Question

choose the correct statements

Answer 1

Answer:

b .nomber is correct

Explanation:

b .nomber is correct

Answer 2

Answer:

The correct statements are as follows-

(a) Before birth, foramen ovale allows the blood to pass from the right atrium to the left atrium, thus bypassing the pulmonary circulation.

(b) Heart is protected by a double-walled pericardium.

(c) The muscle fibres present in the heart are different from smooth muscles in being mesodermal in origin.

Explanation:

• (a) Foramen of ovale or Fossa ovalis, is a depression present on the interatrial septum. This represents the opening present in between two atrial during foetal life.

• In the fetal heart foramen of ovale allows the blood to enter the left atrium from the right atrium. The shunt allows blood flow to bypass the lungs (pulmonary circulation). Thus this statement is correct.

• (b) The heart is enclosed in a double-walled sac called the pericardium. distinct layers are present in the wall of the heart, out of which the outermost is the pericardium.

• The outer wall is a thick fibrous layer and the inner one is thin but again double layer known as the serous layer. Thus it is correct.  

• (c) The muscle fibres present in the heart are similar to skeletal muscles but are branched & interconnected with each other. They are mesodermal in origin. Thus it is correct.

• (d) Near the opening of the superior vena cava, the SA node is present. As it generates waves of contraction, it is also called a Pacemaker.
• Near the tricuspid valve, the AV node is present on the interatrial septum.  
• Nodal tissues such as the AV nodes and SA nodes are modified heart muscles with an inherent power of generating a wave of contraction. Thus it is an incorrect statement.

#SPJ3