Question

Q Give reason
During heart beat, auricles contract first then
ventricles .
b. left ventricles possess a thicker was than the
right ventricle.
e. There is no mixing of deoxygenated and
Oxygenated blood in human heart .​

Answer 1

Explanation:

a)

1. when heart atriums/ auricles contract, the blood from left atrium (oxygenated, came from lungs) gets into ventricles via mitral valve and hence the left ventricle then contract pump it to the whole body.
2. similarly, when right atrium contracts, the blood from atrium ( deoxygenated from vena cava) travels to ventricles via tricuspid valve. So then the ventricles contract and then the deoxygenated blood is pumped towards lungs.
3. So it is important to contract the atriums first and then the ventricles, so that the collected and stored blood from atrium travels into ventricle and then pumped towards respected areas ( for right it is lungs and for left it is whole body).

b)

1. Left ventricles posses thicker wall as it's job is to pump blood to whole body through contraction.
2. But right ventricle's wall is comparatively thinner as it's aim is to pump blood to transmit it towards lungs only.

c)

1. Human heart is four chambered and does not show any mixing of deoxy and oxy blood.
2. It is due the inter-ventricular septum between left and right ventricle, similarly an atreo ventricular septum.
3. (There is no mixing of deoxygenated and oxygenated blood in human heart due to the presence of inter-atrial and inter-ventricular septum. These septa completely divide the atria and ventricles into right and left to avoid mixing of blood. The backflow of the blood is prevented by the presence of valves).

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