Flashcards in structure of blood vessels Deck (10):
what is the role of arteries?
they carry blood away from the heart and into arterioles (under high pressure)
what is the role of arterioles?
smaller arteries that control blood flow from arteries to capillaries
what is the role of capillaries?
tiny vessels that link arterioles to veins
what is the role of veins?
carry blood from capillaries back to the heart
what do arteries, arterioles and veins all have in common?
the same basic layered structure
what is this structure (from the outside inwards)?
tough fibrous outer layer - that resists pressure changes from both within and outside
muscle layer - that can contract and so control the flow of blood
elastic layer - that helps to maintain blood pressure by stretching and springing back (recoiling)
thin inner lining (endothelium) - that is smooth to reduce friction and thin to allow diffusion.
lumen - central cavity of the blood vessel through which the blood flows.
what is different about each type of blood vessel?
the relative proportions of each layer - differences in structure are related to differences in the function of the vessel
how are the structure of arteries related to their function?
thicker muscle layer compared to veins - smaller arteries can be constricted and dilated in order to control the volume of blood passing through them
thicker elastic layer compared to veins - keeps blood pressure in arteries high for blood to reach the extremities of the body.
overall very thick wall - resists the wall bursting under pressure.
there are no valves (except in arteries leaving the heart) - blood is under constant high pressure, so it tends not to flow backwards.
how are the structure of arterioles related to their function?
thicker muscle layer compared to arteries - contraction of muscle layer constricts lumen, restricting flow of blood.
thinner elastic layer compared to arteries - blood pressure is lower.