Class 12 Zoology Diseases of Heart NEET AIIMS
Diseases of Heart
High Yield Facts
l William Harvey first described the blood vascular system in man.
l Science that deals with blood vessels in angiology.
l Science that deals with heart are cardiology.
l Blood vascular system is of two types: open and closed.
l The open circulatory system occurs in arthropods and molluscs.
l When blood flows in open space and channels called lacunae, it is known as an open circulatory system.
l The blood in the open circulatory system is called haemolymph.
l In closed circulatory system blood flows inside the blood vessels only.
l Closed circulatory system is present in the annelids, cephalopods and vertebrate.
l Double circulation is present in lungfishes, amphibians, birds, reptiles and in man where the arteriovenous heart is present.
l Pulmonary circulation occurs when blood flows to and from lungs for oxygenation.
l Systemic circulation is one where blood flows to and from other parts of the body.
l Crocodile, alligator and Gavialis reptiles) have a four-chambered heart.
l Heart is the busiest organ in the body.
l The double membrane sac by which the heart is covered is called the pericardium.
l On the surface of the heart there are two grooves: atrioventricular groove (coronary sulcus) and interventricular groove.
l Sinus Venosus is completely merged into the right atrium in mammals.
l Truncus arteriosus is split into two arches systemic and pulmonary arch in mammals.
l Right auricle receives blood from three large veins: Superior vena cava, inferior vena cava and coronary sinus.
l Valve of Thebesius is present at the opening of the coronary sinus.
l A three lipped valve, present between the right atrium and the right ventricle to prevent backflow of blood, is the tricuspid valve.
l While fibrous threads, which extend from bicuspid and tricuspid valves to papillary muscles and prevent blood flow, are called chordae tendinae.
l The left ventricle is thicker than the right ventricle because it has to push blood to all the body parts.
l The valves present between the great artery and ventricle are semilunar valves.
l Arteries are blood vessels which carry oxygenated blood from the heart to the organs.
l Pulmonary artery is the only artery which carries deoxygenated blood.
l Veins carry deoxygenated blood from body organs to the heart.
l Pulmonary vein is the only vein which carries oxygenated blood.
The heart wall is formed of three layers of 1-1 endocardium, myocardium and pericardium.
l The cyclic repetition of atrial systole, ventricular systole and joint diastole during which blood flows through the heart chamber is called the cardiac cycle.
l Atrial systole takes 0.18 seconds while atrial diastole takes 0.08 seconds.
l The relaxation of atria and contraction of ventricles is called ventricular systole.
l Ventricular systole takes 0.3 seconds while ventricular diastole takes about 0.32 sec.
l When all four chambers of the heart are in diastole, the condition is called joint diastole, which remains for 0.4 seconds.
l Cardiac cycle is completed in 0.88 sec.
l The heart sound can be heard by stethoscope.
l The heart sound produced due to the closing of A.V. valves during ventricular systole is lubb.
l The heart sound produced due to the closing of semilunar valves at the start of relaxation of ventricles is called dupp.
l Portal System is a system made of a portal vein and the capillary complex formed by it in an organ other than the one of its origin.
l The difference between systolic and diastolic blood pressure is called pulse pressure. Its normal value is 40 mm Hg.
l The normal blood pressure of a man is 120/80 mmHg.
l A graphic record of the electrical variation produced by the beating of the heart is called an electrocardiogram.
l The normal rate of a heartbeat at rest is about 70-72 times/min.
l The volume of blood ejected from the heart in the aorta in one minute is called the cardiac output. It is about 5 litres.
l Myogenic heart is the one where cardiac impulse originates in cardiac muscle fibres.
l The heart, where cardiac impulse originates from nerve ganglion cells, is called neurogenic heart. The SA node is the first to originate from the cardiac impulse and determines the rate of heartbeat.
