15 questions · 159 marks · ≈ 3 hours
Fig. 1 shows the structure of the mammalian heart.
Fig. 1
Starting at the point marked W, describe the route taken by the blood as it travels to the point marked X.
For structure Y in Fig. 1:
(i) Name the structure.
(1 mark)
(ii) State its function.
(1 mark)
Extract:
Fig. 1 shows the structure of the mammalian heart.
For Fig. 1:
(i) Identify the stage of the cardiac cycle shown.
(1 mark)
(ii) Explain your answer to part (i).
(3 marks)
Fig. 1 shows the internal structure of the heart.
Fig. 1
A and C represent two heart chambers.
(i) Label chambers A and C.
(2 marks)
(ii) State one difference in the function of A and C.
(1 mark)
The blood on the left and right-hand sides of the heart are kept separate.
State one difference between the blood found on the left and right sides of the heart.
Extract:
Fig. 1 shows the internal structure of the heart.
Fig. 1
The blood on the left and right-hand sides of the heart are kept separate.
A difference between the blood found on the right and left sides of the heart is....
Blood on the left side is oxygenated / has a higher oxygen content WHILE blood on the right side is deoxygenated / has a lower oxygen content.
Structure D is a wall of muscular tissue.
Name structure D and state the purpose of this structure in the heart.
Extract:
Fig. 1 shows the internal structure of the heart.
Fig. 1
Fig. 2 shows changes in pressure in parts of a human heart during 0.8 seconds.
Fig. 2
Identify the letter in Fig. 2 that represents the point at which valve B in Fig. 1 opens.
Table 1 shows some events that occur during the cardiac cycle.
Table 1
| Event of the Cardiac Cycle | Order |
|---|---|
| SAN sends out a wave of excitation | 1 |
| Wave of excitation passes through the AVN | |
| Ventricles contract | |
| Atria contract | |
| Wave of excitation passes through the Purkyne tissue |
Number the events in Table 1 to show the correct order of the events in the cardiac cycle.
The first one has been done for you.
Extract:
Table 1 shows some events that occur during the cardiac cycle.
Table 1
| Event of the Cardiac Cycle | Order | | SAN sends out a wave of excitation | 1 | | Wave of excitation passes through the AVN | | | Ventricles contract | | | Atria contract | | | Wave of excitation passes through the Purkyne tissue | |
When the wave of depolarisation passes through the AVN there is a slight delay before any other events occur.
State why this delay is necessary.
During the cardiac cycle the changes in the heart occur simultaneously on the left and right sides.
While the same events are taking place on the left and right sides of the heart, the pressure in the corresponding chambers on the left and the right is not the same.
(i) Explain the pressure difference between the left and right sides of the heart.
(2 marks)
(ii) State the location of the highest pressure generated in the heart during the cardiac cycle.
(1 mark)
Describe the flow of oxygenated blood through the left side of the heart as it returns from the lungs.
The coronary arteries are part of the external structure of the heart.
Explain the role of the coronary arteries.
The septum is an internal structure of the heart. A heart condition called a septal defect results in a hole in the septum of the heart.
Describe the consequence of this condition to the blood flowing through the heart.
The valves of the heart are another important internal structure. Valves prevent the backflow of blood into the atria or ventricles. Valves also have a role in controlling pressure changes within the heart during the cardiac cycle.
Explain how the valves achieve this.
Valves are also found within blood vessels called veins.
Other than valves, explain how one other structure of veins relates to its function.
Fig. 1 shows the flow of blood in one cardiac cycle.
Fig. 1
Identify the correct order of letters, starting at atrial systole.
Extract:
Fig. 1 shows the flow of blood in one cardiac cycle.
With reference to Fig. 1, describe the events of the cardiac cycle shown in W.
Fig. 2 represents the pressure changes taking place during the cardiac cycle.
Fig. 2
Using Fig. 2, identify the letter(s) that show atrial systole.
