1. Blood & Plasma
| # | Keyword | Description |
|---|---|---|
| 1 | Blood | A fluid connective tissue that circulates in the body; transports nutrients, gases, wastes, and hormones. |
| 2 | Plasma | The liquid matrix of blood; a pale yellow fluid making up about 55% of blood volume. |
| 3 | Fluid matrix | The liquid portion (plasma) in which formed elements are suspended. |
| 4 | Formed elements | Cellular components of blood: RBCs, WBCs, and platelets. |
| 5 | Fibrinogen | A plasma protein essential for blood clotting; converted to fibrin during coagulation. |
| 6 | Globulins | Plasma proteins involved in defense mechanisms (antibodies) and transport. |
| 7 | Albumins | Most abundant plasma proteins; maintain osmotic balance and transport substances. |
| 8 | Serum | Plasma minus clotting factors; the fluid left after blood clots. |
| 9 | Osmotic balance | Maintenance of water balance between blood and tissues; regulated by plasma proteins. |
| 10 | Clotting factors | Proteins in plasma that participate in the cascade of reactions leading to blood clotting. |
| 11 | Connective tissue | A tissue type that connects/supports body structures; blood is a fluid connective tissue. |
2. Formed Elements
| # | Keyword | Description |
|---|---|---|
| 12 | Erythrocytes | Red Blood Cells (RBCs); biconcave, enucleate cells that carry oxygen via haemoglobin. |
| 13 | Red Blood Cells (RBC) | Most numerous blood cells; lifespan ~120 days; produced in red bone marrow. |
| 14 | Leucocytes | White Blood Cells (WBCs); colourless, nucleated cells involved in immunity and defense. |
| 15 | White Blood Cells (WBC) | Less numerous than RBCs; include granulocytes and agranulocytes. |
| 16 | Platelets (Thrombocytes) | Cell fragments produced from megakaryocytes; essential for blood clotting. |
| 17 | Megakaryocytes | Large bone marrow cells that fragment to form platelets (thrombocytes). |
| 18 | Haemoglobin | Iron-containing red pigment in RBCs that binds and transports oxygen. |
| 19 | Biconcave | Disc shape of RBCs — concave on both sides — increasing surface area for gas exchange. |
| 20 | Red bone marrow | Site of production of RBCs, WBCs, and platelets (haematopoiesis). |
| 21 | Spleen | Organ that destroys old RBCs; called the 'graveyard of RBCs'. |
| 22 | Granulocytes | WBCs with granules in cytoplasm: neutrophils, eosinophils, and basophils. |
| 23 | Agranulocytes | WBCs without visible cytoplasmic granules: lymphocytes and monocytes. |
| 24 | Neutrophils | Most abundant WBCs; phagocytic cells that engulf bacteria and foreign particles. |
| 25 | Eosinophils | WBCs that resist infections; involved in allergic reactions and parasite defense. |
| 26 | Basophils | Rarest WBCs; release histamine and heparin; involved in inflammatory responses. |
| 27 | Lymphocytes | WBCs forming 20–25% of total; include B and T cells for immune responses. |
| 28 | Monocytes | Largest WBCs; differentiate into macrophages; involved in phagocytosis. |
| 29 | B lymphocytes | Produce antibodies (humoral immunity) in response to antigens. |
| 30 | T lymphocytes | Mediate cell-mediated immunity; attack infected or cancerous cells directly. |
| 31 | Phagocytic cells | Cells (e.g., neutrophils, monocytes) that engulf and destroy pathogens. |
| 32 | Histamine | Chemical released by basophils/mast cells during allergic and inflammatory reactions. |
| 33 | Serotonin | Released by platelets and basophils; involved in vasoconstriction and inflammation. |
| 34 | Heparin | Anticoagulant substance secreted by basophils; prevents clotting inside vessels. |
3. Blood Groups
| # | Keyword | Description |
|---|---|---|
| 35 | ABO grouping | Blood classification system based on presence/absence of A and B antigens on RBCs. |
| 36 | Rh grouping | Blood classification based on presence/absence of Rh (Rhesus) antigen on RBCs. |
| 37 | Blood group A | Has antigen A on RBCs and anti-B antibody in plasma. |
| 38 | Blood group B | Has antigen B on RBCs and anti-A antibody in plasma. |
| 39 | Blood group AB | Has both A and B antigens; no antibodies; called universal recipient. |
| 40 | Blood group O | Has no antigens; has both anti-A and anti-B antibodies; universal donor. |
| 41 | Antigens | Surface molecules on RBCs (A, B, Rh) that trigger antibody production if foreign. |
| 42 | Antibodies | Proteins in plasma that react with foreign antigens and cause agglutination. |
| 43 | Universal donor | Blood group O (Rh-ve) can donate to any group as it has no surface antigens. |
| 44 | Universal recipient | Blood group AB (Rh+ve) can receive from any group as it has no antibodies. |
