vessels 2 Flashcards
How does the artery structure relate to function?
function= to transport blood rapidly under high pressure from the heart to the tissues
muscle layer thick (compared to veins) so smaller arteries can be constricted and dilated to control the volume of blood passing through
elastic layer thick (compared to veins) to ensure high blood pressure
the layer stretches in systole and recoils in diastole
also smooths pressure surges
great overall thickness restricts vessel bursting at a high pressure
no valves ad blood tends motto flow backwards (bar arteries leaving the heart)
How does the arterioles structure relate to function?
function= carry blood under lower pressure than arteries from arteries to capillaries they control the blood flow.
muscle layer thicker than arteries as the constriction of the lumen restricts the flow of blood
elastic layer thinner compared to arteries so blood pressure is lower
How does the capillary structure relate to function?
function= exchange materials between blood and the cells of the body. The flow is slow to allow more time for exchange of materials
walls mostly lining layer (one cell thick) = short diffusion pathway= rapid diffusion
numerous and highly branched = large SA for exchange
narrow diameter = short diffusion pathway
narrow lumen = squeezed red blood cell= reduced diffusion distance
spaces between endothelial cells= allow white blood cells out
How does the vein structure relate to function?
function= transport blood slowly under low pressure from capillaries to the heart
muscle layer relatively thin (compared to arteries) constriction and dilation cannot control blood flow to the tissues
elastic layer thin (compared to arteries) = low pressure means low chance of bursting and pressure too low for recoil action
valves= blood does not flow backwards when muscles contract, veins are compressed, pressurizing the blood so it flows in one direction, to the heart
What does fluid tissue contain and what is its function?
formed of blood plasma
contains glucose, amino acids, fatty acids, ions in solution and o2 it supplies this to the tissues and receives co2 and waste materials from the tissue.
it bathes all tissues and acts as a medium between blood an cells
Describe how tissue fluid leaves the capillary
and how is it restricted
at the arterial end of the capillary
hydrostatic pressure forces h2o out (hp higher in than out)
ultrafiltration
restricted by hp of outside tissue fluid and lower water potential of blood due to large proteins being unable to leave
Describe how tissue fluid returns to the capillary
loss of the tf from capillaries reduces hp inside and water potential reduced as water lost but proteins kept
so at the venous end of the capillary network hp lower on capillary than outside
water leaves tissue via osmosis down water potential gradient
How does tissue fluid return to the body?
tissue fluid returns to the capillary
or lymphatic system
which is moved via hp and contraction of body muscle
to drain excess fluid
