Blood Vessels and the Circulation Flashcards
circulates throughout the body within a closed system through blood vessels.
Blood
are tube-like structures capable of expanding and contracting
Blood vessels
Blood vessels consist of three types:
capillaries, arteries, and veins
are microscopic blood vessels through which materials are exchanged between blood and tissue cells. These tiny hair-like vessels cover every organ and structure throughout the body. Every cell in the body must be able to make contact with a capillary to receive oxygen and nutrients and rid itself of waste products.
Capillaries
carry blood away from the heart. They carry oxygenated blood (except for the
pulmonary artery). They have thick elastic walls that expand and contract.
Arteries
Arteries branch off into
smaller arteries called (?).
arterioles
The [?] (the hollow passageway) of the artery is narrower than the vein.
lumen
transport blood towards the heart. They carry deoxygenated blood (except for the
pulmonary veins). They have thinner walls and area not as elastic.
Veins
Large veins are made up of smaller
veins called (?) that join together.
venules
They also have small valves which prevent the backflow of
blood, unlike in arteries where due to pressure backflow does not normally occur.
Veins
The walls of the blood vessels have three
layers:
- Tunica intima
- Tunica media
- Tunica externa
Innermost layer (towards the
lumen)
Tunica intima
Comprised of a single layer of
endothelial cells
Tunica intima
Middle layer
Tunica media
Comprised of smooth muscle
cells, elastic and connective
tissue
Tunica media
