3B - The circulatory system Flashcards

1
Q

What type of system is the circulatory system?

A

A mass transport system.

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2
Q

Why do multicellular organisms like mammals need a specialised transport system to carry raw materials from specialised exchange organs to their body cells?

A

Because they have a low SA to volume ratio.

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3
Q

What is the circulatory system made up of?

A

The heart and blood vessels.

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4
Q

What blood vessels leave the heart?

A

Pulmonary artery, aorta.

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5
Q

What blood vessels connect the lungs to the heart?

A

Pulmonary veins/arteries.

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6
Q

How does blood get from the heart to the lungs?

A

Pulmonary artery.

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7
Q

How does blood get from the lungs to the heart?

A

Pulmonary vein.

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8
Q

How does blood get from the heart to the body?

A

Aorta

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9
Q

How does blood get from the body to the heart?

A

Vena cava

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10
Q

What blood vessels enter the heart?

A

Vena cava and pulmonary vein.

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11
Q

What type of blood vessels take blood into the heart?

A

Veins

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12
Q

What type of blood vessels takes blood away from the heart?

A

Arteries

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13
Q

Does the aorta carry oxygenated or deoxygenated blood?

A

Oxygenated.

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14
Q

Does the pulmonary vein carry oxygenated or deoxygenated blood?

A

Oxygenated.

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15
Q

Does the pulmonary artery carry oxygenated or deoxygenated blood?

A

Deoxygenated.

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16
Q

Does the vena cava carry oxygenated or deoxygenated blood?

A

Deoxygenated.

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17
Q

What are the blood vessels associated with the liver and gut?

A

Hepatic artery, hepatic portal vein, hepatic vein.

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18
Q

What are the blood vessels associated with the kidneys?

A

Renal artery and vein.

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19
Q

Where do the hepatic artery, hepatic portal vein and the hepatic vein take blood?

A

Hepatic artery - From heart to liver.
Hepatic portal vein - From the gut to the heart via the liver.
Hepatic vein - From the liver to the heart.

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20
Q

What are the hepatic vein, hepatic artery and hepatic portal vein associated with?

A

The liver and gut.

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21
Q

What are the renal artery and vein associated with?

A

The kidneys.

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22
Q

Where do the renal artery and vein take blood?

A

Renal vein - blood from kidneys to heart.

Renal artery - from heart to kidneys.

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23
Q

Do the renal artery and vein carry oxygenated or deoxygenated blood?

A

Renal artery - oxygenated.

Renal vein - deoxygenated.

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24
Q

Do the hepatic vein, hepatic artery and hepatic portal vein carry oxygenated or deoxygenated blood?

A

Hepatic artery - oxygenated.
Hepatic portal vein - partially oxygenated.
Hepatic vein - deoxygenated.

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25
Q

What does blood transport around the body?

A

Respiratory gases, products of digestion, metabolic wastes and hormones.

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26
Q

What supplies the heart with blood?

A

The coronary arteries.

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27
Q

In what direction do arteries carry blood?

A

Away from the heart.

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28
Q

Describe the structure of the arteries

A

Narrow lumen, lining layer, thick elastic layer, thick muscle layer, tough outer layer.

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29
Q

Describe the structure of the arterioles

A

Narrow lumen (relatively larger than in arteries), lining layer, thick elastic layer, thick muscle layer (relatively thicker than in arteries), tough outer layer.

30
Q

Describe the structure of the veins

A

Large lumen, lining layer, thin elastic and muscle layers, tough outer layer.

31
Q

Describe the structure of the capillaries

A

Medium lumen, lining layer.

32
Q

What is the function of the arteries?

A

To transport blood rapidly under high pressure from the heart to the tissues.

33
Q

What are the adaptations of the arteries that help their function?

A
  • Thick muscle layer compared to veins.
  • Relatively thick elastic layer compared to veins.
  • Overall thickness of the wall is great.
  • No valves.
34
Q

How does the arteries having thick muscle walls compared to veins help their function?

A

So smaller arteries can be constricted and dilated to control the volume of blood passing through them.

35
Q

How does the arteries having a relatively thick elastic layer compared to veins help their function?

A

As it is important to maintain a high bp in the arteries if the blood is to reach the extremities of the body. It is stretched during each systole and springs back when the heart is in diastole. The stretching and recoiling action helps to maintain high pressure and smooth surges of pressure created by the heart beat.

36
Q

How does the arteries having an overall great thickness of walls help their function?

A

It resists the vessel bursting under high pressure.

37
Q

Why don’t arteries have valves?

A

Because blood is under constant high pressure due to the heart pumping blood into the arteries - so it tends not to flow backwards.

38
Q

What arteries have valves and why?

A

The ones leaving the heart so that blood doesn’t flow back into the heart.

39
Q

What is the function of the arterioles?

A

Carry blood, under lower pressure than the arteries, from arteries to capillaries. They also control the flow of blood between the two.

40
Q

What are the adaptations of the arterioles that help their function?

A
  • Relatively thicker muscular layer than arteries.

- Elastic layer is relatively thinner than in arteries.

