1 markThe liquid of plasma forms the tissue fluid. Hydrostatic pressure and oncotic pressure play a vital role in tissue formation.
Oncotic pressure can be defined as:
The pressure exerted by blood
The osmotic pressure exerted by plasma proteins within a blood vessel
The hydrostatic pressure exerted by plasma proteins within a blood vessel
The osmotic pressure exerted by blood
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1 markThe diagram below shows a picture of the internal view of a mammalian heart.
At position X, the pressure in the ventricles rises above that in the aorta and pulmonary artery forcing the valves to open.
Identify the valves at position X.
Atrioventricular valve
Bicuspid valves
Tricuspid valves
Semilunar valves
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1 markWhich of the following options, A to D, is the correct description of atrial systole and ventricular diastole?
Atria relax, the ventricles contract, forcing blood out of the heart
Atria contract, forcing blood into the ventricles
Atria relax, forcing blood into the ventricles
All chambers are relaxed, and blood flows into the heart
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1 markThe heart beats in an ordered rhythmic fashion without any external stimulus.
State the correct order of electrical conduction in the heart.
SA node → AV node → Bundle of His → Purkyne tissues
AV node → SA node → Purkyne tissues → Bundle of His
Purkyne tissues → SA node → AV node → Bundle of His
Bundle of His → SA node → AV node → Purkyne tissues
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1 markHaemoglobin shows cooperative binding behaviour.
Which of the statements, from A to D define the cooperative binding behaviour of oxygen?
 The oxygen binding capacity of haemoglobin decreases with a rise in oxygen levels
Haemoglobin releases oxygen readily as more oxygen binds to it
Haemoglobin can readily accept carbon dioxide rather than oxygen
Haemoglobin can bind oxygen and carbon dioxide at once
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1 markMyoglobin is a protein found in muscle. Myoglobin has a very high affinity for oxygen at most partial pressures of oxygen.
The figure below shows dissociation curves for
   • adult haemoglobin
   • fetal haemoglobin
   • myoglobin.
Which of the following rows, A to D, shows the correct labels for the lines on the graph?
| Â | X | Y | Z |
| A | myoglobin | fetal haemoglobin | adult haemoglobin |
| B | fetal haemoglobin | adult haemoglobin | myoglobin |
| C | adult haemoglobin | fetal haemoglobin | myoglobin |
| D | myoglobin | adult haemoglobin | fetal haemoglobin |
[1]
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1 markWhich of the statements, A to D, explains why diastole follows systole in the mammalian heart?
Cardiac muscle is myogenic.
Cardiac muscle takes a short time to repolarise after being stimulated.
The aorta is capable of maintaining the pressure generated by the left ventricle.
The SAN receives impulses from the AVN.
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1 markBlood vessels are adapted for their function.
Which of the following statements is/are true?
| Statement 1: | The walls of arteries near the heart contain a lot of elastic fibres so that they can stretch and recoil to maintain blood pressure. |
| Statement 2: | The walls of the venules contain little muscle. |
| Statement 3: | The walls of arteries contain a lot of muscle fibres to contract and generate pressure in the blood. |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markThe ECG traces below show four abnormal heartbeats recorded for six seconds.
Which of the traces, A to D, shows bradycardia?
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1 markWhich of the options, A to D, best describes the chloride shift?
Hydrogen carbonate ions and chloride ions moving into red blood cells
Hydrogen carbonate ions moving out of red blood cells and chloride ions moving into red blood cells
Chloride ions acting as a buffer in red blood cells
Hydrogen carbonate ions moving into red blood cells and chloride ions moving out of red blood cells
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1 markWhich of the options, A to D, would be found at the venous end of a capillary network?
hydrostatic pressure < oncotic pressure
hydrostatic pressure = oncotic pressure
oncotic pressure < hydrostatic pressure
oncotic pressure ≥ hydrostatic pressure
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1 markWhich of the options, A to D, on the diagram below shows the time at which the Purkyne tissue conducts a wave of excitation?
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1 markThe graph below shows the oxygen dissociation curve for adult human haemoglobin.
Â
What is the proportion of oxygen molecules released by haemoglobin between 60 mm Hg and 20 mm Hg?
0.31
0.69
0.74
2.21
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1 markThe diagram below shows an internal view of the mammalian heart with the atria removed so valves can be seen.
Which of the valves, labelled A to D, is pushed open by deoxygenated blood entering a ventricle?
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1 markThe desert locust Schistocerca gregaria has a heart that pumps a blood-like liquid called haemolymph around the body cavity.
Which of the statements, A to D, describes the circulatory system of Schistocerca gregaria?
Single closed
Single open
Double open
Double closed
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1 markThe graph below shows changes in pressure during the cardiac cycle.
Calculate the percentage increase in the pressure of the aorta between 0.2 seconds and 0.3 seconds.
45%
31%
16%
10%
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1 markWhich of the statements below do not give a correct comparison between the circulatory systems of mammals and fish?
| 1 | Both carry oxygen. |
| 2 | Blood pressure is lower in mammals. |
| 3 | Both are closed systems. |
| 4 | Mammalian hearts have a septum, fish hearts do not. |
| 5 | Fish use a countercurrent exchange system, mammals do not. |
Statements 1, 2 and 5.
Statements 1 and 2.
Statements 2 and 5
Statements 1, 3 and 4.
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1 markThe ECG traces below show two different heart rhythms:
Using these ECGs, identify which of the following is not a key feature of tachycardia?
Increased heart rate.
Width of the T wave is narrower.
Lower R peak
P and T equal in height.
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1 markThe horned ghost crab Ocypode ceratophthalma has a heart that pumps haemolymph into its body cavity where it mixes with interstitial fluid which surrounds the tissues.
What type of circulatory system does Ocypode ceratophthalma have?
Double open
Double closed
Single open
Single closed
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1 markThe table below shows the properties of a capillary compared with the surrounding tissue fluid:
| Property | Capillary | Tissue fluid |
| Oncotic pressure (kPa) | 3.3 | 0.04 |
| Hydrostatic pressure (kPa) | 3.6 | 0.12 |
The net movement of fluid between the capillary and tissue fluid is dependent on the net driving force (Jv), which is calculated using the formula:
Jv = (Pc - Pi) - σ (πc - πi)
Where:
Pc = capillary hydrostatic pressure
Pi = tissue fluid hydrostatic pressure
Ï€c = capillary oncotic pressure
Ï€i = tissue fluid oncotic pressure
σ = reflectance factor
The reflectance factor is a measure of how permeable the capillary is to the protein albumin and varies between 0 (totally permeable) and 1 (totally impermeable).
In the capillary described above, the reflectance factor was found to be 0.65. Which of the values below correctly states the calculated net driving force?
1.295
0.998
3.164
1.361
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