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OCR A level Biology > 3.1.1 Exchange surfaces and breathing > Flashcards

3.1.1 Exchange surfaces and breathing Flashcards

1
Q

define exchange surface

A

specialised area that is adapted to make it easier for molecules to cross from one side of the surface to another

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2
Q

what factors affect the need for an exchange surface?

A

-increasing size
-level of activity
-SA:V ratio

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3
Q

what are the properties of exchange surfaces?

A

-large surface area
-thin layers
-diffusion gradient
-moist cells
-good blood supply
-ventilation for diffusion gradient

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4
Q

how does a large surface area allow efficient diffusion to occur in exchange surfaces?

A

provides area needed for exchange and overcomes limitations of SA:V ratio

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5
Q

how does thin layers allow efficient diffusion to occur in exchange surfaces?

A

shortens diffusion distance making it more efficient

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6
Q

how does a diffusion gradient allow efficient diffusion to occur in exchange surfaces?

A

areas of high concentrations and areas of low concentration cause diffusion to occur

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7
Q

how do moist cells allow efficient diffusion to occur in exchange surfaces?

A

prevents evaporation from lungs and substances need to be dissolved in water to be transported

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8
Q

how does a good blood supply allow efficient diffusion to occur in exchange surfaces?

A

ensures substances are constantly delivered which maintains a steep concentration gradient

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9
Q

how does ventilation for diffusion gradient allow efficient diffusion to occur in exchange surfaces?

A

helps maintain diffusion gradient

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10
Q

what are some examples of a large surface area in exchange surfaces?

A

root hair cells and villi in small intestine

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11
Q

what are some examples of thin layers in exchange surfaces?

A

alveoli and villi

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12
Q

what are some examples of a diffusion gradient in exchange surfaces?

A

alveoli, gills and villi

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13
Q

what are some examples of moist cells in exchange surfaces?

A

alveoli

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14
Q

what are some examples of good blood supply in exchange surfaces?

A

alveoli, gills and villi

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15
Q

what are some examples of ventilation for diffusion gradient in exchange surfaces?

A

alveoli in lungs and continuous water flow over gills

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16
Q

what is the trachea lined with?

A

columnar epithelial ciliated cells covered in mucus which is produced by goblet cells

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17
Q

what are pleural membranes?

A

they surround the lungs

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18
Q

what is the pleural cavity filled with?

A

pleural fluid

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19
Q

what does pleural fluid do?

A

acts as a lubricant and protects the lungs from the ribs

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20
Q

describe the process of inhalation in the lungs

A

-the external intercostal muscles in the ribs and sternum contract causing ribs to move up and out
-the diaphragm contracts and moves it down (creating a bigger chest cavity)
-the volume of the thorax increases
-the air pressure inside the thorax decreases
-the air moves into the lungs

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21
Q

describe the process of exhalation in the lungs

A

-the external intercostal muscles in the ribs and sternum relax causing ribs to move down and in
-the diaphragm relaxes and moves it up (creating a smaller chest cavity)
-the volume of the thorax decreases
-the air pressure inside the thorax increases
-the air moves out of the lungs

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22
Q

how does forced breathing occur?

A

internal intercostal muscles contract which pulls ribs down hard and fast

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23
Q

label a diagram of the lungs

A

on paper flashcard

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24
Q

list the order in which air passes from the nose to the lungs

A

mouth/nose, trachea, bronchi, bronchioles, alveoli

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25
Q

what are bronchioles?

A

smallest respiratory passageways

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26
Q

what is another name for the windpipe?

A

trachea

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27
Q

where does gas exchange take place?

A

alveoli

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28
Q

what is the epiglottis?

A

stops food “going the wrong way” ie choking during swallowing

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29
Q

what is the pharynx?

A

both air and food pass through this

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30
Q

what is expiration?

A

the movement of air out of the lungs

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31
Q

what is the main muscle involved in inspiration?

A

diaphragm

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32
Q

what are the pleural membranes?

A

membranes that cover the lungs and line the pleural cavity

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33
Q

how does ventilation maintain the steep concentration gradient in the alveoli?

A

inhalation brings in lots of O2 creating a high concentration and exhalation removes CO2 keeping concentration low inside alveoli

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34
Q

alveoli secrete a fluid called surfactant- why is this important?

A
  1. prevents them from drying out
  2. allows gases to dissolve so that they can diffuse across the membrane
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35
Q

there are millions of alveoli in the lungs- why is this important?

A

this creates a larger area of exchange so gas exchange into the blood is quicker

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36
Q

why is it important the alveolar wall is one cell thick?

A

short diffusion distance so quicker diffusion of gases

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37
Q

why is it important the capillary wall is one cell thick?

A

short diffusion distance so quicker diffusion of gases

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38
Q

how does a good blood supply maintain a steep concentration gradient in the alveoli?

A

brings high concentration of CO2 to lungs and has a low concentration of O2, also carries the O2 away straight away maintaining the low concentration of oxygen in the lungs

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39
Q

alveoli are very small- why is this important?

A

this creates a larger SA:V ratio so diffusion distance is shorter so CO2 and O2 can be exchanged into the blood much faster

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40
Q

what different tissues do the trachea contain?