| 45 | Blood transfusion | Transfer of blood from donor to recipient; compatibility of blood group is critical. |
| 46 | Agglutination | Clumping of RBCs caused by antigen-antibody reaction in incompatible transfusion. |
| 47 | Rh positive (Rh+ve) | RBCs carry the Rh antigen; about 80% of humans are Rh+ve. |
| 48 | Rh negative (Rh-ve) | RBCs lack the Rh antigen; can develop anti-Rh antibodies if exposed to Rh+ve blood. |
| 49 | Rhesus monkey | Species in which the Rh antigen was first discovered, giving it its name. |
| 50 | Erythroblastosis foetalis | Condition in which maternal anti-Rh antibodies destroy foetal RBCs in an Rh+ve foetus. |
| 51 | Rh incompatibility | Mismatch between Rh-ve mother and Rh+ve foetus; dangerous in second pregnancy. |
4. Coagulation of Blood
| # | Keyword | Description |
|---|---|---|
| 52 | Coagulation | The process of blood clotting to prevent excessive blood loss after injury. |
| 53 | Coagulam | The clot formed at a wound site; a meshwork of fibrin trapping blood cells. |
| 54 | Fibrin | Insoluble protein threads formed from fibrinogen; forms the clot framework. |
| 55 | Thrombin | Enzyme that converts fibrinogen to fibrin during the clotting cascade. |
| 56 | Prothrombin | Inactive precursor of thrombin; activated during the clotting cascade. |
| 57 | Thrombokinase | Enzyme released by injured tissues/platelets that initiates the coagulation cascade. |
| 58 | Cascade process | Sequential series of enzyme activations that amplify the clotting response. |
| 59 | Calcium ions (Ca²⁺) | Essential cofactors at multiple steps of the blood coagulation cascade. |
5. Lymph (Tissue Fluid)
| # | Keyword | Description |
|---|---|---|
| 60 | Lymph | A colourless fluid similar to blood plasma; flows through the lymphatic system. |
| 61 | Tissue fluid | Fluid that accumulates in intercellular spaces, derived from blood plasma. |
| 62 | Interstitial fluid | Another name for tissue fluid; fills spaces between cells in tissues. |
| 63 | Lymphatic system | Network of vessels draining lymph from tissues and returning it to blood. |
| 64 | Lacteals | Lymphatic vessels in intestinal villi that absorb digested fats (chyle). |
| 65 | Intestinal villi | Finger-like projections of the small intestine mucosa; contain lacteals. |
| 66 | Fat absorption | Digested fats (fatty acids and glycerol) are absorbed via lacteals into lymph. |
6. Circulatory Pathways
| # | Keyword | Description |
|---|---|---|
| 67 | Open circulatory system | Blood flows through open sinuses/body cavities; found in arthropods and molluscs. |
| 68 | Closed circulatory system | Blood flows entirely within vessels; found in annelids and chordates. |
| 69 | Sinuses | Open spaces/cavities in the body through which blood flows in open circulatory systems. |
| 70 | Single circulation | Blood passes through the heart once per circuit; seen in fishes. |
| 71 | Double circulation | Blood passes through the heart twice — once each for pulmonary and systemic circuits. |
| 72 | Incomplete double circulation | Partial separation of oxygenated and deoxygenated blood; seen in amphibians and most reptiles. |
| 73 | Pulmonary circulation | Path from right ventricle → lungs → left atrium; blood gets oxygenated. |
| 74 | Systemic circulation | Path from left ventricle → body tissues → right atrium; delivers O₂ to tissues. |
| 75 | 2-chambered heart | Heart of fishes; one atrium and one ventricle; suited for single circulation. |
| 76 | 3-chambered heart | Heart of amphibians and most reptiles; two atria and one ventricle. |
| 77 | 4-chambered heart | Heart of crocodiles, birds, and mammals; complete separation of oxygenated and deoxygenated blood. |
7. Human Heart — Structure
| # | Keyword | Description |
|---|---|---|
| 78 | Heart | Muscular pumping organ located in the thoracic cavity; drives blood through the body. |
| 79 | Pericardium | Double-walled membranous sac enclosing the heart. |
| 80 | Pericardial fluid | Fluid within the pericardium that reduces friction during heart contractions. |
| 81 | Right atrium | Upper right chamber; receives deoxygenated blood from the body via vena cava. |
| 82 | Left atrium | Upper left chamber; receives oxygenated blood from lungs via pulmonary veins. |
| 83 | Right ventricle | Lower right chamber; pumps deoxygenated blood to lungs via pulmonary artery. |
| 84 | Left ventricle | Lower left chamber; pumps oxygenated blood to the body via the aorta. |
| 85 | Inter-atrial septum | Partition separating the right and left atria. |
