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