Module 3 - Mass transport in animals Flashcards
3 marks
The oxygen dissociation curve for heamoglobin shifts right during vigorous exercise. Explain the advanatge of this shift
- Low pH due to increased CO2/ increased respiration
- Increased dissociation of haemoglobin
- Oygen diffuses from r.b.c to tissues
3 marks
How does exposure to CO affect loading and unloading of oxygen by haemologlobin
- A low Po2 Hb exposed to CO has a higher affinity for oxygen than normal Hb
- In respiring tissue its unloading less oxygen than it should
- At high Po2 (lungs) it has a lower affinity for oxygen than normal Hb- only 50% saturation of the no CO Hb (less oxygen loaded at lungs)
3 marks
Explain why the thickness of the aorta wall changes all the time during each cardiac cycle
- Aorta wall stretches because ventricle contracts (pressure increases)
- Aorta wall recoils because ventricle relaxes (pressure falls)
- Maintain smooth flow / pressure
What does atheroma lead to
Atheroma leads to blockage of coronary artery
Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise.
- Arteriole;
- (Circular/smooth) muscle relaxes;
- Widens/dilates (lumen of) blood vessel so increases blood flow;
2 marks
There is a small increase in pressure and in rate of blood flow in the aorta.
Explain how this happens and its importance.
- Elastic recoil of the aorta wall
- Smooths the blood flow
What factor limits the minimum internal diameter of the lumen of a capillary
Diameter of red blood cell
2 marks
How is the pressure in the ventricle related to the thickness of ventricle wall
- Thickness of wall increases because ventricle wall contracts
- Contraction caused by increase in pressure
3 marks
Explain why high blood pressure leads to the accumulation of tissue fluid
- High blood pressure (as ventricle contracts)= high hydrostatic pressure
- Increase in outward pressure from arteriole end of capillary
- So more tissue fluid formed
3 marks
Why does venule end of capillary have lower blood plasma water potential
- Water has left capillary
- Proteins in blood too large to leave
- Higher concentration of blood plasma proteins
Why does carbonmonoxide kill people. Use loading and unloading of O2.
At low pO2, Hb exposed to CO has higher affinity for O2 than normal Hb
In respiring tissues it is unloading less O2 than it should
At high PO2, it has lower affinity for O2 than normal Hb- less O2 loaded to lungs
6 marks
Explain how tissue fluid is formed and how it may be returned to the circulartory system
- High hydrostatic pressure at arterial end
- Soluble molecules pass out
- Proteins remain - too large
- This lower water potential at venule end
- Water moves back into venule end via osmosis
- Lymphatic system collects any excess tissue fluid which returns to blood
2 marks
High absorption of salt from the diet can result in a higher than normal
concentration of salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid. Explain how.
- Higher salt results in higher blood pressure–> higher hydrostatic pressure
- So more fluid forced out of arteriole end of capillary
OR - Higher salt results in lower water potential of tissue fluid
- So less water returns to capillary by osmosis at venule end
6 marks
Explain how the structures of the walls of arteries, veins and capillaries are related to their functions.
Artery
1. thickest wall, enabling it to carry blood at high pressure / withstand pressure surges
2. most elastic tissue, which evens out pressure
3. most muscle which maintains pressure
4. muscle in wall to control blood flow
Vein
5. thin wall does not have to withstand high pressure
Capillary
6. thin wall, allowing diffusion
7. only endothelium present, allowing short diffusion pathway
All vessels
8. have endothelium that reduces friction
Does artery or vein have larger lumen
Arteries have smaller lumens than veins
