L21 Special Cirulation during exercise

Question 1

Give values for blood flow during exercise in the coronary, cutaneous and splanchnic circulations

Answer 1

Heart
rest –> 0.25 litres per minute
Exercise –> 1.25 litres per min

Skin (cutaneous) circulation
rest –> 100 - 300 ml per min per m^2 of body surface
exercise –> 7-8 l at maximal

Splanchnic circulation 
- flow decreases but o2 consumption remains the same 
Renal blood flow 
rest --> 1200 ml per min 
exercise --> 360 ml per min

Question 2

Describe the redistribution of blood to body organs during exercise

Answer 2

More blood to the working organs such as coronary circulations (heart lungs)
more to working muscles and the brain.

Less to the kidneys and liver

Question 3

Explain some mechanisms regulating coronary blood flow during exercise

Answer 3

Metabolic factors
- chronotropic - heart rate increases
- Inotropic - contractility increases
Adenosine = main metabolic vasodilator

Mechanical factors
- most flow in the coronary takes place during the diastole because of vessel compression during the systole

Question 4

Explain some mechanisms regulating cutaneous blood flow during exercise

Answer 4

Neural

1. Adrenergic vasoconstrictor - for non hairy skin like palms of hands and feet soles + lips
2. Cholinergic vasodilator (hairy skin)

Question 5

Explain some mechanisms regulating splanchnic blood flow during exercise

Answer 5

Sympathetic neural control
Vasoconstriction in exercise
Potential for protein uria in intense exercise