12th zoology book english medium

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Text book published by Government of Tamil Nadu. T. Sargunam Stephen Chairperson Biology (Zoology) Text book writing . The Hexoses(C 6 H 12 6) such as glucose, fructose and galactose are food. Tamil Nadu 12th Class School Textbooks Online: Studyguideindia provides Class First Term: English Medium Chemistry (Tamil Medium) · Bio Chemistry1 (Tamil Medium) · Bio Zoology (Tamil State Wise School Text Books Download.

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12th Zoology Book English Medium

Tamil Nadu Class 12 – Bio-zoology-zoology – English Medium - Possible 5 Mark Download as PDF File .pdf), Text File .txt) or read online. tamilnadu class 12 zoology material. was provided by Th. Dobzhansky in his book titled. Genetics . Tamilnadu 12th New Books Free Download PDF Tamil & English Medium at aracer.mobi Tamilnadu 12th New School Class 12th Tamil Medium New Books - Free Download pdf Bio-Zoology. Download. Pages · · MB · 9, Downloads ·English TEXT-BOOKS OF ANIMAL BIOLOGY A General Zoology of the Invertebrates Vertebrate Zoology.

Search the history of over billion web pages on the Internet. Books by Language uslprototype. G and Research Dept. Arts College Nandanam, Chennai - Reviewers Dr. Vijayaraman Dr.

The term oxytocin refers to rapid birth. This hormone directly stimulates the smooth muscles of uterus and causes the contraction, and helps in the delivery of foetus. Another major physiological role of oxytocin is the secretion of milk from the lactating breast. Oxytocin stimulates the myoepithelial cells, whichsurround the alveoli and ducts of mammary gland.

The contraction of myoepithelial elements in turn expels the milk from the alveoli of the breast into the larger ducts or sinuses. From the sinuses, the milk is ejected out. The vasopressin: It is otherwise called as the antidiuretic hormone ADH. Its main function is the retention of water inside the body by acting on the renal tubules. ADH increases the permeability of the distal tubules and collecting ducts and promotes the reabsorption of water from the renal filtrate.

It causes the constriction of all blood vessels and increases the blood pressure. It also helps in the retention of urea. ADH deficiency leads to Diabetes insipidus. The symptoms of Diabetes insipidus are polyurea excretion of large volumes of dilute urine polydipsia - an intense thirst leading to the consumption of large quantities of liquids.

Functions of Thyroxine S i This hormone is very essential for the development of nervous system particularly at the time of birth and during the first year, ii This hormone increases the metabolism of all tissues except brain, gonads and accessory sex organs, lymph nodes, spleen and lungs, iii The most important function is to increase the absorption of glucose from the small intestine.

Enumerate the risk factors of Myocardial infarction. Habitual cigarette smokers have a substantially increased risk of dying from myocardial infarction. High blood pressure is a major risk factor and the risk increases with higher pressure. The risk of atherosclerosis and coronary artery disease increases dramatically in those who are more than 30 percent overweight. A raised blood cholesterol level increases the risk.

A high fat diet is also a factor. Physical inactivity is also a major factor. It involves synovium, articular surfaces and capsule. Several etiological factors are attributed to the origin of arthirits arthritogenesis. They are diet, psycho-somatic illness, infections, diseases and metabolic abnormalities, etc.

Infective arthiritis: It produces pain in joints. Rheumatic arthiritis: It focalizes the involvement of musculoskeletal system. It is an inflammation of synovial membrane. Rheumatic disease is considered to be of auto immune origin. It is due to immunological disorder against an unknown antigen..

Osteoarthiritis Osteoarthrosis: Osteoarthiritis is a progressive process affecting the articular cartilage of aging joints. It is characterized by focal degeneration of the articular cartilage. In the later stage, the cartilage gets eroded and exposing the sclerosed bone. Metabolic arthiritis: This is a disease due to an inborn error of Purine metabolism. It is commonly called gout. This condition is characterized by the deposition of Sodium Urate crystals uric acid on the articular cartilage, synovial membrane and in the periarticular tissues.

Gout is characterized by onset of pain swelling and reddening of joints. Structure of sarcomere: The central region of the A band is often less dense and is known as the H Zone. The I band is bisected by a dense narrow line, the Z line.

Thus each sarcomere includes repeating units between two Z lines in linear order as Z line, I band, A band, I band and next Z line. Electron microscopic studies have shown that the striations are due to the regular arrangement of 2 types of protein filaments. A band contains a set of thick filaments formed of the contractile protein myosin. It may range upto Ao in diameter and 1. The second set of thin filaments 50 Ao diameter overlap the long filaments in A band.

The second set of filaments extend partly in I band and partly in A band. These filaments are formed of a substance called Actin. Myosin, actin, tropomyosin and troponin are the four major proteins which constitute the contractile machinery of muscle fibre.

The energy for muscle action is provided by ATP molecules. Physiological effects of Insulin: It increases conversion of glucose into glycogen and deposition of it in liver and muscles. It increases the rate of oxidation of glucose in the tissues. It increases the rate of conversion of glucose into fat and facilitates itsstorage in adipose tissue. It also regulates the rate at which amino acids are catabolised into water and CO2.

Moderately, it also regulates the gluconeogenesis in the liver. Briefly explain the importance of Minerals S Along with complex organic substances, such as carbohydrates proteins and lipids, our body needs substances such as minerals, vitamins and water as accessory food factors.

