Circulatory Responses to Exercise W6 Flashcards
What are the metabolic regulators of resistance vessels?
Tissue hypoxia
CO2 increase
pH decrease
Lactate production
Breakdown products of ATP (adenosine, inorganic phosphate)
Potassium
Osmolality
What is nitric oxide converted from?
L-arginine
What is prostaglandins converted from?
Arachidonic acid
What happens to blood flow during exercise?
Increased blood flow to working skeletal muscle
Decreased blood flow to less active organs
What happens when blood flow is decreased to less active organs?
Decreased to liver, kidneys, GI tract
Redistribution depends on metabolic rate
Dependent on exercise intensity
What happens when blood flow is increased to working skeletal muscle?
AT rest, 15-20% of cardiac output to muscle
Increases to 80% during maximal exercise
Why does vasodilation occur?
Due to changes in local factors
Increases in nitric oxide, prostaglandins, ATP and Adenosine
What does vasoconstriction do?
Blood flow is reduced to 20% to 30% of resting values
How much cardiac output can skeletal muscle take during maximal exercise?
90%
How much total blood volume is in the splanchnic region?
20-25%
What happens to oxygen extraction between rest and exercise? (splanchnic circulation)
It increases
Rest: 15-20%
Exercise: 75%
What happens to blood flow between rest and exercise? (splanchnic circulation)
It decreases
Rest:1500mL-min-1 (25% CO)
Exercise: 350mL-min-1 (5% CO)
Why does blood flow decrease and oxygen extraction increase during splanchnic circulation?
Blood flow decrease: Through sympathetic vasoconstriction and circulating catecholamines
Oxygen extraction increase: To compensate blood flow decrease
What is sympathetic neural control?
Constriction in the splanchnic circulation can add blood volume into the circulation back to the heart= increases venous return
What controls non-hairy skin?
Adrenergic vasoconstrictor
