Which one of the following is mainly responsible for the second heart sound?

• Closure of atrioventricular valves

• Opening of atrioventricular valves

• Closure of semilunar valves

• Thrust of blood on ventricular wall during atrial contraction

The vein which is formed from the capillaries of an organ and terminates into capillaries in some other organ before entering the heart is called

• pulmonary vein

• coronary vein

• portal vein

• systemic vein

Choose the right sequential phenomena among the following during the delivery of O₂ from blood to tissue.

I. Absorption of CO₂ by the blood.

II. Reaction of absorbed CO₂ with H₂O to form H₂CO₃ within RBC and its conversion into H⁺ and HCO₃^- ions.

III. Reaction of absorbed CO₂ with H₂O in plasma to form H₂CO₃ and its conversion into H⁺  and HCO₃^- ions.

IV. Combination of H⁺ with haeme portion of HbO₂ to release O₂.

V. Combination of HCO₃^- with haeme portion of HbO₂ to form reduced haemoglobin and release of O₂.

• I, II and V

• I, III and IV

• I, II and IV

• I, III and V

144.

Match the items in column I with those in column II and choose the correct answer.

Column I	Column II
A. Electroencephalography	1. A graphic recording of the electrical activity of heart
B. Electrocardiography	2. A graphic recording of the electrical activity of brain.
C. Endoscopy	3. A technique that gives image automatically in multiple planes.
D. MRI	4. To view within th body without cutting through the overlaying tissues.

• A- 2; B- 1; C- 4; D- 3

• A- 4; B- 2; C- 3; D- 4

• A- 1; B- 3; C- 2; D- 4

• A- 3; B- 4; C- 1; D- 2

The most abundant intracellular cation is

• Na⁺

• Ca²⁺

• H⁺

• K⁺

Figure shows schematic plan of blood circulation in human with labels - A to D. Identify the label and give its function/s.

• A - pulmonary vein - takes impure blood from body parts, pO₂ = 60 mmHg

• B - pulmonary artery - takes blood from heart to lungs, pO₂ = 90 mmHg

• C - vena cava - takes blood from body parts to right auricle, pCO₂ = 45 mmHg

• D - dorsal aorta - takes blood from heart to body parts, pO₂ = 95 mmHg

The diagram given here is the standard ECG of a normal person. The P - wave represents the

• contraction of both the atria

• initiation of the ventricular contraction

• beginning of the systole

• end of systole

Which valve is present at the opening of coronary sinus?

• Mitral valve

• Eustachian valve

• Thebesian valve

• Tricaspid valve

Which blood cells can engulf bacteria by phagocytosis?

• Eosinophil and basophil

• Basophil and lymphocyte

• Neutrophil and monocyte

• Neutrophil and lymphocyte

Which of the following factor(s) increase blood pressure?

• Increase of cardiac output

• Constriction of blood vessel

• Activation of parasympathetic nerve

• Increase of blood volume