201 Ch22- blood vessels and circulation

3 layers of blood vessel walls

Adventitia/ Media/ Intima

vasa vasorum

walls of thickest vessels contain their own blood vessels

intima

endothelium

media

smooth muscle allows blood vessels to vasoconstrict + vasodilate

adventitia

fibrous (collagen & elastin tubes)

largest layer in medium sized veins

cut arteries

maintain circular shape

veins

collapse when cut

some may contain valves to prevent backflow

thin elastic membranes in arteries

media and intima

3 types of arteries

elastic arteries

muscular arteries

arterioles

elastic arteries EX.

aorta and pulmonary artery (trunk)

media layer thicker

in muscular arteries, more smooth muscle

3 capillaries

continuous (most common),

fenestrated,

sinusoids

3 vein types

venules

medium-sized veins

large veins

medium sized veins

contain both elastic fibers and one way valves

purpose of valves in veins

prevent backflow of blood

varicose veins

weak or damaged vein walls/ valves

to decrease risk of varicose veins

exercise

don’t smoke

compression socks

large veins

have some smooth muscle

no valves

large veins EX

superior and inferior vena cava

blood vessels that contain most blood

venules and medium-sized veins

pulmonary circuit

blood that moves between heart and lungs

systemic circuit

blood that moves between heart and body

3 main branches from the aortic arch

brachiocephalic artery

left common carotid artery

left subclavian artery

brachiocephalic artery gives rise to

right common carotid artery

& right subclavian artery

subclavian arteries supply blood to

arm

brain

spinal cord

subclavian arteries form 3 branches

(before becoming axillary arteries)

thyrocervical trunk

internal thoracic artery

vertebral artery

common carotid arteries divide forming

internal/ external carotids

carotid sinus located

at the base of the internal carotid artery

receptors in carotid sinus

baroreceptors

chemoreceptors