Transport in Animals Flashcards

1
Q

Why are specialised transport systems needed?

A
  • Metabolic demands of most multicellular animals are high
  • SA:V ratio gets smaller as muilticelluar organisms get bigger
  • Enzymes and hormones are made in one place and needed in another
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2
Q

Features of a circulatory system

A
  • Liquid transport medium
  • Vessels carry transport medium
  • Pumping mechanisms which move fluid around the system
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3
Q

What is a closed circulatory system?

A

Blood is enclosed in vessels and does not come in direct contact with cells. Substances leave and enter the blood by diffusion through walls of the blood vessels.

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4
Q

What are single closed circulatory systems?

A

Blood flows through the heart and is pumped out to the rest of the body before returning to the heart.

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5
Q

Give an example of an organism which has a single closed circulatory system.

A

Fish

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6
Q

Why do fish have an effective single closed circulatory system?

A

They set up a countercurrent exchange system.

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7
Q

What are double closed circulatory systems?

A

Two circuits…
1) Blood pumped from heart to the lungs in order to pick up oxygen and unload carbon dioxide. Blood returns to heart.

2) Blood pumped around the body and returns to the heart.

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8
Q

Give an example of an organism with a double closed circulatory system.

A

Birds

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9
Q

Why is blood in a double closed circulatory system at a high pressure?

A

To maintain a fast flow of blood.

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10
Q

What is an open circulatory system?

A

Few vessels where blood is pumped directly from heart to the body cavity.

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11
Q

What is the open body cavity of an animal called?

A

Haemocoel.

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12
Q

What is the transport medium like in the harmocoel?

A

Under low pressure. Comes into direct contact with the tissues and cells.

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13
Q

Where are open ended circulatory systems found?

A

Invertebrates

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14
Q

What is insect blood called?

A

Haemolymph

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15
Q

What doesn’t haemolymph carry?

A

Oxygen

Carbon dioxide

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16
Q

What does haemolymph transport?

A

Food
Nitrogenous waste products
Cells involved in defence against disease

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17
Q

True or False,

The amount of haemolymph flowing to a particular tissue can be varied to meet the changing demands.

A

False,

The amount of haemolymph flowing to a particular tissue cannot be changed to meet varying needs.

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18
Q

What is a mass transport system?

A

The transport of substances in a mass of fluid.

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19
Q

How do substances pass out of the capillaries?

A

Through gaps between endothelial cells.

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20
Q

Which capillaries have very tight junctions between cells?

A

Capillaries in the CNS.

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21
Q

Is the blood entering the capillaries mostly oxygenated or deoxygenated?

A

Oxygenated

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22
Q

Where does deoxygenated blood enter the capillaries?

A

Lungs

Placenta

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23
Q

Name 3 ways in which capillaries are adapted for their role.

A
  • Large SA.
  • Total cross-sectional area of the capillaries is greater than the arterioles supplying them so rate of blood flow falls.
  • Walls are a single endothelial cell thick.
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24
Q

Why is it important that blood is slowed down when moving through the capillaries?

A

Gives more time for the exchange of materials by diffusion.

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25
Q

What are elastic fibres?

A

Can stretch and recoil giving flexibility to the vessel.

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26
Q

What are elastic fibres composed of?

A

Elastin

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27
Q

What are smooth muscle?

A

Contracts and relaxes to change the size of the lumen.

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28
Q

What is collagen?

A

Gives structural support to maintain shape and volume of vessel.

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29
Q

Which arteries don’t carry oxygenated blood?

A

Pulmonary artery

Umbilical artery during pregnancy

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30
Q

Is blood under higher pressure in the arteries or the veins?

A

Arteries

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31
Q

What is the role of the umbilical artery?

A

Carries deoxygenated blood from fetus to placenta.

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32
Q

What is the role of elastic fibres in the arteries?

A

Enable them to withstand the force of blood and stretches to take a larger volume of blood.

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33
Q

How is the structure of arterioles different to that of arteries?

A

More smooth muscle

Less elastin

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34
Q

What are present in veins to prevent the backflow of blood?

A

Valves

35
Q

What is the structure of the walls of veins?

A

Lots of collagen
Little elastic fibres
Wide lumen
Smooth endothelium lining for easy blood flow

36
Q

What is the structure of venules?

A

Very thin walls and a little smooth muscle.

37
Q

What are the 3 main adaptations of veins that able blood to move against the force of gravity?

A
  • Valves
  • Breathing movements act as a pump
  • Many bigger veins run between big, active muscles in the body
38
Q

The functions of the blood are to transport…

A
  • Hormones
  • Oxygen
  • Carbon dioxide
  • Platelets
39
Q

How does the blood minimise pH changes?

A

Acts as a buffer.

40
Q

What is plasma?

A

Yellow liquid which carries glucose, amino acids, mineral ions, hormones, red blood cells, white blood cells, platelets and large plasma proteins.

41
Q

Give two examples of large plasma proteins.

A

Albumin

Fibrinogen

42
Q

What is the role of albumin?

A

Maintain osmotic potential of blood.

43
Q

What is the role of fibrinogen?

A

Important in blood clotting.

44
Q

What is oncotic pressure?

A

The tendency of water to move into the blood by osmosis.

45
Q

Explain the movement into or out of a capillary as a result of hydrostatic pressure.

