Choose the correct option for $A , B$ and $C$
Auto-Rhythmicity of Heart
Automatic rhythmicity of the heart is the ability to contract spontaneously, Mammalian heart is myogenic. It means heart beat results from a wave of electrical potential called cardiac impulse arising from sinoatrial node $SA$ node and spreading over cardiac chambers.
$SA-$node lies in the wall of right atrium near opening of superior vena cava and contract about $72$ times per minute. Form $SA$ node cardiac impulse travels to atrioventricular node (lies between right atrium and ventricle)
Then pass to $AV$ bundle (also called bundle to His) and its branches reaches to the Purkinje fibres in ventricles.
Bundle of His provides the only route for the transmission of wave of excitation from atria to ventricles. Purkinje fibres conducts the impulses five times more rapidly than surrounding cells. It forms a pathway for conduction of impulse that ensures that the heart muscle contracts in the most efficient manner
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| Column I (Features of developing embryo) | Column II (Time of Formation) |
| (A) Heart | (i) End of 24 weeks |
| (B) Formation of eyelashes | (ii) Fifth month |
| (C) First movement | (iii) End of 12 weeks |
| (D) Formation of major organs | (iv) After 1 month of pregnancy |
$I$. Avoid sex with unknown
$II$. Avoid sex with multiple partner
$III$. Do protected sex
$IV$. Avoid sharing needle
$(i)$ They have a hard and non-pliable ground substance rich in calcium salts and collagen fibres.
$(ii)$ They support and protect softer tissues and organs.
$(iii)$ Osteocytes are present in the spaces called lacunae.
$(iv)$ They also interact with skeletal muscles attached to them to bring about movements.
Which of the following type of tissue is being described by above statements
$I.$ $1100\; mL -1200\; mL$
$II.$ $500\; mL$
$III.$ $5000\; mL -6000\; mL$
Choose the correct option