mass transport Flashcards
why is the dissociation curve Sigmoidal s shaped?
co-operative binding=
-low partial pressures of O2 haemoglobin has low affinity for O2, doesnt load as readily
-as O2 partial pressures increase affinity of haemoglobin increases. when first O2 molecule loads, changes shape of haemoglobin moleucle =easier
-difficult to become 100% saturated - hard to diffuse and associate into 4th
describe haemoglobin in low oxygen environments
-Hb has higher affinity for O2
-Hb loads more readily at low pO2
-curve shifts to left
describe haemoglobin with high activity levels
-very active
-aerobically respire faster
-need more O2 per unit mass of tissue
-Hb has lower affinity for O2
-Hb unloads more readily at any given pO2
-curve shifted to the right
describe haemoglobin in smaller organisms
-higher SA:V
-transfer heat energy to environment faster
-aerobically respre faster/high metabollic rate
-need more O2 per unit mass of tissue
-Hb loads more readily at any given pO2
-curve shifts to the right
where does the renal artery carry blood from and to?
aorta to kidney
why is the left venticle much thicker?
need to contract more powerfully to pump oxygenated blood around the body
whats the importance of the septum?
separates sides so oxygenated and deoxygenated blood dont mix
also enables different pressures
whats the hearts own blood supply?
coronary arteries
in blood vessels how can blood flow be controlled?
in arterioles
-when muscle relaxes
arterioles dilate
-lumen become wider
-blood flow increases
-when muscle contracts
arterioles constrict
-lumen narrows
-blood flow decreases
what are the 3 stages of the cardiac cycle?
- ventricles relax, atria contract
- ventricles contract,atria relaxes
3.ventricles relax, atria relax
when do atrioventricular valves open?
when pressure in the atria is greater than the ventricles
when do semilunar valves open?
when pressure is higher in the arteries than in the aorta/pulmonary artery
whats the formula for cardiac cycle?
stroke volume x heart rate
define stroke volume
vol of blood pumped during each heart beat in cm3
give 3 examples of contents of plasma
hormones
fatty acids
amino acids
whats the role of tissue fluid?
transport oxygen and nutrients from blood to cells and CO2 and other waste products from cells back to blood
where does formation of tissue fluid occur?
at a capillary network which surrounds cells
how is tissue fluid formed?
at arteriole end:
-blood has higher hydrostatic pressure (due to left ventricle) lower osmotic pressure
-water is forced out of fenestrations
-along with dissolved substances like oxygen and glucose
what is ultrafiltration?
filtration under pressure
how is fluid returned to the capillary?
at venous end:
-blood has lower hydrostatic pressure
-plasma protiens lower water potential
in blood
-higher hydrostatic pressure
-water moves back in by osmosis
other waste by diffusion
-excess tissue fluid moves into lymphatic capillaries where it drains back into circulatory system via subclavian vein
importance of the lymphatic system
-draining excess tissue fluid and returning to blood
-for immune system = lymph nodes produce lymphocytes
-absorp lipids from digestive system into lacteal
describe how not excersizing increases risk of cardiovascular disease
high blood pressure
atheroma formation
blood clots
heart attak
describe how a diet high in saturated fats may increase risk of cardiovascular disease
high blood cholesterol
atheroma formation
blood clots
heart attack
stroke symptoms
think FAST
Face=distorts one side
Arms=weak limbs on one side
Speech=difficulty speaking,slurring
describe 2 ways smoking increases risk of cardiovascular disease
1.carbon monoxide
less oxygen in blood
less oxygen to tissues
heat attack
2.fewer antioxidents
damage to coronary artery walls
atheroma formation
heart attack
posh word for heart attack?
myocardial infarction
how to make a study more representative?
larger sample size
explain how the xylem is adapted to its function
-no end walls=continuous flow of water
-no organelle=hollow=eases flow of water
-walls made of lignin=strength prevents collapsing, maintains adhesion
-bordered pits=lateral flow of water
describe the cohesion-tension theory
1.water evaporates from leaf out of stomata by transpiration
2.lowers water potential of mesophyll cells
3.water is pulled up xylem creating tension
4.water molecules cohere by hydrogen bonds
5.forming continuous water column
6.adhesion of water molecules to walls of xylem
define transpiration
evaporation of water vapour from arial parts of the plants - stomata
importance of transpiration stream
as water is lost from xylem in leaves its replace from below
why is transpiration important?
1.photosynthesis
2.water allows cells to grow and elongate-phototropism
3.turgidity
4.evaporation cooling effect
5.flow of water carries mineral ions up plant
how does temperature effect transpiration?
increase in temp
more Kinetic energy of water molecules
more water vapor lost via stomata
how does humidity affect transpiration?
increase
decreases evaporation from leaf
smaller water potential gradient
adaptations of xerophytes
smaller leaves
thick waxy cuticle
stomata close when hot
hairs
stomata sunk in pits
rolling leaves
loss of leaves high salt concentration in cells
how do hairs on leaf help reduce water loss?
traps water vapour
decreases water potential gradient
how does stomata sunk in pits help reduce water loss?
traps water vapour
close to surface of leaf
decreases water potential
how does rolling leaves help reduce water loss?
traps water vapour
decreases water potential gradient
reduces surface area
how does a high salt concentration in cells help reduce water loss?
decreases water potential gradient in cells
less water lost between cells
what are xerophytes?
plants that can survive in dry climates
limitations of potometer
1.messures water uptake not transpiration
2.cutting plant shoot may damage the plant
3. plant has no roots so no resistance to water being pulled up
describe translocation
movement of assimilates like sucrose
requires ATP
source to sink
define source
part of the plant that releases assimilates (makes)
define sink
part of the plant that receives assimilates
structure of seive tube elements
-few organelles,no nucleus
-sieve plates form cross walls connect elements
-elements lined end to end
-plasmodesmata link the cytoplasm of companion cells and sieve tube elements
structure of companion cell and function
-cytoplasm
-many mitochondria for ATP for active transport
-large nucleus so many proteins in plasma membrane and many ribosomes
compare structure of xylem and phloem
xylem:
-lignin
-one way flow
-no end walls
phloem:
-thin walls
-two way flow
-sieve plates form cross walls
describe the mass flow hypothesis/translocation
1.active transport is used by companion cells to actively load sucrose into sieve tube elements
reducing water potential
2.water enters the sieve tube elements by osmosis from surrounding tissues
3.this increases hydrostatic pressure in seive tube element
4.sucrose removed from sieve tube and increases water potential
5.water moves out of sieve tube and reduces hydrostatic pressure
4 ways of evidence for mass flow
1.using aphids
2.ringing a tree
3.radioactive tracers
4.metabolic inhibitors
explain how aphids can be used for evidence of mass flow
can investigate pressure in phloem
sap flows out quicker nearer leaves than further down stem
explain how ringing a tree can be used for evidence for mass flow
(removing a ring of bark including phloem not xylem)
bulge forms above ringed area as sugars cant pass
decreases water potential and water moves into the cells
evidence for downwards flow of sugars
how can radioactive tracers provide evidence for mass flow?
tracers like radioactive carbon- (14C) can be used to track movement of organic substances in a plant
how can metabolic inhibitors be used for evidence of mass flow?
translocation can be stopped by using a metabolic poison e.g. cyanide that inhibits respiration so ATP cant form
evidence that active transport is used
what is evidence against mass flow?
1.sugar travels to many different sinks not just the one with lowest hydrostatic pressure
2.sieve plates would create a barrier to mass flow
pressure needed
