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biology a level OCR > Exchange surfaces > Flashcards

Exchange surfaces Flashcards

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1
Q

state 3 factors that affect the need for exchange systems

A
  • SA:VOL ratio
  • metabolic rate (oxygen demand)
  • endothermic (warm blooded or ectothermic (cold blooded)
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2
Q

what tends to require a circulatory system, a unicellular organism or a multicellular organism

A

A single celled organism

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3
Q

name 3 feature of an efficient exchange surface

A
  • large surface area to volume ratio
  • good blood supply
  • permeable (to allow gases to pass through)
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4
Q

in what direction does the blood flow past the alveoli

A

deoxygenated blood from pulmonary artery and then oxygenated blood, to pulmonary vein

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5
Q

why do alveoli contain capillary’s

A

in order to have good blood supply, to allow oxygen to diffuse down the concentration gradient into the lungs from the alveoli into the blood, and for carbon dioxide to move down the concentration gradient, from the blood into the alveoli

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6
Q

what do the elastic fibres do, to expel air?

A

elastic fibres, stretch and recoil in order to expel air

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7
Q

what is the pulmonary surfactant?

A

a mixture of lipids and proteins, secreted into the alveolar space

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8
Q

what is the role of the pulmonary surfactant?

A

to lower the surface tension, at the air/ liquid interface, within the alveoli, stopping the walls of sticking together and collapsing, as we exhale

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9
Q

what is the partial pressure of oxygen in the alveoli

A

104

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10
Q

what is the partial pressure of oxygen in the blood

A

40

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11
Q

what is the partial pressure of carbon dioxide in the alveoli

A

40

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12
Q

what is the partial pressure of carbon dioxide in the blood

A

45

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13
Q

what is the role of cilia

A

to beat rhythmically, to waft mucus up towards the back of the thoat.

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14
Q

what is the role chemoreceptors

A

to detect a change in the blood Ph levels, if there is a decrease in blood Ph levels, the sympathetic nervous system will be stimulated by the medulla oblongata, in order to increase heart rate, thus meaning more oxygen is entering the blood and more carbon dioxide is leaving the blood

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15
Q

be able to label the breathing system

A
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16
Q

describe how inspiration occurs

A

external intercostals and diaphragm contract -> ribs move up and out and the diaphragm flattens -> increase in volume and a decrease in thorax pressure -> air drawn into lungs, down pressure gradient (opposite for expiration)

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17
Q

what is the function of cartilage

A

to prevent the collapse of the trachea and bronchus.

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18
Q

what is the function of goblet cells

A

in order, to secrete mucus (containing glycoproteins) and trap dust, that contains pathogens

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19
Q

what is the function of ciliated cells

A

to move in a synchronised pattern, to waft mucus up the airways, in order to be digest or coughed out

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20
Q

what is the function of smooth muscle

A

to narrow the airways, in order to restrict flow if there are harmful substance present in the air. They can dilate to increase air flow

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21
Q

what is the function of elastic fibres

A

they stretch during inhalation, to prevent alveoli from bursting and recoil, to expel air from the airways

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22
Q

what is the function of squamous epithelium

A

they are thin cells, to ensure that there is a short diffusion distance, thus resulting in an increased rate of gaseous exchange.

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23
Q

what shape is the cartilage in the trachea

A

C - shape rings

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24
Q

why does oxygen, always have a steep concentration gradient

A

due to blood being pumped away from the heart once oxygenated

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25
Q

what does ventilation do

A

brings in fresh air, increasing the concentration of oxygen in the alveoli and decrease the concentration of carbon dioxide in the alveoli, to ensure a steep concentration gradient

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26
Q

what to the intercostal muscles and the diaphragm do?

A

work together to change the shape of the thorax, to perform inspiration or expiration.

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27
Q

what are the names of the intercostal muscles

A

external and internal intercostals

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28
Q

is inhalation an active or passive process

A

active ( requires energy (ATP))

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29
Q

is exhalation an active or passive process

A

passive process ( muscles relaxing)

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30
Q

what happens during expiration

A

The external intercostal muscles relax and so does the diagram, becoming dome shaped, decreasing the volume and increasing the pressure, helping to force air out

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31
Q

when can exhalation become an active process and why?

A

when we exhale strongly, due, to causing the internal intercostal muscles to contract

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32
Q

how does a spirometer work

A
  • A spirometer works, where the static lower half of the tank, is filled with water and the mobile upper half of the tank is filled with oxygen.
  • When the subject breathes out, lid rises, when the subject breaths in lid falls
33
Q

what is tidal volume

A

the volume of air breathe in or out the lungs per breath (during quiet breathing) (at rest around 0.5 dm3.

34
Q

what is the inspiratory reserve volume

A

is the maximum volume of air that can be inspired in excess of tidal volume.

35
Q

what is the expiratory reserve volume

A

the maximum volume of air that can be expired in excess of tidal volume.

36
Q

what is vital capacity

A

the maximum volume of air, that can be moved by the lungs in one breath. (2.5 dm3 – 5dm3.

37
Q

what is residual volume

A

is the volume of air left in the lungs after forced expiration (1.5 dm3)

38
Q

What problems, do fish have regarding gaseous exchange

A
  • water is denser and more viscous than air, so the oxygen needs more kinetic energy to cross the gas exchange surface,
  • fish have small SA: vol ratio, so diffusion is not enough therefore the fish need a specialised exchange surface
  • o2 conc in air is 21% in water it is 1%
39
Q

how many pairs of lungs do most fish have

A

4-5 pairs of lungs

40
Q

what is the role of gill rakers

A

to stop food particles from reaching gill filaments.

