The Circulatory System (Cambridge (CIE) AS Biology): Flashcards
Exam code: 9700
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Define closed circulatory system.
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Cards in this collection (39)
Define closed circulatory system.
In a closed circulatory system, blood is always contained within blood vessels and the heart, and does not directly bathe the tissues.
Define double circulation.
In a double circulation, blood passes through the heart twice for each complete circuit of the body.
Name the two circuits of the mammalian double circulation.
The pulmonary circulation — between the heart and the lungs.
The systemic circulation — between the heart and the rest of the body.
List the five types of blood vessel blood flows through, in order away from the heart.
Arteries → arterioles → capillaries → venules → veins.
The mammalian circulatory system is a closed circulation.
The mammalian circulatory system is a closed double circulation.
True or False?
In a double circulation, blood passes through the heart only once per complete circuit.
False.
Blood passes through the heart twice for each complete circuit of the body.
What is the function of the pulmonary artery?
It carries deoxygenated blood from the heart (right ventricle) to the lungs.
What is the function of the pulmonary vein?
It carries oxygenated blood from the lungs back to the heart (left atrium).
What is the function of the aorta?
It carries oxygenated blood from the heart (left ventricle) to the body.
What is the function of the vena cava?
It carries deoxygenated blood from the body back to the heart (right atrium).
Which two vessels make up the pulmonary circulation?
The pulmonary artery (heart → lungs) and the pulmonary vein (lungs → heart).
Unusually, the pulmonary carries deoxygenated blood.
Unusually, the pulmonary artery carries deoxygenated blood.
How can you recognise an artery in a transverse section?
It has a thick wall and a relatively small, round lumen, often with a folded (wavy) inner lining.
How can you recognise a vein in a transverse section?
It has a thin wall and a large, irregular lumen.
How can you recognise a capillary?
It has a wall one cell thick and a lumen just wide enough for a single red blood cell.
Define a plan diagram.
A plan diagram is a low-power drawing showing the outlines of tissues, with no individual cells drawn.
A plan diagram shows the outlines of tissues but never individual .
A plan diagram shows the outlines of tissues but never individual cells.
In which two planes can a blood vessel be sectioned to draw a plan diagram?
Transverse section (TS) — a cross-section across the vessel.
Longitudinal section (LS) — a lengthways section along the vessel.
How is the structure of an elastic artery related to its function?
Its wall contains much elastic tissue that stretches and recoils.
This smooths out the high-pressure surges from the heart, maintaining a steadier blood flow.
How is the structure of a muscular artery related to its function?
Its wall contains smooth muscle that contracts and relaxes.
This controls the volume of blood distributed to different organs.
How is the structure of a vein related to its function?
It has a thin wall, a wide lumen and valves.
This returns blood to the heart at low pressure, with the valves preventing backflow.
How is the structure of a capillary related to its function?
Its wall is only one cell thick, giving a short diffusion distance.
This allows efficient exchange of substances between the blood and tissues.
Define the endothelium.
The endothelium is the smooth, single layer of cells that lines all blood vessels, reducing friction with the blood.
in the veins prevent the backflow of blood.
Valves in the veins prevent the backflow of blood.
How do you recognise a red blood cell?
It is a small biconcave disc with no nucleus.
How do you recognise a neutrophil?
It has a multi-lobed nucleus and granular cytoplasm.
How do you recognise a lymphocyte?
It has a large, round nucleus that fills most of the cell, with only a thin rim of cytoplasm.
How do you recognise a monocyte?
It is the largest white blood cell and has a bean-shaped (kidney-shaped) nucleus.
A red blood cell has no , leaving more room for haemoglobin.
A red blood cell has no nucleus, leaving more room for haemoglobin.
is the main component of both blood and tissue fluid.
Water is the main component of both blood and tissue fluid.
How does the solvent action of water help transport in mammals?
Many substances (such as glucose, ions and oxygen) dissolve in water.
This allows them to be carried in solution in the blood plasma.
How does the high specific heat capacity of water help mammals?
Water resists changes in temperature.
This lets the blood distribute heat around the body and helps keep body temperature stable.
Define specific heat capacity.
Specific heat capacity is the energy needed to raise the temperature of a substance by a given amount; water's is high, so it warms and cools slowly.
True or False?
Water is a poor solvent, which limits transport in the blood.
False.
Water is an excellent solvent, allowing many substances to be transported dissolved in the plasma.
Define tissue fluid.
Tissue fluid is the fluid that surrounds and bathes the body's cells, formed from blood plasma.
State the functions of tissue fluid.
It supplies cells with oxygen, glucose and other nutrients.
It removes waste products (such as carbon dioxide) from cells.
It acts as the medium of exchange between the blood and the cells.
How is tissue fluid formed at the arterial end of a capillary?
The high hydrostatic pressure forces plasma (without large proteins and cells) out through the capillary wall.
This is called ultrafiltration.
Why does water return to the capillary at the venous end?
Hydrostatic pressure has fallen, and the remaining plasma proteins give the blood a low water potential.
So water re-enters the capillary by osmosis.
Excess tissue fluid that is not reabsorbed drains into the system.
Excess tissue fluid that is not reabsorbed drains into the lymphatic system.
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