BSI 2 Lecture 16-17: Circulation Flashcards
Briefly describe circulation from arteries to veins.
Arteries carry oxygenated blood which enters the capillaries, via arterioles, in order to carry out gas and nutrient exchange. It then passes through venules and into the veins which carry the deoxygenated blood back to the heart.
What are the three layers of arteries?
Tunica interna, tunica media, and tunica externa
What is the tunica interna composed of?
It contains simple squamous epithelium, basement membrane, and a layer of elastic tissue
What is the tunica media composed of?
Elastic fibers and smooth muscle that extend around the lumen
What is the tunica externa composed of?
Elastic fibers and collagen
Which layer of the arteries is the thickest?
The tunica media
What separates the tunica externa from the tunica media in muscular arteries?
an external elastic lamina
Which arteries have a larger diameter? Muscular or elastic arteries?
Elastic
What does the tunica media, in elastic arteries, contain?
large amounts of elastic fibers
Why are muscular arteries capable of greater vasoconstriction and vasodilation than elastic arteries?
Because they have more smooth muscle that is innervated by the SNS
Do capillaries have smooth muscle?
No, they have thin walls of endothelium and basement membrane for gas exchange. They cannot vasoconstrict or vasodilate
What are the three layers of a vein?
Same as an artery. Tunica interna, tunica media, and tunica externa
What is the difference between the layers of an artery and vein?
The vein has a thinner tunica interna and tunica media, but a thicker tunica externa.
Which one is more compliant? Veins or arteries?
Veins are about 24 times more compliant than arteries
What do veins contain to prevent backflow?
valves
What three factors relate when it comes to blood flow?
cardiac output, mean arterial pressure, and total peripheral resistance (CO = MAP/TPR or MAP = CO x TPR)
What is blood pressure?
The force the blood is exerting on the walls of the blood vessel
What is the formula for MAP?
MAP = DBP + 1/3(SBP-DBP)