Calcium, Magnesium and Phosphorus - body building activities such as formation of bones and teeth 2. Iron - oxygen transport 3. Iodine - hormone synthesis 4. Manganese, Copper, Zinc intermediary metabolism.

Chlorine, Sodium and Potassium constituents of the body fluids. Magnesium, Sodium and Potassium neuro-muscular irritability. Calcium - blood clotting. Potassium and Calcium - cardiac functions. The degree of obesity is assessed by the body mass index BMI. It is calculated as weight in Kg divided by the square of height in meters.

For example, a 70 Kg person with a height of cms would have a BMI of Normal BMI range for adults is 19 - Describe Genetic Drift. Briefly describe Sewall- Wright effect. It is concerned with the gene frequency of a reproducing small population. In a small population not all the alleles which are representatives of that species may be present.

Thus the process of inheritance is in violation of Hardy-Weinberg law. In such a small population a chance event may increase the frequency of a character that has little adaptive value. Thus the genetic drift may remain a significant factor in the origin of new species on islands and other isolated populations. Due to loss of alleles having low frequency, amount of genetic variation may get reduced in small populations. Further, continual mating within such populations may cause decrease in the proportion of heterozygotes and increase in the number of homozygotes.

However the small population as a whole may develop characters different from that found in the main population. Such deviations may even lead to speciation or formation of a new species.

When a small group of individuals due to genetic drift become founders of a new population the phenomenon is termed as founder principle. The new population often has genotype frequencies different from the parent population. Sometimes genotypic frequencies may get changed in a small population isolated temporarily due to natural calamities.

When the population regains its original size the members of the small population may have diverged genetically from the original parental population.

Hence interbreeding between members of small and larger populations may not be possible. The small population might have evolved into a new species. This type of genetic drift is referred to as bottleneck effect. M, M, S, M A species is a natural, biological unit. Among the various taxa, a species is not man made. It is a natural reality. The process of evolution operates at the species level only.

It is because of these reasons, in evolution much importance is given to the Origin of Species. There are several types of species. Allopatric species Species occupying different geographical areas. The two land areas are separated by the Gulf of Mannar.

Sympatric species Closely related species living together in one common locality, yet maintain their species identity Ex: Ranahexadactyla, R. What are the three types of selection processes in natural Selection? Stabilizing selection 2. Directional selection 3. Disruptive selections Stabilizing selection In stabilizing selection competition in nature is not severe.

The phenotypic features coincide with normal environmental situations. However this selection may eliminate characters that are abnormal and harmful and it tends to maintain the phenotypic stability within population for successive generations. Directional selection The directional selection operates in response to gradual changes in the environment.

It operates within the phenotypic range available within the population. The selection gradually changes the phenotypic character towards a possible extreme condition found suitable for the changed environmental situation.

This selection will increase the frequency of desirable phenotypic character within the population. Thus it results in gradual evolutionary change. Disruptive selections In disruptive selection the selection pressure may favour the existence of more than one phenotype in a population. It may even split a population into two sub- populations. If gene flow between such sub-populations is prevented a new species or a sub specie may evolve. When a disruptive selection produces more than one phenotype within a populationthe phenomenon is known as polymorphism.

Explain the various mechanism to prevent inter-specific crosses. OR Explain pre-mating isolation. J, J, J, J, J, S a Ecological isolation Members of the populations occur in different habitates in the same general region. Write a account on Population genetics. What are the conditions under which Hardy - Weinberg law operates? M, M A population is defined as an assemblage of living beings showing a closely interacting system.

A population comprising of sexually interbreeding organisms is termed as the genetic population or Mendelian population. A genetic population may be defined as a community of similar individuals living within a limited circumscribed area at a given time and capable of interbreeding. The genes of all the individuals of such a Mendelian population will constitute the gene pool. A gene pool comprises a diverse forms of a gene combining and recombining by the process of sexual reproduction.

The frequency of genes and genotypes in a population had been worked out by mathematical formulations. The gene frequency refers to the proportion of an allele in the gene pool as compared with other alleles at the same locus. Hence the gene frequency can be calculated by substracting the number of a particular gene in question from the total number of genes present on that locus in the population.

A fundamental idea in the form of a law to understand population genetics was provided by G. Hardy of England and W. Weinberg of Germany in The law proposed by them is known as Hardy-Weinbergs law. It is the foundation of population genetics and of modern evolutionary theory. According to this law the relative frequencies of various kinds of genes in a large and randomly mating sexual population tend to remain constant from generation to generation in the absence of mutation, selection and gene flow or migration.

This law concerns a theoretical situation for a population not undergoing any evolutionary change. Thus according to the law the normal mendelian genic frequencies are maintained under certain conditions only. If such conditions are not followed, the gene frequency will change leading to deviations and cause variations, such variation will be the sources for future evolution.

Write a short note on Neo-Lamarckism. S Lamarcks theory of inhertitance was further studied by a group of scientists. Their ideas supporting Lamarcks opinion collectively constitute neo-Lamarckism. The neo-Lamarckians were of the opinion that adaptions are universal in nature. An adaptation happens through causal relationship of structure, function and environment. Due to changes in the environment, habits and life style of organism gets altered.

Thus gradually the organism acquires new structures. The newly obtained character gradually becomes an inheritable trait. This opinion and argument is a modified form of Lamarckism. These ideas stressed direct action of environment on organisms.

