MICROANATOMY

BLOOD CARDIOVASCULAR SYSTEM LYMPHOID ORGANS

LYMPHATIC SYSTEM

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
____ starts in the heart and causes the heart muscle to contract and the heart to beat
A
Enzymes
B
Electrical impulses
C
Hormones
D
Neurons
Explanation: 

Detailed explanation-1: -Normally, the heartbeat starts in the right atrium in a group of special heart cells called the sinoatrial (or sinus) node. These cells act as a pacemaker for the heart. The heart’s pacemaker sends out an electrical signal (impulse) that spreads throughout the heart along electrical pathways.

Detailed explanation-2: -An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node). This is a small mass of specialized tissue located in the right upper chamber (atria) of the heart. The sinus node generates an electrical stimulus regularly, 60 to 100 times per minute under normal conditions.

Detailed explanation-3: -Cardiac muscle, like skeletal muscle, is made up of sarcomeres that allow for contractility. However, unlike skeletal muscle, cardiac muscle is under involuntary control. The cardiac muscle is responsible for the contractility of the heart and, therefore, the pumping action.

Detailed explanation-4: -So, the correct option is ‘ S A Node AV Node AV Bundle Purkinje fibres’.

There is 1 question to complete.