BY2 - Transport In Animals (3)
- Created by: beth-marie2511
- Created on: 30-05-16 15:24
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- BY2 - Transport In Animals
- What causes the pressure changes in the arteries?
- Rhythmic rise and fall due to ventricular systole
- Arteries drop in pressure because of friction with the vessel walls and blood.
- Arterioles can dilate (widen) and constrict (narrow).
- This affects pressure
- Arterioles have a large total surface area which reduces pressure.
- What causes pressure changes in the veins?
- Non-rhythmic
- Due to the veins being a large distance away from the heart and the aorta.
- Non-rhythmic
- How does blood return to the heart?
- Massaging effect
- Semi-lunar valves ensure blood returns to the heart.
- What causes pressure changes in the capillaries?
- Decrease in pressure due to the capillaries having a large cross-sectional area.
- Capillary bed
- Capillary bed creates an even greater resistance to blood flow.
- Slows blood flow
- Drop in pressure is also due to leakage from capillaries into the tissues.
- Decrease in pressure due to the capillaries having a large cross-sectional area.
- Red Blood Cells
- Structure
- Biconcave
- No nucleus
- Increases surface area to volume ratio
- More room for haemoglobin.
- Function
- Transport oxygen from lungs to respiring tissues.
- E.G. Muscle tissues.
- Transport oxygen from lungs to respiring tissues.
- Structure
- Transport of Oxygen
- Structure of Haemoglobin
- Each haemoglobin carries 4 O2.
- Haemoglobin can change its affinity for oxygen in the presence of CO2 by changing its shape.
- Altered shape binds more loosely with O2 and releases it.
- Myoglobin
- More stable than haemoglobin.
- Won't release O2 unless the partial pressures of O2 are extremely low.
- Found in the muscles and acts as an energy store.
- Foetal & Maternal Haemoglobin
- Foetal haemoglobin has a higher affinity for oxygen.
- Oxygen is absorbed from the mother.
- Foetal haemoglobin becomes fully saturated at lower partial pressures of oxygen.
- Process
- Red blood cells 'load up' O2 in the lungs where the partial pressures of O2 are high.
- Haemoglobin becomes saturated with oxygen.
- Red blood cells carry the oxygen as oxy-haemoglobin to repiring tissues.
- E.G. Muscles
- Partial pressures of oxygen are low in the muscles.
- Respiration uses up oxygen.
- Red blood cells 'load up' O2 in the lungs where the partial pressures of O2 are high.
- Structure of Haemoglobin
- Why is the Dissociation Curve S-Shaped?
- First molecule of O2 finds It difficult to combine with the haemoglobin.
- This alters the shape of the haemoglobin.
- The change in shape makes it easier for the second molecule of O2 to attach itself to the haemoglobin.
- This once again alters the shape of the haemoglobin.
- This change in shape makes it even easier for the third molecule of O2 to attach itself to the haemoglobin.
- The curve levels off at the top because the joining of the fourth molecule of O2 is more difficult.
- Haemoglobin does not easily combine with O2 at low partial pressures of O2 - it actually releases the O2 its carrying.
- This benefits the organism because the O2 released will be used for respiration.
- An advantage of the S-Shaped curve in the tissues is that as partial pressures of O2 decrease more O2 is released.
- An advantage of the S--Shaped curve in the lungs is that as partial pressures of O2 increase haemoglobin becomes saturated and O2 is released less easily/readily.
- An advantage of the S-Shaped curve in the tissues is that as partial pressures of O2 decrease more O2 is released.
- This benefits the organism because the O2 released will be used for respiration.
- At high partial pressures of O2 in the lungs haemoglobin becomes fully saturated with O2.
- Haemoglobin easily picks up the O2 but does not easily release it at high partial pressures.
- Bohr Effect
- CO2 is constantly produced by respiring cells.
- CO2 diffuses from the cells into the blood plasma and then into the red blood cells.
