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a-level biology > 7 - Exchange Surfaces And Breathing 🫁 > Flashcards

7 - Exchange Surfaces And Breathing 🫁 Flashcards

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AP® Biology flashcards
1
Q

What do organisms need to exchange?

A

water, minerals, oxygen, fats, proteins, glucose

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2
Q

How do Amoeba obtain substances required to survive?

A

diffusion across membrane

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3
Q

How do multicellular organisms ensure sufficient materials to survive?

A

transport systems

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4
Q

What are the 2 main reasons why diffusion alone is enough to supply the needs of single-celled organisms?

A
  • large SA:V ratio
  • metabolic activity is low, so resource demands are low too
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5
Q

Specialised Exchange Surface

List the 4

A

increased SA, good blood supply, thin layers, ventilation to maintain diffusion gradient

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6
Q

Specialised Exchange Surface

How does increased SA help exchange?

A

provides the area for exchange and overcomes limitations of SA:V

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7
Q

Specialised Exchange Surface

How do thin layers help?

A

decreases diffusion pathway

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8
Q

Specialised Exchange Surface

How does good blood supply help?

A

The steeper the conc gradient, the faster diffusion takes place. So having a good blood supply keeps substances constantly moving

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9
Q

Specialised Exchange Surface

How does ventilation to maintain diffusion gradient help?

A

maintains gradient and makes the process more efficient

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10
Q

What is the formula for percentage yield?

A

actual yield / theoretical yield X100

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11
Q

What is the formula for surface area of a cuboid?

A

2(bh+bl+hl)

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12
Q

What is the formula for volume of a cuboid?

A

hbl

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13
Q

When can organisms use simple diffusion to exchange gases?

A

When the diffusion pathway is less than 1mm

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14
Q

What is Fick’s Law?

A

SA x conc gradient / thickness of membrane

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15
Q

What else affects diffusion that isn’t in Fick’s Law?

A

moisture

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16
Q

What is a peak flow meter?

A

A simple device that measures the rate at which air can be expelled from the lungs

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17
Q

What are vitalographs?

A

More sophisticated versions of peak flow meters

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18
Q

How does a vitalograph work?

A

Patient being tested breathes out as quickly as possible through a mouthpiece, and the instrument reproduces a graph of the amount of air they breath out and how fast

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19
Q

What is a spirometer?

A

A device that detects changes in ventilation and presents the data on a digital display

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20
Q

Why is a nose clip used in spirometry?

A

To stop the patient from exchanging air not in the tank

  • this would make the experiment invalid
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21
Q

What is the purpose of a soda lime canister in spirometry?

A

To absorb the CO2 so it isn’t breathed in

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22
Q

In inspiration, what happens to the graph line in spirometry?

A
  • air chamber decreases in volume
  • graph line goes down
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23
Q

In expiration, what happens to the graph line in spirometry?

A
  • air chamber increases in volume
  • graph line goes up
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24
Q

What is vital capacity?

A

The maximum volume of air that can be breathed in and out in 1 breath

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25
Q

What is tidal volume?

A

The volume of air breathed in and out at rest (normal breathing)

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26
Q

What is the breathing rate?

A

The number of breaths take in 1 minute

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27
Q

What is oxygen uptake?

A

The volume of oxygen used up by someone in a given time

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28
Q

How do you calculate pulmonary ventilation?

A

Tidal volume (dm3) X ventilation rate (min-1)

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29
Q

What is the residual volume?

A

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

  • this can not be measured directly
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30
Q

What is inspiration reserve volume?

A

The maximum volume of air you can great in over and above a normal inhalation

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31
Q

What is expiratory reserve volume?

A

The extra amount of aid you can force out of your lungs over and give the normal tidal volume

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32
Q

How do you calculate total lung capacity?

A

Vital capacity + residual volume

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33
Q

What are some control variables when testing lung capacity using a spirometer?

A
  • height
  • gender
  • medical history
  • location eg. higher altitudes
  • lifestyle eg. smoker/obese
  • oftenest of exercise
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34
Q

Why do insects have high oxygen requirements?

