Circulatory Responses to Exercise

Question 1

What are the major purposes of the cardiovascular system?

Answer 1

• The transport of 02 to tissues and removal of wastes
• The transport of nutrients to tissues
• The regulation of body temperature

Question 2

Briefly outline the structure of the heart, why is the heart often called two pumps in one?

Answer 2

The heart has two pumps in one, the left side known as the systemic circulatory system delivers oxygenated blood around the body and the right side known as the pulmonary circuit delivers blood to the lungs.
Right- vena cava, right atrium, tricuspid valve, left ventricle, pulmonary artery
Left- pulmonary vein, left atrium, tricuspid valve, left ventricle, aorta

Question 3

Graph the HR, SV and Q response to incremental exercise?

Answer 3

-SV- an increase to plateau at 40% V02 max (not in endurance athletes)
-Q- “increases in direct proportion to the metabolic rate required to perform the exercise task”- at 3-4 mins usually plateau
-HR- large/ sharp increase and then a plateau followed by a steep decline

Question 4

What factors regulate heart rate during exercise and SV?

Answer 4

HR- sympathetic- via accelerator nerve / parasympathetic- via vagus nerve control of the heart (central command theory)
Increase in HR at onset of exercise- CNS stimulation and initial parasympathetic withdrawal

SV- an increased force of contraction increases SV
1. Sympathetic nervous system stimulation (adrenaline and noradrenaline)
=Direct stimulation of heart muscle
2. Increased EDV= increased stretch of ventricular sarcomeres- increased force of contraction

Question 5

How does exercise influence venous return?

Answer 5

Increase in VR due to an increase in exercise at incremental pace
Increases due to:
1. The muscle pump
2. The respiratory pump
3. Venoconstriction= reducing the volume of blood in the veins, a reduction in vein holding capacity increases the volume of blood that moves back to the heart.

Question 6

6. Discuss EDV in relation to/ regulation of SV?

Answer 6

SV is regulated by three variables
1) EDV- the volume of blood in the ventricles at the end of diastole
2) The average aortic blood pressure
3) The strength of ventricular contraction

Question 7

Define EDV?

Answer 7

• EVD- end diastolic volume- often referred to as preload and it influences SV, an increase in EVD results in a lengthening of cardiac fibres which improves the force of contraction in a manner like that seen in skeletal muscle. The primary valuable that influences EDV is the volume of venous return

Question 8

What happens during prolonged exercise within heat/ at an altitude?

Answer 8

Decrease in SV due to decrease in venous return
= CARDIAC DRIFT- an increase in HR