41
Q

what is the role of lamellae

A

to increase the surface area for gas exchange

42
Q

what does each gill consist of

A

two rows of filaments and gill rakers

43
Q

why are the walls of the gill filaments thin

A

to allow for short diffusion distance

44
Q

why is there a capillary network surrounding the lamellae

A

to maintain a steep concentration gradient.

45
Q

why do the tips of gill filaments overlap

A

to increase resistance to water flow

46
Q

what is counter current

A

blood, and water flow in opposite direction, to maintain a high concentration gradient.

47
Q

explain what happens during inspiration in fish

A
  • the mouths opens and operculum closes,
  • thus meaning that buccal cavity floor lowers, thus increasing the volume of the buccal cavity and decreasing the pressure.
  • The water that flows into the mouth, is moving down a pressure gradient.
48
Q

what happens during expiration in fish

A
  • the buccal floor raises as the mouth closes
  • thus increasing pressure and decreasing volume in the buccal cavity,
  • then water is forced to flow over the gills, and the sides of the operculum, move in and open to allow water to be expelled from fish.
  • (Water only flows in one direction).
49
Q

what do insects have

A

trachea, tracheoles and spiracles

50
Q

what is connected to the muscle fibres

A

the tracheoles

51
Q

why do insects have a small size

A

so that diffusion distance are small

52
Q

what are spiracles

A

they are what can be opened or closed, to help control the air drawn in and out, but can also control water loss

53
Q

why is the water potential in the muscles lower

A

lower meaning that it will move into the muscles via osmosis, increasing diffusion of oxygen.

54
Q

as the size of the organism increases, what happens to the SA:VOL ratio

A

it decreases (there will come a point where a specialised exchange system is required)

55
Q

what cell forms the wall of the alveolus

A

squamous epithelial cells

56
Q

what is pulmonary surfactant

A

a mixture of lipids and proteins, secreted into the alveolar space

57
Q

what does pulmonary surfactant do

A
  • Lowers the surface tension at the air/liquid interface, within the alveoli
  • this, stops the walls sticking together and collapsing as we exhale
58
Q

what is the trachea lined with

A

ciliated epithelial cells, which in turn, waft mucus up the airways out fo the trachea

59
Q

what is the trachea lined with

A

ciliated epithelial cells, which in turn, waft mucus up the airways and out of the trachea, to be swallowed and digested in the stomach or expelled by a cough

60
Q
A
61
Q

how is cartillage arranged in the trachea

A

in C-shaped rings

62
Q

how is cartilage arranged in the trachea

A

in C-shaped rings

63
Q

describe a spirometer trace

A
64
Q

what is the equation for pulmonary ventilation rate

A

tidal volume X breathing rate = pulmonary ventilation rate

65
Q

what are the two adaptations of the trachea

A
  • the trachea has C shaped cartilage rings to allow the oesophagus to change shape, due to there being a region absence of cartilage near the oesophagus
  • the walls are lined with ciliated epithelial cells, which have cilia to move the mucus. the Goblet cells produce mucus, which trap and attach to the pathogens
66
Q

what happens when smooth muscles relaxes in the bronchioles

A

the walls of the bronchioles widen, allowing for more air, to be passed through

67
Q

where is the site of gas exchange

A

the alveoli

68
Q

how many cells thick are the wall of the alveolus and the wall of the capillary and why

A

so there is a short diffusion distance

69
Q

ventilation involves the action of which two sets of muscles

A

the diaphragm and the intercostal muscles

70
Q

what are the names for the two intercostal muscles

A
  • internal
  • external
71
Q

what happens during inhalation

A

the external intercostal muscles contract
the diaphragm contracts, causing them to flatten

72
Q

why is inhalation an active process

A

because it involves muscle contraction

73
Q

why is exhalation a passive process

A

due to the muscles relaxing

74
Q

what happens during exhalation

A
  • the external intercostal muscles relax, and return to their original length
  • the diaphragm. also relaxes returning to its original domed shape, thus reducing the volume of the thorax and lungs. to force air out
75
Q

what is the alveoli structure

A
  • walls are 1 cell thick
  • outer layer of squamous epithelial cells
  • around 100-300um wide airspace
  • elastic fibres + collagen are there to stretch and recoil, to help expel air.
76
Q

why is blood only 95% saturated with oxygen

A
  • some of the inhaled air does not take part in gaseous exchange (dead space)
  • some blood in the lungs, doesn’t go through any alveolar capillaries
77
Q

why does exhalation become an active process

A

exhalation, becomes an active process as the internal intercostal muscles contract pulling up the ribs down hard and abdominal muscles, contract forcing the diaphragm up to force air out of the lungs more forceful. (this requires energy from respiration)

78
Q

how might athletic training, affect the condition of the lungs

A
  • stronger intercostal muscles
  • stronger diaphragm
  • tidal volume will thus increase
  • the alveoli, will get bigger
  • increase in lung volume
79
Q

how does the structure of the gills relate to their function?

A
  • gill filaments + lamellae = large SA
  • thin walls of the lamellae = short diffusion distances
  • gill filaments overlap, to slow down water flow (increasing resistance), this allows for sufficient time for diffusion
  • capillary network, to keep a high concertation gradient
  • counter current, to maintain a high concentration gradient

biology a level OCR (32 decks)

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