| 86 | Inter-ventricular septum | Partition separating the right and left ventricles. |
| 87 | Atrio-ventricular septum | Partition between the atria and ventricles. |
| 88 | Tricuspid valve | Three-flap valve between right atrium and right ventricle; prevents backflow. |
| 89 | Bicuspid valve (Mitral valve) | Two-flap valve between left atrium and left ventricle; prevents backflow. |
| 90 | Semilunar valves | Valves at the opening of pulmonary artery and aorta; prevent backflow into ventricles. |
| 91 | Chordae tendinae | Tendon-like cords attaching AV valves to papillary muscles; prevent valve inversion. |
| 92 | Aorta | Largest artery; carries oxygenated blood from the left ventricle to the body. |
| 93 | Vena cava | Large veins (superior and inferior) returning deoxygenated blood to the right atrium. |
| 94 | Pulmonary artery | Carries deoxygenated blood from the right ventricle to the lungs. |
| 95 | Pulmonary veins | Carry oxygenated blood from the lungs to the left atrium. |
| 96 | Sino-atrial node (SAN) | Pacemaker of the heart; generates action potentials at 70–75/min in the right atrium. |
| 97 | Atrio-ventricular node (AVN) | Node at the lower left corner of right atrium; relays impulse from SAN to ventricles. |
| 98 | AV bundle | Bundle of nodal fibres conducting impulse from AVN through atrio-ventricular septa. |
| 99 | Bundle of His | Alternative name for the AV bundle; conducts electrical impulse to ventricular walls. |
| 100 | Purkinje fibres | Fine fibres branching from AV bundle throughout ventricular musculature; conduct impulse. |
| 101 | Nodal tissue | Specialised cardiac muscle tissue that can generate and conduct action potentials. |
| 102 | Cardiac muscles | Involuntary, striated muscle cells that make up the heart wall. |
| 103 | Pacemaker | The SAN; sets the rhythm of the heartbeat at ~70–75 beats per minute. |
| 104 | Autoexcitable | Property of nodal tissue to generate action potentials without external stimuli. |
| 105 | Myogenic | Heart contraction originating from muscle tissue itself, not from neural signals. |
| 106 | Action potential | Electrical impulse generated by nodal cells that triggers cardiac muscle contraction. |
8. Cardiac Cycle
| # | Keyword | Description |
|---|---|---|
| 107 | Cardiac cycle | One complete sequence of contraction and relaxation of the heart; lasts ~0.8 seconds. |
| 108 | Systole | Phase of cardiac contraction; blood is pumped out of the chamber. |
| 109 | Diastole | Phase of cardiac relaxation; chamber fills with blood. |
| 110 | Atrial systole | Contraction of both atria simultaneously, pushing blood into ventricles. |
| 111 | Ventricular systole | Contraction of both ventricles; pumps blood into pulmonary artery and aorta. |
| 112 | Ventricular diastole | Relaxation of ventricles; coincides with atrial contraction. |
| 113 | Joint diastole | Phase when all four chambers are relaxed simultaneously; blood flows freely. |
| 114 | Stroke volume | Volume of blood pumped by each ventricle per beat; approximately 70 mL. |
| 115 | Cardiac output | Volume of blood pumped by each ventricle per minute; ~5000 mL (5 litres) normally. |
| 116 | Heart rate | Number of cardiac cycles (heartbeats) per minute; normally 72 beats/min. |
| 117 | Heart sounds | Two sounds (lub and dub) produced during each cardiac cycle; heard via stethoscope. |
| 118 | Lub (First heart sound) | Sound produced by closure of tricuspid and bicuspid valves at start of ventricular systole. |
| 119 | Dub (Second heart sound) | Sound produced by closure of semilunar valves at the end of ventricular systole. |
| 120 | Stethoscope | Instrument used to auscultate (listen to) heart sounds and other body sounds. |
9. Electrocardiogram (ECG)
| # | Keyword | Description |
|---|---|---|
| 121 | Electrocardiogram (ECG) | Graphical recording of the electrical activity of the heart during a cardiac cycle. |
| 122 | Electrocardiograph | The machine used to record an ECG; displays voltage traces on a screen. |
| 123 | P-wave | ECG wave representing depolarisation (electrical excitation) of the atria. |
| 124 | QRS complex | ECG deflection representing depolarisation of the ventricles; initiates ventricular contraction. |
| 125 | T-wave | ECG wave representing repolarisation (return to resting state) of the ventricles. |
| 126 | Depolarisation | Reversal of electrical charge across the cell membrane triggering muscle contraction. |
| 127 | Repolarisation | Restoration of resting electrical charge; corresponds to muscle relaxation. |
| 128 | Excitation | Electrical stimulation of cardiac muscle cells triggering their contraction. |