Support to neo-Lamarckian concept - Experiments McDougall Experiment McDougall tried to prove that learning is an acquired character that can be inherited.

He did his experiments on rats. He deviced a T shaped tank. The tank had two exits. One exit was well lighted. However at the terminal region of the exit he deviced an arrangement for giving electrical shock. The pathway to the other exit was kept dark. At the terminal exit point a small piece of cheese was kept as a reward. McDougall dropped several rats into the tank. Many of the rats preferred lighted pathway to escape and at the exit they received electric shock. Those rats, that preferred dark pathway received the cheese.

He repeated the trial several times. Gradually many rats learnt the correct route for escape. Subsequently the rats were allowed to breed and the next generation developed. The same experiment was repeated in the second generation. According to Mc Dougall, it was claimed that the number of mistakes committed, gradually got reduced. The speed of learning increased from generation to generation. Thus he concluded that learning is an acquired character.

However later workers found some technical mistakes in the work of Mc Dougall. The same experiment while repeated in other laboratories failed to give similar results. Sumner Experiment Temperature related changes in the body of mice was noted by F.

Sumner He reared one set of white mice in warmer temperature 20 - c and another set in cold conditions. He found that in warmer conditions the mice developed larger ears and longer tails. He further claimed that these characters were inherited. Through similar works claim for inheritance of acquired characters were made by Lindsey, Guyer and Smith and Kammerer. In all these works while repeating, critics have found technical mistakes and rejected them outright.

However, the controversy over inheritance of acquired characters still continues. This theory of Lamarck while has not been disproved totally,it remains to be proved correct. Explain chromosomal aberrations. S During the process of meiosis one or more chromosomes may break. Such broken fragments of chromosomes may be subjected to several modified organizations: Sometimes a pair of homologous chromosomes may fail to separate in meiosis.

It will result in gametes with one chromosome less or one chromosome more, than normal. The progeny formed from such gametes are called polysomics. They will have fewer or more chromosomes than normal. In certain cases, whole set of homologous chromosomes do not separate in meiosis.

It results in diploid gametes. Fusion of such gametes with a normal haploid gamete gives rise to progeny with a triploid chromosome number. This condition is called polyploidy. It is commonly observed in plants.

Polyploids are usually more vigorous. Such forms can give rise to new species. While recombinations provide regular variations, mutations enrich such variations. Phenomena such as chromosomal abberrations, polysomics and polyploidy while, found advantageous to the organisms, provide new directions for speciation and further evolution.

Describe the modern concept of natural selection. J Modern development in biological fields such as Cell biology, Genetics and Populations genetics helped in the development of modern synthetic theory of evolution. It was caused due to contributions made by eminent scientists such as Th.

Dobzhansky, S. Wright, H. Muller, J. Huxley, R. Fisher, Ernst Mayr, G. Stebbins and others. The basic concept of modern synthetic theory was provided by Th. Dobzhansky in his book titled Genetics and the Origin of species G.

Stebbins in his book Process of organic evolution suggests five basic processes essential for evolution. They are 1. Contributions made by others provided additional factors such as Hardy-Weinberg equilibrium, Genetic drift and Polymorphism. Describe the Polymorphism M, J It is the the existence in a natural population of two or more alleles in frequencies too large to be explained by recurrent mutation.

Thus a polymorphic population will have several alleles of a gene as a permanent feature of the species. The varied alleles are favoured and maintained in the population by genetical mechanisms. A classical example for such a polymorphism could be the existence of a genetic disorder in humans, namely sickle-cell anaemia.

This disease reduces the oxygen-carrying capacity of the blood and affects blood supply to various organs. This disorder is inherited as a Mendelian recessive.

It is more frequent among American blacks than American whites. In spite of its harmful nature the allelic gene responsible for the disorder is maintained in the black population. According to the work of Allison , 61 it was shown that in Africa the same allelic gene conferred an advantage, that is it protected the inheritors of such gene from malaria.

Thus the connection between sickle-cell anaemia and malaria was estabilished. Hence selection has encouraged the existence of such a polymorphic allele in the population. What are the objections to Darwinism.

S While the ideas of Darwin, related to reproductive capability,prevalence of variations, concept of struggle and survival of suitable forms are all commonly accepted, there are certain drawbacks in his original theory. Darwin could not explain, the origin and cause for variations while insisting their importance in progressive evolution.

He overemphasized the importance of the fittest organisms. During later periods it has been suggested that fit and fitter forms can also exist along with the fittest. As the principle of inheritance as explained in the later years were not available during Darwins time. Hence he believed in the theory of pangenesis. According to this concept from every organ in the body very minute such replicate structures will orginate. Later they are transferred to the gonads for transmission to future generations.

Over-specialization as in Irish deer and its consequent harmful effect on animals had not been accounted for by Darwin. Uploaded by revamanian. Flag for inappropriate content. For Later.

Related titles. Jump to Page. Search inside document. Related Searches Zoology Apologia zoology Intermediate zoology. Ram Iyer. Rahmayani Isma. Alexis Cano Cubas. John Christopher L. Emma Saelens. Joan Bulario. Aamir Khan. Ramsey Mora. Iknow Imdabest. Samuel Sourab. Anastasia N. Rasha Emad. Niluh Ita. Jon Chow. Johnathon Buckley. More From revamanian. How to Prepare for the Civil Services Examination. Gokul Adarsh. Gowtham Raj. Shiv Shankar. Popular in Science. Golam Masud. Teamwork and Collaboration in Early Years Settings.

