D3) Nervous control of the cardiac cycle

Question 1

Sino Atrial Node (SAN)

Answer 1

Pacemaker
Located in the wall of the right atrium
SAN sends an impulse through the atrial walls
Causing them to contract
Force blood from the atrium to the ventricles

Question 2

Atrio-Ventricular Node (AVN)

Answer 2

Located in the centre of the heart- between atria & ventricles
Slows down the AVN signal
Allows atriums to contract before ventricles
Ventricles are relaxed to receive the blood from the atrium

Question 3

Bundle of HIS

Answer 3

Transports electrical impulses from the AVN
Found in the walls of the ventricle & septum

Question 4

Purkinje fibres

Answer 4

At the end of the bundle of HIS
Allow the ventricle to contract
Forcing blood out of the ventricles

Question 5

Autonomic nervous system

Answer 5

Regulates breathing & heart rate (Involuntary)

Question 6

Sympathetic nervous system

Answer 6

Prepares body for intense physical activity
Fight or flight response
During Exercise- cause heart & lungs to work harder

Question 7

Accelerator nerve

Answer 7

Increases firing rate to the SAN (number of impulses)
- atria contract more
Increased number of impulses to the AVN, bundle of HIS, Purkinje fibres
- increasing ventricle contraction
Allows you to produce more energy to meet demand & increase oxygen supply

Question 8

Parasympathetic nervous system

Answer 8

Relaxes the body as it slows high energy functions
Rest & digest response
After exercise- slow the heart rate to normal resting levels

Question 9

Vagus nerve

Answer 9

Decreases firing rate to the SAN
- atria contract less
Decreased number of impulses to the AVN, bundle of HIS & Purkinje fibres
- decreasing ventricle contraction
Lowers heart rate down to rest, less demand for oxygen for oxygen when exercise is finished