A

1) At the arterial end of the capillaries the hydrostatic pressure is high, so fluid is forced out of the capillaries. The fluid is referred to as tissue fluid and fills spaces between cells.
2) The tissue fluid has the same composition of the blood plasma but doesn’t contain red blood cells and plasma proteins.
3) At the venous end, the hydrostatic pressure falls and there is a flow of fluid back into the capillary.
4) Water moves back into the capillaries by osmosis.

46
Q

Where does some of the tissue fluid end up?

A

Lymph capillaries

47
Q

What is tissue fluid referred to as when it is in lymph capillaries?

A

Lymph

48
Q

How does the composition of lymph differ to that of plasma and tissue fluid?

A

Less oxygen and nutrients

Contains fatty acids

49
Q

How is fluid transported around lymph capillaries?

A

By squeezing of body muscles.

50
Q

How are lymph nodes linked to antibody production?

A

Lymphocytes build up in the lymph nodes.

51
Q

What are enlarged lymph nodes a sign of?

A

That the body is fighting off an invading pathogen.

52
Q

What are erythrocytes?

A

Red blood cells

53
Q

What are the adaptations of erythrocytes?

A
  • Biconcave shape increases SA

- Mature ones have lost their nuclei so more room for haemoglobin

54
Q

Equation for the formation of oxyhaemoglobin…

A

Hb + 4O2 <=> Hb(O2)4

55
Q

What is positive cooperatively?

A

When the binding of one oxygen molecule to a haem group makes it easier for the next molecule of oxygen to bind.

56
Q

What is the Bohr effect?

A

As the partial pressure of carbon dioxide increase, haemoglobin gives up oxygen more easily.

57
Q

Is a lower partial pressure of oxygen further to the left or to the right on the oxygen dissociation curve?

A

Left

58
Q

Is the oxygen dissociation curve for fetal haemoglobin to the left or to the right of adult haemoglobin?

A

Left

59
Q

How is oxygen transferred from the mother to the fetus?

A

As fetal haemoglobin has a higher affinity for oxygen at each point on the curve, oxygen is moved from the maternal blood.

60
Q

Is haemoglobin with a high affinity for oxygen further left or right?

A

Left

61
Q

How is carbon dioxide transported from tissues to the lungs?

A

5% carried dissolved in plasma
10-20% combined with amino groups in polypeptide chains of haemoglobin to form carbaminohaemoglobin
75-85% converted into HCO3- in cytoplasm of red blood cells

62
Q

Equation for…

CO2 + H2O <=>

A

H2CO3 <=> H+ + HCO3-

63
Q

Why does the reaction of carbon dioxide with water happen quickly in red blood cells?

A

Cytoplasm contains high levels of carbonic anhydrase

64
Q

What is the chloride shift?

A

Movement of chloride ions into the red blood cells as hydrogen ions move out to maintain an electrochemical gradient.

65
Q

Why is carbon dioxide converted to HCO3- ions?

A

The erythrocytes maintain a steep concentration gradient for carbon dioxide to diffuse from the respiring tissue into the erythrocytes.

66
Q

What is tachycardia?

A

Heartbeat is very rapid (over 100bpm). This can be caused by problems in the electrical control of the heart and may require surgery.

67
Q

When is tachycardia normal?

A

Exercise

Fever

68
Q

What is bradycardia?

A

When the heart rate slows down below 60bpm. May require a pacemaker to keep heart beating steadily.

69
Q

Why do some people have bradycardia?

A

They are fit, caused by exercise.

70
Q

What is ectopic heartbeat?

A

Extra heartbeats out of normal rhythm.

71
Q

What is atrial fibrillation?

A

Example of arrhythmia which means abnormal rhythm of the heart.

72
Q

What does ECG stand for?

A

Electrocardiogram

73
Q

What does ECG measure?

A

Tiny electrical differences in your skin which result from the electrical activity of the heart.

74
Q

What makes the heart sound?

A

Blood pressure closing the heart valves.

75
Q

Define myogenic.

A

Has its own intrinsic rhythm.

76
Q

Explain the basic rhythm of the heart…

A

1) Wave of electrical excitation begins in the SAN.
2) Causes atria to contract.
3) Layer of non-conducting tissue prevents excitation passing to the ventricles.
4) Excitation is picked up by the AVN which imposes a slight delay before stimulating the bundle of His which penetrate through the septum between the ventricles.
5) The bundle of His splits into two branches and conducts the wave of excitation to the apex of the heart.
6) At the apex the Purkyne fibres spread through the walls of the ventricles.
7) The spread of excitation causes the ventricles to contract, starting at the apex.

77
Q

What are the bundle of His made up of?

A

Purkyne tissue

78
Q

Why does contraction start at the apex (bottom) of the heart?

A

More efficient emptying of valves.

79
Q

Why is there a short delay at the AVN?

A

Ensures the atria have stopped contracting before the ventricles contract.

80
Q

What happens in diastole?

A

Heart relaxes, atria and then ventricles fill with blood so the volume and pressure build. Pressure in the arteries is at a minimum.

81
Q

What is systole?

A

Atria contract, followed by the ventricles. Pressure increases dramatically and blood is forced out. Blood pressure in arteries is at a maximum.

82
Q

What side of the heart has thicker walls and why?

A

Left- Blood is pumped around the body so must be under high pressure.

83
Q

What prevents oxygenated and deoxygenated blood from mixing?

A

Septum