41
Q

How does the arterioles having a relatively thicker muscular layer than arteries help their function?

A

The contraction of this muscle layer allows constriction of the lumen of the arteriole, restricting the flow of blood and so controls its movements into the capillaries that supply the tissues with blood.

42
Q

How does the arterioles having an elastic layer that is relatively thinner than in arteries help their functions?

A

Helps lower the bp so blood can flow into capillaries without bursting them.

43
Q

Why do arterioles have thinner elastic walls than arteries?

A

Because blood is under lower pressure in the arterioles.

44
Q

What is the function of the veins?

A

Transport blood slowly, under low pressure, from the capillaries in the tissues to the heart.

45
Q

How are the veins adapted to carry blood from the tissues to the heart?

A
  • They have relatively thin muscle layer compared to arteries.
  • Elastic layer is relatively thin compared to arteries.
  • Overall thickness of walls is small.
  • Valves at intervals throughout.
46
Q

Why do veins have a relatively thinner muscle layer than arteries?

A

Because they carry blood away from the tissues so their constriction and dilation cannot control the blood flow to the tissues.

47
Q

Why do veins have a relatively thinner elastic layer compared to the arteries?

A

As the low pressure of the blood within the veins will not cause them to burst and pressure is too low to create a recoil action.

48
Q

Why is the overall thickness of the veins small?

A

As there is no need for thick walls as the pressure in the veins is too low to create any risk of it bursting. Also allows them to be flattened easily, aiding blood flow within them.

49
Q

Why do veins have valves at regular intervals throughout?

A

To ensure backflow doesn’t occur which it may otherwise because the pressure is so low. When body muscles contract, veins are compressed, pressurising the blood within them. Valves only direct blood in 1 direction - towards the heart.

50
Q

What is the function of the capillaries?

A

To exchange metabolic materials, e.g. oxygen, carbon dioxide and glucose, between the blood and the body cells. Blood within these flows much slower.

51
Q

How are the capillaries adapted to carry out their functions?

A
  • Walls consist mostly of the lining layer.
  • There are numerous and they’re highly branched.
  • Narrow diameter.
  • Narrow lumen.
  • Spaces between the lining (endothelial) cells.
52
Q

Why do the capillaries walls consist mainly of the lining layer?

A

So they’re very thin so there’s a short diffusion pathway allowing for rapid diffusion of materials between the blood and the cells.

53
Q

Why are there numerous, highly branched capillaries?

A

So there is a large SA for exchange.

54
Q

Why do capillaries have a narrow diameter?

A

So permeate tissues, which means that no cell is far from a capillary and there is a short diffusion pathway.

55
Q

Why do capillaries have a narrow lumen?

A

So the RBC’s are squeezed flat against the side of the capillary bringing them even closer to the cells to which they supply oxygen, again reducing the diffusion distance.

56
Q

Why are there spaces between the lining (endothelial) cells in capillaries?

A

As these allow the WBC’s to escape to deal with infections in tissues.

57
Q

What allows the arteries to stretch?

A

The endothelial (lining) cells create an endothelium which is folded to maintain high bp.

58
Q

What is blood flow through veins helped by?

A

Contraction of body muscles surrounding them.

59
Q

How are the capillaries adapted for gas exchange?

A

Found near cells in exchange tissues so there is a short diffusion pathway.

Walls are one cell thick so short diffusion pathway.

Large no. of capillaries to increase SA for exchange.

60
Q

What are networks of capillaries called?

A

Capillary beds.

61
Q

What are capillary beds?

A

Networks of capillaries.

62
Q

What is tissue fluid?

A

The fluid that surrounds cells in tissues.

63
Q

What is tissue fluid made from?

A

Small molecules that leave the blood plasma, e.g. oxygen, water and nutrients.

64
Q

What doesn’t tissue fluid contain and why?

A

RBC’s or big proteins because they are too large to be pushed out through the capillary walls.

65
Q

How do cells interact with the tissue fluid?

A

Cells take in oxygen and nutrients from the tissue fluid, and release metabolic waste into it.

66
Q

How do substances move out of the capillaries into the tissue fluid in a capillary bed?

A

By pressure filtration.

67
Q

What is pressure filtration used in?

A

The movement of substances from the capillaries into the tissue fluid in a capillary bed.

68
Q

Explain the process of pressure filtration (ultrafiltration):

A

At the start of the capillary bed, nearest the arteries, the hydrostatic (liquid) pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid.

This different in hydrostatic pressure means an overall outward pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid.

As fluid leaves, the hydrostatic pressure reduces in the capillaries, so the hydrostatic pressure is much lower at the venule end of the capillary bed.

Due to the fluid loss and an increasing concentration of plasma proteins, the water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid.

This means that some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.

69
Q

Where is excess tissue fluid drained?

A

Into the lymphatic system.

70
Q

What is the lymphatic system?

A

A network of tubes that acts a bit like a drain which transports excess tissue fluid from the tissues and dumps it back into the circulatory system.

71
Q

What is tissue fluid formed from?

A

Plasma

72
Q

What is ultrafiltration?

A

Filtration under pressure.