A

-ciliated epithelium
-cartilage
-elastic fibres
-muscle

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41
Q

what different tissues do the bronchus contain?

A

-ciliated epithelium
-cartilage
-elastic fibres
-muscle

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42
Q

what different tissues do the bronchioles contain?

A

-elastic fibres
-muscle

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43
Q

what different tissues do the alveoli contain?

A

-squamous epithelium
-elastic fibres

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44
Q

what does the ciliated epithelium tissue do in the trachea and bronchus?

A

the cilia waft rhythmically and goblet cells produce mucus which is moved upwards

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45
Q

what does the squamous epithelium tissue do in the alveoli?

A

one cell thick for short diffusion distance

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46
Q

what does the cartilage tissue do in the trachea?

A

c-shaped cartilage holds it open and allows for expansion

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47
Q

what does the cartilage tissue do in the bronchus?

A

irregular distributions of cartilage holds tube open

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48
Q

what do elastic fibres do in the trachea, bronchus and bronchioles?

A

elastic fibres are for stretch and recoil

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49
Q

what do elastic fibres do in the alveoli?

A

elastic fibres provide strength and flexibility, they stretch and recoil to push air out

50
Q

what does muscle tissue do in the trachea and bronchus?

A

involuntary muscles

51
Q

what does muscle tissue do in the bronchioles?

A

involuntary muscles contract to make them narrower

52
Q

what are insects exoskeletons made of?

A

chitin

53
Q

what are the characteristics of chitin?

A

-little or no gas exchange occurs over this
-tough, light and allows movement
-has a waxy cuticle

54
Q

what does the waxy cuticle on an insects exoskeleton do?

A

reduces water loss to reduce dehydration risk on land

55
Q

describe what gas exchange is like in insects

A

-open circulatory system and a high oxygen requirement
-oxygen is delivered directly to cells

56
Q

what do spiracles do in insects?

A

-open and close depending on oxygen demands
-help reduce water loss

57
Q

what does tracheal fluid do in insects?

A

-it limits the surface area through which gases can diffuse into cells
-if oxygen demand increases, lactic acid will build up (this lowers water potential of cells) causing water to move out of the tracheoles by osmosis
-this exposes more surface area for diffusion

58
Q

why do insects need ventilation?

A

large beetles, locusts, grasshoppers and bees have very high energy demands so they need to be able to supply respiring cells with additional oxygen

59
Q

how do insects ensure they have enough oxygen for their high energy demands?

A

through mechanical ventilation and collapsible enlarged tracheae

60
Q

describe mechanical ventilation in insects

A

-rhythmical flattening and expanding of the thorax and abdomen
-creates differences in volume and therefore pressure
-air is drawn into and out of the tracheae and tracheoles as the pressure changes

61
Q

describe the collapsible enlarged tracheae

A

-act as air reservoirs
-inflated and deflated by mechanical ventilation

62
Q

what are the problems for fish?

A

water is a problematic exchange medium

63
Q

why is water a problematic exchange medium?

A

-water has around 20 times less oxygen per cm³ than air
-water is much denser than air

64
Q

how do fish overcome the problem of water being a problematic exchange medium?

A

fish have an exchange surface to obtain oxygen and a mechanisms to maximise water movement over the surface

65
Q

what are the different types of fish?

A

cartilaginous and bony

66
Q

what is the ventilation system in cartilaginous fish?

A

parallel flow

67
Q

what does it mean by a parallel flow system?

A

blood travels through the gills in the same direction as water

68
Q

what is the ventilation system in bony fish?

A

counter-current flow

69
Q

what does it mean by counter-current flow system

A

blood travels through gill capillaries in the opposite direction to the water

70
Q

describe the ventilation in bony fish

A

TO TAKE IN WATER:
pressure in mouth is decreased by:
-opening mouth, lowering the floor of the buccal cavity
-increases volume of mouth
-water rushes into mouth

TO PUSH WATER OUT THROUGH GILLS:
increasing pressure in mouth by:
-closing mouth and raising floor of buccal cavity
-this decreases volume of mouth
-the operculer valve closes the opening at the back of the thorax
-so, water moves out over the gills

71
Q

what does counter current exchange ensure?

A

it ensures that a steep concentration gradient is maintained

72
Q

what does counter current exchange successfully do?

A

it successfully removes up to 80% of oxygen from the water

73
Q

what happens if the current flows in the same direction as the blood in fish?

A

-initially there is a steep concentration gradient from water to blood
-equilibrium is then reached
-no more net movement of oxygen from water to blood

74
Q

what happens if the current flows in opposite directions to the blood?

A

-a steep concentration gradient is maintained along the gill
-so oxygen can continuously diffuse into the blood
-equilibrium is not being reached
-the blood carries the oxygen away further maintaining the diffusion gradient
-carbon dioxide also removed from the blood in a parallel system

75
Q

what does the graph of a parallel flow system look like?

A

see paper flashcard

76
Q

what does the graph of a counter current system look like?

A

see paper flashcard

77
Q

what is the organ involved in gaseous exchange in fish?

