Heart Rate Regulation

Question 1

Neural heart rate regulation EXERCISE:

Answer 1

1. Chemoreceptors detect increase in CO2/decrease in 02
2. proprioceptors detect increase in muscle movement
3. Baroreceptors detect increase in blood pressure
   —> CCC (cardiac control centre) (controlled by autonomic nervous system) —> sympathetic nervous system —> accelerator nerve —> increases firing rate of SA node/ increase HR

Question 2

Neural heart rate regulation RECOVERY:

Answer 2

1.chemoreceptors detects decrease in CO2/ increase in O2
2. Proprioceptors detect decreased muscle movement
3. Baroreceptors detect decreased blood pressure
—> CCC (cardiac control centre) (controlled by autonomic nervous system) —> parasympathetic nervous system —> vagus nerve —> decreases firing of SA node/ decreases HR

Question 3

Intrinsic heart rate control

Answer 3

1. Increased temperature -> increase speed of nerve transmission -> increased blood viscosity
2. Increased Venous return -> more blood returns back to right atrium -> right atrium stretch causes SA to increase firing rate
   —> SA node —> blood is forced down into the ventricles —> increased ventricle stretch/ contraction force —> increased stroke volume/ cardiac output

Question 4

Hormonal control of heart rate

Answer 4

Release of Adrenaline from the adrenal gland. —> sympathetic nervous system —> increases firing rate of SA node/ increases HR

Question 5

Cardiac cycle

Answer 5

Atrial systole - atria contract which forces blood into ventricles
Ventricular systole - ventricles contract which pushes blood away from heart
Diastole - the relaxation phase of the heart which allows blood to enter heart

Question 6

Conduction system

Answer 6

SA node
AV node
Bundle of his
Bundle branches
Purkinje fibres

Question 7

SA node

Answer 7

Generate electrical impulse causing atria walls to contract

Question 8

AV node

Answer 8

Delays electrical impulse by 0.1 secs

Question 9

Bundle of his

Answer 9

Splits electrical impulse into 2

Question 10

Bundle branches

Answer 10

Carries impulse to base of ventricles

Question 11

Purkinje fibres

Answer 11

Distribute impulses through ventricle walls causing ventricular systole

Question 12

Venous return definition

Answer 12

The return of blood back to the heart via veins

Question 13

Venous return mechanism

Answer 13

Muscle pump - veins situated between muscle squeeze to push blood back to the heart
Respiratory pump - pressure change in thoracic cavity causes suction effect and pulls blood back to heart
Smooth muscle - vein walls constrict to push blood back to heart
Pocket valve - prevent back flow of blood
Gravity - from upper body pushes blood back to heart

Question 14

Vascular shunt definition

Answer 14

Redistribution of blood flow to the body

Question 15

Vascular shunt

Answer 15

Vasomotor control centre detects increase in CO2/ temp/ blood pressure/ muscle movement
Vasoconstriction to non essential organs
Vasodilation to working muscles
Arterioles
Sphincters (pre capillary)
(Via the ^^)
Increased sympathetic stimulation limits blood flow
Decreased sympathetic stimulation increases blood flow
80% blood flow to working muscles 20% blood flow to non essential organs