Vessels Flashcards
What is the use of arteries having elastic fibres in their walls?
They stretch when blood is pumped through at a high pressure when the heart contracts, and recoil when the heart relaxes
What is an adaptation of arteries that helps them to maintain high blood pressure?
They have a narrow lumen and thick muscular wall
How do veins prevent the backflow of blood?
They have valves
What is the use of arterioles having a large number of muscle cells?
They can contract and close their lumen to stop blood flow to certain organs
State 4 ways which capillaries are adapted for their function
Thin walls (one cell thick), small diameter, narrow lumen/ slow blood flow, fenestrations, permeable capillary wall
How does the thin capillary wall help exchange substances
There is a short diffusion distance and and endothelial cells have pores which allow plasma to leak out and form tissue fluid
How does slow blood flow help capillaries exchange substances?
More time for diffusion into capillary wall
Why do fenestrations help capillaries exchange substances with their environment?
They allow large molecules through their pores
