mass transport A

• Explain how water from tissue fluid is returned to the circulatory system.

  • proteins remain in blood after ultrafiltration (too large)
  • Reduces water potential of blood
  • Water moves to blood by osmosis
  • Returns to blood by lymphatic system
• Explain how an arteriole can reduce the blood flow into capillaries.

  • muscle contracts
  • to constrict and/ or narrow arterioles
• VENTRICLES AND ARTERIES:

  • Ventricle muscles relaxed
  • No blood movement to arteries

  ARTIA AND VENTRICLES:

  • Atria muscle contracted
  • Blood movement from atria into ventricles

  
• veins carry blood at the lowest pressure
• Use evidence from diagram above to explain why the pressure in the left ventricle is increasing while the rate of blood flow has not yet started to increase in the aorta.

  • Aortic semi-lunar valves is closed
  • Because pressure in aorta higher than in ventricle

  
• At Q on the diagram above 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 aortic tissue
  • Maintains rate of blood flow

  
• Describe the advantage of the Bohr effect during intense exercise

  • Increases dissociation of oxygen (reduced affinity)
  • For aerobic respiration at the tissues
• Explain how the physiological change would allow for the removal of the increase in the volume of carbon dioxide produced.

  • Increase in breathing rate
  • same partial pressure of CO2 per breath, but more breaths
• EPO can increase the haematocrit (the percentage of red blood cells in blood).

  A heart attack is caused by a lack of glucose and oxygen being delivered to cardiac muscle via the coronary arteries. The overuse of EPO can increase the risk of a heart attack. Suggest how.

  • EPO causes blood to thicken
  • which could block the coronary arteries and cause blood clots
• Describe and explain the effect of increasing carbon dioxide concentration on the dissociation of oxyhaemoglobin.

  • more oxygen dissociation/unloading
  • increasing acidity of blood as CO2 acidic
• Use information in the graph to explain how the seal’s myoglobin dissociation curve shows the seal is adapted for diving.

  • Higher affinity for oxygen than haemoglobin
  • Provides oxygen when haemoglobin unloaded

  
• Explain how valve A in Figure 1 maintains a unidirectional flow of blood.

  • Pressure in (left) atrium is higher than in ventricle/B causing atrioventricular valve to open
  • Pressure in (left) ventricle/B is higher than in atrium causing atrioventricular valve to close

  
• Name the blood vessels that carry blood to the heart muscle

  • coronary arteries
• Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind. Explain why.

  • Binding of first oxygen changes quaternary structure of haemoglobin
  • Uncovers another haem group for second oxygen molecule to bind to
• Explain the role of the heart in the formation of tissue fluid.

  • Contraction of ventricles produces high hydrostatic pressure
  • This forces water (and some dissolved substances) out of blood capillaries
• Explain how changes in the shape of haemoglobin result in the S-shaped (sigmoid) oxyhaemoglobin dissociation curve for HbA.

  • First oxygen binds (to Hb) causing change in shape
  • allows for O2 to bind easily - positive cooperative binding

  
• At birth 98% of the haemoglobin is HbF. By the age of 6 months, the HbF has usually completely disappeared from the baby’s blood and been replaced by HbA.

  Use the graph above to explain why it is an advantage for the baby.

  • (HbA has) lower affinity for O2 at low partial pressures
  • Easier unloading of O2 for respiration

  
• • obesity is highly significant strongly suggesting its link to asthma being less than 0.5 is not due to chance
  • burned wood is greater than 0.5 so not significant
  • lived with a cat or dog is significant

  
• • semi lunar valve opens = 2
  • semi lunar valve closes = 3
  • atrioventricular valve opens = 4
  • atrioventricular valve closes = 1

  
• Describe and explain the advantage of the counter-current principle in gas exchange across a fish gill

  • Water and blood flow in opposite directions
  • Maintains diffusion gradient
  • Along whole length of lamellae
• What can you conclude about the uptake of oxygen over the entire body of the lungworm?

  • Enters by diffusion
  • Down a concentration gradient
  • most across parts of body with gills
  • Gills provide a larger surface area (for absorption)
  • could include values

  
• explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake?

  • larger organisms have smaller surface area to volume ratio
  • to the specialised system overcomes the long diffusion pathway