Name: Circulatory System in Amphibians
Uploaded: 2019-07-19
Duration: 3 min 3 s
Description: Is it true that amphibians have closed circulatory systems? Why is it said that amphibians have a partial or incomplete double circulation? To answer the questions, play the video.

Question

When are the sounds "LUBB" and "DUP" produced respectively during heart beat?

Accepted Answer

The sequence of events that occur from the beginning of one heartbeat to the beginning of another heartbeat (completion of one heartbeat) is called the cardiac cycle. The cardiac cycle involves two main phases of the heart chambers: systole and diastole.

Ventricular systole: The ventricles contract, which results in the rise of ventricular pressure, and both the atrioventricular valves are closed to prevent the backflow of the blood. The first sound LUBB is produced due to the closure of atrioventricular valves. The contraction of ventricles is so strong, as a result, the semilunar valves open. The blood is now pumped to the lungs through the pulmonary artery and to the body organs through the aorta.

Ventricular diastole: The ventricular systole is followed by ventricular diastole, during which, there is a fall in the ventricular pressure. The semilunar valves close to prevent the backflow of the blood. The second sound DUPP is produced. At the same time, the atrioventricular valves open to allow the flow of blood from both the auricles to their respective ventricles.

Column A	Column B
(a) SA Node	(i) Plasma
(b) Defective haemoglobin in RBC	(ii) Serum
(c) Muscle fibres located in the heart	(iii) Pacemaker
(d) The liquid squeezed out of blood during the clotting	(iv) Sickle cell anaemia
(e) Never tires, keep on contracting and relaxing	(v) Purkinje fibres
(f) Cardiac cycle	(vi) Cardiac muscles
(g) Liquid part of the blood without corpuscles	(vii) 0·85 sec

substance	From	To
_____	Lungs	Whole-body

Substance	From	To
Digested carbohydrates	Intestines	_____ (lungs/blood/whole body)

When are the sounds "LUBB" and "DUP" produced respectively during heart beat?

Important Questions on The Circulatory System

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