A

They are active, so have a high metabolic demand

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35
Q

Why do insects have exoskeletons with a waxy coating?

A

Acts as a support structure and protection as it is made from chitin

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36
Q

Why can’t gas exchange happen across the exoskeleton in insects?

A

It is impermeable to gases

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37
Q

What is the system in insects used to deliver oxygen directly to tissues?

A

Tracheal system

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38
Q

Gas exchange in insects

What are spiracles?

A

An opening in the exoskeleton of insects to allow air to enter and flow into the tracheae

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39
Q

Gas exchange in insects

What is also lost through spiracles and how is this adapted?

A

Water - spiracles can be opened or closed by sphincters

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40
Q

Gas exchange in insects

What do spiracles have around them and how does this help?

A

Have hairs around them to prevent and trap water vapour

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41
Q

Gas exchange in insects

What are trachea?

A

Largest airways in the system (diameter up to 1mm) leading from spiracles to tracheoles

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42
Q

Gas exchange in insects

What are trachea tubes lined with?

A

Spirals of chitin, which keep them open if they are bent or pressed

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43
Q

Gas exchange in insects

What are tracheoles?

A

Single, elongated cells with no chitin lining so they are freely permeable to gases

44
Q

Gas exchange in insects

How do tracheoles allow most gas exchange to take place?

A

As they are very small in size (0.6-0.8um) so can run between cells

45
Q

Gas exchange in insects

In most insects, air moves along the tracheae and tracheoles by…

A

diffusion alone

46
Q

Gas exchange in insects

How do insects increase their SA:V to ensure diffusion?

A

By having many small tracheoles

47
Q

Gas exchange in insects

What is at the end of tracheoles?

A

Tracheal fluid, which limits the penetration of air for diffusion

48
Q

Gas exchange in insects

What happens to tracheal fluid when oxygen demands build up (eg. when the insect is flying)?

A

A lactic acid builds up in the tissues, resulting in water moving out of the tracheoles by osmosis, exposing more SA for gas exchange

49
Q

Gas exchange in insects

How do collapsible enlarged tracheae of air sacs help increase level of gas exchange?

A

Act as air reservoirs, increasing amount of air moved through the gas exchange system

50
Q

Gas exchange in insects

How does mechanical ventilation of the tracheal system help increase gas exchange?

A

Air is actively pumped into the system by muscular pumping movements of the thorax/abdomen

These movements change the volume of the body, changing pressure, drawing air in or forcing it out

51
Q

Gas exchange in insects

At rest, what happens to tracheal fluid?

A

Seeps into tracheoles, decreasing SA as fluid is in the way

52
Q

Why do fish need an exchange system to cope with breathing in water?

A
  • water is 1000x denser than air
  • 100x more viscous
  • lower oxygen content
53
Q

Gas exchange in bony fish

What is the operculum?

A

A moveable gill cover that is reinforced with rays of bones and encloses the fill within an operculum cavity

54
Q

Gas exchange in bony fish

What is the gill arch?

A

Resembles a backbone for the gills

55
Q

Gas exchange in bony fish

What is attached to each gill arch?

A

Two stacks of filaments (stack is a plate)

56
Q

Gas exchange in bony fish

What is on the surface of each filament?

A

Many lamellae perpendicular to filaments, consisting on single layer of flattened cells

57
Q

Gas exchange in bony fish

Why are gills good for gas exchange in fish?

A
  • large SA
  • good blood supply
  • thin layers = short diffusion pathway
58
Q

Gas exchange in bony fish

What do fish need to ensure to allow efficient gas exchange at all times?

A

To maintain a continuous flow of water over the gills, even when they’re not moving

59
Q

Gas exchange in bony fish

How do fish keep water flowing over gills when they are swimming?

A

By simply opening their mouth and operculum

60
Q

Gas exchange in bony fish

What is the counter-current system?

A

The capillary system within the lamellae ensures that the blood flow is in the opposite direction to water flow

61
Q

Gas exchange in bony fish

Why do fish have counter-current mechanisms?

