Mass Transport In Mammals 1 - Haemoglobin & Oxygen Dissociation Curves Flashcards
State and explain 3 adaptations of red blood cells
Biconcave disc shaped = increases SA over which diffusion takes place
No nucleus = has most amount of space for haemoglobin
Flexible to squeeze through capillaries = aids in quick transport
Name the two subunits in haemoglobin
Protein chain (globin)
Prosthetic group (haem)
What is the oxyhaemoglobin equation and what does it show about haemoglobin?
Hb + 402 -> HbO8
Shows that one haemoglobin can combine with up to four oxygen molecules
Why is an oxygen dissociation curve S-shaped?
The first oxygen molecule binds with difficulty but once attached, it causes a change in haemoglobin and the subsequent 3 molecules bind easily
Describe the difference between oxyhaemoglobin binding at a high and low partial pressure
High partial pressure = oxyhaemoglobin combines readily
Low partial pressure = oxyhaemoglobin dissociates
How is carbon dioxide transported
Solution in blood plasma 5%
Combined with haemoglobin 10%
Hydrogen carbonate ions (HCO3) 85%
Describe the formation of hydrogen carbonate ions
CO2 produced by tissues diffuses into red blood cells and reacts with water to form carbonic acid (H2CO3) and is catalysed by carbonic anahyrdrase~ H20 + CO2 -> H2CO3
Carbonic acid dissociates into H+ and H2CO3 ~ H2CO3 -> H+ + HCO3-
H+ displaces oxygen from haemoglobin (haemoglobinic acid) so oxygen is released
HCO3- diffuses out of red blood cells into plasma
CL- ions go to red blood cells as HCO3- ions are transported (chloride shift)
What is the BOHR Shift?
Second dissociation curve is shifted to the RIGHT as haemoglobin is less saturated in an area with higher PCO2, lower pH and higher temperature
Curves to the RIGHT have a lower affinity for oxygen
More O2 release at the same PO2 so actively respiring trusses receive more O2 for respiration
Describe oxygen dissociation curves to left with the example of foetal haemoglobin
Foetal Hb has a lower affinity for oxygen than maternal Hb
This means the foetal Hb can load with oxygen at partial pressures of oxygen in which maternal Hb is unloading
What is myoglobin? What does its curve look like?
The respiratory pigment found in muscles ~ one protein chain and one haem group
Mb dissociation curve is to the LEFT of Hb ~ it only gives you oxygen at a low pO2
Acts as an oxygen reserve in muscles when demand temporarily exceeds supply
How does altitude affect the dissociation curves of mammals
High altitude = pO2 decreases with altitude so it is difficult to load Hb with oxygen
Low altitude = produce more red blood cells ~ kidneys release a hormone called renin due to lack of oxygen & renin increases rate of mitosis in bone marrow = more RBC produced
