Chapter 3- Structure and function of the normal heart & blood vessels

Question 1

What are the factors affecting cardiac performance for preload?

Answer 1

Total blood volume
Venous (sympathetic tone)
Body position
Intrathoracis and intrapericardial pressures
Atrial contraction
Pumping action of skeletal muscle

Question 2

What are the factors affecting cardiac performance for afterload (impedance against which the left ventricle must eject blood)?

Answer 2

Peripheral vascular resistance
Left ventricular volume (preload, wall tension)
Physical characteristics of the arterial tree (elasticity of vessels or presence of outflow obstructions)

Question 3

What are the factors affecting cardiac performance for contractility (cardiac performance independent of preload or afterload)?

Answer 3

Sympathetic nerve impulses
Increased contractility
Digitalis, calcium, or other ionotropic agents
Circulating catecholamines
Increased heart rate or post-extrasystolic augmentation
Anoxia, acidosis
Decreased contractility
Pharmacologic depression
Loss of myocardium
Intrinsic depression

Question 4

What are the factors affecting cardiac performance for heart rate?

Answer 4

Autonomic nervous system
Temperatures, metabolic rate
Medications, drugs

Question 5

What is the physiological response to exercise for increased heart rate?

Answer 5

Increased sympathetic stimulation

Question 6

What is the physiological response to exercise for increased stroke volume?

Answer 6

Decreased parasympathetic stimulation

Question 7

What is the physiological response to exercise for increased contractility?

Answer 7

Increased sympathetic stimulation

Question 8

What is the physiological response to exercise for increased venous return?

Answer 8

Sympathetic- mediated vasoconstriction
Pumping action of skeletal muscles
Decreased intrathoracic pressure with deep inspirations
Arteriolar vasodilation in exercising muscles

Question 9

What is the physiological response to exercise for decreased afterload?

Answer 9

Arteriolar vasodilation in exercising muscle (mediated chiefly by local metabolites)

Question 10

What is the physiological response to exercise for increased blood pressure?

Answer 10

Increased cardiac output

Vasoconstriction (sympathetic stimulation) on nonexercising vascular beds

Question 11

What is the physiological response to exercise for increased O2 extraction?

Answer 11

Shift in oxyhemoglobin dissociation curve as a result of local acidosis