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biology - component 3 > adaptations for gas exchange > Flashcards

adaptations for gas exchange Flashcards

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1
Q

define gas exchange

A

process by which oxygen reaches cells and carbon dioxide is removed from them

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2
Q

define gas ventilation

A

the process of moving the respiratory medium (air or water) over the respiratory surface to maintain a concentration gradient, replacing stale area high in CO2 with fresh oxygenated air

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3
Q

define respiration

A

series of chemical reactions that result in the release of energy in the form of ATP

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4
Q

define respiratory pigment

A

a molecule which increases the oxygen-carrying capacity of the blood

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5
Q

define trachea

A

a system of branched chitin lined air tubes in insects

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6
Q

define “ends of tracheoles”

A

site of gas exchange in insects

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7
Q

define spiracles

A

holes in an insect’s exoskeleton which can open and close like valves to allow exchange of gases and reduce water loss

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8
Q

define gill lamellae

A

site of gas exchange in fish

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9
Q

define alveoli

A

site of gas exchange in mammals

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10
Q

define parallel flow

A

gas exchange system where blood in the gill capillaries circulates in the same direction as water flowing over the gills

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11
Q

define “counter-currenter flow”

A

gas exchange system where blood in the gill capillaries circulates in the opposite direction to water flowing over the gills

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12
Q

define operculum

A

bony structure in bony fish that provides a protective covering the gill

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13
Q

what are the two functions of diffusion?

A
  • to supply nutrients
  • to remove waste
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14
Q

what is the relationship between SA:V and size

A

as size increases, SA:V ratio decreases

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15
Q

describe amoeba in terms of gas exchange

A
  • extremely large SA:V ratio
  • gas exchange occurs across whole surface
  • permeable membrane allows diffusion of gases
  • specialised gas exchange organs are not required
  • diffusion is sufficient to meet the oxygen requirements of the organism
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16
Q

describe flatworm in terms of gas exchange

A
  • these organisms have evolved a flattened shape to overcome the problem of an increase in size
  • this increases the SA:V, therefore no cell in the body is far from the surface (short diffusion distance) - so there is no need for specialised gas exchange organs.
  • they exchange gases directly with the environment via diffusion ; diffusion across the permeable membrane is sufficient to meet the oxygen requirements of the organism
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17
Q

what shape do earthworms develop during gas exchange?

A

a tubular shape
restricted to damp environments

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18
Q

what do earthworms secrete and why?

A

they secrete mucus to keep the cells of the body surface moist, which allows gases to dissolve and diffuse

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19
Q

describe gas exchange in earthworms

A
  • elongated shape provides a large SA:V compared with a compact organism of similar volume
  • they exchange gases directly with the environment by diffusion across the moist surface ; blood vessels close to the body surface so gases can diffuse in/out of the blood and then across the cell covering the body surface
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20
Q

describe blood in earthworms (in terms of gas exchange)

A
  • blood circulates in the vessels, this maintains a concentration gradient for diffusion of oxygen into the cells and carbon dioxide out
  • blood contains the respiratory pigment haemoglobin to carry oxygen to body cells
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21
Q

what is meant by a terrestrial organism?

A

an organism that lives on land

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22
Q

what do all respiratory surfaces need to have to achieve the maximum rate of diffusion?

A
  • large surface area
  • short diffusion distance
  • oxygen and carbon dioxide
  • moist - to allow gases to dissolve and diffuse
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23
Q

what additional feature increases the efficiency of gas exchange in organisms which possess a circulatory system and respiratory pigment?

A
  • extensive blood supply and blood circulates to maintain a diffusion gradient
  • respiratory pigment such as haemoglobin increasing the oxygen carrying capacity of blood
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24
Q

the spiracles open and open like valves - why is this important?

A
  • to allow exchange of gases
  • to reduce water loss
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25
Q

what is the gas exchange system for insects?

A

air diffuses into the insect through paired holes called spiracles running along each side of the body
the spiracles lead to a system of branched chitin lined air tubes called trachea

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26
Q

why do many insects have air sacs off the trachea?

A

to aid ventilation of the tracheal system

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27
Q

during periods of activity, how is the trachea ventilated?

A

by the movements of the abdomen

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28
Q

why are the gas exchange retained inside the body of all terrestrial organisms?

A
  • reduces water loss
  • reduces heat loss
  • protection by the diaphragm or exoskeleton in insects
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29
Q

what are the advantages of the insect tracheal system?

A
  • oxygen is supplied directly to issues
  • no respiratory pigment in needed
  • oxygen diffuses faster in air than in blood
  • spiracles close to reduce water loss
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30
Q

what is the disadvantage of the insect tracheal system?

A
  • limits the size of the organism (diffusion distance would be too large)
  • tracheoles are not extensively ventilated and diffusion distance is too big (takes too long for gases to diffuse down the tracheoles)
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31
Q

what is the role of chitin in insects?

A
  • surface of tracheoles is lined with a spiral fold of chitin
  • keeps airways open during body movements, while allowing some flexibility
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32
Q

how does the fluid at the end of the tracheoles help to improve the efficiency of gas exchange?

