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#	Question	Answer
1	Why do living cells require an efficient transport mechanism?	To receive nutrients, oxygen, and essential substances and to remove harmful wastes continuously.
2	Which simple organisms circulate water through body cavities for exchange of substances?	Sponges and coelenterates.
3	What is the most commonly used body fluid for transport in higher organisms?	Blood.
4	Which other body fluid helps in transport of certain substances besides blood?	Lymph.
5	Define blood.	Blood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.
6	What are the two major components of blood?	Plasma and formed elements.
7	What is plasma?	Plasma is a straw-coloured, viscous fluid constituting nearly 55% of blood.
8	What percentage of plasma is water?	90 - 92%.
9	What percentage of plasma is made up of proteins?	6 - 8%.
10	Name the major plasma proteins.	Fibrinogen, globulins, and albumins.
11	What is the function of fibrinogen?	It is needed for clotting or coagulation of blood.
12	What is the primary role of globulins?	Defense mechanisms of the body.
13	What is the function of albumins?	They help in osmotic balance.
14	Which nutrients are present in plasma in transit?	Glucose, amino acids, and lipids.
15	What is serum?	Plasma without clotting factors.
16	Which components are collectively called formed elements?	Erythrocytes, leucocytes, and platelets.
17	What percentage of blood is constituted by formed elements?	Nearly 45%.
18	Which blood cells are the most abundant?	Erythrocytes or RBCs.
19	Where are RBCs formed in adults?	Red bone marrow.
20	What is the shape of mammalian RBCs?	RBCs are biconcave in shape and devoid of nucleus in most mammals.
21	Which protein gives RBCs their red colour?	Haemoglobin.
22	What is the normal haemoglobin level in healthy individuals?	12 - 16 g per 100 mL of blood.
23	What is the major function of haemoglobin?	Transport of respiratory gases.
24	What is the average lifespan of RBCs?	120 days.
25	Why are leucocytes called white blood cells?	Because they lack haemoglobin and are colourless.
26	What are the two main categories of WBCs?	Granulocytes and agranulocytes.
27	Which cells are associated with allergic reactions?	Eosinophils.
28	What percentage of WBCs are lymphocytes?	20 - 25%.
29	What are the two major types of lymphocytes?	B lymphocytes and T lymphocytes.
30	What is the function of B and T lymphocytes?	They are responsible for immune responses of the body.
31	What are platelets also called?	Thrombocytes.
32	From which cells are platelets produced?	Megakaryocytes in the bone marrow.
33	What is the major function of platelets?	They release substances involved in coagulation or clotting of blood.
34	What happens when platelet count decreases?	It leads to clotting disorders and excessive loss of blood.
35	Which two blood grouping systems are widely used all over the world?	ABO grouping and Rh grouping.
36	ABO grouping is based on the presence or absence of which antigens?	Surface antigens A and B on RBCs.
37	What are antigens?	Chemicals that can induce immune response.
38	What natural antibodies are present in blood group A?	Anti-B antibodies.
39	Which antigens are present on RBCs of blood group B?	Antigen B.
40	Which blood group has both A and B antigens?	AB blood group.
41	Which blood group has no antigens on RBCs?	O blood group.
42	Which blood group is called the universal donor?	Blood group O.
43	Why is blood group O called the universal donor?	Because it can be donated to persons with any blood group.
44	Which blood group is called the universal recipient?	Blood group AB.
45	Why is blood group AB called the universal recipient?	Because persons with AB blood group can accept blood from all groups.
46	What is Rh factor?	An antigen similar to one present in Rhesus monkeys found on RBC surface.
47	What are Rh positive individuals?	Individuals having Rh antigen on RBCs.
48	What are Rh negative individuals?	Individuals lacking Rh antigen on RBCs.
49	Why should Rh groups be matched before blood transfusion?	To avoid antibody formation against Rh antigens.
50	What is erythroblastosis foetalis?	A condition where Rh antibodies from an Rh-ve mother leak into the blood of an Rh+ve foetus and destroy its RBCs.
51	In which pregnancy does Rh incompatibility usually become dangerous?	Subsequent pregnancies after the first child.
52	How can erythroblastosis foetalis be prevented?	By administering anti-Rh antibodies to the mother immediately after first delivery.