Md Nurul Islam. Anonymous BfckuAj6e. Jean Desingermain. Ouma Shehata. Geezus Luvsu. Mohammad Rawoof. X-ray crystallography can give a skeleton model of a protein from its results on its atomic details.

With atomic data, computers nowadays generate graphic images of the molecules on high-resolution screen. Computer modeling of protein began as early as The computer-generated models depict not only the properties of amino acids in a protein but also help to understand the protein function.

Computer graphic models is the Glowing coal Uses : Protein structure helps in understanding biomolecular arrangement in tissue or cellular architecture.

Protein structures, protein models and computer aided graphic models help to understand biological reactions mediated by enzymes proteins.

Graphic models provided by computers are valuable to predict which fragments of a medically important protein can be used to design drugs and vaccines. Proteomics also helps in chemical industries to manufacture drugs, various chemical compounds and enzymes. Describe the karotyping of human chromosomes The 23 pairs of chromosomes in human are classified into seven groups viz, A-G based on position of centromere.

Group A includes 1, 2 and 3 chromosomes. It includes the largest chromosomes. Metacentric with two equal arms. Group B : Group B includes 4 and 5 chromosomes. Submetacentric with two unequal arms.

Group C : Group C includes 6,7,8,9,10,11,12 and X chromosomes. This is the largest group Submetacentric with two unequal arms. The X chromosome resembles the chromosome 6 in this group. Group D includes 13,14 and 15 chromosomes. Acrocentric Group E includes 16,17 and 18 chromosomes. Meta or submetacentric. Group F includes 19 and 20 chromosomes. Group G : Group G includes 21, 22 and Y chromosomes.

Explain Dr Ian Wilmut's cloning mechanism. S Dr. Ian Wilmut has produced a cloned sheep called Dolly by nuclear transplantation method. To produce cloned sheep he took the udder cell which is a somatic cell with diploid number of chromosomes. An egg cell was also removed from a donor sheep. The egg cell cannot grow into a new sheep on its own because it only has half a set of chromosomes n. The body cell cannot grow into a new sheep on its own because it is not a reproductive cell.

So udder cell nucleus 2n was removed. Similarly the egg cell nucleus n was also removed. The nucleus of the somatic cell Udder was injected into the enucleated egg. The egg after the nuclear transplantation comes to possess full set of chromosomes viz. The egg was then transplanted back into the uterus of the sheep from which it was removed. The egg also can be transplanted to a new surrogate mother for development.

The egg cell grew and developed into a sheep Dolly. This cloned sheep is genetically identical to the donor sheep, which donated the diploid nucleus of its somatic cell and not the sheep which donated the egg cell. It helps to know more about the diseases. It helps to understand more about the fundamental biology and the thread of life, - the DNA.

It paves the way for the medical and bio engineering applications. It helps to apply the biophysical and biotechnologicl principles to biological studies.

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In turn, it will help to design new drugs and new chemical compounds to be used in health and environmental management respectively.

What is database? What are its types? Gaseous exchange in the alveoli Once the air is within the lungs the process of gaseous exchange begins. Capillaries of the pulmonary artery remains close to the wall of the alveloli. This enhances the exchange of gases.

Exchange of gases in the alveolus Oxygen and carbon-di-oxide are exchanged across the alveolar membrane by diffusion from the site of higher to low partial pressure until the partial pressure of the two regions are equal. This process is a simple physical one which does not involve any secretary or active transport mechanism.

The alveolar P0 2 is about mm Hg and the P0 2 of venous blood is about 40mm Hg. This pressure gradient is sufficient for the transfer of 2. The PC0 2 of venous blood is 46mm.

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Hg and that of alveolar air is only 6mm. C0 2 diffuses 20 times faster than 2. Regulation of respiration: In the brain the medulla oblongata contains a respiratory center. This controls breathing. The respiratory center consists of an inspiratory center and an expiratory center.

The axons from the nerve cells of these centres lead to the intercostals muscle through the intercostals nerves and the diaphragm via the phrenic nerves. These nerve fibres transmit impulses to the external intercostal muscles and internal intercostal muscles alternately. The walls of the alveoli have sense endings which are stimulated by changes in the tension of alveolar walls.

This sequence of events is called Herring - Breuer reflex. In addition the medulla contains a pneumotaxic center which is connected to the breathing centre and helps to ensure rhythmic breathing.

During inspiration, the inspiratory part of the respiratory center sends impulses to the pneumotaxic center which responds by sending impulses to the expiratory part of the respiratory center.

The expiratory center is then activated and so the inspiratory center is inhibited reflexly, respiratory rhythm is controlled in this manner by these centers in the brain. Inflammation of the lungs due to infection is called pneumonia. Pneumonia is caused by viruses or bacteria. The most common bacterial pneumonia is Pneumococcal pneumonia.

Pneumonia may also be caused by a mycoplasma an organism that is intermediate between a bacterium and a virus Symptoms and Signs: Symptoms and signs include fever, chills, shortness of breath and a cough that produces yellow - green sputum and occasionally blood.