| 129 | Electrical leads | Electrodes attached to the body surface to detect the heart's electrical signals. |
| 130 | Cardiac arrest | Sudden cessation of heart activity; ECG shows a flat line (no QRS complexes). |
10. Blood Vessels
| # | Keyword | Description |
|---|---|---|
| 131 | Arteries | Blood vessels carrying blood away from the heart; thick-walled and elastic. |
| 132 | Veins | Blood vessels carrying blood towards the heart; thinner walls, contain valves. |
| 133 | Arterioles | Small branches of arteries that lead into capillaries. |
| 134 | Venules | Small vessels collecting blood from capillaries and joining into veins. |
| 135 | Capillaries | Smallest blood vessels; site of exchange of gases, nutrients, and wastes with tissues. |
| 136 | Tunica intima | Innermost layer of blood vessels; lined with squamous endothelium. |
| 137 | Tunica media | Middle layer of blood vessels; composed of smooth muscle and elastic fibres. |
| 138 | Tunica externa | Outermost layer of blood vessels; composed of collagen fibres for structural support. |
| 139 | Squamous endothelium | Flat epithelial cells lining the inner surface (lumen) of blood vessels. |
| 140 | Lumen | The inner space/channel of a blood vessel through which blood flows. |
| 141 | Elastic fibres | Fibres in tunica media allowing arteries to stretch and recoil with each heartbeat. |
| 142 | Collagen fibres | Tough protein fibres in tunica externa giving structural support to vessels. |
| 143 | Hepatic portal system | Unique vascular pathway carrying blood from intestine to liver before systemic circulation. |
| 144 | Hepatic portal vein | Vein that carries nutrient-rich blood from the digestive tract to the liver. |
| 145 | Coronary system | Network of blood vessels supplying blood exclusively to the cardiac musculature. |
| 146 | Dorsal aorta | Main artery distributing oxygenated blood from the heart to all body tissues. |
11. Regulation of Cardiac Activity
| # | Keyword | Description |
|---|---|---|
| 147 | Autonomic nervous system (ANS) | Part of the nervous system controlling involuntary functions including heart rate. |
| 148 | Sympathetic nerves | ANS nerves that increase heart rate and cardiac output during stress or activity. |
| 149 | Parasympathetic nerves | ANS nerves that decrease heart rate and slow impulse conduction during rest. |
| 150 | Medulla oblongata | Brain region containing neural centres that regulate cardiac activity. |
| 151 | Adrenal medullary hormones | Hormones (e.g., adrenaline) secreted by the adrenal gland that can increase cardiac output. |
| 152 | Neural signals | Nerve impulses from the ANS that modulate heart rate and contraction strength. |
| 153 | Hormonal mechanisms | Regulation of heart activity by blood-borne hormones such as adrenaline. |
12. Disorders of the Circulatory System
| # | Keyword | Description |
|---|---|---|
| 154 | Hypertension | Persistently high blood pressure (≥140/90 mm Hg); damages heart and vital organs. |
| 155 | High Blood Pressure | Another term for hypertension; increases risk of heart disease, stroke, and kidney damage. |
| 156 | Systolic pressure | Blood pressure during ventricular contraction; the higher number (normal: 120 mm Hg). |
| 157 | Diastolic pressure | Blood pressure during ventricular relaxation; the lower number (normal: 80 mm Hg). |
| 158 | mm Hg | Millimetres of mercury; unit used to measure blood pressure. |
| 159 | Coronary Artery Disease (CAD) | Disease affecting arteries supplying the heart muscle; often caused by atherosclerosis. |
| 160 | Atherosclerosis | Narrowing and hardening of arteries due to deposits of calcium, fat, and cholesterol. |
| 161 | Angina (Angina pectoris) | Acute chest pain caused by insufficient oxygen supply to the heart muscle. |
| 162 | Heart failure | Condition where the heart cannot pump blood effectively to meet the body's needs. |
| 163 | Congestive heart failure | Heart failure with lung congestion as a major symptom; not the same as cardiac arrest. |
| 164 | Heart attack | Sudden death of heart muscle tissue due to inadequate blood supply; myocardial infarction. |
| 165 | Cholesterol | Fatty substance that accumulates in arterial walls in atherosclerosis. |
| 166 | Fat deposits | Accumulation of lipids in artery walls contributing to narrowing of the lumen. |
| 167 | Calcium deposits | Mineral accumulation in artery walls causing hardening (calcification) in CAD. |
| 168 | Fibrous tissues | Tough connective tissue accumulating in artery walls as part of atherosclerotic plaques. |