The SA node is the first to originate the cardiac impulse and determines the rate of heartbeat.
l SA node has the highest rate of autorhythmicity.
l AV node or atrioventricular node is called the pacesetter.
l Bundle of His and Purkinje fibres are a network of fine fibres which conduct the impulses to the muscle of the ventricle.
l Narrowing of blood vessels due to deposition of fat is called atherosclerosis.
l Bradycardia is the condition when the heart rate slows down usually less than 60 times/min. The reverse condition is called tachycardia.
l Cessation of all rhythmic impulses of the heart is called cardiac arrest.
l Formation of a blood clot inside the blood vessel is called thrombosis.
l A baby born with an atrial or ventricular septal defect is called a blue baby.
l The largest artery is the aorta.
l Heart pumps blood more forcefully in older people than younger ones due to a decrease in elasticity of arteries.
l Heartbeat is accelerated by sympathetic nerves and epinephrine.
l A person with antigen A in RBC and antibody B in plasma belongs to blood group A.
Spleen is termed the ‘graveyard’ of RBC.
l Universal donors have no antigens in RBC’s but have both antibodies A and B. They belong to blood group O.
l The instrument used for measuring blood pressure is known as a sphygmomanometer.
l Cords if Billroth is blood space found in the spleen.
l Squeezing of leucocytes out from the capillary walls to fight foreign agents is known as diapedesis.
l Blood circulation that starts as capillaries and terminates as capillaries are called portal circulation.
l The heart murmur is due to a defective leaky valve.
l ESR (erythrocyte sedimentation rate) is meant for knowing the degree of disease progression. Most commonly used in TB.
l Hepatic portal vein is produced by coming together of gastric, intestinal and splenic veins.
l Universal recipient blood group is AB.
l A person with blood group O can receive the blood of group O only.
l In man, blood passes from the post caval into the diastolic right atrium of the heart because of the beating of SA node.
l The artery can be distinguished from the vein in having thicker walls and not having valves.
l Blood from a donor with the AB group can be given to a person with AB blood group only.
l R.B.C. in mammals has no nucleus because it has degenerated during development.
l Lymph glands or lymph nodes help to destroy pathogens.
l If the Spleen is removed from the body of an adult man then filtration of dead RBC will stop.
l Blood group AB has no antibody.
l Blood groups were discovered by Landsteiner.
l One person having blood group B requires transfusion. The blood which can be given should belong to group O and B.
l A blood group having blood group A and B antigens but no antibodies is AB.
l Blood of AB group cannot be given to B group patient because the patient has antibodies A.
l Blood transfusion is possible between groups donor AB and recipient AB.
l A child of blood group O cannot have parents of blood groups AB.
l Rh factor is named after rhesus macaque monkey.
l Rh factor was discovered by Landsteiner and Weiner.
l If a man is Rh+ and woman Rh– the first child will survive.
l Clumping of RBC may occur when the blood of one person is mixed with serum or blood of another person. This is due to the antigen-antibody reaction.
l The disease erythroblastosis foetal of a human baby is due to maladjustment of the Rh factor.
l The name of disease connected with the Rh factor is erythroblastosis.
l Hereditary disease in which blood does not coagulate is haemophilia.
l Buffer for blood is NaHCO3 (sodium bicarbonate).
l Except for pulmonary artery all arteries carry oxygenated blood.
l Pulse beat is measured from arteries.
l A yellow substance oozing from a wound is lymph + RBC+ dead pathogens.
l Heart covering is the pericardium.
l Tricuspid value is found in between the right auricle and the right ventricle.
l Rate of heartbeat is highest in mice.
l The ratio of RBC of WBC in humans is 600:1.
l A vein possesses, a large lumen because tunica media is a thin coat.
l Wall of blood capillary is formed of endothelial cells.
l Heartbeat is stimulated by epinephrine.
l Origin of heartbeat and its conduction is represented by SA node AV node Bundle of His Purkinje fibres.
l Mitral/Bicuspid valve connects left atrium and left ventricle.
l Blood vessel supplying diaphragm is called phrenic.
l Carotid artery carries oxygenated blood to the brain.
l Lymph returns interstitial fluid to the blood.
The largest heart is of an elephant.