A

To maintain a conc gradient for maximum diffusion

62
Q

Gas exchange in bony fish

How is a counter-current system achieved?

A

The water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood

63
Q

Gas exchange in bony fish

Why don’t fish use parallel exchange systems?

A

Fails to provide a persistent oxygen concentration gradient, so equilibrium is reached and no further gas is exchanged

64
Q

Gas exchange in bony fish

How is ventilation achieved then?

A

Volume changes in the buccal cavity and opercular cavity creates pressures that are responsible for providing an almost continuous flow of water

65
Q

Gas exchange in bony fish

How does the tips of gill filaments overlapping help gas exchange?

A

Increases resistance to the flow of water over the gill surfaces, and slows down the movement of water so there is more time for gas exchange

66
Q

Gas exchange in bony fish

How does inspiration happen in a fish?

A
  • muscle contraction lowers the floor of the pharynx
  • volume of buccal cavity increases
  • this decreases pressure
  • water enters the mouth as pressure outside fish is higher than inside mouth
  • operculum bulges outwards
  • this lowers pressure
  • opercular valves are closed
  • pressure decreases in cavities
  • causing water to flow into opercular cavity
67
Q

Gas exchange in bony fish

How does expiration happen in fish?

A
  • buccal cavity contracts
  • floor of pharynx is raised, closing mouth
  • pressure increases, forcing water through gill slits
  • water moves across gills = pressure rises
  • also opercular cavities contract
  • pressure increases
  • causing opercular calved to open and water to be expelled
68
Q

Gas exchange in bony fish

What is ram ventilation?

A

Fish swim with their mouths partly open to force water to flow over gill vents continuously

Eg. Mackerel, sharks

69
Q

Mammalian gas exchange

What is ventilation?

A

A term used to describe air moving in and out of the lungs due to pressure changes in the thorax

70
Q

Mammalian gas exchange

Define the thorax

A

The chest cavity

71
Q

Mammalian gas exchange

What does the rib cage provide?

A

A semi-rigid case within which pressure can be lowered

72
Q

Mammalian gas exchange

What is the diaphragm?

A

A broad, domed sheet of muscle, forming the floor of the thorax

73
Q

Mammalian gas exchange

Where are the intercostal muscles found?

A

Between the ribs

74
Q

Mammalian gas exchange

What lines the thorax?

A

Pleural membranes, which surround the lungs

75
Q

Mammalian gas exchange

The spaces between pleural membranes, the pleural cavity, is filled with what?

A

A thin layer of lubricating fluid so the membranes can easily slide over each other during breathing

76
Q

Mammalian gas exchange

What happens when the pressure in the chest is less than the atmospheric pressure?

A

Inspiration (active)

77
Q

Mammalian gas exchange

What causes expiration (passive)?

A

When the pressure in the chest is greater than the atmospheric pressure

78
Q

Mammalian gas exchange

What is the process of inspiration?

A
  • diaphragm contracts
  • diaphragm flattens & lowers
  • external intercostal muscles contract
  • internal intercostal muscles relax
  • causing ribs to up and out
  • volume of thoracic cavity increases
  • so pressure in thorax is reduced
  • drawing air in, increasing lung volume
79
Q

Mammalian gas exchange

What is the process of expiration?

A
  • diaphragm muscles relax
  • diaphragm moves up and domed
  • volume of thoracic cavity decreases
  • external intercostal muscles relax
  • internal intercostal muscles contract (forced expiration)
  • ribs move down and inwards
  • elastic fibres in alveoli recoil
  • pressure inside thorax is greater than outside, so air moves out
80
Q

Mammalian gas exchange

What happens in forced exhalation?

A
  • intercostal muscles contract
  • this pulls ribs down fast and hard
  • abdominal muscles contract, forcing diaphragm up to increase pressure in lungs rapidly
81
Q

Mammalian gas exchange

Why do athletes train at altitudes?

A

To increase EPO = the hormone producing red blood cells

82
Q

What happens to smooth muscle and the bronchioles in an asthma attack?