The drugs prescribed depend on the causative microorganism. They may include antibiotic drugs or antifungal drugs. Aspirin or paracetamol may be given to reduce fever. Oxygen therapy and artificial ventilation may be required. Tuberculosis TB It is an infections disease, caused in humans by the bacterium Mycobacterium tuberculae. It was once common world wide and was a killer disease. People infected with HIV are highly susceptible to tuberculosis and the disease is becoming more common again in communities with high rates of HIV infection.

The bacteria breathed into the lungs multiply to form an infected "focus". In a high proportion of cases, the body's immune system then halts the infection and healing occurs.

The infection can also occur in intestines, bones and kidneys. The main symptom includes coughing sometimes bringing up blood chest pain, shortness of breath, fever and sweating at night poor appetite and weight loss. The main complications of tuberculosis of the lungs are pleural effusion. Collection of fluid between the lung and the chest wall. Bronchitis Bronchitis is the inflammation of the bronchi, the air ways that connect the trachea wind pipe to the lungs, resulting in cough that may produce considerable quantities of sputum Phlegm.

Two forms, of the disease are recognized as acute bronchitis sudden onset and short duration and chronic bronchitis Persistent over a long period and recurring over several years. Both are more common in smokers and in areas with high atmospheric pollution.

Acute bronchitis: It is caused by viral infection or by the effect of air pollutants. Bacterial infection may cause acute bronchitis. Attacks occur more often in winter. Smokers, babies, the elderly and people with lung diseases are particularly susceptible. Chronic Bronchitis: It is a form of bronchitis in which sputum is coughed up on most days for atleast three consecutive months. The disease results in narrowing and obstruction of the air - ways in the lungs. It often coexists with another form of lung disease, emphysema widening of alveoli.

Chronic bronchitis and emphysema together are called chronic obstructive lung disease COLD or chronic obstructive airways disease. Pollution and smoking are the causes of chronic bronchitis. It stimulates the production of mucus in the lining of the bronchi. Most of the body cells are located at some distance from the nutrient sources such as the digestive tract and sites of waste disposal such as kidneys. The cardiovascular system which consists of the heart, blood vessels and blood, connects the various tissues of the body.

While the heart pumps the blood through the blood vessels, the blood delivers nutrients and collect waste products. Functioning of Human heart Heart is a pumping organ. It receives blood from different parts of the body through the veins that open through inferior and superior vena cavae and pulmonary veins. While the right atrium receives deoxygenated blood, the left atrium receives the oxygenated blood from the lungs. When the wall of the atria contract the right and left atria pump the blood into the right and left ventricles respectively.

A pulmonary trunk arising from the right ventricle takes away the blood to the lungs for oxygenation. The left ventricle gives rise to an aorta, from which oxygneated blood is supplied to the coronary arteries and the systemic circulation of the body. Functioning of human heart bicuspid valve left ventricle 38 The blood flow between the right atrium and the right ventricle is regulated by the tricuspid valve.

The bicuspid or mitral valve regulates the flow on the left chambers of the heart. In the pulmonary trunk and the aorta, back flow of blood is prevented by a set of semilunar valves. Origin and conduction of heart beat During pumping action of heart, the heart muscles cause rhythmic contraction and relaxation of the heart chambers in a specific sequence. The rhythmic, sequential functioning of the cardiac chamber is maintained by sino-atrial node SA node , atrio- ventricular node AV node , bundle of His and Purkinje fibres.

Origin and conduction of heart beat The S A node situated in the upper, lateral wall of the right atrium is a small, flattened strip of muscle fibre that is 1. The fibres of the SA node are closely associated with the muscles of auricles. SA node is capable of generating action potential that can travel throughout the auricles. The velocity of conduction is 0. The excitation from the SA node stimulates the AV node. The AV node in turn conducts the stimulus to bundle of His and Purkinje fibres.

These myocardial fibres are found all over the wall of the ventricles. In the conduction of stimulus through the AV node and the fibrous system there is a delay in transmission. Cardiac cycle The sequential events occuring from the initiation of one heartbeat to the commencement of the next is called as one cardiac cycle.

In this cycle, the contraction phase is called systole. The relaxation phase is the diastole. Atrial systole: There is a continuous flow of blood into the right atrium through superior and inferior vena cava and coronary sinus.

Simultaneously the left atrium receives blood from 4 plulmonary veins. Ventricular filling: When the valves in between atria and ventricles open nearly two-third of the ventricle is filled. Remaining space gets filled up by atrial contraction. Ventricular systole: As the atrial systole ends, the action potential generated by the SA node reaches the AV node and rest of the fibrous system. It causes contraction of the ventricular wall.

Thus ventricular pressure results. The very strong ventricular pressure pumps the blood into respective arteries by causing the semilunar valves to open. Ventricular diastole: Soon after the blood leaves the ventricles there is a fall in the ventricular pressure.

The semilunar valves close and the atrial valves open to begin the next cycle. Heart sound: The heart sound felt by a stethescope is caused due to the closure and opening of the valves. The generation of sound is rhythmic. The first sound is louder lubb and of longer duration 0. It is due to closure of the atrioventricular valves at the beginning of the ventricular systole. The second sound is of shorter duration dubb 0.

It is caused at the end of the ventricular systole by the closure of semilunar valve. The heart beats at the rate of about times per minute in adults. The ventricular systole causes a wave of distension due to blood flow. It is called as arterial pulse. It can be felt on the wrist. The pulse rate corresponds to rate of heartbeat. Coronary blood vessel and its significance There are two main coronary arteries the left and the right. The left one branches into the left circum flex artery and the left anterior descending artery.