53	What is coagulation or clotting of blood?	A mechanism to prevent excessive loss of blood after injury or trauma.
54	What is a blood clot mainly made of?	A network of fibrin threads trapping dead and damaged blood cells.
55	How are fibrins formed?	By conversion of inactive fibrinogens by thrombin.
56	Thrombin is formed from which inactive substance?	Prothrombin.
57	Which enzyme complex is required for blood coagulation reactions?	Thrombokinase.
58	What activates the mechanism of coagulation after injury?	Factors released by platelets and injured tissues.
59	Which ions play an important role in blood clotting?	Calcium ions.
60	What is tissue fluid or interstitial fluid?	Fluid released from blood capillaries into spaces between tissue cells.
61	How is tissue fluid formed?	Water and small water-soluble substances move out of capillaries into tissue spaces.
62	Which components usually remain inside blood vessels during tissue fluid formation?	Larger proteins and most formed elements.
63	What is the mineral composition of tissue fluid compared to plasma?	It has the same mineral distribution as plasma.
64	Through which fluid does exchange of nutrients and gases occur between blood and cells?	Tissue fluid (interstitial fluid).
65	What is the function of the lymphatic system?	It collects tissue fluid and drains it back to major veins.
66	What is lymph?	The fluid present in the lymphatic system.
67	What type of cells are present in lymph?	Specialised lymphocytes.
68	What is the role of lymphocytes in lymph?	They are responsible for immune responses.
69	Besides immunity, what is another function of lymph?	Transport of nutrients and hormones.
70	How are fats absorbed in the intestine?	Through lymph in the lacteals present in intestinal villi.
71	What are the two types of circulatory systems?	Open circulatory system and closed circulatory system.
72	In which animals is open circulatory system present?	Arthropods and molluscs.
73	What are sinuses in open circulatory system?	Open spaces or body cavities into which blood is pumped.
74	Which animals possess a closed circulatory system?	Annelids and chordates.
75	Why is closed circulation considered advantageous?	Because flow of fluid can be more precisely regulated.
76	What type of heart do all vertebrates possess?	Muscular chambered heart.
77	Describe the heart of fishes.	Two-chambered heart with one atrium and one ventricle.
78	Which vertebrates have a three-chambered heart?	Amphibians and most reptiles except crocodiles.
79	Which animals possess a four-chambered heart?	Crocodiles, birds, and mammals.
80	What is single circulation?	Blood passes through the heart only once in one complete circulation.
81	In which animals is single circulation present?	Fishes.
82	What is incomplete double circulation?	Oxygenated and deoxygenated blood mix in a single ventricle.
83	Which animals show incomplete double circulation?	Amphibians and reptiles.
84	What is double circulation?	Presence of two separate circulatory pathways without mixing of blood.
85	Which animals have double circulation?	Birds and mammals.
86	What is another name for the human circulatory system?	Blood vascular system.
87	What are the components of the human circulatory system?	Heart, blood vessels, and blood.
88	From which germ layer is the heart derived?	Mesoderm.
89	Where is the human heart located?	In the thoracic cavity between the lungs, slightly tilted to the left.
90	What is the approximate size of the human heart?	About the size of a clenched fist.
91	What protects the heart?	A double-walled membranous bag called pericardium.
92	What fluid is enclosed within the pericardium?	Pericardial fluid.
93	How many chambers are present in the human heart?	Four chambers.
94	Name the upper chambers of the heart.	Atria.
95	Name the lower chambers of the heart.	Ventricles.
96	What separates the right and left atria?	Inter-atrial septum.
97	What separates the right and left ventricles?	Inter-ventricular septum.
98	What separates atrium and ventricle of the same side?	Atrio-ventricular septum.
99	Which valve guards the opening between right atrium and right ventricle?	Tricuspid valve.
100	Which valve guards the opening between left atrium and left ventricle?	Bicuspid or mitral valve.
101	Which valves are present at the openings of the pulmonary artery and aorta?	Semilunar valves.
102	What is the function of heart valves?	They allow blood flow only in one direction and prevent backward flow.
103	Which type of muscles make up the heart?	Cardiac muscles.
104	Which chambers of the heart have thicker walls?	Ventricles.
105	What is nodal tissue?	Specialised cardiac musculature distributed in the heart.
106	What is SAN?	Sino-atrial node located in the right upper corner of the right atrium.
107	Where is the atrio-ventricular node (AVN) located?	In the lower left corner of the right atrium near the atrio-ventricular septum.
108	What is the AV bundle?	A bundle of nodal fibres continuing from the AVN.
109	Through which septum does the AV bundle pass?	Atrio-ventricular septum.
110	Into what does the AV bundle divide?	Right and left bundles.
111	What are Purkinje fibres?	Minute fibres arising from AV bundle branches throughout ventricular musculature.
112	What does autoexcitable mean in cardiac nodal tissue?	Ability to generate action potentials without external stimuli.
