mass transport in animals Flashcards
what is the order of blood vessels?
artery - arterioles - capillary bed - venuole - vein
explain capillaries
● structure: highly branched - thin endothelium layer and small diameter creates lots of friction - slows rate of RBC movement
● uses: gas exchange - exchange materials between blood and tissues
● single cell thick: decreases diffusion distance
● branched: increases surface area
● narrow: ensures RBC in contact with wall to give short diffusion pathway
● permeable: substances can pass in and out
explain arteries
● endothelial layer: one cell thick to reduce friction
● elastic layer: stretches and recoils under pressure - stops pressure getting too high
● muscle layer: contracts to maintain pressure
● outer layer: gives support and strength
explain arterioles
● smaller than an artery
● muscle layer: thinner than artery but still relatively thick - contracts to limit blood flow to organs - redirect blood flow
● elastic layer: thinner than artery as blood is at lower pressure
explain veins
● endothelial layer: one cell thick and reduces friction
● elastic layer: very thin as blood pressure is low - no need to stretch and recoil
● muscle layer: very thin - no need to contract at all as blood going to heart
● valves: to reduce back flow of blood
pulmonary artery
● carries blood from heart
● carries blood to lungs
pulmonary vein
● carries blood from lungs
● carries blood to heart
aorta
● carries blood from heart
● carries blood to body
vena cava
● carries blood from body
● carries blood to heart
renal artery
● carries blood from body
● carries blood to kidney
renal vein
● carries blood from kidneys
● carries blood to inferior vena cava
hepatic vein
● carries blood from liver
● carries blood to inferior vena cava
hepatic artery
● carries blood from heart
● carries blood to liver
hepatic portal vein
● carries blood from gut
● carries blood to liver
explain pressure filtration and water reabsorption
● blood from left ventricle (at high hydrostatic pressure)
● pressure filtration: small molecules (e.g. glucose, amino acids and water are forced out blood) forming tissue fluid
● rbc and plasma proteins too large to leave blood
● o2 diffuses into respiring cells at capillary bed
● low water potential at venous end, high water potential in tissue fluid (plasma proteins lower water potential)
● water reabsorption: 90% of water moves back into blood by osmosis from high water potential in tissue fluid to low water potential in blood plasma
● blood draining back into right atrium (low hydrostatic pressure)
● lymphatic vessel - drains excess tissue fluid not reabsorbed into blood - now called lymph