A
  • cells lining bronchioles release histamines
  • stimulates goblet cells to make more muscle
  • smooth muscle in bronchiole walls contracts
  • causes bronchi to constrict
  • can’t breathe
83
Q

Mammalian gas exchange

What is the structure of the lungs?

A

Right lung has 3 lobes and left lung has 2 lobes (due to heart)

84
Q

Mammalian gas exchange

Order of structures in gas exchange

A

Nasal cavity
Pharynx (cavity at back of throat)
Larynx
Trachea
Bronchi
Bronchioles
Alveoli

85
Q

Mammalian gas exchange

What features does the nasal cavity have?

A
  • large SA with a good blood supply
  • goblet cells and hairy lining
  • moist surfaces
86
Q

Mammalian gas exchange

What does the nasal cavity do?

A
  • blood supply warms the air
  • mucus traps particulates
  • humidifies air to protect more delicate structures in lungs
87
Q

Mammalian gas exchange

What does the trachea do?

A

A wide tube that carries clean, warm, moist air from the nose down into the chest

88
Q

Mammalian gas exchange

What stops the trachea from collapsing?

A

Has incomplete rings of cartilage and smooth muscle that divides into the 2 primary bronchi at mid-thorax

89
Q

Mammalian gas exchange

Why is the cartilage in the trachea C-shaped?

A

So that food can easily pass down the oesophagus, which is behind the trachea

90
Q

Mammalian gas exchange

Why is the trachea lined with ciliated epithelium?

A

As a source of goblet cells, to secrete mucus onto the lining of the trachea, to trap microorganism and be wafted by cilia to throat to be swallowed

91
Q

Mammalian gas exchange

What is the effects of cigarettes on cilia?

A

Stops them beating

92
Q

Mammalian gas exchange

What adaptations do bronchi have?

A
  • cartilage and smooth muscle
  • lined with ciliated epithelium cells and goblet cells
93
Q

Mammalian gas exchange

What does each bronchus divide into?

A

Secondary, then tertiary bronchi then bronchioles

94
Q

Mammalian gas exchange

What don’t bronchioles have?

A

No cartilage rings

95
Q

Mammalian gas exchange

What does smooth muscle in bronchiole walls do?

A

Smooth muscle contracts, causing bronchioles to constrict

Smooth muscle relaxes, causing bronchioles to dilaye

96
Q

Mammalian gas exchange

What are bronchioles lined with?

A

A thin layer of squamous epithelium for a short diffusion pathway

97
Q

Mammalian gas exchange

The smallest bronchioles don’t have smooth muscle. What do they have instead?

A

Elastic fibres

98
Q

Mammalian gas exchange

What occurs at the alveoli?

A

Exchange of O2 and CO2 by diffusion

99
Q

Mammalian gas exchange

What does each alveolus consist of?

A

A layer of thin squamous epithelium, collagen, elastic fibres

100
Q

Mammalian gas exchange

How do elastic fibres in alveoli help their function?

A

Allows alveoli to stretch as air is drawn in, and recoil when air is exhaled

101
Q

Mammalian gas exchange

How big are alveoli?

A

200-300um

102
Q

Mammalian gas exchange

Why are there so many alveoli?

A

To create a large SA:V for diffusion

103
Q

Mammalian gas exchange

Why are alveoli made of squamous epithelium?

A

To provide a thin layer = short diffusion pathway

104
Q

Mammalian gas exchange

Why do alveoli have good blood supply from many capillaries?

A

To maintain a conc gradient for diffusion

105
Q

Mammalian gas exchange

What makes alveoli moist?

A

A lung surfactant, allowing the lungs to remain inflated and for oxygen to dissolve in the water before diffusion

106
Q

Mammalian gas exchange

Alveoli

What are type 1 pneumocytes?

A
  • Line alveoli
  • are squamous
  • can’t replicate
  • 95% are type 1
107
Q

Mammalian gas exchange

Alveoli

What are type 2 pneumocytes?

A
  • 5% of cells
  • secrete surfactant which reduces surface tension and helps gases dissolve

a-level biology (23 decks)

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