Fig. 1 shows a representation of parts of the circulatory system.
Fig. 1
Identify the following blood vessels:
(i) J
(ii) K
(iii) L
(iv) M
Extract:
Fig. 1 shows a representation of parts of the circulatory system.
Identify the following blood vessels: (i) J (ii) K (iii) L (iv) M
The blood vessels can be identified as follows...
The heart chambers connecting to blood vessels J and M are similar in structure but not identical.
Describe and explain one structural difference between the two heart chambers.
Extract:
Fig. 1 shows a representation of parts of the circulatory system.
Identify the following blood vessels: (iv) M
M = Aorta
The heart chambers connecting to blood vessels J and M are similar in structure but not identical.
The left ventricle / chamber connecting to M has (a) thicker muscle (wall).
Fig. 2 shows the changes in pressure in the heart and some of the blood vessels.
Fig. 2
Describe and explain the differences in pressure between the heart chamber and blood vessel M.
Extract:
Fig. 2 shows the changes in pressure in the heart and some of the blood vessels.
Explain why blood pressure in Fig. 2 continues to drop in blood vessel O and in the capillaries.
Fig. 1 shows the external view of the mammalian heart.
Fig. 1
(i) Identify the structure marked X.
(1 mark)
(ii) Suggest and explain one possible symptom that might result from a blockage inside structure X
(3 marks)
Fig. 2 shows the pressure changes in various parts of the heart during the cardiac cycle.
Fig. 2
Calculate the heart rate of the individual in Fig. 2
Extract:
Fig. 2 shows the pressure changes in various parts of the heart during the cardiac cycle.
Fig. 2 shows separate lines for the left and right ventricles.
(i) State the reason for this difference
(1 mark)
(ii) Explain the benefits of this difference to the function of the circulatory system
(2 marks)
Extract:
Fig. 2 shows the pressure changes in various parts of the heart during the cardiac cycle.
Identify the times on Fig. 2 at which the following events take place:
(i) The first ventricular systole begins.
(1 mark)
(ii) The semilunar valves close.
(1 mark)
(iii) Diastole begins.
(1 mark)
The mammalian circulatory system is described as a closed double circulation.
Explain why it is called a *closed and double *circulation.
Fig.1 shows a drawing of an external view of a mammalian heart.
Two cross-sections were made of the heart:
Drawings of the two sections were viewed from above as shown by the arrow on Fig. 1. Fig. 2 is a drawing of section A–B. Fig. 3 is a drawing of section C–D.
(i)Name structures 1, 2 and 3, as shown in Fig. 2.
(3 marks)
(ii) Explain why the wall of chamber Y is thicker than the wall of chamber X, as shown in Fig. 3.
(3 marks)
Explain how the contractions of the chambers of the heart are coordinated during one cardiac cycle.
The sinoatrial node (SAN) and the atrioventricular node (AVN) are two regions of the heart.
Explain the role of the SAN and the role of the AVN in the cardiac cycle.
Fig. 1 shows features that are observed in transverse sections of three types of blood vessel.
Fig.1
(i) Complete Fig.1 by stating the type of blood vessel indicated by D, E and F.
(1 mark)
(ii) The inner layer of the walls of D and E is composed of endothelial tissue.
List two structural features of endothelial tissue.
(2 marks)
Table 1 shows the pressure changes in the left side of the heart during one complete cardiac cycle.
Table 1
| Pressure changes (mmHg) | ||
|---|---|---|
| Time (s) | Left atrium | Left ventricle |
| 0.0 | 5.3 | 2.3 |
| 0.1 | 7.5 | 15.0 |
| 0.2 | 1.5 | 93.8 |
| 0.3 | 1.5 | 114.8 |
| 0.4 | 7.5 | 33.8 |
| 0.5 | 3.8 | 7.5 |
| 0.6 | 4.5 | 2.3 |
| 0.7 | 5.2 | 2.3 |
(i) State the time window that the bicuspid valve, between the atrium and ventricle, is closed. Explain your answer.