A

oxygen dissolves in the fluid and when muscles contract, this fluid (with oxygen) is drawn into muscle cells

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33
Q

what problems are caused by living in water?

A
  • water has less oxygen than air
  • the rate of diffusion is slower in water
  • water is a dense medium and so does not flow as freely as air
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34
Q

what two main groups can fish be categorised into and what is this according to?

A
  1. cartilaginous fish
  2. bony fish
    - according to material which makes up their skeleton and also their gill ventilation mechanisms
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35
Q

give an example of cartilaginous fish

A

shark

36
Q

describe cartilaginous fish

A
  • have a skeleton made entirely of cartilage
  • nearly all live in sea water
  • just behind the head on each side are 5 gill clefts which open at gill slits
  • water is taken into the mouth and is forced through the gill slits when the floor of the mouth is raised
37
Q

what is the gill ventilation mechanism in cartliaginous fish?

A

gas exchange involves PARALLEL flow - blood in the gill capillaries circulates in the SAME direction as water flowing over the gills

38
Q

give an example of a bony fish

A

herring

39
Q

describe bony fish

A
  • have an internal skeleton made of bone
  • gills are covered with a flap called the OPERCULUM
40
Q

what is the gill ventilation mechanism in bony fish?

A

gas exchange involved COUNTER-CURRENT flow - blood in the gill capillaries circulates in the OPPOSITE direction as water flowing over the gills

41
Q

distinguish between respiration, ventilation and gas exchange

A

RESPIRATION - reaction producing ATP
VENTILATION - bringing gases into/out of blood and cells
GAS EXCHANGE - bringing gas exchange medium to/from gas exchange surface

42
Q

give 3 features that a gas exchange surface should have to maximise efficiency

A
  • high SA:V
  • thin
  • moist
  • warm
  • concentration gradient maintained
43
Q

describe how your gas exchange surface meets one of these requirements

A

large SA - many alveoli
thin walls - 1 cell thick
moist - lined with water
concentration gradient - ventilation / good blood supply

44
Q

compare insects ventilation during rest and movement

A

REST - no ventilation
MOVEMENT - abdominal pumping

45
Q

why are gas exchange organs required inside the body for terrestrial organisms?

A
  • to reduce heat loss and water loss
  • allows protection by ribs / exoskeleton
46
Q

give 2 ways insects meet the requirements for an efficient exchange surface

A

thin - short distance from tip of tracheoles to muscle
large SA:V - many tracheoles

47
Q

explain the ventilation mechanism when the water flows in

A

mouth - opens
operculum - closed
floor of buccal cavity - lowers
volume - increases
pressure - decreases
directon of water flow - in through the mouth

48
Q

explain the ventilation mechanism when the water flows out

A

mouth - closes
operculum - open
floor of buccal cavity - rises
volume - decreases
pressure - increases
direction of water flow - over the gills and out of the operculum

49
Q

what part of the fish’s head allows a one way current of water?

A

the buccal cavity

50
Q

explain the structure of the gills in bony fish

A
  • along each gill arch there are many thin filaments
  • on the thin filaments there are the gill lamellae
  • the gill filaments have a large surface area for gas exchange
  • blood circulates through the gill lamellae into the capillaries and carbon dioxide diffuses out into the water
51
Q

describe counter-current flow

A
  • blood always meets water with a higher oxygen concentration
  • the gradient for diffusion of oxygen into the blood from the water is maintained over the whole length of the gill lamellae
  • oxygen diffuses into blood across whole length of gill lamellae
  • counter current flow is more efficient than parallel flow as it results in a higher blood oxygen saturation level
52
Q

describe parallel flow

A
  • water is taken into the mouth and blood flows through the gill capillaries in the same direction as the water
  • gas exchange is very efficient at first as there is a very steep concentration gradient
  • however, about halfway along the gill lamellae, equilibrium is reached and diffusion of oxygen and carbon dioxide is no longer possible
53
Q

what are the five classes of vertebrates?

A
  • amphibians
  • reptiles
  • birds
  • fish
  • mammals
54
Q

describe gas exchange in adult amphibians when inactive and active

A

INACTIVE - diffusion across their moist surface
ACTIVE (e.g mating) - lungs

55
Q

describe the lung structure of an amphibian

A

lungs have a simple structure with little folding (giving a small surface area) of the gas exchange tissues

56
Q

what is the gas exchange system in amphibian larvae?

A

the larvae (tadpoles) live in water and have gills for gas exchange

57
Q

Rings of cartilage support the trachea, bronchi and bronchioles. Suggest a reason for this cartilage

A

to prevent the airway from collapsing during inspiration/inhalation when the pressure is low

58
Q

what is the name of the airtight compartment of the body that encloses the lungs?

A

thorax

59
Q

explain what happens during inspiration / inhalation

A
  • intercostal muscles contract
  • rib cage moves up and out
  • diaphragm contracts and flattens
  • pleural membranes go out
  • volume of thorax increases
  • pressure decreases, so air is pushed by external pressure
60
Q

what is the role of goblet cells?

