7.2 Transport of Oxygen
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- Created by: germaineconroy
- Created on: 05-02-18 15:19
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- 7.2 Transport of Oxygen
- Oxygen dissociation curves
- hb exposed diff PPs of O, does not bind evenly
- Graph of relationship btwn saturation hb w/ O & PP O known as ODC
- (1) Shape hb mol makes diff for first O mol to bind to one sites on 4 polyp chains bc they're closely united
- @ Low O conc = little O binds to hb
- Curve of graph = shallow initially
- @ Low O conc = little O binds to hb
- (2) Binding of 1st O mol changes 4 struc, cause mol to change shape. Change makes easier for subunits to bind to O mol.
- Binding of 1st induces other subunits to bind 2 O.
- (3) So, takes smaller incr in PP of O to bind 2nd O mol than it did to bind to 2nd
- Positive cooperativity
- Gradient of curve steepens
- Positive cooperativity
- (4) changes aftr bind 3rd mol - in theory easier, prac harder. Due 2 probability. Majority binding sites occupied, less likely single O mol find empty site.
- Gradient curve reduces & flattens off
- bc diff HBs - large num diff ODCs - sim shape but differ - axis.
- further to left the curve = greater affinity of hb for O (loads easier, unloads harder)
- Further right = lower affinity (loads harder, unloads more easy)
- Effects CO2 conc
- Presence CO2 = hb lower affinity O
- ^conc CO2, more readily hb releases (Bohr effect)
- Behaviour hb change - diff regions.
- GE surf (lungs) conc CO2 low bc diffuses across ES & excreted = affinity ^ & ^ conc O in lung
- Rapidly resp tissues - CO2 conc ^ . Affinity hb reduced + low O conc means unloaded from hb (-> musc cells)
- Greater conc CO2 = more rapidly hb rel O. Dissolved CO2 = acidic, low pH cause hb change shape.
- Presence CO2 = hb lower affinity O
- Loading, transport & unloading oxygen
- At GE surf, CO2 const removed
- pH ^ due low conc CO2
- Lugworm = not active - covered by sea water, circulates burrow. Tide out - burrow water looses O - lugworm extracts as much O as possible from water until tide comes in. Higher affinity
- At GE surf, CO2 const removed
- Oxygen dissociation curves
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