Circulatory Systems, Heart & Blood Vessels (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Biology): Flashcards
Exam code: 0654 & 0973
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Circulatory system
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Circulatory system
A system of blood vessels with a pump (the heart) that transports substances around the body.
What does the circulatory system transport around the body?
Oxygen, dissolved nutrients, hormones and heat to cells.
Carbon dioxide and other waste products away from cells.
The circulatory system is made up of the heart, blood and blood .
vessels
Double circulation
A circulatory system in which the blood passes through the heart twice for each complete circuit of the body.
In humans the heart pumps blood around circuits: one to the lungs and one to the body.
two
Compare the circulation of a fish and a mammal (Extended).
Fish have a single circulation: blood passes through the heart once per circuit of the body.
Mammals have a double circulation: blood passes through the heart twice per circuit.
Fish have a circulation, where blood passes through the heart once per circuit.
single
Name and describe the two circuits in a double circulatory system.
Pulmonary circulation: heart → lungs → heart.
Systemic circulation: heart → body → heart.
What is the advantage of a double circulation (Extended)?
Blood can be pumped to the body at higher pressure.
This delivers oxygen and nutrients faster, supporting a higher metabolic rate.
A double circulation can deliver oxygen faster because blood is pumped to the body at a higher .
pressure
Name the four chambers of the mammalian heart.
Right atrium
Right ventricle
Left atrium
Left ventricle
Which side of the heart carries oxygenated blood, and which carries deoxygenated blood?
The left side carries oxygenated blood.
The right side carries deoxygenated blood.
The ventricle has a thicker muscular wall because it pumps blood to the whole body.
left
What is the function of the heart valves?
They prevent the backflow of blood, keeping it flowing in one direction.
Blood enters the heart through the and is pumped out by the ventricles.
atria
Septum
The wall of muscle separating the left and right sides of the heart, preventing oxygenated and deoxygenated blood from mixing.
Give ways the activity of the heart can be monitored.
An ECG (electrocardiogram) records the electrical activity of the heart.
The pulse rate can be measured where an artery is near the surface.
Heart sounds can be heard with a stethoscope.
An records the electrical activity of the heart.
ECG
Pulse
The surge of blood through an artery each time the heart beats; counting it gives the heart rate.
The number of heartbeats per minute is called the rate.
heart
Outline how to investigate the effect of physical activity on heart rate.
Measure the resting pulse rate in beats per minute.
Do a period of exercise (e.g. running on the spot).
Measure the pulse rate immediately after exercising.
Repeat and calculate a mean.
What result would you expect from this investigation?
Heart rate increases with exercise.
It then gradually returns to the resting rate during recovery.
During exercise the heart increases.
rate
How do you measure your pulse rate?
Place two fingers on an artery (e.g. at the wrist or neck) and count the beats in a set time.
What is coronary heart disease?
When the coronary arteries that supply the heart muscle become blocked by fatty deposits.
This reduces blood flow, so the heart muscle receives less oxygen.
Coronary heart disease is caused by fatty deposits blocking the arteries.
coronary
List the main risk factors for coronary heart disease.
A diet high in saturated fat.
Lack of exercise.
Smoking.
Stress.
Increasing age and genetic factors.
How can the risk of coronary heart disease be reduced?
Eat a balanced diet that is low in saturated fat.
Exercise regularly.
Do not smoke.
A diet high in fat increases the risk of coronary heart disease.
saturated
Describe how blood moves through the heart during a heartbeat (Extended).
The atria contract, pushing blood into the ventricles.
The ventricles contract, pushing blood out into the arteries.
The valves close to prevent backflow.
Why does the left ventricle have a thicker wall than the right ventricle (Extended)?
The left ventricle pumps blood all around the body, which needs a high pressure.
The right ventricle only pumps blood the short distance to the lungs.
The left ventricle has a thicker wall to pump blood at higher to the body.
pressure
What is the role of the atrioventricular and semilunar valves (Extended)?
Atrioventricular valves prevent backflow from the ventricles into the atria.
