Circulatory System in Humans (WJEC GCSE Science (Double Award): Biology): Flashcards
Exam code: 3430
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- FrontThe Blood
Name the four main parts of the blood.
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Name the four main parts of the blood.
Red blood cells
White blood cells
Platelets
Plasma
What is the function of red blood cells?
They transport oxygen from the lungs to the respiring cells of the body.
What is the function of white blood cells?
They are part of the immune system. They detect and destroy pathogens.
What is the function of platelets?
They enable blood clotting, which reduces bleeding and infection at wound sites.
What is the function of plasma?
Plasma is the liquid part of the blood. It transports dissolved substances such as glucose, carbon dioxide, hormones and urea, and helps distribute heat around the body.
Describe the features you should show when drawing a red blood cell.
A circular shape, sometimes with an inner circle to show the biconcave form.
No nucleus.
A labelled cell membrane.
Describe the features you should show when drawing a phagocyte.
No fixed shape, because it flexes to engulf pathogens.
A three-lobed nucleus.
Labelled cell membrane, nucleus and cytoplasm.
Why does a phagocyte have no fixed shape?
So that it can change shape to engulf pathogens.
Red blood cells transport ＿＿＿＿＿＿＿＿ from the lungs to the body's cells.
Red blood cells transport oxygen from the lungs to the body's cells.
＿＿＿＿＿＿＿＿ is the liquid part of the blood that transports dissolved substances.
Plasma is the liquid part of the blood that transports dissolved substances.
True or False?
Red blood cells have a nucleus.
False.
Red blood cells have no nucleus, which leaves more room to carry oxygen.
True or False?
A phagocyte is a type of white blood cell.
True.
Phagocytes are white blood cells that engulf and destroy pathogens.
Name three substances carried dissolved in the plasma.
Any three of:
Glucose and other soluble food
Carbon dioxide
Hormones
Urea
What is the heart made of, and what does it do?
The heart is made of cardiac muscle, which contracts to pump blood around the body.
What is the role of the coronary vessels?
They supply the heart muscle itself with blood, delivering oxygen and glucose for respiration and removing waste products.
Name the structures of the heart you should be able to label on a diagram.
Left and right atria
Left and right ventricles
Tricuspid and bicuspid valves
Semi-lunar valves
Pulmonary artery and pulmonary vein
Aorta and vena cava
Why does the left ventricle have a thicker muscle wall than the right?
It must pump blood at high pressure around the whole body.
The right ventricle only pumps blood a short distance to the lungs, at lower pressure.
Which blood vessel carries blood from the heart to the lungs?
The pulmonary artery.
It is the only artery that carries deoxygenated blood.
Describe the passage of deoxygenated blood through the heart.
Blood enters the right atrium from the vena cava.
The atrium contracts, forcing blood through the tricuspid valve into the right ventricle.
The ventricle contracts, pushing blood through the semi-lunar valve into the pulmonary artery and on to the lungs.
Describe the passage of oxygenated blood through the heart.
Blood returns from the lungs via the pulmonary vein into the left atrium.
The atrium contracts, forcing blood through the bicuspid valve into the left ventricle.
The ventricle contracts, pushing blood through the semi-lunar valve into the aorta and on to the body.
What is the function of the valves in the heart?
They control the one-way flow of blood, opening and closing to prevent backflow as the heart beats.
Where are the tricuspid and bicuspid valves found?
Between the atria and the ventricles.
The tricuspid is on the right side and the bicuspid is on the left.
Where are the semi-lunar valves found and what do they do?
At the base of the aorta and the pulmonary artery.
They prevent blood flowing back into the ventricles when the heart muscle relaxes.
The ＿＿＿＿＿＿＿＿ valve lies between the right atrium and the right ventricle.
The tricuspid valve lies between the right atrium and the right ventricle.
Deoxygenated blood from the body enters the heart through the ＿＿＿＿＿＿＿＿.
Deoxygenated blood from the body enters the heart through the vena cava.
True or False?
The right side of the heart carries oxygenated blood.
False.
The right side carries deoxygenated blood to the lungs. The left side carries oxygenated blood to the body.
True or False?
Both atria contract at the same time, and both ventricles contract at the same time.
True.
The events on the left and right sides of the heart happen simultaneously, even though we usually describe one side at a time.
On a heart diagram, why does the left side appear on the right of the page?
The heart is labelled as if it were in the chest of the person facing you, so their left is on your right.
Why is blood pumped to the lungs at a lower pressure than to the body?
Lower pressure prevents damage to the delicate capillaries surrounding the alveoli in the lungs.
What do arteries and veins each do?
Arteries carry blood away from the heart to the organs
Veins carry blood back towards the heart
Describe how blood flows through an organ.
Arteries carry blood to the organ, then narrow into capillaries as they pass through it.
The capillaries then widen into veins as the blood leaves the organ.
Name the four main blood vessels attached to the heart.
Aorta — heart to body
Pulmonary artery — heart to lungs
Vena cava — body to heart
Pulmonary vein — lungs to heart
Define double circulatory system.
A circulatory system in which blood passes through the heart twice on each complete circuit of the body.
Describe the pulmonary circulation.
It carries deoxygenated blood from the heart to the lungs, where it becomes oxygenated, then carries it back to the heart.
Describe the systemic circulation.
