Blood distribution in exercise Flashcards
The autoregulation of blood flow to skeletal muscles in exercise is due to…
Locally produced factors - NO, prostaglandins and adenosine - also known as EDRF’s
Greatest resistance in the CV is?
Arterioles
What metabolic factors lead to vasodilation? (6)
- Hypoxia and hypercapnia
- Decreased pH
- Increased lactate
- Metabolite accumulation
- Increased potassium
- Increased osmolality
Describe the action of NO
Endothelial cells release NO via NO synthase into vasculature smooth muscle, which releases cGMP and promoting vasodilation
Name the factors that influence blood flow in the
1. Conduit arteries
2. Feed arteries
3. Arterioles
- SNS and EDRF’s
- SNS, metabolic responses and EDRF’s
- Metabolic responses and EDRF’s
What % of Q is distributed to the skeletal muscle during rest and exercise?
Rest - 15-20% of 5L
Exercise - 80-85% of 25L
What happens to blood flow in the splanchnic region during exercise?
Reduced blood flow - 25 to 5% Q
But, oxygen extraction becomes more efficient
What does vasoconstriction improve in terms in blood flow during exercise?
Increased VR, therefore EDV, therefore SV
What occurs in skin flow regulation during exercise
Non-hairy skin vasoconstricts via NE
Hairy skin vasodilates via ACh
What is proteinuria and when does it occur?
In maximal exercise, due to decreased blood flow to the kidneys, high levels of protein and other excretion products may be present in the blood for a while
Outline the Dallas bed rest study and the results
P’s we placed in bed rest for 20 days, followed by 50 days of retraining
- Greater decrease in VO2max in trained
- Greater increase in VO2max in untrained following training
- Bed rest - increased HR, decreased SV
- Training - decreased HR, increased SV
What causes BBF to increase - CO2 or O2
CO2 - which therefore increases breathing frequency
What is renal flow reduced to during exercise?
20% to 4%
Give the values of the splanchnic region
1500 to 350 ml