Right main coronary artery and the left coronary arteries branch off from the aorta, surround and penetrate the heart muscle. Arterioles and capillaries 40 branch off from the coronary arteries to supply heart muscle with oxygen rich blood. Deoxygenated blood drains into the coronary veins, which carry it back into the heart's right atrium. Damage to the coronary blood vessel or narrowing of the coronary vessel leads to coronary artery disease CAD.

Blood flow through the arteries is restricted, leading to damages of the heart muscle. Heart disor- ders like heart attack, myocardial infarction, the chest pain or Angina are usually caused by CAD. In many parts of the world mortality from coronary artery disease is rising due to changing life style factors.

Myocardial infarction: Myocardial infarction is a coronary artery disease which involves sudden death of part of the heart muscle due to blockage in the coronary artery. It may cause severe unremitting chest pain. The coronary arteries that supply the heart muscle with fresh oxygenated blood become narrowed. This narrowing is usually due to an accumulation of droplets of fatty substances, like cholesterol.

The fibrous cover of the fat deposit sometimes rupture, triggering the formation of a blood clot. If this blood clot blocks the artery, blood flow to an area of the heart muscle stops, causing myocardial infarction and leads to death of tissue. About one in five people experience no chest pain in myocardial infarction. However, there may be fainting, sweating and pale skin. This pattern of symptom is known as "silent infarction".

This type of infarction is common in people with diabetes mellitus or those with elevated blood pressure. Risk factors 1. Habitual cigarette smokers have a substantially increased risk of dying from myocardial infarction. High blood pressure is a major risk factor and the risk increases with higher pressure.

The risk of atherosclerosis and coronary artery disease increases dramatically in those who are more than 30 percent overweight.

A raised blood cholesterol level increases the risk. A high fat diet is also a factor. Physical inactivity is also a major factor. Angina pectoris: Angina is a term that describes a strangling or constrictive pain.

Angina has become synonymous with the heart disorder called Angina pectoris. This heart disorder refers to chest pain caused by insufficient supply of oxygen to the heart muscle, usually a result of poor blood supply. Angina pectoris usually occurs when the demand for oxygen is increased during exercise and at the time of stress.

The pain usually comes on suddenly. The pain ranges from a tight ache to intense crushing agony. It lasts for 30 minutes or more and it is not relieved by rest. Causes 1. Inadequate blood supply to heart due to coronary artery disease such as atherosclerosis 2.

Severe attack of anaemia which reduces the oxygen carrying capacity of blood. Polycythemia Increased number of red blood cells which thickens the blood, causing it to slow its flow through the heart muscle.

Thyrotoxicosis a disorder caused by excessive secretion of thyroxine can precipitate angina pectoris by making the heart work harder and faster than its blood supply will permit. Angiogram Angiogram is a special contrast X ray and can be used to detect an abnormality in a blood vessel such as a narrowing of a large diseased artery. Coronary Angiography Coronary angiography is used to image the arteries that supply the heart muscle with blood. Angiography can image narrowed or blocked coronary arteries, which are not visible on a normal X-ray.

A local anesthesia is injected and a fine flexible catheter is passed within the femoral artery, through the aorta and into a coronary artery. A contrast dye is injected through the catheter and a series of x rays taken. The procedure is painless. Under local anesthesia, a guide wire is inserted through the femoral artery in the groin and up into the affected coronary artery. A baloon catheter is passed up the wire and the baloon is inflated in the narrowed area to widen it.

Sometimes, a metal tube called a stent is inserted afterward. It keeps the artery open. Coronary bypass surgery is an operation to circumvent narrowed or blocked coronary arteries by grafting additional blood vessels to transmit blood flow. During this procedure the heart is temporarily stopped and blood circulation and oxygenation is taken over by a heart lung machine. Atherosclerosis Atherosclerosis is narrowing of the arteries caused by plaques on their inner linings. These plaques are composed mainly of fats deposited from the blood stream.

They disrupt the normal flow of blood through the affected artery. Atherosclerosis encourages thrombus and embolus fragment of blood clot. Men are affected earlier than women because women are protected by natural oestrogen hormones. Narrowing of the vessel is due to the development of raised patches called plaques.

These plaques consists of athroma fat and oil mixture , decaying muscle cells, fibrous tissue, clumps of blood platelets, cholesterol and calcium abnormal blood clot Risk factors: Cigarette smoking, Hypertension, male gender, obesity, physical inactivity, diabetes mellitus, heredity, aggressive personality.

Severe effects of atherosclerosis is stroke loss of blood supply to brain , heart attack loss of blood supply to heart. Heart block Complete failure of the system that conducts electrical impulses from the upper to the lower heart chamber is called the heart block. Normally, 43 electrical impulses pass from the sinu auricular node to the atrio- ventricular node in the right atrium and then to the ventricle. In complete heart block, the impulses cannot reach the ventricle.

This defective production of the sinu atrial impulses and its conduction in the heart is called heart block. Echo cardiography Echo cardiography is a technique that uses ultra sound waves to image the interior of heart. It is used to diagnose disorders of the heart and the heart valves. The test is usually done by using an ultrasound transducer probe placed on the skin of the chest directly over the heart. In some cases a small probe is passed down the oesophagus. Heart Valves: Heart valves are essential for precisely controlling the flow of blood in between auricles and ventricles and between the heart and major blood vessels.

