Arteries, arterioles, capillaries, venules and veins Flashcards
What is the purpose of arteries?
to carry blood from the heart to the rest of the body (arteries away)
What type of blood do arteries typically carry?
-oxygenated blood
-pulmonary artery carries deoxygenated blood
Features of an artery that help it maintain high pressure
-layer of elastic tissue to stretch and recoil with heartbeats to maintain high pressure
-folded endothelium allows artery to expand to maintain high pressure
-small lumen maintains high pressure so blood travels easily
Features of an artery for strength
-layer of collagen to add stability and strength
-layer of smooth muscle to withstand pressure of blood
What are arterioles?
arteries branch into arterioles, which are smaller
Features of an arteriole
-less elastic tissue
-layer of smooth muscle allows them to expand/contract to control blood flow
What are capillaries and what are their function?
-arterioles branch into capillaries which are the smallest blood vessel
-substances are exchanged between cells and capillaries eg. glucose and oxygen
Features of a capillary
-flattened endothelium for shorter diffusion distance
-only one cell thick for shorter diffusion distance
-very narrow lumen for proper exchange of nutrients and gases
What are venules?
Capillaries connect to form venules
Features of venules
-very thin walls
-contain some muscle cells
What are veins and what are their function?
-venules join to form veins
-take blood back to heart under low pressure
What type of blood do veins typically carry?
-deoxygenated blood
-pulmonary vein carries oxygenated blood to the heart
Features of a vein
-wide lumen as blood travels at a lower pressure
-thin layers of collagen, elastic fibres and smooth muscle as lower pressure requires less strength of walls
-valves prevent blood flowing backwards
-body muscles around veins contract to assist blood flow
