IMPORTANT TERMS:
Arterial Pulse:Wave of distension experienced in the arteries as a result of ventricular systole.
v Atrio-Ventricular Node (AV node):Specialised muscle fibres present in the interatrial septum that conducts cardiac impulse from SA node to bundles of His.
v Bicuspid Valve (Mitral Valve):A valve consisting of two flaps between left atrium and left ventricle in the heart.
v Blood Pressure (BP): The pressure exerted by the blood against the walls of arteries. BP of a normal person at rest is 120/80 mm of Hg, ie., systolic pressure=120; diastolic pressure=80.
v Cardiac Cycle:Rhythmic contraction and relaxation of cardiac chambers in a specific manner during one heart beat.
v Closed Circulatory System:The circulatory system in which the blood flows through heart and blood vessels.
v Diastole:Relaxation of cardiac chamber.
v Electrocardiogram (ECG):A graphic record of the electric current produced by the excitation of cardiac muscles.
v Haemocoel: Body cavity containing blood.
v Interstitial Fluid: The fluid that occurs in the spaces between the cells of a tissue.
v Joint Diastole:Relaxation of cardiac chambers- both atria and ventricles together.
v Lymph: Transparent fluid derived from blood containing lymphocytes but low in protein.
v Myogenic Heart: The heart in which cardiac impulse originates in cardiac muscle fibres as in vertebrates.
v Neurogenic Heart:The heart in which cardiac impulse originates by specialized nerve fibres as in invertebrates.
v Open Circulatory System:The circulatory system in which the blood flows through open spaces (lacunae) and channels (sinuses).
v Pacemaker:The structure that initiates the cardiac impulse, eg. SA node.
v Pericardium: A double walled membranous sac that encloses the heart.
v Pulmonary Circulation:The flow of deoxygenated blood from right ventricle to the lungs and the oxygenated blood from the lungs to the atrium back.
v Semilunar Valves: The valves containing three flaps present at the base of pulmonary artery and aorta in the heart.
v Sinoatrial Node (SA Node):Also called pacemaker. It is present in the right atrium and initiates cardiac impulse.
v Sinus Venosus: A chamber present before the right auricle to collect deoxygenated blood in the hearts of fishes and amphibians.
v Systemic Circulation:The flow of oxygenated blood from the left ventricle to all parts of the body (except lungs) and flow of deoxygenated blood from all parts of the body to the right atrium.
v Systole:Contraction of cardiac chambers.
v Tricuspid Valve:A valve consisting of three flaps present between right atrium and right ventricle.
v Vagus Nerve:A nerve from parasympathetic system that slows down the heart rate.
ADDITIONAL INFORMATION:
v Cardiology:Study of heart and its functions.
v Heart Skeleton:Ring of connective tissues in the heart muscle (myocardium) act as cardiac skeleton.
v Cardioscope:An instrument fitted with lens and light for examining the inside of the heart.
v Cardiomegaly:Enlargement of heart.
v Myocardial Ischaemia:Deficient blood supply to heart muscle, causes angina pectoris.
v Angiography:A non surgical technique of determining the arrangement of blood or lymphatic vessels by X-rays after injecting radio-opaque material. Angiography of the arteries supplying the heart is termed as coronary angiography.
v Varicose Vein:When the walls of a vein become weak, blood collects in it and distends it so much that the valve flaps cannot meet to check reverse flow of blood. Blood collects in the weakened vein, which is then called a varicose vein. Generally found in lower limb.
v Haemotoma:Blood collected in the tissues outside the blood vessels, a common skin bruise due to blow.
v Haemorrhage:Loss of blood from injured blood vessels.
v Haemodialysis: Removal of waste products from the blood in an artificial kidney.
v Blue Baby:A baby with a blue tinge to the skin due to insufficient oxygenation of the blood. It indicates a congenital heart or lung defect.
v Brachycardia:Decreased heart beat than the normal.
v Tachycardia: Increased heart beat than the normal.
v HDL (High Density Lipoproteins):These are called ‘good lipoproteins’. Their high level in the blood may help reduce the risk of coronary heart disesase.
v LDL (Low Density Lipoproteins):These are called ‘bad lipoproteins’. Their high level in the blood increases the risk of coronary heart diseases.
v Stroke:A thrombosis in the blood vessels in the brain.
v Haemorrhoids:These are varicose veins in the walls of rectum. They develop due to pressure as in constipation and pregnancy.
v Coronary Thrombosis:Formation of clot in the coronary artery. It generally occurs in the left anterior descending artery.
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