Circulation Flashcards
What do arteries do?
Carry blood away from the heart and branch into smaller arteries
What do veins do?
Carry blood to the heart and merge into larger veins
What joins arteries to veins
Capillaries
What are the layers of walls and arteries called?
Tunics
What are the layers of walls and arteries
Tunica Intima: Most inner layer; simple squamous epithelium and areolar CT
Tunica Media: Circularly arranged smooth muscle that can cause vasoconstriction
Tunica Externa: CT that aids in anchoring blood vessel
What are the small arteries found in the tunica externa?
Vasa Vasorum (to accomodate a blood supply to large blood vessels)
Elastic Arteries
Largest; contains elastic fibers in all three tunics and branch into the muscular arteries
Muscular Arteries
Medium size; two concentric rings of elastic fibers; inner ring is the internal elastic lamina which separates the tunica intima from the tunica media; outer ring is the external elastic lamina which separates the tunica media from tunica externa
Arteioles
Smallest; contain smooth muscle in their tunica media when contracted leads to an increase in BP and when relaxed it would lead to a drop
Blood flow is unidirectional except
Venous system of brain
Capillaries
-smallest of blood vessels
-only tunica intima (diameter the size of a erythrocyte)
-only blood vessel where metabolic exchange can occur between blood and tissues
-form capillary beds
Continuous Capillary
Most common, complete lining
Fenestrated Capillary
Contains pores that allow for fluid exchange.
Sinusoid Capillary
Has large gaps and incomplete basement membrane. Transports large molecules and cells to and from the blood.
Veins
Drain capillaries and return blood to the heart
-same layers as artereies but thinner esp tunica media
-60% of blood volume at rest known as blood resevoir
