Lecture 18: Cardiovascular adjustments to exercise

Question 1

Describe the early response

Answer 1

body anticipates exercise. vasoconstriction at skin, gastrointestinal tract, kidneys, inactive muscles. Increases sympathetic stimulation to the beta1 receptor to increase cardiac output.

Question 2

Describe the 3 components of the delayed response

Answer 2

1) skeletal muscle dependent. both mechanical and chemical pathways. Mechanical: muscle pump increases VR, increases SV and CO. Chemical: release of vasodilators, decrease arterial pressure, sensed by baroreflex, stimulate to increase HR and contractility.
2) sympathetic output: adrenaline from adrenal medulla, acts on beta2 adrenergic receptors in skeletal muscle for vasodilation
3) increased core temp: sensed by thermoreceptors, inhibit dermal vasoconstriction to release heat to environment

Question 3

What limits O2 consumption?

Answer 3

uptake of O2 by lungs, deliver of O2 from lungs to blood, extraction of O2 by blood. Delivery is rate-limiting

Question 4

How do you change the different components of Fick’s principle

Answer 4

can increase flow by increase CO through sympathetic stimulation at SA node at beta1, or to increase contractility and venous return

Can increase extraction by increasing capillary exchange surface and through Bohr effect

Question 5

What changes occur with training?

Answer 5

no change in max HR, change in venous return. Lower resting heart rate (allows longer time in diastole for filling, therefore larger stroke volume and cardiac output). little increase in MAP due to decrease in TPR. increase in contractility most important due to increase in plasma volume and hypertrophy.

Question 6

Describe the difference between eccentric and concentric hypertrophy

Answer 6

eccentric: increase in length of cells, seen with volume overload. increase wall thickness and ventricular dilation.
concentric: increase in width of cells, seen with pressure overload. increase wall thickness but no dilation.

Question 7

Discuss the difference between pathological and physiological hypertrophy

Answer 7

physiological is reversible. pathological involves fibrosis. physiological uses PI3K to regulate cell growth and survival, pathological activates Gq