Papillary muscles:
a) prevent the av valve leaflets bulging too far into the aorta during ventricular systole.
b) are a type of smooth muscle.
c) are smooth muscle extensions of the walls of the ventricles.
d) assist the opening of closure of the semi-lunar valves.
e) upon contraction, pull on the chordae tendinae holding the av valve leaflets closed.

The correct answer will be option-E.

Explanation:

The papillary muscles are the small muscles which arise in ventricles of the heart. These muscles are attached to the atrio-ventricular valves of the heart through chordae tendineae made up of fibrous tissues.

These muscle help prevent the backflow of the blood to the atria during ventricular systole or contraction. These muscle gets activated before the contraction which pulls the chordae tendinae attached to the cusps of the valve, thus closes the leaflets.

Thus, option- E is the correct answer.

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