113	Which part of the nodal system generates maximum action potentials?	Sino-atrial node (SAN).
114	How many action potentials can SAN generate per minute?	70 - 75 per minute.
115	Why is SAN called the pacemaker?	Because it initiates and maintains rhythmic contractile activity of the heart.
116	What is the normal heart rate in humans?	70 - 75 beats per minute (average 72 beats/min).
117	What is joint diastole?	Relaxed state of all four chambers of the heart.
118	Which valves remain open during joint diastole?	Tricuspid and bicuspid valves.
119	Which valves remain closed during joint diastole?	Semilunar valves.
120	What is atrial systole?	Simultaneous contraction of both atria.
121	Which node generates the action potential initiating atrial systole?	SAN.
122	By approximately how much does atrial systole increase blood flow into ventricles?	About 30%.
123	How is the action potential conducted to the ventricles?	Through AVN and AV bundle.
124	What transmits impulses throughout ventricular musculature?	Bundle of His.
125	What is ventricular systole?	Contraction of ventricular muscles.
126	What happens to atria during ventricular systole?	Atria undergo relaxation (diastole).
127	What causes closure of tricuspid and bicuspid valves?	Increased ventricular pressure during ventricular systole.
128	Why do semilunar valves open?	Due to further increase in ventricular pressure.
129	What happens during ventricular diastole?	Ventricles relax and ventricular pressure falls.
130	Why do semilunar valves close during ventricular diastole?	To prevent backflow of blood into ventricles.
131	What causes reopening of tricuspid and bicuspid valves?	Pressure exerted by blood accumulated in atria.
132	Define cardiac cycle.	Sequential events in the heart repeated cyclically involving systole and diastole.
133	How many cardiac cycles occur per minute in a healthy heart?	About 72 cardiac cycles.
134	What is the duration of one cardiac cycle?	0.8 seconds.
135	What is stroke volume?	Volume of blood pumped out by each ventricle during one cardiac cycle.
136	What is the approximate stroke volume of each ventricle?	About 70 mL.
137	Define cardiac output.	Volume of blood pumped out by each ventricle per minute.
138	What is the average cardiac output in a healthy individual?	About 5000 mL or 5 litres per minute.
139	Why is cardiac output higher in athletes?	Due to higher stroke volume and/or heart rate.
140	What is ECG?	Graphical representation of electrical activity of the heart during a cardiac cycle.
141	How is a standard ECG recorded?	By connecting the patient to an electrocardiograph using three electrical leads.
142	Where are the three electrical leads attached in a standard ECG?	One to each wrist and one to the left ankle to continuously monitor heart activity.
143	Why are multiple leads attached to the chest region during ECG?	For detailed evaluation of heart function.
144	What do the peaks labeled P to T in an ECG represent?	Specific electrical activities of the heart.
145	What does the P-wave represent?	Electrical excitation (depolarisation) of the atria.
146	What happens due to atrial depolarisation represented by the P-wave?	Contraction of both atria.
147	What does the QRS complex represent?	Depolarisation of the ventricles.
148	What is initiated by the QRS complex?	Ventricular contraction.
149	What marks the beginning of systole in ECG?	Contraction shortly after the Q wave.
150	What does the T-wave represent?	Repolarisation of ventricles.
151	What does the end of the T-wave indicate?	End of systole.
152	How can heart beat rate be determined from ECG?	By counting the number of QRS complexes in a given time period.
153	What does deviation from normal ECG shape indicate?	Possible abnormality or disease.
154	Why is ECG clinically important?	It helps detect abnormalities and diseases of the heart.
155	What are the three layers of arteries and veins?	Tunica intima, tunica media, and tunica externa.
156	What forms the tunica intima?	Inner lining of squamous endothelium.
157	What does the tunica media consist of?	Smooth muscle and elastic fibres.
158	What forms the tunica externa?	Fibrous connective tissue with collagen fibres.
159	In which blood vessels is the tunica media comparatively thin?	Veins.
160	Which ventricle pumps blood into the pulmonary artery?	Right ventricle.
161	Which ventricle pumps blood into the aorta?	Left ventricle.
162	What type of blood enters the pulmonary artery?	Deoxygenated blood.
163	Where is blood oxygenated in pulmonary circulation?	Lungs.
164	Which vessels carry oxygenated blood from lungs to the left atrium?	Pulmonary veins.
165	Define pulmonary circulation.	Circulation of blood from right ventricle to lungs and back to left atrium.
166	What is systemic circulation?	Circulation of oxygenated blood from left ventricle to body tissues and return of deoxygenated blood to right atrium.
167	Which vessels carry oxygenated blood to tissues in systemic circulation?	Arteries, arterioles, and capillaries.
168	Which vessels collect deoxygenated blood from tissues?	Venules, veins, and vena cava.
169	What substances are supplied to tissues through systemic circulation?	Nutrients, oxygen, and other essential substances.