- High partial pressures of CO2 causes haemoglobin to release the oxygen its carrying.
- CO2 lowers blood pH which reduces the affinity the haemoglobin has for oxygen.
- The more the curve moves to the right the less easily / readily haemoglobin picks up the O2 and it more readily releases O2
- The higher the concentration of CO2 the more readily oxygen is released.
- CO2 is constantly produced by respiring cells.
- First molecule of O2 finds It difficult to combine with the haemoglobin.
- Transport Oxygen in Other Animals
- Lugworm
- Low metabolic rate
- Lives in sands on the seashore.
- Low levels of oxygen
- Pumps seawater through its burrow.
- Limited amount of dissolved oxygen present.
- Has special haemoglobin that more readily picks up oxygen.
- S-Shaped curve is more to the left when compared to human haemoglobin.
- Llama
- Has a greater affinity for oxygen compared with human haemoglobin.
- Lives at high altitudes
- Low partial pressures of O2
- Creatures that live at high altitudes have larger numbers of red blood cells.
- Lugworm
- Transport of CO2
- 1. CO2 diffuses from body cells into the plasma, then into the red blood cells.
- CO2 combines with water to form carbonic acid (H2CO3) - the reaction is catalysed by the enzyme carbonic anhydrase.
- 2. Carbonic acid breaks up into H+ and HCO3-. H+ lowers blood pH and causes O2 to be released.
- HCO3- diffuse out into the plasma where they combine with sodium to form sodium hydrogen carbonate.
- 3. H+ cause the haemoglobin to dissociate / release oxygen as H+ moves into the oxy-haemoglobin
- 4. Oxygen diffuses out of red blood cells and into the tissues.
- 5. H+ combine with haemoglobin to form haemo- globonic acid. (HHb).
- 6. Outward movement of negative HCO3 ions are balanced by the inward movement of Cl- ions.
- This is known as chloride shift. It maintains electro-chemical neutrality.
- 6. Outward movement of negative HCO3 ions are balanced by the inward movement of Cl- ions.
- 5. H+ combine with haemoglobin to form haemo- globonic acid. (HHb).
- 4. Oxygen diffuses out of red blood cells and into the tissues.
- 1. CO2 diffuses from body cells into the plasma, then into the red blood cells.
- Intercellular Fluid
- The function of the capillaries is to exchange substances between the blood and cells.
- Adaptations of Capillaries
- Thin
- Large cross sectional area
- Semi-permeable (pores)
- Blood flows slowly to allow the exchange of substances.
- Formation of Tissue Fluid
- Fluid movement depends upon the difference between HYDRO-STATIC pressure and OSMOTIC pressure
- If hydrostatic pressure of the blood is higher than osmotic pressure then there will be a net flow of water out of the blood.
- If hydrostatic pressure n the blood is lower than osmotic pressure there will be a net flow of water into the blood.
- Osmotic pressure changes because of water (plasma) moving out of the capillary at the arterial end.
- This reduces the water potential of the blood moving towards the venous end.
- Water will move by osmosis from the tissue fluid back into the capillary at the venous end because water moves from a high to low water potential.
- If fluid does not return in this way then it will drain into the m=lymphatic system via the thoracic duct which empties into a vein near the heart.
- What happens to the blood that leaks out of the capillaries?
- Substances that leak out are: glucose, O2, vitamins, minerals, H2O and amino acids.
- They leak out at the arterial end of the capillary bed.
- Large molecules won't be able to leak out e.g. red blood cells and plasma proteins.
- The fluid that leaks out is TISSUE FLUID which surrounds the body cells.
- It supplies cells with glucose, amino acids, minerals, vitamins and O2.
- Tissue fluid removes waste substances from cells e.g. CO2 and urea.
- It supplies cells with glucose, amino acids, minerals, vitamins and O2.
- The fluid that leaks out is TISSUE FLUID which surrounds the body cells.
- What causes the pressure changes in the arteries?
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