It carries oxygenated blood from the heart to the body tissues, where oxygen is delivered for respiration, then carries the deoxygenated blood back to the heart.
The circulation between the heart and the lungs is called the ＿＿＿＿＿＿＿＿ circulation.
The circulation between the heart and the lungs is called the pulmonary circulation.
The circulation between the heart and the rest of the body is called the ＿＿＿＿＿＿＿＿ circulation.
The circulation between the heart and the rest of the body is called the systemic circulation.
Which artery carries deoxygenated blood, and which vein carries oxygenated blood?
The pulmonary artery is the only artery carrying deoxygenated blood
The pulmonary vein is the only vein carrying oxygenated blood
True or False?
All arteries carry oxygenated blood.
False.
The pulmonary artery carries deoxygenated blood from the heart to the lungs.
True or False?
In a double circulatory system, blood passes through the heart twice per circuit.
True.
Once through the pulmonary circuit to the lungs, and once through the systemic circuit to the body.
Why is a double circulatory system an advantage?
Blood is returned to the heart after passing through the lungs and can be re-pressurised.
This delivers oxygenated blood to the body at high pressure, so oxygen reaches respiring cells quickly.
What happens to the oxygen in the blood as it passes through an organ?
Respiring cells in the organ take up the oxygen from the blood, so the blood leaving the organ is deoxygenated.
Define capillary.
A very small blood vessel with walls one cell thick, where substances are exchanged between the blood and the tissues.
How do substances move between the blood and the cells of an organ?
By diffusion through the walls of the capillaries.
Which substances pass out of the blood into the tissues, and which pass in?
Out of the blood: substances needed by cells, e.g. oxygen and glucose
Into the blood: substances produced by cells, e.g. carbon dioxide
Why are the thin walls of capillaries an advantage for diffusion?
They give a short diffusion distance between the blood and the cells, so substances are exchanged quickly.
Why do capillaries form extensive networks?
So that every cell is close to a capillary carrying blood, allowing substances to reach and leave all cells efficiently.
The walls of a capillary are just ＿＿＿＿＿＿＿＿ cell thick.
The walls of a capillary are just one cell thick.
Substances move between the blood and the tissues by ＿＿＿＿＿＿＿＿ through the capillary walls.
Substances move between the blood and the tissues by diffusion through the capillary walls.
Name two exchange surfaces in the body that are surrounded by capillary networks.
The alveoli in the lungs
The wall of the small intestine
State two adaptations of capillaries for efficient exchange.
Very thin walls, only one cell thick, giving a short diffusion distance
They form extensive networks, so every cell is near a capillary
True or False?
Capillaries are the smallest blood vessels in the body.
True.
Capillaries are very small vessels that link arteries to veins and allow exchange with the tissues.
True or False?
Exchange between blood and tissues happens in the arteries.
False.
Exchange happens in the capillaries. Arteries have thick walls and simply carry blood to the organs.
Explain why a tissue with a high respiration rate needs a dense capillary network.
Its cells need a large supply of oxygen and glucose and produce a lot of carbon dioxide.
A dense network keeps every cell close to a capillary, so exchange can happen fast enough.
What happens to arteries as they enter an organ?
They narrow into capillaries, which spread through the organ before widening again into veins.
Which two substances diffuse out of the blood to respiring cells?
Oxygen
Glucose
Define cardiovascular disease.
Any disease that affects the heart and/or the blood vessels. Coronary heart disease is one example.
What happens to the coronary arteries in coronary heart disease?
Layers of fatty material called an atheroma build up inside them, narrowing the lumen and reducing blood flow to the heart muscle.
What is the effect of a partial blockage of a coronary artery?
Blood flow to the cardiac muscle cells is restricted, causing severe chest pain.
What is the effect of a complete blockage of a coronary artery?
Cells in that area of the heart cannot respire aerobically, leading to a heart attack.
Give the main risk factors for cardiovascular disease.
A diet high in fat and salt
High blood pressure
High blood cholesterol
Smoking
Lack of exercise
Genetic factors
How does smoking increase the risk of cardiovascular disease?
Chemicals in smoke increase plaque build-up and raise blood pressure.
Carbon monoxide also reduces the oxygen-carrying capacity of red blood cells.
How does high blood pressure increase the risk of cardiovascular disease?
It increases the force of blood against the artery walls, which damages the vessels.
How does regular exercise reduce the risk of cardiovascular disease?
It helps with weight loss and lowers blood pressure and blood cholesterol.
A build-up of fatty material called an ＿＿＿＿＿＿＿＿ narrows the coronary arteries.
A build-up of fatty material called an atheroma narrows the coronary arteries.
Give three lifestyle changes that reduce the risk of cardiovascular disease.
Quit smoking
Reduce animal fats and eat more fruit and vegetables
Exercise regularly
True or False?
A diet high in fat and salt raises the risk of cardiovascular disease.
True.
It is a diet high in fat and salt specifically. "Poor diet" on its own does not say what actually raises the risk.
True or False?
Cardiovascular disease can be caused by genetic factors as well as lifestyle.
True.
Some people inherit a genetic risk of CVD, although this does not mean they will definitely develop it.
Why does the heart muscle need its own blood supply?
Cardiac muscle cells respire constantly and need a steady supply of oxygen and glucose, with waste such as carbon dioxide removed.
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