3.3.4.1 MASS TRANSPORT IN ANIMALS Flashcards
What are the haemoglobins?
A group of chemically similar molecules found in many different organisms
What is haemoglobin?
- globular protein
- quaternary structure e
How many polypeptide chains does haemoglobin have?
4
What do the 4 polypeptide chains in haemoglobin associated with?
- there are 4 haem groups (prothstetic groups)
- each group contains an Fe2+ ion which can combine with a single oxygen molecule- each haemoglobin can carry 4 oxygen molecules as there are 4 haem grouod
When oxygen binds to haemoglobin, what does it form?
Oxyhaemoglobin
Why is haemoglobin required?
Oxygen has a low solubility in water (plasma) at body temperatures
What is loading/associating?
Process by which haemoglobin binds with oxygen, takes place in the LUNGS
What is unloading/dissociating?
Process by which haemoglobin releases the oxygen it is carrying, occurs in RESPIRING TISSUES
What is high affinity?
Picks oxygen up easily but doesn’t release it easily
What is low affinity?
Doesn’t pick oxygen up easily but releases it easily
Can haemoglobin change its affinity?
Yes- can change under different circumstances due to how the 4 polypeptide chains bind together
Red blood cell adaptations to carry more haemoglobin:
1) minimal organelles= more room for haemoglobin
2) biconcave shape= large SA:V ratio
3) small diameter= minimises diffusion distance between tissues + red blood cells
What does it mean if the line is closer to the left on the oxyhaemoglobin dissociation curve?
- GREATER affinity of Hb for oxygen
- think of affinity for oxygen as how strongly it attracts oxygen
What does it mean if the line is further to the right on the oxyhaemoglobin dissociation curve?
- LOWER affinity of Hb for oxygen
- think of affinity of haemoglobin for oxygen as how strongly it attracts oxygen
What is cooperative binding?
- when the first oxygen molecule binds to haemoglobin, it causes a change in the protein’s shape
- makes it EASIER for other oxygen molecules to bind to it- call this COOPERATIVE BINDING
- affinity of haemoglobin for oxygen is INCREASED
What is partial pressure on the oxyhaemoglobin dissociation curve?
The pressure a particular gas contributes to the total pressure of the gas mixture
Outline how CO2 is transported:
- CO2 diffuses form respiring tissues in the blood plasma and then into the red blood cells
- the majority of CO2 reacts with water to form carbonic acid, this is catalysed by the enzyme carbonic anhydrase
- carbonic acid partially dissociates to form H+ and hydrogen carbonate ions
- the H+ binds to haemoglobin to form haemoglobinic acid
- some CO2 can also be transported by being dissolved in the blood plasma or binding directly to haemoglobin
Outline the Bohr effect:
- Haemoglobinic acid has a different quaternary structure than haemoglobin
- Haemoglobinic acid has a LOWER affinity for oxygen than haemoglobin
- This means that oxygen dissociates more readily
- Supplies oxygen more rapidly to respiring tissues
- We see the Bohr effect as ashift of the curve to the right when CO2 concentrations are higher
Do mice have a high or low affinity for oxygen?
- Curve shift to the right- LOW affinity
- mice has a lower affinity for oxygen than humans as a mouse is smaller and has a higher SA:V ratio, so it has a much higher rate of respiration to maintain it’s body temp
Outline atrial systole:
(Contraction)
1. Higher pressure in atria than ventricles
2. Blood moves into ventricles
3. Increase ventricular volume, decreased atrial volume
4. Atrioventricular valves close, semi-lunar valves open
Outline ventricular systole:
(Contraction)
1. Higher pressure in ventricles than atria or arteries
2. Blood moves into arteries
3. Increased arterial volume, decreased ventricular volume
4. Atrioventricular valves close, semi-lunar valves open
Outline ventricular diastole:
(Relaxation)
1. Higher pressure in atria and arteries than ventricles
2. Blood flows away in the arteries
3. Blood flows into the atria (venous return) and then into ventricles
4. Increase atrial and ventricular volumes, decrease arterial volumes
5. Semi-lunar valves close, atrioventricular valves open
Outline the stages that happen when our body detects that our blood pH is too low:
- chemoreceptors in the carotid arteries detect low pH
- sends an impulse along sensory neurone to cardiovascular centre in medulla oblongata
- medulla oblongata increases the frequency of impulses to the sinoatrial node along accelerator nerve via sympathetic division if autonomic NS
- increases the waves of excitation from SAN