A

produce and secrete mucus to trap microorganisms

61
Q

what is the role of cilia?

A

waft to move the mucus up and out of the trachea

62
Q

what is the effect of emphysema lung tissue?

A

breaks down alveoli air sac walls and drastically reduces gas exchange surface area

63
Q

what is a surfactant?
what is the role of a surfactant?

A

a chemical substance which covers the surface of the alveoli.
reduces surface tension and prevents the alveoli from sticking together and collapsing when breathing out.

64
Q

suggest why the cellular demand for oxygen is higher in a mammal compared to a fish of the same size?

A
  • mammal has higher body temperature than the fish
  • mammal’s metabolic rate is higher
  • more energy required for support in mammals whereas fish are bouyant
65
Q

why are alveoli suitable as a gas exchange surface?

A
  • permeable = oxygen and carbon dioxide are able to diffuse
  • small and many of them = large surface area
  • alveoli, capillary walls are one cell thick = short diffusion distance
  • each alveolus has an extensive capillary network, circulation of blood = maintains concentration gradient
  • moist surfactant = gases dissolve and diffuse easily
66
Q

what is the function of the intercostal muscles?

A

when these contract the ribs are pulled up and out, increasing the volume of the thorax

67
Q

what is the function of the bronchiole?

A

bronchi branch into these smaller tubes

68
Q

what is the function of the larynx?

A

box shaped structure above trachea, contains vocal cords

69
Q

what is the function of the alveoli?

A

main site of gas exchange, have a large surface area

70
Q

what is the function of the bronchi?

A

trachea splits in two of these

71
Q

what is the function of the surfactant?

A

this prevents the alveoli from sticking together and collapsing, it also reduces surface tension

72
Q

what is the function of the trachea?

A

tube held open by ring of C-shaped cartilage

73
Q

what is the function of the ribs?

A

these bones are moved by the intercostal muscles and alter the size of the thorax (chest cavity)

74
Q

what is the function of the diaphragm?

A

this dome shaped muscle relaxes and contacts altering the volume of the thorax

75
Q

explain the pressure during inspiration

A
  • the diaphragm flattens and the rib cage expands pulling on the outer pleural membrane, which lowers the pressure in the pleural cavity
  • the inner pleural membrane pulls on the lungs, which increases the volume of the alveoli
  • this decreases the pressure in the alveoli
  • the pressure in the alveoli is below atmospheric pressure, so air moves in
76
Q

what is the function of the pleural cavity?

A

contains pleural fluid which acts as a lubricant to reduce friction between the lungs and inside wall of thorax during ventilation

77
Q

what is the function of the epiglottis?

A

flap of skin that stops food entering the trachea when swallowing

78
Q

what is the function of the pleural membranes?

A

acts as a lubricant allowing friction-free movement against the inner wall of the thorax

79
Q

what is the role of a respiratory pigment?

A

increases the oxygen carrying capacity of the blood

80
Q

how are the leaves adapted for gas exchange?

A
  • the leaf blade is flat and thin = short diffusion distance
  • the spongy mesophyll layer allows diffusion and circulation of gases which maintains diffusion gradients
  • the stomatal pores open and close to allow gas exchange to occur
  • mesophyll have a partially permeable membrane to allow diffusion of gases
81
Q

how are leaves adapted to reduce water loss?

A
  • waxy cuticle on upper surface reduces water loss (by evaporation) / waterproofs the leaf
  • stomatal pores in lower epidermis reduce water loss by evaporation
  • guard cells can control opening to reduce water loss
82
Q

how are leaves adapted for photosynthesis?

A
  • large surface area to absorb as much light as possible
  • leaves can orientate themselves towards the sunlight
  • leaves are thin to allow light to penetrate layers
  • cuticle and epidermis are transparent to allow light to pass to the mesophyll below
  • palisade cells are elongated and densely packed together and contain many chloroplasts
  • chloroplast can rotate and move to maximise absorption
  • intercellular air spaces allow carbon dioxide to diffuse into the cells
83
Q

STOMATA
- where in the leaf are stomata found?
- what is their role?
- how many guard cells surround each stoma?
- what is unusual about guard cells?

A

STOMATA
- lower epidermis
- open and close to allow gas exchange and reduce water loss
- 2
- they are the only epidermal cells that contain chloroplasts & they have unevenly thickened cell walls

84
Q

describe the mechanism for stomatal opening

A
  • potassium ions are actively transported from the epidermal cells into the guard cells
  • stored starch in the guard cells is converted into malate (soluble) by enzymes in the cytoplasm
  • the water potential in the guard cells is lowered (due to presence of solutes) so water enters by osmosis
  • the guard cells become turgid and curve apart because the outer cell walls are thinner than the inner cell walls
85
Q

why are stomata usually open during the day and closed at night?

A

OPEN DURING THE DAY to allow carbon dioxide to diffuse into the leaf for photosynthesis

CLOSED AT NIGHT to reduce the loss of water

biology - component 3 (8 decks)

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