gas transport

Samantha bruce
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lecture 5

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Samantha bruce
Created by Samantha bruce 2 months ago
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Question Answer
how is gas transported in many animals bulk flow in circulatory fluid
what is the problem with oxygen delivery in the circulatory system alone and what is the solution to this - cant be efficiently transported dissolved in the blood require the use of respiratory pigments these are called metalloproteins--> reversible bind oxygen commonly have a metal ion bound to polypeptide
where are the metalloproteins found erythrocyte membranes or blood plasma
describe respiratory pigment function -these do different things at different partial pressures bind to oxygen and carry it around the circ. system
blood pigment function at high pp high pp is at the respiratory surface - this is where the proteins bind to oxygen
blood pigment action at low pp this is at the tissues commonly O2 release
name the most common and widespread respiratory pigment haemoglobin - found in all vertebrates and most annelids, some arthropods, molluscs and nematodes
describe haem structure tetrameric structure -4 subunits (in humans) differs in different species e.g. annelids = 150 subunits haem group at the centre of each globulin
where is haem found generally in the erythrocytes where it is termed intracellular (humans) In some species it is found in the extracellular plasma
what is myoglobin - generally used for o2 storage for longer time periods found in the muscles - e.g. the cardiac muscles
where would you find neuroglobins neurons protect the cells from oxidative damage
what is cytoglobin found in all tissues -function not known hypothesised to supply oxygen to cells, protective and as a sensor to when there is a changes in o2 conc/ partial pressure
name 2 different respiratory pigments you might find in different species haemocyanin haemerythrin
describe the function of haemocyanin -arthropods and molluscs -Cu2+ reactive centre these are larger molecules and typically exist as hexamers that form cylinders these are only extracellular -->due to large size
describe the function of haemerythrin found in obscure marine invertebrates iron centre- but no haem group the iron is bound to the protein directly mostly intracellular known as a pink blood cell- due to colou of the pigment
what is the pigment that you may find in the blood of some annelids clorocruorin and erythocruonon
what are clorocruorin and erythocruonon properties similar to haemoglobin but much larger molecules only found extracellular
describe the oxygen saturation of arterial and venous blood supply arterial- 95% saturation venous- around 75% saturated
describe the shape of the oxygen equilibrium curve sigmoidal
what is the shape of the myoglobin binding curve hyperbolic
why does the binding of myoglobin and haemoglobin differ myoglobin is a monomer and doesn't bind cooperatively
what are the 2 states that haemoglobin can be found in tense - unbound R - saturated
what Is p50 partial pressure at which 50% of the respiratory pigments are saturated
what does a low p50 indicate high affinity to oxygen
how would you describe the relationship between the initial affinity and ease of offloading inverse relationship - low p50 curve moves to the left, affinity greater and harder to offload
what effect does higher temperatures have on the P50 -higher p50 shifted to the right lower affinity
higher p50 at higher temperatures? is this adaptive or disadvantageous ectotherms echotherms, cannot regulate body temp - environment dependent temp increase= increased metabolic rate this means higher requirement for o2 at tissues and higher temp means that this is offloaded easier and more readily at tissues
higher p50 at higher temperatures? is this adaptive or disadvantageous endotherms can regulate temp of body local temp increases e.g during periods of exercise - higher p50 would mean that delivery to these tissues would be increased
what effect does the blood pH have on affinity to oxygen -pH decrease = affinity drops this is called the Bohr effect
describe the relationship between partial pressure and PCO2 -
why does the affinity for oxygen drop when in Lower pH -protons binding to the pigment alternatively and the affinity to O2 drops
why does o2 affinity decrease when Pco2 increases -co2 reacts with water forming carbonic acid that is quickly dissociated forming H+ binding to the pigment and reducing o2 affinity
is pH dependent oxygen binding adaptive ir disadvantageous advantageous - facilitates the release of oxygen at the tissues because the tissues produce Co2 that increase the Pco2 and lowers the pH makes it easier to release bound oxygen to the cells and tissues this is the opposite at the lungs where o2 pp is high
why might is be beneficial to alter the amount of oxygen carrying pigments in the blood seasonal changes- cold acclimation - more respiratory pigment = efficient oxygen delivery locomotory activity -stimulate the release of erythrocytes from the spleen hypoxia= rbc production - altitude acclimisation -works via transcription factor hypoxia inducible factor- produced erythropoietin == RBC stress and disease e.g. anaemia
name the 3 ways that CO2 can be transported in the blood 1- physically dissolved gas 5-10% 2- bound to haemoglobin (carbinohaemoglobin) 25-30% 3-bicarbonate 60-70%
where does the bicarb. Co2 reaction take place erythrocytes - carried out her quicken than it does in the plasma because the enzyme for conversion is in the blood cells
name the ezyme that is used for conversion from water and co2 to carbonic acid carbonic anhydrase
describe the ability of bicarb to move once internalised in cell cannot cross membrane
summarise the gas transport -Co2 moves into RBC, this is produced by tissues- defuses into plasma and then erythrocytes -some is bound to the haemoglobin (carbohaemoglobin) active trasnporter-- removes the bicarb from the cell in exchange for chloride ions transporter called band 3 protein
what would happen if the band 3 didn't trasport the CO2/ bicarb out of the cell -build up of bicarb shift in the cell chemistry - move to the left equilibrium impairment to the formation of bicarb
would would be the effect of build up of bicarb impaired CO2 uptake
CO2 removal from the red blood cell--> how? a the alveoli the bicarb is transported to the erythrocytes reverse reaction Co2 formation Co2 can move across the membrane where it is healed and removed from the body