Cardiovascular System

Question 1

Outline the conduction system of the heart

Answer 1

1. ) starts at the sinoatrial Node (SA node) located in the right atrial wall
2. ) Pulse travels down into the Atrioventricular Node (AV node). It collects the impulse and delays it for about 0.1 seconds-allows the atrium to finish contracting
3. ) Impulse passes to the Bundle of His, located in the septum of the heart. BOS splits into 2
4. ) impulse passes through the bundle branches which carry the impulse to the base of each ventricle
5. ) the pulse travels down into the Purkyne fibres, which distributes the impulse through the ventricle walls, causing them to contract

Question 2

What is the average resting heart rate?

Answer 2

72bpm

Question 3

What should athletes heart rate be and why?

Answer 3

Lower than 60bpm, known as bradycardia, resulting from cardiac hypertrophy

Question 4

How do you work out cardiac output?

Answer 4

Stroke volume X Heart rate

Question 5

Outline the vascular shunt mechanism (redistribution of Q from rest to exercise)

Answer 5

1. ) 3 receptors detect the change in body (chemo/baro/proprioceptors)
2. ) information send to vasomotor control centre (VCC) located in the brain, which controls mechanism
3. ) VCC uses sympathetic nervous system to increase/decrease sympathetic stimulation
4. ) at muscles->stimulation is decreased->diameter of arteriole and pre-capillary sphincter widens->increase blood flow->causes vasodilation
5. ) at organs->stimulation increased->diameter of arteriole and pre-capillary sphincter narrows->decrease blood flow->causes vasoconstriction