Semilunar valves prevent backflow from the arteries into the ventricles.
Explain why heart rate increases during exercise (Extended).
During exercise the muscles respire more and need more oxygen and glucose.
The heart beats faster to deliver oxygen and glucose, and to remove carbon dioxide, more quickly.
During exercise, muscles need more for increased respiration.
oxygen
After exercise, why does the heart rate stay high for a while?
To keep supplying extra oxygen to the muscles to break down the lactic acid that built up during exercise (repaying the oxygen debt).
A faster heart rate during exercise removes from the muscles more quickly.
carbon dioxide
Name the three types of blood vessel and what each does.
Arteries — carry blood away from the heart.
Veins — carry blood back to the heart.
Capillaries — connect arteries and veins and allow the exchange of substances.
carry blood away from the heart at high pressure.
Arteries
carry blood back towards the heart.
Veins
What is the function of capillaries?
Their walls are only one cell thick, allowing substances such as oxygen and glucose to be exchanged between the blood and the tissues.
Describe the blood vessels connecting the heart and lungs (Extended).
Pulmonary artery: carries deoxygenated blood from the heart to the lungs.
Pulmonary vein: carries oxygenated blood from the lungs to the heart.
Describe the roles of the aorta and the vena cava (Extended).
Aorta: carries oxygenated blood from the heart to the body.
Vena cava: carries deoxygenated blood from the body back to the heart.
The is the largest artery, carrying oxygenated blood from the heart to the body.
aorta
The largest vein, the , returns deoxygenated blood from the body to the heart.
vena cava
Which vessel is unusual because it carries deoxygenated blood away from the heart?
The pulmonary artery — it carries deoxygenated blood from the heart to the lungs.
How is an artery adapted to its function (Extended)?
Thick, muscular and elastic walls to withstand and maintain high pressure.
A narrow lumen.
No valves (except at the heart).
How is a vein adapted to its function (Extended)?
Thin walls, as blood is at low pressure.
A large lumen.
Valves to prevent the backflow of blood.
How is a capillary adapted to its function (Extended)?
Walls are only one cell thick.
This gives a short diffusion distance for the exchange of substances with the tissues.
have valves to prevent the backflow of blood.
Veins
Arteries have thick, muscular and walls to withstand high pressure.
elastic
Name the four components of blood.
Red blood cells
White blood cells
Platelets
Plasma
What is the function of red blood cells?
They transport oxygen (using haemoglobin) from the lungs to the body cells.
What is the function of blood plasma?
It is the liquid that transports dissolved substances such as carbon dioxide, nutrients, hormones, urea and heat.
What is the function of platelets?
They help the blood to clot at a wound.
is the liquid part of blood that transports dissolved substances.
Plasma
How can you tell red and white blood cells apart under a microscope?
Red blood cells: small, biconcave discs with no nucleus.
White blood cells: larger, have a nucleus, and are fewer in number.
Red blood cells contain the red pigment , which binds oxygen.
haemoglobin
Why is blood clotting important?
It seals wounds to prevent blood loss.
It stops pathogens from entering the body.
Describe how a blood clot forms (Extended).
Platelets release chemicals at the wound.
This causes soluble fibrinogen to change into insoluble fibrin.
Fibrin forms a mesh of fibres that traps blood cells, forming a clot.
During clotting, soluble fibrinogen is converted into insoluble .
fibrin
are the cell fragments that trigger blood clotting.
Platelets
What do phagocytes do (Extended)?
Phagocytes engulf and digest pathogens.
This process is called phagocytosis.
What do lymphocytes do (Extended)?
Lymphocytes produce antibodies.
The antibodies attach to pathogens, destroying them or marking them for destruction.
engulf and digest pathogens by phagocytosis.
Phagocytes
Lymphocytes produce that target specific pathogens.
antibodies
What is the difference between a phagocyte and a lymphocyte?
Phagocytes engulf and digest pathogens (a non-specific response).
Lymphocytes produce specific antibodies against particular pathogens.
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