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(OCR A) - A-level Biology > 3.1.2 Transport in animals > Flashcards

3.1.2 Transport in animals Flashcards

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1
Q

Why do animals need specialised transport systems?

A
  • High metabolic demand
  • Small SA:V ratio
  • Hormones and enzymes needed around the body
  • Food needed around the body
  • Waste product removal
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2
Q

What is the open body cavity in insects?

A

Haemocoel

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3
Q

What pressure is blood under in an open circulatory system?

A

Low pressure

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4
Q

Describe the flow of blood in an open circulatory system?

A

Pumped from heart into open body cavity where blood is not contained within blood vessels, instead comes into direct contact with cells where exchange occurs

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5
Q

Why does haemolymph not carry oxygen or carbon dioxide?

A

No haemoglobin to bind to

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6
Q

Why can flow of blood not be varied to meet changing demands in an open circulatory system?

A

No blood vessels which widen and narrow to control pressure

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7
Q

Which organism have an open circulatory system?

A

Insects

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8
Q

Where does the exchange of oxygen and carbon dioxide occur in a single closed circulatory system?

A

The first capillary at the gills

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9
Q

Where does oxygenated blood get exchanged between the gills and body?

A

Second capillary in the organs

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10
Q

What organism has a single closed circulatory system?

A

Fish

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11
Q

Why is the efficiency of single closed circulatory system limited?

A

Blood passes through narrow capillaries to blood pressure is low and blood travels slowly

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12
Q

Why is a single closed circulatory system efficient for fish?

A
  • Due to counter current exchange
  • Body weight supported by water
  • Constant temperature of water so no need to maintain body temperature (reduced metabolic demands)
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13
Q

What organism has a double closed circulatory system?

A

Mammals

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14
Q

What is a double closed circulatory system?

A

Blood is pumped twice around the heart in one circuit, one is deoxygenated (right) and other is oxygenated (left) blood

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15
Q

Why is a double closed circulatory system the most efficient?

A

High blood pressure so blood flows from heart to body quickly

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16
Q

What is the function of arteries?

A

Transport oxygenated blood away from the heart (usually at high pressure) to tissues

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17
Q

Which artery carries deoxygenated blood?

A

Pulmonary artery from heart to lungs

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18
Q

What is the function of veins?

A

Transport deoxygenated blood to the heart (usually at low pressure)

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19
Q

Which veins carry oxygenated blood?

A

Pulmonary vein (and umbilical vein) from the lungs to the heart

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20
Q

What is the order of flow of blood in blood vessels?

A

Artery -> arteriole -> capillary -> venule -> vein

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21
Q

What is the structure of arteries?

A
  • Narrow lumen
  • Thick layer of smooth muscle and elastic fibres
  • Inner endothelial layer
  • External collagen layer
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22
Q

What is the function of the endothelial layer in blood vessels?

A

Reduces friction for free blood flow

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23
Q

What is the function of smooth muscle cells in blood vessels?

A
  • Strength to withstand pressure
  • Contract to narrow lumen for reduced blood flow
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24
Q

What is the function of elastic tissue in blood vessels?

A

Stretches and recoils (flexible) under high pressures

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25
Q

What is the function of collagen in blood vessels?

A

Structural support

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26
Q

Why is there a pulse in arteries and not in veins?

A

Surge of blood in arteries which is lost after blood passes capillaries and enters veins

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27
Q

What is the structure of arterioles?

A

More smooth muscle and less elastin than arteries (allows for vasoconstriction and vasodilation)

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28
Q

What is the structure of capillaries?

A
  • Small lumen - force blood to travel slowly so more time for exchange, only allows one RBC at a time
  • Wall is one cell thick - decreased diffusion distance
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29
Q

What is the structure of veins?

A
  • Wider lumen
  • Fewer smooth muscle cells and elastic fibres
  • Inner layer of endothelial cells
  • Outer layer of collagen
  • Valves to prevent back flow of blood
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30
Q

What does plasma contain?

A
  • Dissolved glucose and amino acids
  • Mineral ions
  • Hormones
  • Large plasma proteins
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31
Q

Where does the exchange of substances between cells and blood occur?

A

Tissue fluid

32
Q

Explain the movement of water at the arterial end of the capillary?

A
  • Hydrostatic pressure > oncotic pressure
  • Net movement of water OUT of capillary
  • Formation of tissue fluid
33
Q

Explain the movement of water at the venous end of the capillary?

A
  • Hydrostatic pressure < oncotic pressure
  • Net movement of water INTO capillary
34
Q

What is the function of the plasma protein albumin?

A

Maintaining osmotic pressure

35
Q

What is oncotic pressure?

A

Tendency of water to move into blood by osmosis

36
Q

What happens to the 10% of fluid which does not return to the venous end of the capillary?

A

Enters the lymphatic system

37
Q

What is the importance of the lymphatic system?

