Exam Qs - 3.4.1 Mass Transport in animals

• Some people produce a much higher ventricular blood pressure than normal. This can cause tissue fluid to build up outside the blood capillaries of these people. Explain why

  • MORE fluid / water forced/filtered out of capillary/blood due to high pressure
  • Less return of fluid into capillary/blood due to pressure
  • Lymphatic system cannot drain away all excess fluid
• Some drugs used to reduce high ventricular blood pressure cause widening of blood vessels.

  Suggest how widening of blood vessels can reduce ventricular blood pressure. [2 marks]

  • Larger lumen/volume of blood vessels
  • Reduces blood pressure in blood vessels
  • Less friction/resistance in blood vessels
• Synthetic EPO can increase blood pressure. Suggest why. [1 mark]

  • Blood thicker / denser / more viscous / more ‘concentrated’
  • heart CONTRACTION greater / increases volume of blood;
• Blood vessel B contains smooth muscle in its walls. Explain how this muscle may reduce the blood flow to the small intestine. [2 marks]

  • Contracts
  • Causing vasoconstriction / narrows lumen;
• Elastic tissue in the walls of blood vessel A helps to even out the pressure of blood through this vessel. Explain how [2 marks]

  • Elastic tissue stretches when pressure is high
  • Springs back / recoils / returns to normal
• Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs

  1. Renal vein - from kidneys INTO the heart
  2. Vena cava to right atrium
  3. Right ventricle to pulmonary artery;
• Identify the blood vessel labelled M

  • VEIN
  • Wide(r) lumen OR
  • Thinner wall

  
• What can you conclude from the appearance of valves in the image above about heart muscle activity and blood movement between:

  1. ventricles and arteries

  • Ventricle (muscles) relaxed OR arteries recoiled
  • OR no muscle activity OR diastole OR arteries smoothing blood flow
  • SO there is no blood backflow into ventricles

  
• What can you conclude about heart muscle activity and blood movement of atria and ventricles?

  • 3. Atria (muscle) contracted
  • Blood movement from atria into ventricles

  
• 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.

  • At point Q of the diagram, there is elastic recoil in the aorta wall / tissue NOT! muscle contracting
  • This smoothes the blood flow // maintains the rate of blood flow // maintains blood pressure

  
• Describe the advantage of the Bohr effect during intense exercise

  • Increases dissociation of oxygen;
  • For aerobic respiration at the tissues/muscles/cells
  • OR anaerobic respiration delayed at tissues / muscles / cells
  • OR less lactate at tissues / muscles / cells
• Suggest a physiological change that causes pCO2 in air that did not increase, but the body DID increase in volume of CO2 produced.

  • Increases in breathing rate / tidal volume
  • SO similar / same partial pressure of carbon dioxide breathed out, but with MORE breaths

  
• • EPO causes blood to THICKEN - SINCE THERE IS MORE RED BLOOD CELLS IN BLOOD than normal so SLOWER BLOOD FLOW
  • (The thickened blood) could block the coronary arteries // slows blood flow // thicker blood could cause blood clots

  
• Describe and explain the effect of increasing carbon dioxide concentration on the dissociation of oxyhaemoglobin.

  • Increases/more oxygen dissociation/unloading OR Deceases haemoglobin’s affinity for O2;
  • (By) decreasing (blood) pH/increasing acidity;
• Use information in the graph to explain how the seal’s myoglobin dissociation curve shows the seal is adapted for diving.

  • Myoglobin has high(er) affinity for O2 (than haemoglobin) OR Dissociates oxygen less readily OR Associates oxygen more readily
  • Allows (aerobic) respiration when diving/at lower partial pressure of oxygen
  • Delays anaerobic respiration/lactate production;

  
• Explain how valve A (atrioventricular) in Figure 1 maintains a unidirectional flow of blood

  • Pressure in (left) ATRIUM! is higher than in ventricle/B CAUSING! valve to open
  • When pressure above valve is higher than BELOW valve it opens ((NOT in front // behind))
  • Other side of the argument = Pressure in (left) ventricle/B is higher than in atrium causing valve to close
  • OR When pressure in BELOW valve is higher than above valve it closes

  
• Explain how their cardiac output could stay the same even when their resting heart rate had decreased.

  • Cardiac output = stroke volume × heart rate
  • (So) stroke volume increases / increased size or volume of ventricles
• Use information from the figure to explain how the pressure in the dog’s ventricle is related to blood flow into the aorta.

  • Ventricle pressure rises THEN blood starts to flow into aorta because pressure causes (aortic / semilunar) valve to open;
  • Ventricle pressure starts to fall so blood flow falls;
  • idea of SEQUENCE IS IMPORTANT

  
• Use information from the figure to explain how the pressure in the dog’s ventricle is related to the thickness of the ventricle wall.

  • Thickness of wall increases BECAUSE ventricle (wall) contracts
  • Contraction CAUSES the increase in pressure;
• Use Figure 1 to describe how haemoglobin loads and unloads oxygen in the body.

  • Loading / uptake / association of oxygen at high p.O2;
  • In lungs (haemoglobin) is (almost) fully saturated / in lungs haemoglobin has a high affinity for oxygen;
  • Unloads / releases / dissociates oxygen at low p.O2
  • Unloading linked to higher carbon dioxide concentration;

  
• Same question as 2019 Q9

  • Smaller mammal has greater surface area to volume ratio
  • Smaller mammal / larger SA:Vol ratio more heat lost (per unit body mass)
  • Smaller mammal / larger SA:Vol ratio has greater rate of respiration / metabolism
  • Oxygen required for respiration so (haemoglobin) releases more oxygen / oxygen released more readily / haemoglobin has lower affinity

  
• Name layer C

  • Epithelium / endothelium

  
• The aorta has many elastic fibres in its wall. An arteriole has many muscle fibres in its wall.

  (i) Explain the importance of elastic fibres in the wall of the aorta.

  • Stretches / ’expands’ under high pressure / when ventricle contracts / systole and recoils / ’springs back’ under low pressure / when ventricle relaxes / diastole;
  • Smooths blood flow / maintains blood pressure / reduces pressure surges
• Explain the importance of muscle fibres in the wall of an arteriole

  • (Muscle) contracts;
  • (Arteriole) constricts / narrows / alters size of lumen / reduces / regulates blood flow to CAPILLARIES
• The rate of blood flow decreases from the aorta to the capillaries. Use information from the graph to explain why.

  • Large / increase in (total) cross sectional area / friction / resistance

  
• Efficient exchange of substances in the capillaries is linked to the rate of blood flow. Explain how.

  • (More) TIME!!!! for exchange of substances;
• Give one way in which an electrocardiogram could have produced more reliable results than counting the pulse.

  • Records every heart beat / does not miss heart beats / gives more precise / accurate measurements;
• (a) The results of the ivabradine trial were reliable. (i) Explain the importance of the ivabradine investigation being a large-scale trial.

  • Identifies anomalies / minimises effect of anomalies / unusual results / results more likely to be representative / more reliable mean;
  • Accept likely to see side effects

  
• Explain how oxygen is loaded, transported and unloaded in the blood. [6 marks]

  1. Haemoglobin carries oxygen / has a high affinity for oxygen / oxyhaemoglobin
  2. Loading / uptake / association in lungs
  3. at high p.O2
  4. Unloads / dissociates / releases to respiring cells / tissues
  5. at low p.O2
  6. Unloading linked to higher carbon dioxide concentration