Lecture 30 - Integration

Question 1

Determinants of venous return?

Answer 1

right atrial pressure, degree of filling (venous capacitance), systemic vascular resistance

Question 2

Mean circulatory filling pressure?

Answer 2

drastically effected by change in volume and sympathetic stimulation

Question 3

Filling pressure, sympathetic activation and cardiac output?

Answer 3

increased stimulation increases output at any filling pressure due to increase in ionotrpy and heart rate

Question 4

Guyton analysis?

Answer 4

cardiac output must match venous return, therefore equilibrium point will be where cardiac function curve and vascular function curve intercept

Question 5

Lying to standing?

Answer 5

initial drop in venous return causing drop in cardiac output, then sympathetic stimulation restores to normal

Question 6

Exercise?

Answer 6

as well as sympathetic stimulation and decreased systemic resistance, need for increased venous return: muscle pump action, increased ventilation and venous constriction

Question 7

Compensation in heart failure?

Answer 7

increased sympathetic activation, waer retention to increase venous return

Question 8

Treating compensations of hearth failure?

Answer 8

to reduce afterload/inotropy to reduce work demand -

diuretics (reduce venous pressure & oedema), ACE inhibitors (vasodilation), beta blockers (reduce energy demand)