A healthy adult man has, on an average, 5 million to 5.5 million of RBCs mm-3 of blood.
- RBCs are formed in the red bone marrow in the adults. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
- They have a red coloured, iron containing complex protein called haemoglobin, hence the colour and name of these cells.
- RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs).
White Blood Cells (WBC)
- Leucocytes are also known as white blood cells (WBC) as they are colorless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm-3 of blood. Leucocytes are generally short lived. We have two main categories of WBCs – granulocytes and agranulocytes.
- Neutrophils, eosinophils and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes.
- Neutrophils are the most abundant cells (60-65 per cent) of the total WBCs and basophils are the least (0.5-1 per cent) among them.
- Neutrophils and monocytes (6-8 per cent) are phagocytic cells which destroy foreign organisms entering the body.
- Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.
- Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions.
- Lymphocytes (20-25 per cent) are of two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are responsible for immune responses of the body.
- Platelets also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the bone marrow).
- Blood normally contains 1,500,00-3,500,00 platelets mm-3.
- Platelets can release a variety of substances most of which are involved in the coagulation or clotting of blood.
BLOOD GROUPS & BLOOD TRANSFUSION
1. ABO blood Group system
The A, B, and O blood groups were first identified by Austrian immunologist Karl Landsteiner in 1901.
The basis of ABO grouping is of two antigens- Antigen A and Antigen B. The ABO grouping system is classified into four types based on the presence or absence of antigens on the red blood cells surface and plasma antibodies.
- Group A – contains antigen A and antibody B.
- Group B – contains antigen B and antibody A.
- Group AB – contains both A and B antigen and no antibodies (neither A nor B).
- Group O – contains neither A nor B antigen and both antibodies A and B.
The ABO group system is important during blood donation or blood transfusion as mismatching of blood group can lead to clumping of red blood cells with various disorders. It is important for the blood cells to match while transfusing i.e. donor-recipient compatibility is necessary. For example, a person of blood group A can receive blood either from group A or O as there are no antibodies for A and O in blood group A.
- Individuals of blood group O are called as universal donors, whereas individuals of blood group AB are universal recipients.
2. Rh Blood Group System
• In addition to the ABO blood grouping system, the other prominent one is the Rh blood group system.
• About two-thirds of the population contains the third antigen on the surface of their red blood cells known as Rh factor or Rh antigen; this decides whether the blood group is positive or negative.
• If the Rh factor is present, an individual is rhesus positive (Rh+ve); if an Rh factor is absent individual is rhesus negative (Rh-ve) as they produce Rh antibodies.
• Therefore, compatibility between donor and individual is crucial in this case as well.
- A special case of Rh incompatibility (mismatching) has been observed between the Rh-ve blood of a pregnant mother with Rh+ve blood of the foetus.
- Rh antigens of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta.
- However, during the delivery of the first child, there is a possibility of exposure of the maternal blood to small amounts of the Rh+ve blood from the foetus.
- In such cases, the mother starts preparing antibodies against Rh antigen in her blood.
- In case of her subsequent pregnancies, the Rh antibodies from the mother (Rh-ve) can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs.
- This could be fatal to the foetus or could cause severe anaemia and jaundice to the baby. This condition is called erythroblastosis foetalis.
- This can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.
3. Bombay Blood Group
Recently there has been a spike in demand for a rare blood type called Bombay blood group.
- Under the ABO blood group system, blood groups are classified into four common blood groups i.e. A, B, AB and O.
- Each red blood cell has antigen over its surface, which helps determine which group it belongs to.
- For instance, in the AB blood group, both antigens A and B are found. A will have A antigens; B will have B antigens. In O, there are no A or B antigens.
The Bombay blood group (also called hh), is deficient in expressing antigen H.
- It means the RBC of hh blood group has no antigen H.
- Often the hh blood group is confused with the O group. The difference is that the O group has Antigen H, while the hh group does not.
- The rare Bombay blood group was first discovered in Mumbai (then Bombay) in 1952 by Dr Y M Bhende.
- Globally, the hh blood type has an incidence of one in four million. However, this blood type is more common in South Asia than anywhere else because of inbreeding and close community marriages.
- In India, one person in 7,600 to 10,000 is born with this type.
- Due to the rarity of hh blood type, patients face problems during a blood transfusion, often leading to death due to non-availability of hh blood.
- The individuals with Bombay blood group can only be transfused blood from individuals of Bombay hh phenotype only which is very rare.
- Rejection may occur if they receive blood from A, B, AB or O blood group.
- In contrast, hh blood group can donate their blood to ABO blood types.
- This group is generally not stored in blood banks, mainly because it is rare and the shelf life of blood is 35-42 days.
Acute and Chronic Diseases
- Some diseases last for only very short periods of time, and these are called acute diseases. We all know from experience that the common cold lasts only a few days.
- Other ailments can last for a long time, even as much as a lifetime, and are called chronic diseases. An example is the infection causing elephantiasis, which is very common in some parts of India.
- Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases.
