Cardiovascular physiology #3 (9/17/15) Flashcards
______ determine the relative blood flow to a given organ.
Arterioles
F organ = ?
(MAP - venous pressure)/Resistance
Relaxing of Arteriole smooth muscle causes ______.
Vasodilation
What controls the smooth muscles of arterioles?
- Local controls:
- Extrinsic controls
When does auto regulation of flow occur?
When metabolic activity of organ is NOT changing
What are examples of Local controls?
Active Hyperemia = accumulation of CO2, H+, K+, NO…
Flow auto regulation = myogenic responses -“stretch receptors” = some arteriolar smooth muscle respond to increase stretch caused by increased pressure by contracting to a greater extent.
What organs have flow auto regulation?
All of them!
What is reactive hyperemia?
Kind of a mix of both auto regulation, and active hyperemia. *it occurs when there is cessation of blood flow.
Sympatheic stimulation of alpha-adrenergic receptors causes _______.
vasoconstriction to decrease blood flow to that location.
Sympathetic stimulation of Beta-adrenergic receptors causes __________.
vasodilation to cause increase in blood flow to that location.
What are examples of Extrinsic controls of Arterioles?
- Sympathetic nerves
- Parasympathetic
- Noncholinergic, nonadrenergic autonomic nerves
- Hormones
(Epinephrine, Norepinephrine)
What are endothelial controls of Arterioles?
Paracrine effect = release of Vasodilators or Vasoconstrictors
Flow induced arterial vasodilation
What are the major factors affecting Arteriolar radius?
Neural Control:
- vasoconstrictors (sympathetic nerves)
- Vasodilators (Neurons that release NO)
Hormonal controls:
- Vasoconstrictors (Epinephrine, Angiotension II, Vasopression)
- Vasodilators (Ephinerine, Atrial natriuretic peptide)
Local Controls:
- Vasoconstrictors (Internal blood pressure, Endothelia-1)
- Vasodilators (decrease in oxygen, NO,)
What control is resting muscle under?
Neural Control (extrinsic)
When muscle is working what control is it under?
Local Control
The heart is under what type of control?
Local
What control is the skin under?
Extrinsic (neural), except for during intense exercise it increases for reasons of thermal regulation.
What type of control are splanchnic organs under?
under extrinsic (neural) control except for right after a meal
What type of control is the brain under?
Local control
What type of control are the lungs under?
Extrinsic control
What structural feature helps capillaries exhale material between blood and interstitial fluid?
Intercellular clefts
T or F Capillaries have smooth muscle?
False
_____ is the movement of fluid and solutes into the blood.
Absorption
_______ Movement of fluids and solutes out of the blood.
Filtration
Interstitial hydrostatic presser moves water where?
into the capillary (absorption)
Capillary hydrostatic pressure moves water where?
Out of capillary (filtration)
Osmotic force due to plasma protein concentration favors movement to where?
into the capillary
Osmotic force due to interstitial fluid proteins concentration favors movement to where?
Out of the capillary
How can you decrease MAP?
Decrease blood volume
MAP describes_______.
Flow
A decrease in MAP = _________.
Decrease in total organ blood flow.
Approx. _____% of blood is in the veins.
60%
Is there parasympathetic innervation in the veins?
No just sympathetically mediated venoconstriction to increase return to the heart.
What are the 3 ways to get blood back to the heart?
- Increase blood volume
- Increase venoconstriction
- increase sympathetic veins skeletal pump mechanism
