Capillaries- Bill Lab

what are the 3 layers of blood vessels?

tunica externa, tunica media, tunica intima

what is the outermost layer?

tunica externa

what is another name for tunica externa?

adventitia

what tissue is the tunica externa comprised of?

areolar connective tissue

true or false: connective tissue gets more dense as you get closer to tunica media

true

what is the network of small arteries in large arteries called?

vasa vasorum

what does the tunica media contain?

elastin and collagen fibers

what is the tunica media separated from the adventitia by?

external elastic membrane

what type of muscle does the tunica media contain?

smooth muscle

what is caused when the tunica media muscle contracts?

vasoconstriction

what does vasoconstriction cause?

decreases diameter of the blood vessel

what happens when the muscle of tunica media relaxes?

vasodilation

what does vasodilation do

increase diameter and blood flow

what tissue is the tunica intima facing the lumen made of?

simple squamous

what is the next superior layer of the tunica intima?

basement membrane + thin layer of connective tissue

what is the layer closest to the tunica media of the tunica intima?

internal elastic layer

what is the largest tunic in arteries?

tunica media

what is the largest tunic in veins?

tunica adventitia

what type of arteries have the largest diameter?

elastic arteries

why do elastic arteries have the largest diameter?

to be able to withstand blood pressure changes

what provides elastic properties?

elastic lamina

what do collagen fibers provide?

strength

what prevents blood pressure from falling rapidly in elastic arteries?

recoil

what predominates the tunica media of muscular arteries?

circular smooth muscle

what do distributing arteries do?

regulate blood flow to body regions

what are the smallest type of arteries?

arterioles

what is the internal lining of simple squamous epithelial cells of capillaries called?

endothelium

how do substances move through capillaries?

diffusion through fenestrations

what type of capillaries does gas exchange take place?

continuous capillaries

what type of capillaries have small openings with a thin membrane that facilitate gas diffusion?

fenestrated capillaries

what type of capillaries have large openings?

sinusoidal capillaries

what elements do sinusoidal capillaries allow to pass?

proteins

where are sinusoidal capillaries

liver and other organs

how does blood flow from arterioles?

through metarterioles

what is the distal part of metarterioles?

thoroughfare channels

what do thoroughfare channels connect with?

venous capillaries and venule

what does the venule do?

drain the capillary bed

what controls blood flow through true capillaries?

smooth muscle sphincters

true or false: there is enough blood to fill the capillaries at any given time

false

what is the velocity of flow in the blood in the center of the vessel is far greater than that towards the outer edge?

laminar flow of blood

what is it called when the rate of blood flow becomes too great?

turbulent flow

what is the volume of blood flowing through the arteries, veins and capillaries?

perfusion

what has a large effect on perfusion and blood pressure?

increasing elasticity

how does blood move?

higher pressure to lower pressure

what is the first factor of the pressure of blood between the two ends of the vessel?

pressure gradient

what is the second factor?

vascular resistance (impediment to blood flow through vessel)

what is the resistance in the circulatory system that is used to create blood pressure?

peripheral vascular resistance (SVR)

when blood vessels constrict what happens?

increase in SVR

what happens when blood vessels dilate?

decrease in SVR

what is the pump where muscle contractions become a compressive force pushing blood up?

musculovenous pump

what is retrograde flow from the pump obstructed by?

closing valves