Flashcards in Gas Transport Deck (24)
Describe the structure of haemoglobin
Protein in rbcs
Has 4 subunits each with a haem group each containing an iron ion that can bind 1 oxygen molecule
Adult hb= 2 alpha and 2 beta subunits
Feral hb= 2 alpha and 2 gamma
When hb is 100% saturated how does 1g of hb carry ?
What is the normal concentration of hb in blood ?
So oxygen carry capacity of hb in blood is 200ml
If CO is 5l/mins how much oxygen is delivered around the blood in 1 min ?
- resting oxygen consumption is 250ml so remaining 750ml returns to lungs - large reserve of oxygen bound
What shaped is the hb-oxygen dissociation curve and why ?
Binding of 1 oxygen molecule changes the conformation of hb and increases the affinity of the other oxygen binding so it is easily to bind another molecule
If a factor decreases hbs affinity for oxygen which way does the curve shift ?
Anything that increases hb affinity for oxygen shifts curve to the ..,
How does temperature affect hb affinity for oxygen ?
Increase in temperature decreases oxygen affinity
Good because during metabolism heat is produced so increasing the temperature will favour oxygen unloading which is what the tissue needs
How does pH affect hb affinity for oxygen ?
Decrease in pH decreases affinity for oxygen
Good because during metabolism proton concentration. Increases so increasing oxygen unloading is favourable
How does carbon dioxide (carbamino effect) effect hb affinity for oxygen ?
Increases in carbon dioxide decreases oxygen affinity
Carbon dioxide binds to amino acids in hb and creates caraminohaemoglobin which has a lower affinity for oxygen
How does 2,3-DPG affect hb affinity for oxygen ?
Oxyhemoglobin inhibits enzyme that produces 2,3-DPG
When oxygen levels are reduced 2,3-DPG levels rise and decrease affinity of hb for oxygen which is good because 2.3-DPG is produced during high metabolism so the tissue will be requiring oxygen
What is the difference between fetal and maternal hb ?
Fetal has a higher affinity for oxygen because it has 2 gamma subunits instead of beta
What is the purpose of myoglobin ?
Short term store of oxygen in skeletal muscle
Much higher affinity for oxygen than hb
Releases its stores when intracellular oxygen is low - used in short intense muscle contraction
What are the 3 transport mechanisms for carbon dioxide in blood ?
Dissolved in plasma
Dissolved in the form of bicarbonate ions
Bound to hb
What enzyme catalyses the reaction converting carbon dioxide to bicarbonate ions ?
What is the chloride shift ?
When bicarbonate ions are produced protons are also produced in the rbcs
To maintain the concentration gradient so more carbon dioxide is converted to bicarbonate ions the bicarbonate ions are exchanged for a chloride ions
What is the haldane effect ?
Binding of oxygen to hb reduces affinity of hb for carbon dioxide
The greater the partial pressure of oxygen the more carbon dioxide is unloaded so therefore this effect increases elimination of carbon dioxide at the lungs
Effect is beneficial at respiring tissues because oxygen is low which promotes carbon dioxide binding helping to remove carbon dioxide
What is anaemia ?
Decrease in oxygen carrying capacity of the blood
What is nutritional anaemia ?
Dietary deficiency - iron or folic acid
Causes a decrease in hb synthesis - iron
Inhibits DNA synthesis and cell division- folic acid
What is pernicious anaemia?
Deficiency of intrinsic factor needed to absorb bit b12 - inhibits DNa synthesis
What is aplastic anaemia?
Defect in bone marrow
What is renal anaemia ?
Decreased EPO resulting in decreased red blood cell synthesis
What is haemorrhagic anaemia ?
Rapid loss of blood - takes weeks to restore red blood cell levels