Ch. 21 Blood Vessels (E4) Flashcards
What are the 3 layers of arteries?
1) Tunica interna (intima)
2) Tunica media
3) Tunica externa (adventitia)
Which vessel layer is capable of vasodilation and vasoconstriction?
Tunica media
What 2 structural components allow for vasodilation and vasoconstriction in the tunica media?
1) Smooth muscle
2) Elastic tissue
This artery type has the thickest tunica media to withstand/stretch in response to high pressures
What is elastic/conducting?
This artery type can vasodilate/vasoconstrict to redirect blood flow
What is muscular/medium/distributing?
What are the 2 functions of arterioles?
1) Direct blood to metarterioles
2) Regulate capillary network flow
The site of exchange within surrounding tissues.
What are capillaries?
What is the difference between continuous, fenestrated, and sinusoidal capillaries?
1) Continuous - no gaps, barely permeable
2) Fenestrated - windows, permeable (small molecules)
3) Sinusoidal - deadass holes, permeable (large molecules)
Capillary exchange is bypassed by thoroughfare channels when { } are constricted (HINT: 2 words.
Precapillary sphincters
What are the 2 functions of a venule?
1) Drain capillary network
2) Deliver to veins
Is a vein’s outermost layer thicker than the middle layer?
Yes
Why are veins so floppy?
To serve as blood reservoir
Given the low pressure in veins, what keeps blood from moving backward?
One-way valves
What 2 types of pumps assist venous return?
1) Skeletal muscle
2) Respiratory
What is the relationship between blood velocity and the cross-sectional area of a vessel?
Inversely proportional
