control of heart rate

Question 1

describe the role of receptors and the nervous system in the increase of heart rate during exersice

Answer 1

chemoreceptors will detect a change in co2 (increase)
they will send impulses to the cardiac centre
this sends more impulses to the SAN through sympathetic nervous system

Question 2

explain how the heart beat is initiated by the SAN

Answer 2

electrical activity through the bundle of His
wave of electrical activity passes through both ventricles at the same time

Question 3

explain what happens of there is decrease in blood pressure

Answer 3

stimulus is low blood pressure
this stimulus is detected by baroreceptors in the right atrial wall
more impulses sent to medulla oblongata
impulses sent via the parasympathetic nervous system to the SAN
this reduces heart rate responsively
blood pressure decreases

Question 4

how is heart rate controlled by SAN and AVN

Answer 4

SAN releases a wave of depolarisation
this causes muscle contraction in cardiac muscle
the AVN releases another wave once the first has reached cardiac muscle
this doesnt reach the ventricles due to layer of non conductive tissue between them
instead it travels through the bundle of His and punkye

Question 5

why is there a delay between the first and second depolarisation

Answer 5

allows the atrium to pump all blood to ventricles s