Cardiovascular
Vessels
Veins venules
Baroreceptors
- monitor the degree of stretch in the expandable organs
homeostatic
Circulatory Physiology
Arteries form arterioles
3 layers of the walls
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provide blood to the capillaries
2
tunica media
3
tunica externa
1 tunica interna
Venules ( smallest vessels in the nervous system )
innermost layer
endotheliel lining of the vessel and underlying layer of connective tissue.
middle layer
smooth muscle, in frame work of collagen fibers and elastic fibers
contraction cause size to decrease
relax makes vessels size increase
outer layer
sheath of connective tissue around a vessel. Collagen fibers may intertwine with adjacent tissues
stabilizing and anchoring the blood vessels
Elastic arteries
Ventricular systole
Ventricular Diastole
blood pressure rises quickly
diameter increases as vessel is stretched
expansion dampens the rise in pressure
- Blood pressure declines
*Elastic fibers recoil to original diameter (relax phase)
Muscle arteries
example - external carotid arteries
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Vascular resistance
blood pressure
- precapillary sphincters
pressure and resistance
Liquids and blood cannot be compressed result force exerted against a liquid generates a fluid
= hydrostatic
*vascular resistance is friction between the blood and vessel walls
Turbulaence
- blood flows through a vessel smoothly
- with the slowest flow near the walls
*fast in the center
waste goes into the Lyphatic vessels
baroreceptors location
arotic sinuses in the walls of the aorta proximal to the heart
cartoid sinuses near the bases if the internal carotid arteries
Wall of the right atrium
tissue perfusion
- cardiac output
- Peripheral resistance
Blood pressure
Autoreguulation
- change in tissue conditions act directly on precapillary sphincters to alter peripheral resistance
if autoregulation cant help then neural and endocrine are activated
Neural Mechanisms
respond to changes in arterial pressure or blood gas levels at specific sites
automomic nervous system adjusts cardiac output and periphaeral resistance to maintain adequate blood flow
Endocrine mechanisms
releases hormones that enhance short term adjustments
directs long term changes in Cardiovascular performance