- Examples of such diseases include cholera, common cold, chicken pox and tuberculosis.
- Example of a carrier is the female Anopheles mosquito, which carries the parasite of malaria. Female Aedes mosquito acts as carrier of dengue virus.
- Robert Köch (1876) discovered the bacterium (Bacillus anthracis) which causes anthrax.
- How do infectious diseases spread? Many microbial agents can commonly move from an affected person to someone else in a variety of ways. In other words, they can be ‘communicated’, and so are also called communicable diseases.
- Such disease-causing microbes can spread through the air. Examples of such diseases spread through the air are the common cold, pneumonia and tuberculosis.
- Diseases can also be spread through water. This occurs if the excreta from someone suffering from an infectious gut disease, such as cholera, get mixed with the drinking water used by people living nearby.
- The sexual act is one of the closest physical contact two people can have with each other. Not surprisingly, there are microbial diseases such as Syphilis or AIDS that are transmitted by sexual contact from one partner to the other.
- Other than the sexual contact, the aids virus can also spread through blood-to-blood contact with infected people or from an infected mother to her baby during pregnancy or through breast feeding.
- We live in an environment that is full of many other creatures apart from us. It is inevitable that many diseases will be transmitted by other animals. These animals carry the infecting agents from a sick person to another potential host. These animals are thus the intermediaries and are called vectors. The commonest vectors we all know are mosquitoes.
- In many species of mosquitoes, the females need highly nutritious food in the form of blood in order to be able to lay mature eggs. Mosquitoes feed on many warm-blooded animals, including us. In this way, they can transfer diseases from person to person.
Organ-Specific and Tissue Specific Diseases
- Different species of microbes seem to have evolved to home in on different parts of the body. In part, this selection is connected to their point of entry.
- If they enter from the air via the nose, they are likely to go to the lungs. This is seen in the bacteria causing tuberculosis.
- If they enter through the mouth, they can stay in the gut lining like typhoid causing bacteria. Or they can go to the liver, like the viruses that cause jaundice.
- An infection like HIV, that comes into the body via the sexual organs, will spread to lymph nodes all over the body.
- Malaria-causing microbes, entering through a mosquito bite, will go to the liver, and then to the red blood cells.
- The virus causing Japanese Encephalitis, or brain fever, will similarly enter through a mosquito bite. But it goes on to infect the brain.
- The signs and symptoms of a disease will thus depend on the tissue or organ which the microbe targets. If the lungs are the targets, then symptoms will be cough and breathlessness. If the liver is targeted, there will be jaundice. If the brain is the target, we will observe headaches, vomiting, fits or unconsciousness.
- In addition to these tissue-specific effects of infectious disease, there will be other common effects too.
- Most of these common effects depend on the fact that the body’s immune system is activated in response to infection.
- An active immune system recruits many cells to the affected tissue to kill off the disease-causing microbes. This recruitment process is called inflammation. As a part of this process, there are local effects such as swelling and pain, and general effects such as fever.
- In some cases, the tissue-specificity of the infection leads to very general-seeming effects. For example, in HIV infection, the virus goes to the immune system and damages its function. Thus, many of the effects of HIV-aids are because the body can no longer fight off the many minor infections that we face every day. Instead, every small cold can become pneumonia. Similarly, a minor gut infection can produce major diarrhoea with blood loss. Ultimately, it is these other infections that kill people suffering from HIV-aids.
Diseases in Indian Children
- Gastroentitis is an infection in the digestive system and it is one of the most common childhood illnesses.
- Symptoms of gastroentitis include diarrhoea, nausea and vomiting, tummy cramps, and fever.
- One of the main risks with gastroentitis is that it causes dehydration in children.
- Rickets occurs due to Vitamin D deficiency.
- Deficiency of Vitamin D occurs in a child because of lack of exposure to sunlight.
- Lack of adequate calcium in the diet can also cause rickets.
- Rickets is a disease which involves softening and weakening of bones in children.
- Children between the ages of 6 to 24 months are at the highest risk of developing the disease because that is the age when their bones are rapidly growing.
- Conjunctivitis is caused due to inflammation of the conjunctiva.
- Conjunctiva is the outermost layer of the eye and the inner surface of the eyelids.
- Conjunctivitis often starts in one eye at first and then spreads to the other eye.
- For children suffering from conjunctivitis it is important to see a doctor to know what kind of conjunctivitis it is.
- Symptoms of conjunctivitis include redness of eyes, irritation in the eye, and eye watering.
- Scabies is an infection of the skin.
- Scabies is caused by tiny insects called mites.
- These scabies mites burrow into the skin and lay eggs which become adult mites very soon.
- Symptoms of this infection include superficial burrows, rash and severe itching.
- Blisters on the palm and soles of the feet are characteristic symptoms of scabies in infants.
- Scabies is one of the highly contagious diseases and a child can develop it by coming into contact with someone else who has been infected.
- Children with scabies must not be sent to school or day care until it gets completely cured.
Upper Respiratory Tract infection (URTI)
- Upper Respiratory Tract Infections are extremely common due to air pollution and vehicular emission.