A

gills

78
Q

what are the key features of gills that allow them to be successful in gas exchange?

A

-thin layers
-good blood supply
-large surface area

79
Q

where are the gills found?

A

gill cavity

80
Q

what is the role of the operculum?

A

to protect the gills and it’s active in maintaining water flow

81
Q

what are lamellae?

A

thin plate like structures that are distributed across all of the gill filaments

82
Q

why are the lamellae the main site of gas exchange in fish?

A

because they have:
-good blood supply
-large surface area
-thin layers

83
Q

what is the gill arches function?

A

to support the structure of the gills

84
Q

what is the main adaptation of the gill filaments?

A

large surface area

85
Q

how are the gill filaments kept apart to ensure their adaptation of a large surface area is utilised?

A

flow of water around them and the fact they are four separate stacks so water can flow through them

86
Q

how do cartilaginous fish maintain water flow?

A

by continuously moving

87
Q

what structures do bony fish rely on to maintain the movement of water across the gills?

A

the operculum and the buccal cavity (its mouth)

88
Q

why can diffusion not occur through the exoskeleton of an insect?

A

it is impermeable to gases

89
Q

when do spiracles open in an insect?

A

-oxygen demand is raised
-when carbon dioxide levels build up

90
Q

when do spiracles close in an insect?

A

-when an insect is inactive
-when oxygen demand is very low

91
Q

what is the purpose of spiracles?

A

to allow air to enter and leave

92
Q

what do the spiracle sphincters do?

A

they open and close the spiracles

93
Q

what is a tracheole?

A

a minute tube made of elongated cells

94
Q

why are tracheoles freely permeable to gases?

A

there is no chitin

95
Q

where does most gas exchange occur within an insects body?

A

tracheoles

96
Q

what is the purpose of chitin?

A

hold tracheae open and make it impermeable

97
Q

what is the diameter of the tracheae?

A

1mm

98
Q

does gas exchange occur through the tracheae and why?

A

no, they are impermeable to gases because it’s made of chitin

99
Q

what do the tracheae branch into?

A

tracheoles

100
Q

what are the ways to measure the volume of air in the lungs?

A

-using a peak flow meter
-using a lung capacity bang
-using a spirometer

101
Q

describe a peak flow meter

A

-sterile mouthpieces
-use 3 times and take highest reading

102
Q

describe a lung capacity bag

A

-gives an air volume using a scale on the bag
-take a deep breath and exhale into the bag

103
Q

define tidal volume

A

the volume of air that moves into and out of the lungs with each resting breath

104
Q

define vital capacity

A

the volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath

105
Q

define inspiratory capacity

A

the maximum volume of air that can be inhaled at the end of a normal expiration

106
Q

define residual volume

A

the volume of air that is left in your lungs when you have exhaled as hard as possible

107
Q

define inspiratory reserve volume

A

the maximum volume of air you can breathe in over and above a normal inhalation

108
Q

define expiratory reserve volume

A

the extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breathe out

109
Q

label a typical spirometer trace

A

on paper flashcard

110
Q

what are the different things you can calculate from a spirometer?

A

-breathing rate
-tidal volume
-vital capacity
-oxygen consumption
-ventilation rate
-maximum inspiratory reserve
-minimum expiratory reserve

111
Q

how do you calculate ventilation rate?

A

breathing rate x tidal volume

112
Q

what is the reason for calibrating the spirometer?

A

this allows us to calculate the actual volumes breathed

113
Q

what is the reason for filling the drum with fresh air in the spirometer?

A

to ensure normal levels of oxygen in the air to be breathed by the subject

114
Q

what is the reason for needing the subject to be in good health when using the spirometer?

A

to avoid any medical problems

115
Q

what is the reason for the subject wearing a nose clip when using the spirometer?

A

to prevent them from breathing through their nose instead of their mouth which allows valid measurements

116
Q

what is the reason for the subject breathing normally into the spirometer using the mouthpiece?

A

to record volume of air being breathed

117
Q

what is the reason for using a sterile mouthpiece in the spirometer?

A

to avoid infection

118
Q

what is the reason for the subjects exhaled air passing through a can of soda lime in the spirometer?

A

to absorb the CO2

119
Q

what is the reason for turning on the kymograph in the spirometer?

A

to start the recording of the trace

120
Q

what is the reason for the subject breathing normally for at least three full breaths into the spirometer?

A

to record resting breathing rate

121
Q

what is the reason for the drum moving up and down in the spirometer?

A

it moves up as the subject breathes out and down as they breathe in

122
Q

what are the steps for using a spirometer?

A
  1. calibrate the spirometer, the details vary from machine to machine but you need to know how to measure a litre and a minute on the trace
  2. fill the drum with fresh air
  3. subject should be in good health
  4. subject wears a nose clip
  5. subject breathes normally into the machine through the mouthpiece
  6. use a sterile mouthpiece
  7. the subjects exhaled air passes through a canister of soda lime
  8. turn on the kymograph
  9. subject breathes normally for at least three full breaths
  10. the drum will move up and down

OCR A level Biology (4 decks)

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