In humans, blood passes from the post-caval to the diastolic right atrium of heart due to
1. Pressure difference between the post-caval and atrium
2. Pushing open of the venous valves
3. Suction pull
4. Stimulation of the sinoatrial node
What is most likely to happen if the SA node suddenly stops generating the impulse?
1. The heart will stop.
2. The ventricles will contract, but the atria will stop.
3. Another part of the heart, possibly the AV node, will become the pacemaker.
4. The atria will keep contracting, but the ventricles will stop.
1. | Mollusks and arthropods have closed circulatory system |
2. | All vertebrates possess a muscular chambered heart |
3. | In fishes, the heart pumps out deoxygenated blood |
4. | The left atrium receives oxygenated blood in amphibians and reptiles |
Given below are four statements (a-d) regarding human blood circulatory system:
(a) | Arteries are thick-walled and have narrow lumen as compared to veins. |
(b) | Angina is acute chest pain when the blood circulation to the brain is reduced. |
(c) | Persons with blood group AB can donate blood to any person with any blood group under the ABO system. |
(d) | Calcium ions play a very important role in blood clotting. |
Which two of the above statements are correct?
1. (a) and (b) | 2. (b) and (c) |
3. (c) and (d) | 4. (a) and (d) |
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Capillary walls are different from the walls of veins and arteries as they are composed of:
1. endothelium only.
2. endothelium and smooth muscle.
3. a tunica interna and a tunica media.
4. smooth muscle and elastic connective tissue.
At which point, the pulmonary artery is different from the pulmonary vein:
1. Its lumen is broad
2. Its wall is thick
3. It has valves
4. It does not possess endothelium
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