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A-level biology > 3.1.1 - exchange surfaces > Flashcards

3.1.1 - exchange surfaces Flashcards

1
Q

what is an exchange surface

A

a surface on/inside an organism over which exchange of gases, nutrients and waste can take place

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2
Q

what is a mass transport system

A

a system by which large quantities of exchanged materials can be moved around the body to the cells that need them

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3
Q

why is simple diffusion not good for multicellular organisms

A

diffusion pathway is too long + too many substrates get used up as they move to the centre cells

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4
Q

what is metabolic activity

A

the sum of all the reactions in a cell/body

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5
Q

does a large organism have a big or small SA:V

A

small

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6
Q

does a small organism have a big or small SA:V

A

big

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7
Q

what are the features of an efficient gas exchange

A

large SA:V
short diffusion distance
good blood supply

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8
Q

what maintains a large SA:V in an exchange surface

A
  • Small alveoli (100-300 micrometres)
    • small but there are lots that increase the SA of the lungs
  • surfactant producing cells
    • surfactant - substance reducing cohesive forces of a liquid (phospholipid)
    • coats the internal surface of alveoli to reduce cohesive forces between water molecules. These forces may make alveoli collapse - reducing SA
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9
Q

what maintains a short diffusion distance in an exchange surface

A
  • alveolus and capillary walls are 1 cell thick
    • barrier is only 2 cells thick which is less than 1 micrometre
  • alveolar walls made of squamous epithelial cells
    • flattened so thin barrier
  • capillaries are in close contact with alveolus wall
    • decreased diffusion distance
  • capillaries are so narrow that red blood cells are squeezed against the capillary wall
    • rbcs are very close to the air in the alveoli and have a very short diffusion distance
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10
Q

what maintains a good blood supply distance in an exchange surface

A
  • blood system transports CO2 from tissue to lung
    • higher conc of CO2 in the blood than alveoli so it can diffuse into the alveoli for exhalation
  • blood transports O2 from lungs
    • lower conc of O2 in blood than alveoli so it can diffuse into the blood
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11
Q

what is inhalation

A

getting air into the lungs

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12
Q

what happens to volume during inhalation

A

diaphragm flattens / moves down
external IM contract
internal IM relax
ribs move up and out
volume inside chest (thorax) increases

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13
Q

what happens to pressure during inhalation

A

pressure decreases

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14
Q

what happens to the movement of air during inhalation

A

air rushes into the lungs

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15
Q

what is exhalation

A

getting air out of the lungs

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16
Q

what happens to volume during exhalation

A

diaphragm relaxes and moves up
external IM relax
internal IM contract
ribs move down and in
volume inside chest (thorax) decreases

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17
Q

what happen to pressure during exhalation

A

pressure increases

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18
Q

what happens to the movement of air during exhalation

A

air rushes out of the lungs

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19
Q

why do we say the diaphragm contracts and relaxes

A

it is made out of muscle

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20
Q

what does a spirometer do

A

measures lung volume

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21
Q

why does the spirometer have a disposable mouthpiece

A

prevents infection between patients

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22
Q

why is a noseclip worn when using a spirometer

A

prevents air entering/escaping through the nose

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23
Q

why does a spirometer have soda-lime

A

absorbs CO2 so it doesn’t go into the chamber

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24
Q

why does the lid of the spirometer go up and down

A

happens when you breathe in and out

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25
Q

why does the patient have to be healthy and free from asthma when using a spirometer

A

more safe and the transfer of disease between patients is less likely

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26
Q

why should the soda-lime in a spirometer be fresh and functioning

A

so that is absorbs the CO2 and it doesn’t go into the chamber

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27
Q

why should there be no leaks in the spirometer

A

air can escape and results won’t be accurate

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28
Q

why should the spirometer mouthpiece be sterilised

A

reduced transfer of disease

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29
Q

why shouldn’t the water chamber in a spirometer be overfilled

A

so that the person doesn’t inhale water

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30
Q

what is the tidal volume

A

the volume of air inhaled or exhaled in one normal breath - usually at rest

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31
Q

what is the volume breathed in or out at tidal volume

A

~0.5dm3

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31
Q

what is the inspiratory reserve volume

A

additional air that can be inhaled with maximum effort above normal breath

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32
Q

what is expiratory reserve volume

A

additional air that can be exhaled with maximum effort above normal breath

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33
Q

what is the vital capactiy

A

max volume of air that can be moved by the lungs in 1 breath ( measured by taking a deep breath)

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34
Q

how do you find the vital capacity

A

inspiratory reserve volume + expiratory reserve volume + tidal volume

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35
Q

what is the approximate volume of the vital capacity

A

~2.5-5.0 dm3

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36
Q

what is the residual volume

A

volume of air that remains in the lungs even after forced exhalation

37
Q

where does the residual volume air stay

A

remains in the airways and in the alveoli

38
Q

what is the approximate volume of the residual volume

A

~1.5 dm3

39
Q

what is total lung capacity

A

total amount of air held in the lungs

40
Q

how do you calculate the total lung capacity

A

vital capacity + residual volume

41
Q

what do the airways consist of

A

trachea, bronchi and bronchioles

42
Q

what must the airways be like

A
  • large enough to allow sufficient airflow without obstruction
  • supported to prevent collapse when air pressure is low
  • flexible to allow movement
43
Q

where is the ciliated epithelium located

A

trachea bronchi and bronchioles

44
Q

what kind of cells are in the ciliated epithelium and what do they do

A

goblet cells which release mucus to trap pathogens

45
Q

what kind of shape is the ciliated epithelium

A

columnar

46
Q

what do the cilia in the ciliated epithelium do

A

move/waft mucus at the top of the airways where it is swallowed

47
Q

where is smooth muscle located

A

in the trachea, bronchi and bronchioles

48
Q

what does the smooth muscle do

A

can contract and narrow the lumen of the airways which restricts airflow to and from the alveoli