The valves are delicate pockets and their function is to prevent any backward flow of blood. The heart valve's functioning is vital for the efficiency of the heart as a pump. The opening and more particularly the closing of heart valves during each heart cycle are responsible for heart sounds. Any of the four heart valves may be affected by stenosis narrowing which causes the heart to work harder to force blood through the valve. Incompetence or insufficiency leaki- ness makes the valve unable to prevent backwash of blood.

These defects cause characteristic heart murmurs which can be heard by a doctor. RHD is a crippling desease. Rheumatic fever develops due to an infection usually of the throat, caused by streptococcal bacteria.

The condition is caused by the immune system attacking the body's own tissues in response to the infection. The symptoms of Rheumatic fever may include high fever, pain and swelling in bone joints. Intensive Coronary Care Unit to care for people in a critical or unstable condition.

This unit has a wide variety of sophisticated equipments for constantly monitoring the condition of the seriously ill patient. The patient may be connected to a ventilator to maintain breathing.

Body fluids and blood sugar levels are maintained by intra venous infusion of salts and glucose. Nutrients may also be supplied intravenously. Urine is collected through a catheter. Blood pressure is continuously monitored by an automatic sphygmomanometer. Heart rate and rhythm are monitored by an ECG machine. Results are often relayed to a central monitoring unit. Monitors are fitted with alarms to alert the staff if there is any dangerous variation from the normal range.

Blood Pressure Blood pressure is the force exerted by the flow of blood against the walls of the main arteries while flowing through them. Blood pressure rises or falls as the heart responds to the varying demands made by the body during different activities such as exercise, stress and sleep. Two types of pressure are measured. Systolic the highest is the pressure created, by the ventricular muscle and the elastic recoil of the aorta main vessel leaving the heart as the blood flows through it.

Diastolic pressure the lowest is recorded during relaxation of the ventricles between beats. It reflects the resistance of all the small arteries in the body and the load against which the heart must work. The pressure wave transmitted along the arteries with each heart beat is felt as the pulse.

Blood pressure is measured using a sphygmomanometer. Hg - systolic and 80 mm Hg - diastolic. Abnormally high blood pressure is known as hyper ten- sion. Hyper tension is defined as the "Systolic pressure equal to or greater than mm Hg and or the diastolic pressure equal to or greater than 95 mm Hg". Abnormally low pressure is termed hypotension. Apart from increasing the risk of having a stroke or developing heart failure or coronary artery disease, high blood pressure may cause kidney damage and retinopathy damage to the retina at the back of the eye.

Causes Hypertension is linked with obesity and in some people to a high intake of salt, alcohol, smoking appears to aggravate the effects of hypertension. Preventive measures: Obese persons should make an attempt to reduce weight through restriction of food intake and try regular exercise.

The dietary intake of animal fat milk, cream, cheese fatty meat and eggs should be reduced. A restricted intake of salt is recommended. Heart transplantation involves replacement of a person's damaged or diseased heart by a healthy human heart taken from a donor in whom brain death has been certified. Heart transplantation in animals was first achieved in 1 The first human heart transplant was performed by Professor Christian Bernard in South Africa in Limiting factors for Heart transplant surgery 1.

Problem of timing: A heart transplant is possible only when a suitable donor heart is available at right time. Problem of fall-back system: If the heart is rejected attacked by the body's immune system the only hope for the patient is another transplant. Problem in the certification of brain death. The success of heart transplant lies in allowing doctors to certify brain death while the heart was beating.

Heart is generatly removed for transplantation from a person certified for brain death by doctors. The pulse can be described in terms of its rate number of expansion per minute its rhythm, strength and whether the blood vessel feels hard or soft.

The pulse rate is determined by counting the beats in a set period minimum 15 to 20 seconds and multiplying to give the beats per minute. The pulse rate usually corresponds to the heart rate which varies according to the persons state of relaxation or physical activity. Abnormal rhythm may be a sign of heart disorder. If the pulse feels weak, it may be a sign of heart failure, shock or an obstruction to the blood circulation. Weak or absent pulse in one or both legs is a sign of peripheral vascular disease.

Cardio - Pulmonary Resuscitation Cardio - pulmonary resuscitation is the administration of the life - saving measures of external cardiac compression massage and mouth to mouth resuscitation Artificial respiration to someone collapsing with Cardiac arrest Cessation of heart beat It is vital to restore the circulation of oxygen carrying blood to the brain as quickly as possible because permanent brain damage is likely to occur if the brain is starved of oxygen for more than three to four minutes The blood: It consists of liquid plasma and cells.

The total blood volume in human female is about litres and litres in males. It is straw coloured. Water 2. Plasma proteins- Albumin Globulins Fibrinogen 3. Nutrients - Glucose, amino acids, triglycerides, cholesterol, vitamins.

Waste products - Urea, uric! Gases Oxygen CO Nitrogen 7. Regulating substances Hormones and Enzymes Functions - as a slovent and suspending medium for blood components. Males have about 5. Females have about 4. Their main component is a pigmented protein, haemoglobin. It gives red colour to the blood. Erythrocytes stay in circulation for about days in males and 1 10 days in females.