170	What substances are removed from tissues by systemic circulation?	Carbon dioxide and other harmful substances.
171	What is the hepatic portal system?	Unique vascular connection between digestive tract and liver.
172	What is the function of the hepatic portal vein?	Carries blood from intestine to liver before systemic circulation.
173	What is the coronary system?	Special blood vessel system supplying blood to cardiac musculature.
174	Why is the heart called myogenic?	Because its activities are auto-regulated by specialised muscles (nodal tissue).
175	Which part of the brain moderates cardiac function?	Neural centre in the medulla oblongata.
176	Through which system does the medulla oblongata regulate heart activity?	Autonomic nervous system (ANS).
177	What is the effect of sympathetic nerves on the heart?	Increase heart rate, strength of ventricular contraction, and cardiac output.
178	What is the effect of parasympathetic nerves on the heart?	Decrease heart rate, conduction speed, and cardiac output.
179	Which hormones can increase cardiac output?	Adrenal medullary hormones.
180	What is hypertension?	Blood pressure higher than normal (120/80).
181	What does 120 mm Hg represent in blood pressure?	Systolic or pumping pressure.
182	What does 80 mm Hg represent in blood pressure?	Diastolic or resting pressure.
183	At what blood pressure is a person considered hypertensive?	140/90 or higher.
184	Which organs are affected by high blood pressure?	Heart, brain, and kidney.
185	What is Coronary Artery Disease (CAD)?	Disease affecting blood vessels supplying blood to heart muscles.
186	What is another name for Coronary Artery Disease?	Atherosclerosis.
187	What causes narrowing of arteries in CAD?	Deposits of calcium, fat, cholesterol, and fibrous tissues.
188	What is angina also called?	Angina pectoris.
189	What is the main symptom of angina?	Acute chest pain due to insufficient oxygen reaching heart muscles.
190	In which age group is angina more common?	Middle-aged and elderly people.
191	What causes angina?	Conditions affecting blood flow.
192	What is heart failure?	State in which the heart cannot pump blood effectively to meet body needs.
193	What is another name for heart failure?	Congestive heart failure.
194	Why is heart failure called congestive heart failure?	Because congestion of lungs is one of its main symptoms.
195	Is heart failure the same as cardiac arrest?	No. Cardiac arrest means the heart stops beating.
196	Is heart failure the same as a heart attack?	No. Heart attack occurs due to sudden damage to heart muscle from inadequate blood supply.
197	What type of tissue is blood?	Fluid connective tissue.
198	What is the function of blood in vertebrates?	Transport essential substances and carry waste substances.
199	Which fluid besides blood helps in transport of substances?	Lymph (tissue fluid).
200	What are the formed elements of blood?	RBCs, WBCs, and platelets.
201	What are RBCs also called?	Erythrocytes.
202	What are WBCs also called?	Leucocytes.
203	What are platelets also called?	Thrombocytes.
204	On what basis are human blood groups classified into A, B, AB, and O?	Presence or absence of A and B antigens on RBCs.
205	What is Rh factor?	Another antigen present or absent on RBC surface.
206	How is lymph different from blood?	Lymph lacks high protein content and formed elements found in blood.
207	What type of circulatory system do vertebrates possess?	Closed circulatory system.
208	What are the components of the human circulatory system?	Heart, blood vessels, and blood.
209	How many atria and ventricles are present in the human heart?	Two atria and two ventricles.
210	What does auto-excitable cardiac musculature mean?	Cardiac muscles can generate impulses on their own.
211	Which node acts as the pacemaker of the heart?	Sino-atrial node (SAN).
212	How many action potentials per minute are generated by SAN?	70 - 75 per minute.
213	What is systole?	Contraction phase of atria and ventricles.
214	What is diastole?	Relaxation phase of atria and ventricles.
215	What is stroke volume?	About 70 mL blood pumped out by each ventricle during one cardiac cycle.
216	Define cardiac output.	Volume of blood pumped out by each ventricle per minute.
217	What is the approximate cardiac output in humans?	About 5 litres per minute.
218	What is electrocardiogram (ECG)?	Recording of electrical activity of the heart obtained using an electrocardiograph.
219	Name the two circulatory pathways in complete double circulation.	Pulmonary circulation and systemic circulation.
220	What happens in pulmonary circulation?	Deoxygenated blood goes from right ventricle to lungs and oxygenated blood returns to left atrium.
221	What happens in systemic circulation?	Oxygenated blood goes from left ventricle to body tissues and deoxygenated blood returns to right atrium.
222	Can heart functions be moderated despite being autoexcitable?	Yes, by neural and hormonal mechanisms.