Question: 100% NCERT covered from Particular Keyword.Explanations are 100% from NCERT | [Difficult level: Easy] From NCERT NEET Derived Question.
The cardiac pacemaker in a patient fails to function normally.
The doctors find that an artificial pacemaker is to be grafted
in him. It is likely that it will be grafted at the site of
(a) Atrioventricular bundle
(b) Purkinje system
(c) Sinuatrial node
(d) Atrioventricular node
Answer: c
👉The entire heart is made of cardiac muscles.
👉A specialised cardiac musculature
called the nodal tissue is also distributed in the heart .
👉A patch of Nodal tissue is present in the right upper corner of the right atrium
called the sino-atrial node (SAN)
👉Another mass of nodal tissue is seen in
the lower left corner of the right atrium close to the atrio-ventricular septum
called the atrio-ventricular node (AVN).
👉A bundle of nodal fibres, atrioventricular
bundle (AV bundle) continues from the AVN which passes
through the atrio-ventricular septa to emerge on the top of the interventricular
septum and immediately divides into a right and left bundle.
These branches give rise to minute fibres throughout the ventricular
musculature of the respective sides and are called purkinje fibres.
👉The nodal musculature has the ability to generate action potentials without
any external stimuli, i.e., it is autoexcitable.
👉The SAN can generate the maximum number of action
potentials, i.e., 70-75 min^–1, and is responsible for initiating and
maintaining the rhythmic contractile activity of the heart. Therefore, it is
called the pacemaker.
👉Sino-atrial node
(SAN) generates the maximum number of action protentials per minute (70-75/min) and
therefore, it sets the pace of the activities of the heart. Hence it is called the Pacemaker.
👉
Sino-atrial node is called the pacemaker of our heart. Why?