49
Q

why is it good if the smooth muscle contracts

A

important if harmful substances are in the air for example it is involuntary in an allergic reaction

50
Q

where is elastic fibres found

A

trachea, bronchi, bronchioles and alveoli

51
Q

what do elastic fibres do

A
  • works with smooth muscle
  • when muscle contracts, elastic fibres are deformed/stretched. When muscle relaxes, elastic fibres recoil to original shape + size
52
Q

where is cartilage found

A

trachea, bronchi and some large bronchioles

53
Q

what does cartilage do

A

supports the airway to prevent collapse

54
Q

what kind of cartilage is in the trachea

A

c - shaped which allows for flexibility and space for food to pass down the oesophagus

55
Q

hat kind of cartilage is in the bronchi

A

fragmented

56
Q

what is the terminal bronchiole

A

the part of the bronchioles that is close to the alveoli. It has an increased SA and no cartilage

57
Q

is alveoli part of the airways

A

no

58
Q

what does the alveolar tissue contain

A

elastic fibres that stretch during inhalation but recoil to push out air during exhalation

59
Q

where is the squamous epithelium found

A

in alveoli

60
Q

what does squamous mean

A

flattened

61
Q

why is it good that squamous epithelial cells are flattened

A

reduce diffusion distance

62
Q

where are capillaries found in the lungs

A

trachea, bronchi, bronchioles, alveoli

63
Q

how do you measure the breathing rate from a trace

A

count the number of breaths taken per min on the trace by counting either the peaks or the troughs.

64
Q

how do you measure the tidal volume from a trace

A

draw 2 lines on the trace, one above and one below the tidal volume peak and trough. Measure between lines of 3-4 peaks and take an average

65
Q

what is the pulmonary breathing rate

A

total volume of air breathed in a minute

66
Q

how to calculate the pulmonary breathing rate from a trace

A

tidal volume x breathing rate

67
Q

how do you calculate the vital capacity from a trace

A

measure the height of the vital capacity

68
Q

how to find the oxygen consumption from a trace

A

look how much the line has fallen in 1 min (look at 1 of the 2 lines) and divide by 60 to find oxygen consumption per second.

69
Q

how many times denser is water than air

A

1000x

70
Q

how many times more viscous is water than air

A

100x

71
Q

does water have a higher or lower O2 content than air

A

lower

72
Q

describe the inspiration of a bony fish

A
  • mouth opens (operculum is closed)
  • buccal cavity floor is lowered
  • this increases the volume and decreases the pressure of the buccal cavity compared to outside
  • water rushes into the mouth down a pressure gradient
  • buccal cavity floor is raised AND opercular cavity expands
  • the pressure inside the buccal cavity is now higher than in the opercular cavity
  • water moves from the buccal cavity over the gills into the opercular cavity
73
Q

describe the expiration of a bony fish

A
  • mouth closes AND the operculum opens
  • the sides of the opercular cavity move inwards, increasing the pressure
  • water rushes out of the fish through the operculum
74
Q

how do bony fish maintain a good blood supply

A

has a counter current exchange system

75
Q

what do gill rakers do

A

they act like a sieve and prevent harmful grit and debris from passing over the gill filaments

76
Q

how big are gill lamellae

A

~ 5 micrometres

77
Q

why is it good that the gill lamellae are very thin

A

maintains a short diffusion distance between capillaries

78
Q

what is the purpose of a gill arch

A

provides structural support and keeps rows from sticking together

79
Q

roughly what is the size of gill lamellae

A

around 5 micrometers

80
Q

why is it good that the gill lamellae are very thin

A

maintains a short diffusion distance between capillaries

81
Q

what do gill rakers do

A

act like a sieve and prevent harmful grit and debris from passing over gill filaments

82
Q

what kind of exchange system does a fish have

A

counter current

83
Q

what does a counter current exchange system mean

A
  • blood is always adjacent to the water which has a higher O2 concentration and therefore oxygen continuously diffuses into the blood and an equilibrium is never reached
  • even when water has little O2, it still has more than the blood and maintains a concentration gradient (constant rate of diffusion)
84
Q

what are the features of an insect gas exchange

A

spiracle, tracheae, tracheole, tracheal fluid

85
Q

what does the spiracle do

A
  • allows gases in and out
  • open when active (O2 in and Co2 out)
  • most close when at rest (less H2O loss)
86
Q

what does the tracheae do

A

carries air into the body

87
Q

what is the tracheae lined with and what does it do

A

lined with chitin which provides support and is impermeable to gas

88
Q

what happens in the tracheoles

A

there is no chitin lining so gas exchange can take place

89
Q

what does the tracheal fluid do

A

limits O2 penetration into the tracheoles
a little bit can dissolve into fluid that is enough to sustain the insect at rest

90
Q

what happens in the exchange system when the insect is active

A
  • tracheal fluid is initially low which decreases the O2 in muscle cells
  • activity begins
  • muscle cells have to anaerobically respire
  • increased lactic acid in cells
  • decreased water potential of cells
  • water/tracheal fluid moves from the tracheoles into muscle cells vio osmosis down a water potential gradient
  • increased SA of tracheoles so more O2 can go in
  • there is an increased O2 in tracheoles that diffuses into muscle cells
  • aerobic respiration releases energy for activity
  • CO2 can diffuse from the cells into the tracheoles and out of the spiracles

A-level biology (25 decks)

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