They are manufactured in the marrow of bones such as ribs and vertebrae. They disintegrate in the spleen and liver. They are nucleated cells exhibiting amoeboid movement. They protect the body against invading micro-organisms and remove dead cells from the body.

There are five types of leucocytes. Different types of WBC a. Their nuclei can occur in more than one form. Hence they are called polymorphonuclear neutrophils PMN. Eosinophils 0. During allergy reaction their number increases. Basophils 0. They contain heparin which inhibits blood clotting. They are more common in lymphatic tissues namely the lymph nodes, spleen, tonsils and thymus. Lymphocytes, called B-cells can produce proteins called antibodies that can get attached to the bacteria and destroy them.

T-cells 49 protect us against viruses by attacking and destroying cells in which viruses are reproducing. They destroy bacteria, dead cells and cell fragments. During chronic infection their number increases. Blood Platelets or Thrombocytes These are minute fragments of cells that play a very important role in coagulation of blood. Their life expectancy is days. Clotting of Blood or Haemostasis When a blood vessel is damaged, it results in coagulation or clotting of blood.

A blood clot is a network of thread like protein fibers, called fibrin, that traps blood cells, platelets and fluid. The clotting depends on several proteins in the plasma. They are called coagulation factors. Normally these factors are in an inactive state. After injury they are activated to produce a clot.

The activation can happen in three stages. Stage 1 - Formation of thrombokinase - Damaged tissues release a mixture of lipoproteins and phospholipids called tissue factor TF or thromboplastin. This factor in the presence of certain factors in the blood form a complex called prothrombinase or thrombokinase. Stage 2 - Formation of thrombin - During this stage soluble plasma protein prothrombin is converted into the enzyme thrombin by prothrombinase.

Prothrombin synthesis in liver requires vitamin K. Clotting is a normal response that prevents bleeding when a blood vessel wall is injured. However thrombus formation is abnormal if it occurs in an intact vessel. A thrombus within an artery may block the artery preventing blood and oxygen from reaching the organ or tissue supplied by an artery.

A thrombus that forms within one of the coronary arteries supplying heart muscle is known as coronary thrombosis. This is the cause for heart attack. A thrombus within arteries supplying the brain is known as cerebral thrombosis.

It causes stroke. When a portion of a thrombus clot becomes fragmented and enters the circulating blood, it is called embolus. Embolus may block a circulation to vital parts resulting in serious consequences such as stroke. Co-ordination systems Nervous Co-ordination All living animals maintain a constant inner state, irrespective of changes happening in the environment. This phenomenon is named as homoeostasis. It is achieved due to coordination of response.

The coordination is due to the animal body, acting as a self -regulating system capable of making appropriate responses to stimuli. The coordinating system of the body contains suitable structures for detecting stimuli, transmitting information and responding to stimuli. There are feedback mechanisms that ensure that degree of responses is related to the intensity and direction of the stimuli.

Mammals have two main coordinating systems, namely the nervous system and the endocrine system. They help in conducting the stimuli in between the receptor organs - spinal cord, brain and effector organs.

The neurons conduct the stimulus as electrochemical events. These sequential events involve migration of 'Na' and 'K' ions outside and inside the neuronal cells. This phenomenon is known as Sodium- Potassium pump. This sequence of electro chemical events is known as the impulse. A synapse The junctions of neurons in nerve pathway are called the synapses. A synapse is formed between the bulb-like end structure of the axon called boutons and the cyton or dendrite of the adjacent neuron.

At the junction there is a gap called the synaptic cleft, which is usually about 10 to 20 nm. At this point, transmission of stimulus happens through transmitter substances such as acetylcholine. In the nervous system the bundles of parallel axons of the nervous tissue having myelin sheath constitute the white matter. Collection of neurons having unmyelinated axons form the grey matter.

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The axons make up the white matter of the CNS for nerve tracts. They propogate action potentials. The grey matter performs integrative functions.

The outer surface of the brain cortex and the central area of the spinal cord consist of grey matter. Within the brain, collections of grey matter form centers called nuclei. An estimate shows that the cerebral cortex alone has about 10 synapses. Thus the brain is a complex organ. On structural and functional basis the brain can be divided into 3 regions.

Fore brain, 2. Midbrain, 3. Hind brain. Fore Brain Prosencephalon: The diencephalon is formed of thalamus and hypothalamus. This region contains a cluster of nuclei.

Most of the sensory inputs are conducted to the cerebral cortex through the thalamus. Axons carrying auditory, visual and other sensory informations synapse with specific nuclei of this region. This region may also influence mood and general body movements due to strong emotions such as fear or anger.

The nuclei called mamillary bodies are involved in olfactory reflexes and emotional responses to odours. The funnel shaped infundibulum from the hypothalamus connects it to the posterior pituitary or neurohypophysis. This region controls the secretions of the pituitary gland. The hypothalamus receives inputs from several sensory systems such as tongue, nose and external genitalia.

It is associated with emotional and mood relationships. It provides a relaxed feeling. Feeling good after a meal, rage and fear are also due to this region. It also coordinates responses to the sleep- wake cycle with other areas.

It weighs about g in males and g in females. Larger brains are normally associated with larger bodies and not with greater intelligence. It forms clusters deep inside the brain called nuclei. The inner part of the brain, in between the cortex and the nuclei has white matter named as cerebral medulla. Cerebral cortex - functional areas Cerebral cortex:

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