(2 marks)
(ii) Explain what can be concluded about the cardiac cycle between 0.2 and 0.3 seconds.
(4 marks)
Extract:
Table 1 shows the pressure changes in the left side of the heart during one complete cardiac cycle.
Table 1
| | Pressure changes (mmHg) | | Time (s) | Left atrium | Left ventricle | | 0.0 | 5.3 | 2.3 | | 0.1 | 7.5 | 15.0 | | 0.2 | 1.5 | 93.8 | | 0.3 | 1.5 | 114.8 | | 0.4 | 7.5 | 33.8 | | 0.5 | 3.8 | 7.5 | | 0.6 | 4.5 | 2.3 | | 0.7 | 5.2 | 2.3 |
The heart beats for one minute at the rate shown in the table.
Calculate the total time the ventricles are contracted during one minute. Give your answer to two significant figures.
Two structures, the sinoatrial node (SAN) and the atrioventricular node (AVN) are involved in the cardiac cycle.
Describe how these structures control the cardiac cycle.
Fig. 1 shows a diagram of a human heart that has some defects.
Fig.1
Identify structures W to Z in Fig. 1.
The heart shown in Fig.1 shows a combination of heart defects known as tetralogy of Fallot.
Identify three heart defects visible in Fig.1 and suggest explanations for the possible impacts of the defects on heart function.
Extract:
The heart shown in Fig.1 shows a combination of heart defects known as tetralogy of Fallot.
The heart defects visible in Fig.1 and suggested explanations of their possible impacts on heart function are...
AND
AND
The mixing of blood in the two ventricles causes problems as it means that the blood pumped around the body by the left ventricle will contain a quantity of deoxygenated blood from the right ventricle; this reduces its overall oxygen saturation and means that there is less oxygen available to the cells as the blood travels around the body.
The thickened valve in the pulmonary artery reduces blood flow to the lungs, further reducing the oxygenation of the blood; this results both from a reduction in the volume of oxygenated blood returning from the lungs and from increased mixing of blood between the ventricles.
Suggest and explain one possible symptom in sufferers of tetralogy of Fallot.
State why the heart muscle is described as myogenic.
Fig. 1 shows a graph that results from the monitoring of the electrical activity of the heart, along with the stages of the cardiac cycle to which the electrical activity corresponds. The T wave corresponds to diastole, during which the electrical charge across the cells of the heart returns to normal as the wave of excitation ends.
Fig.1
Describe the electrical activity taking place in the heart, relating it to the P wave and the QRS complex shown in Fig.1
Extract:
Fig. 1 shows a graph that results from the monitoring of the electrical activity of the heart, along with the stages of the cardiac cycle to which the electrical activity corresponds. The T wave corresponds to diastole, during which the electrical charge across the cells of the heart returns to normal as the wave of excitation ends.
Fig.1
The electrical activity taking place in the heart involves:
This relates to the P wave and QRS complex in the following ways:
Fig. 2 shows ECG traces from three individuals. Individual A has healthy heart function while individuals B and C have been diagnosed with heart problems.
Fig. 2
State the abnormalities in electrical activity that seem to be present in the ECG traces of individuals B and C shown in Fig. 2
Extract:
Fig. 2 shows ECG traces from three individuals. Individual A has healthy heart function while individuals B and C have been diagnosed with heart problems.
The abnormalities present in the ECG traces of individuals B and C are:
Individual C experienced symptoms such as the feeling of a fluttering heart and chest pain.
Suggest and explain one other physical symptom that individual C in Fig. 2 might be experiencing.
Describe the roles of the sinoatrial node (SAN) and the atrioventricular node (AVN) in the initiation and control of the cardiac cycle.
The Purkyne fibres pass down the septum and extend to the cardiac muscle at the base (apex) of the heart.
Explain why it is important that the Purkyne fibres extend to the base of the heart.