- Upper respiratory tract infections include common cold, influenza and sore throat.
- Tonsillitis is also one of upper respiratory tract infections.
- Tonsillitis is caused due to infection of the tonsils.
- Tonsils are the areas of lymphoid tissue on either side of the throat.
- Symptoms of tonsillitis include a severe sore throat, coughing, headache and difficulty swallowing.
- Tuberculosis also affects children and is known as Primary Complex or Childhood Tuberculosis infection.
- Children under the age of two years are more at risk of developing tuberculosis because their immune system is under developed or still developing.
- Tuberculosis is completely curable and early diagnosis can help in effective treatment.
- It is a water borne disease rampant in children due to poor sanitation.
- Cases of typhoid are more common in countries like India and some other South Asian countries and in other low developed nations and have been seen lesser in countries like the USA.
- Symptoms of typhoid in children are poor appetite, body ache, discomfort in abdomen, lethargy and weakness, fever with rising and falling pattern.
- Some children may also experience headache, chest congestion, diarrhoea and vomiting and rose spots on the abdomen.
Bronchitis and Asthma
- Bronchitis and asthma are common in children.
- Bronchitis and asthma are caused due to high exposure to air borne pollutants.
- Bronchitis and asthma need to be treated with antibiotics and bronchodilators.
Diseases Caused by Worms
- Ascaris, the common round worm and Wuchereria, the filarial worm, are some of the helminths which are known to be pathogenic to man. Ascaris, an intestinal parasite causes ascariasis.
- Symptoms of these disease include internal bleeding, muscular pain, fever, anemia and blockage of the intestinal passage. The eggs of the parasite are excreted along with the faeces of infected persons which contaminate soil, water, plants, etc. A healthy person acquires this infection through contaminated water, vegetables, fruits, etc.
- Wuchereria (W. bancrofti and malayi), the filarial worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and the disease is called elephantiasis or filariasis. The genital organs are also often affected, resulting in gross deformities. The pathogens are transmitted to person through the bite by the female mosquite.
Old Age Diseases: Dementia
- Dementia is “one of the major causes of disability and dependency among older people worldwide”
Pollution related diseases: Silicosis
- Silicosis is a lung disorder caused by inhalation, retention and pulmonary reaction to crystalline silica, as a result of exposure during mining, stone crushing and quarrying activities.
- Zoonotic diseases — are spread between animals and humans, and are common in societies where poverty is widespread
- Chikungunya, dengue, Avian influenza, plague, SARS and acute encephalitis syndrome (AES) are some of the zoonotic diseases.
- Vitamins are organic compounds that are required in small amounts in our diet but their deficiency causes specific diseases.
- Most of the vitamins cannot be synthesized in our body but plants can synthesize almost all of them, so they are considered as essential food factors.
- However, the bacteria of the gut can produce some of the vitamins required by us.
- All the vitamins are generally available in our diet. Different vitamins belong to various chemical classes and it is difficult to define them on the basis of structure.
- They are generally regarded as organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism.
- Vitamins are designated by alphabets A, B, C, D, etc. Some of them are further named as sub-groups e.g. B1, B2, B6, B12, etc.
- Vitamin A keeps our skin and eyes healthy.
- Vitamin C helps body to fight against many diseases. Vitamin C gets easily destroyed by heat during cooking.
- Vitamin D helps our body to use calcium for bones and teeth.
- Excess of vitamins is also harmful and vitamin pills should not be taken without the advice of doctor.
- The term “Vitamine” was coined from the word vital + amine since the earlier identified compounds had amino groups.
- Later work showed that most of them did not contain amino groups, so the letter ‘e’ was dropped and the term vitamin is used these days.
- Vitamins are classified into two groups depending upon their solubility in water or fat.
Fat soluble vitamins
Vitamins which are soluble in fat and oils but insoluble in water are kept in this group. These are vitamins A, D, E and K. They are stored in liver and adipose (fat storing) tissues.
Water soluble vitamins
B group vitamins and vitamin C are soluble in water so they are grouped together.
Water soluble vitamins must be supplied regularly in diet because they are readily excreted in urine and cannot be stored (except vitamin B12) in our body.
A person may be getting enough food to eat, but sometimes the food may not contain a particular nutrient. If this continues over a long period of time, the person may suffer from its deficiency.
Deficiency of one or more nutrients can cause diseases or disorders in our body. Diseases that occur due to lack of nutrients over a long period are called deficiency diseases.
Vitamin A——— Night blindness
Vitamin B2——– Ariboflavinosis
Vitamin B3 ——–Pellagra
Vitamin B5 ——–Paresthesia
Vitamin B6 ——–Anemia
Vitamin B7 —— Dermatitis, enteritis
Vitamin B9 & Vitamin B12 —– Megaloblastic anemia
Vitamin C —— Scurvy, Swelling of Gums
Vitamin D —— Rickets & Osteomalacia
Vitamin E —— Less Fertility
Vitamin K —— Non-Clotting of Blood.