3.3 Mass transport Flashcards
describe the structure of the arteries related to their function
thick smooth muscle layer
- contract, pushing blood along
- control/maintain blood flow/pressure
elastic tissue/layer
- stretch as ventricle contracts (when under high pressure) , recoil when relaxes (under low pressure)
- reduces pressure surges/evens blood pressure + maintains high pressure
thick wall
-withstand high pressure + prevent artery bursting
smooth endothelium
-reduces friction
narrow lumen
-increases + maintains high blood pressure
describe the structure of arterioles related to their function
thicker muscle layer than arteries
- constricts to reduce blood flow by narrowing lumen
- dilates to increase blood flow by increasing lumen
thinner elastic layer as lower blood pressure surges
describe the structure of veins related to their function
wider lumen than arteries very little elastic than arteries valves -prevent backflow of blood contraction of skeletal muscles squeezes veins -maintaining blood flow
structure of capillaries related to their function
narrow lumen -reduces flow rate so more time for diffusion permeate tissue -short diffusion pathway pores in walls between cells -allows substances to escape
what is tissue fluid
- provides respiring cells with water/o2/glucose/amino acids
- enables waste substances to move back into blood
formation of tissue fluid
at arteriole end of capillary
- higher hydrostatic pressure inside capiilaries than tissue fluid so overall outward pressure
- forces fluid out capillaries into spaces surrounding cells
- large plasma proteins remain in capillary as too large to leave
at venule end
- hydrostatic pressure reduces as fluid leaves capillary
- so increasing conc of plasma proteins due to water loss, so low wp in capillary than in tissue fluid
- water reenters capillaries from tissue fluid by osmosis down wp gradient
- excess water drained by lymphatic system
cardiact output=
stroke vol x heart rate
heart rate in bmp
60/time taken for one cardia cycle
how can an atheroma lead to a heart attack
atheroma causes narrowing of coronary arteries
restricts blood flow to heart muscle
heart anaerobically respires ->less ATP->not enough energy to contract->lactate produced->damages heart tissue/muscle
risk factors of heart disease
age diet in salt/high saturated fat alcohol stress smoking genetics
why is high bp bad
increases risk of damage to endothelium of artery wall
increases risk of atheroma
can lead to blood clot
what are haemoglobins
group of chemically similar molecules
found in many different organisms
protein with a quaternary structure
describe the loading + unloading of o2 onto haemoglobin
haemoglobin can carry 4 o2 molecules, one at each haem group
in lungs
-high PO2 -> haemoglobin has high affinity for o2->o2 readily loads + associates with haemoglobin
at respiring tissues
-low PO2-> o2 readily unloads
explain the o2 dissociation curve
haemoglobin has low affinity for o2 when first o2 binds -so slow saturation shape of haemoglobin changes -easier for 2 + 3 o2 to bind -saturation rate increases after 3, haemoglobin slowly saturated, shape of haemoglobin changes -harder for last o2 to bind -saturation rate decreases
describe the cohesion tension theory
- water evaporates at open stomata due to transpiration
- reduces wp in cell, increasing wp gradient
- water drawn out xylem
- creating tension
- cohesive forces between water molecules pull water up as a colum
- water enters root via osmosis
- water moves up against gravity
- water adhesive so sticks to xylem walls