The activity of the SAN is controlled by the nervous system. Noradrenaline is released by nerve cells in the SAN.
Fig. 1 shows the role of noradrenaline in causing calcium ions (Ca2+) to enter a cell in the SAN.
Fig. 1
With reference to Fig.1, outline the process of cell signalling.
Note: This past paper question assesses knowledge from other topics alongside the knowledge of the heart assessed in 8.3
Woolly foxglove, Digitalis lanata, shown in Fig. 1A, and common oleander, Nerium oleander, shown in Fig. 1B, are plants grown for the attractive flowers that they produce.
Both plants are poisonous, as their leaves produce toxic organic compounds known as cardiac glycosides. Cardiac glycosides have a powerful effect on the action of cardiac muscle.
Fig. 1
N. oleander is able to grow in very dry conditions. The leaves have adaptations to reduce water loss by transpiration.
State the term used to describe a plant, such as N. oleander, that has adaptations to allow it to grow in conditions where water is in short supply.
Aphids are small insects that feed on plant fluids using piercing and sucking mouthparts. When aphids feed on the sap present in vascular tissue of leaves and stems, a sugary liquid called honeydew is passed out of the gut. The honeydew can be analysed to find out what is present in the sap.
(i) State the name of the vascular tissue from which the aphids feed.
(1 mark)
(ii) An investigation found that aphids feeding on *D. lanata *produced honeydew containing cardiac glycosides.
Suggest why cardiac glycosides were present in the sap from the vascular tissue.
(2 marks)
Cardiac glycosides have an effect on the movement of ions into and out of cardiac muscle cells. The outcome is an increased ability for the cells to contract.
Investigations into the action of the cardiac glycoside oleandrin, extracted from* N. oleander*, have shown that it acts to prevent the correct functioning of Na/K‐ATPase, a membrane transport protein.
Na/K‐ATPase has a role as an enzyme and as a transport molecule.
(i) Explain what is meant by the hydrolysis of ATP.
(2 marks)
(ii) Name the type of transport mechanism involved in the transport of Na+ and K+ across the cell surface membrane of cardiac muscle cells.
(1 mark)
(iii) Oleandrin is a non‐competitive reversible inhibitor of ATPase. Describe the mode of action of oleandrin and explain how this will affect ion movement through Na/K‐ATPase transport proteins of the cell surface membranes of cardiac muscle cells.
(4 marks)
Extract:
Cardiac glycosides have an effect on the movement of ions into and out of cardiac muscle cells. The outcome is an increased ability for the cells to contract.
Digoxin, a cardiac glycoside extracted from D. lanata leaves, can be purified and used as a drug to treat some heart disorders.
Examples of these heart disorders are:
(i) Describe the sequence of events occurring in the left side of the heart during one normal cardiac cycle. Include reference to blood pressure changes.
The first event in the sequence is described for you.
The left atrium fills with blood during relaxation of the left atrium and left ventricle.
(4 marks)
(ii) Suggest how the health of a person with heart failure can be improved by treatment with the drug digoxin.
(3 marks)
The graph shown in Fig. 1 shows the relationship between the left ventricular volume and left ventricular pressure.
Fig. 1
(i) Identify the stages of the cardiac cycle shown by the letters A - D.
(4 marks)
(ii) Explain the changes in the left ventricle shown at stage C.
(2 marks)
(iii) Determine the valve identified by the letter X on Fig. 1 and state if the valve is open or closed.
(2 marks)
Extract:
The graph shown in Fig. 1 shows the relationship between the left ventricular volume and left ventricular pressure.
Stroke volume is the volume of blood pumped out of the left ventricle of the heart during each cardiac cycle.
Use Fig. 1 to determine the stroke volume of this left ventricle.
Extract:
The graph shown in Fig. 1 shows the relationship between the left ventricular volume and left ventricular pressure.
Calculate the percentage change between the maximum and minimum left ventricular pressure using the data shown in Fig. 1.