A

Produces lymphocytes needed in immune system

38
Q

What is the function of the coronary arteries on the surface of the heart?

A

Provide the blood supply for aerobic respiration

39
Q

What does the inferior vena cava carry?

A

Deoxygenated blood from the lower body to the right atrium

40
Q

What does the superior vena cava carry?

A

Deoxygenated blood from the upper body to the right atrium

41
Q

Where is the tricuspid valve found and what is it’s function?

A
  • Right side of the heart, separating the right atrium from the right ventricle
  • Prevents back flow of blood into atrium
42
Q

Where is the semilunar valve found, and what is it’s function? (There are two types)

A
  • Between the right ventricle and left pulmanory artery (pulmonary valve)
  • OR between the left and aorta (aortic valve)
  • Prevents back flow of blood into heart
43
Q

Where is the bicuspid valve found and what is it’s function?

A
  • Between left atrium and left ventricle
  • Prevents back flow of blood into atrium
44
Q

Where is the aortic valve found and what is it’s function?

A
  • Between the left ventricle and the aorta
  • Prevents back flow of blood into heart
45
Q

What is the function of the septum?

A

Prevents the mixing of oxygenated and deoxygenated blood

46
Q

How long does a heart beat last?

A

0.8 seconds

47
Q

What happens during atrial systole?

A

Left atria contracts and empties blood into left ventricle

48
Q

What happens to the pressure of the left atrium and ventricle during atrial systole?

A

Increases slightly

49
Q

What happens to the AV valve at the start of ventricular systole?

A

Closes

50
Q

What happens to the pressure of the left atrium during ventricular systole?

A

Decreases as volume increases

51
Q

What happens to the pressure of the left ventricle during ventricular systole?

A

Increases as volume decreases

52
Q

What happens to the aortic valve during ventricular systole?

A

Opens

53
Q

Describe the pressure difference between the aorta and left ventricle during ventricular systole?

A

Pressure in left ventricular exceeds that in aorta so blood enters aorta

54
Q

What happens to the left ventricle during diastole?

A
  • Relaxes and emptied of blood
  • Pressure falls below that in aorta
55
Q

What happens to the aortic valve and AV valve during diastole?

A

Aortic valve closes
AV valve opens

56
Q

What causes the LUB sound?

A

Blood is forced against AV valve as ventricle contract

57
Q

What causes the DUB sound?

A

Blood is forced against semilunar (aortic) valve

58
Q

Cardiac output formula

A

Heart rate x stroke volume

59
Q

Describe the stages involved in the initiation of the heart?

A

1) Sinoatrial node sends out wave of excitation
2) Atria contract
3) Atrioventricular node sends out wave of excitation
4) Stimulates bundle of His
5) Excitation passes into Purkyne fibres
6) Ventricles contract

60
Q

What are the two effects of the SAN?

A
  • Atria contracts
  • Initiates heartbeat
61
Q

Why does the excitation from the SAN not pass directly to ventricles?

A

Due to presence of non-conduction tissue

62
Q

What is the importance of the AVN delay?

A

Makes sure atria stops contracting and ventricles can fill up before they contract

63
Q

What is tachycardia?

A

Heart beats too fast (ECG peaks close together)

64
Q

What is bradycardia?

A

Heart beats too slow (ECG peaks far apart)

65
Q

What is ectopic heartbeat?

A

Extra heartbeats that come too early

66
Q

What is fibrillation?

A

Irregular heart beat with no rhythm

67
Q

Why do the successive oxygen molecules bind easier to Hb?

A

Binding of first oxygen molecule changes structure of Hb

68
Q

What are three ways in which carbon dioxide is transported?

A

1) 10% dissolves in blood plasma forming H2CO3
2) 20% binds to amino acids to form carbaminohaemoglobin
3) 70% dissolves in cytoplasm of RBC

69
Q

Which enzyme catalyses the reaction between CO2 and H2O? What does it form?

A
  • Carbonic anhydrase
  • H2CO3
70
Q

What does H2CO3 dissociate into?

A

HCO3- + H+

71
Q

What does an increase in H+ ions cause in the RBC?

A
  • Decrease in blood pH
  • Alters structure of Hb
  • Oxygen released more easily
72
Q

How does haemoglobin act as a buffer?

A

Accepts H+ ions to avoid changing blood pH

73
Q

What is the chloride shift?

A

Movement of chloride ions into RBC to balance out the electrical imbalance due to:
- HCO3- leaving RBC
- H+ potentially building up

74
Q

What happens to Hb affinity for oxygen when the partial pressure of carbon dioxide is high

A

Decreases (oxygen released more easily)

75
Q

Why does foetal Hb have a higher affinity for oxygen?

A

Oxygen concentration in placenta blood of mother is lower than the concentration of oxygen in air inside lungs

(OCR A) - A-level Biology (26 decks)

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