Mass transport - blood vessels and their functions Flashcards
What do arteries do
Away from heart to arterioles
Arterioles
Control blood flow from arteries to capillaries
Capillaries
Link arterioles to veins
Veins
From capillaries to heart
Layers both arteries and veins have
Tough fibrous outer layer
Muscle layer
Elastic layer
Thin inner lining
Lumen
What does touch fibrous outer layer do
Resists pressure changes
What does muscle layer do
Contract to control flow of blood
What does elastic layer do
Maintain blood pressure by stretching and springing back
What does thin inner lining do
Reduces friction because its smooth
Thin to allow diffusion
What does lumen do
Hole that lets blood flow through
Artery function of muscle layer
Thick
Constricts and dilates to control volume of blood
Artery function of elastic layer
Thick
Controls high and smooth blood pressure
Artery function of wall
Thick
Resists bursting
Arteries valves
No valves
Under constant high pressure
Tends to not flow backwards
Arteriole muscle layer function
Thicker than arteries
Restricts flow of blood so controls its movement
Arteriole elastic layer function
Thin because blood pressure is lower
Vein function of muscle layer
Thin
Carry blood from tissues
Cannot control flow of blood
Vein elastic layer function
Thin
Low pressure if blood within veins
Veins wall function
Small
Pressure too low to create a risk of bursting
Veins valves at intervals
No backflow
Pressure is low
Capillary lining layer
Thin
Short diffusion paths
Rapid diffusion
Why is it good that there are so many capillaries
Numerous and highly branched
Larger surface area for exchange
Capillary function of lumen
Narrow
Red blood cells close to wall
Reducing diffusion distance
Capillary holes in lining
Spaces between lining
Allow white blood cells to escape to deal with infections
