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BIOLOGY > gas exchange > Flashcards

gas exchange Flashcards

1
Q

how does an organisms size relate to their surface area to volume ratio?

A
  • the larger the organism, the lower the surface area to volume area .
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2
Q

how does an organisms surface area to volume ratio relate to their metabolic rate ?

A
  • the smaller the surface area to volume ratio, the higher the metabolic rate .
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3
Q

how might a large organism adapt to compensate for its small surface area to vol ratio ?

A
  • changes that increase surface area (folding, body parts become larger - elephant ears) developing a specialised gas exchange surface .
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4
Q

why do multicellular organisms require specialised gas exchange surfaces ?

A
  • their smaller surface area to volume ratio means distance that needs to be crossed is larger + substances cannot easily enter cells in single - cells organisms
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5
Q

explain the adaptions to control body temp.

A
  • animals with smaller SA to vol ratio lose less heat than ones more SA : vol . smaller organisms = higher metabolic rates (generate more heat energy - replace heat lost)
  • increased surface area (desert fox) - huge ears stick out to maximise heat loss
  • high SA : vol ratio organism = lose more water by evaporation from body surface (kidney adapted to conserve water )
  • animals live cold climates - thick layers of insulating fat, fur and may hibernate
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6
Q

name 3 features of an efficient gas exchange surface .

A

1) large surface area - provide more space for diffusion of gases .

2) thin/short —> short diffusion pathway across exchange surface .

3) steep conc gradient - maintained by blood supply / ventilation .

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7
Q

why can’t insects use their bodies as an exchange surface ?

A
  • they have waterproof chitin exoskeleton and small surface area to vol ratio in order to conserve water
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8
Q

name and describe the 3 main desires of an insects gas transport system

A
  • spiracles = holes on body’s surface which may be opened / closed by a valve for gas/ water exchange
  • tracheae = large tubes extending through all body tissues, supported by rings to prevent collapse .
  • tracheoles = smaller branches dividing off the tracheae . (speeds up diffusion of gases to cells)

—> rhythmic abdominal movements = push air into + out spiracles + maintains steep conc gradient

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9
Q

explain the process of gas exchange in insects .

A
  • gases move in and out of tracheae through the spiracles
  • a diffusion gradient allows O2 to diffuse into the body tissue while water CO2 diffuses out.
  • contraction of muscles in tracheae allows mass movements of air in + out .
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10
Q

why can’t fish use their bodies as an exchange surface?

A
  • they have waterproof , impermeable outer membrane + a small surface area to vol ratio.
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11
Q

name and describe the two main features of a fish’s gas transport system.

A
  • gills = located within body = supported by arches, along which are multiple projections of gill filaments (stacked up in piles)
  • lamellae = thin wall (reduce diffusion distance ) —> at right angles to gill filaments , give an increased surface area. blood + water flow across them in opposite directions (countercurrent exchange system)
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12
Q

explain the process of gas exchange in fish.

A
  • the fish open its mouth to enable water to flow in, then closes mouth to increase pressure
  • water passes over the lamellae, + O2 diffuses into bloodstream
  • waste CO2 diffuses into water and flows badk out of gills.
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13
Q

how does the countercurrent exchange system maximise oxygen absorbed by the fish?

A
  • maintains a steep conc gradient , as water always next to blood of lower oxygen conc . keeps rate diffusion constant along whole length of gill = enable 80% O2 absorbed
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14
Q

name and describe 3 adaptations of a lead that allow efficient gas exchange .

A

1) thin + flat = provide short diffusion pathway + larger surface area to vol ratio

2) many minute pores in underside of lead (stomata) allows gases to easily enter

3) air spaces in mesophyll allow gases move around leaf , facilitating photosynthesis.

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15
Q

how do plants limit their water loss while still allowing gases to be exchanged ?

A
  • stomata regulated by guard cells which allows them to open + close as needed .
  • most stay closed to prevent water loss while some open to let oxygen in
  • guard cells = control opening/closing of stomata prevent excess transpiration.
  • air spaces in spongy mesophyll layer allows gases to circulate (O2 + CO2 diffuse from air spaces into plant cells )
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16
Q

how are xerophytes adapted to prevent excess water loss?

A
  • sunken stomata = stomata sunken in pits which trap water vapour + reduce water potential gradient between inside + outside of leaf
  • hairs around stomata = hairs trap water vapour + reduce water potential gradient
  • curled leaves = also traps water vapour + reduce gradient
  • fewer stomata = so less sites for loss of water
  • thicker cuticle = acts as barrier to evaporation .
17
Q

describe the pathway taken by air as it enters mammalian gaseous exchange system.

A
  • nasal cavity —> trachea —> bronchi —> bronchioles —> alveoli
18
Q

describe the function of the nasal cavity in mammalian gaseous exchange system.

A
  • good blood supply warms + moistens air entering lungs.
  • goblet cells in membrane secrete mucus
19
Q

describe the trachea and its function in the mammalian gaseous exchange system .

A
  • wide tube supported by C-shaped cartilage to keep air passage open during pressure changes .
  • lined by ciliated epithelium cells which move mucus towards throat to be swallowed —> prevent lung infection
  • carries air to bronchi
20
Q

describe the brochi + their function in mammalian gaseous exchange system .

A
  • like trachea - they supported by rings of cartilage and lined by ciliated epithelium cells
  • but they narrower and there’s 2 of them - one for each lung.
  • allow passage of air into the bronchioles .
21
Q

describe the bronchioles and their function in mammalian gaseous exchange system .

A
  • narrower than bronchi.
  • don’t need to be kept open by cartilage , this mostly have only muscle + elastic fibres so can contract + relax easily during ventilation
  • allow passage of air into alveoli
22
Q

describe the alveoli and their function in mammalian gaseous exchange system .

A
  • mini air sacs , lined with epithelium cells, site of gas exchange.
  • walls only one cell thick , covered with network of capillaries , 300 million in each lung, all of which facilitates gas diffusion.
23
Q

describe the gas exchange process in respiratory system .

A
  • oxygen diffuses from region of high concentration alveoli to region low concentration in bloodstream
  • travels to diff tissues of body and used for respiration
  • CO2 travels in other direction from region high concentration in bloodstream to region low concentration in alveoli .
24
Q

define what’s meant by pleural membrane .

A
  • lungs surrounded by this
  • moist membrane forms airtight seal around lungs
  • ribcage protects organs of a respiratory system + surrounded by intercostal muscles + diaphragm = moves rib cage during breathing to help bring air into or out of lungs
25
Q

explain the process of inspiration and the changes that occur through the thorax .

A
  • external intercostal muscles contact (whilst internal relax) , pulling ribs up and down.
  • diaphragm contracts and flattens
  • volume of the thorax increases
  • air pressure outside of lungs is therefore higher then air pressure inside, so air moves in to rebalance .
26
Q

explain the process of expiration and the changes that occur throughout the thorax.

A
  • external intercostal muscles relax (while internal contract), bringing ribs down and in.
  • diaphragm relaxes and domes upwards
  • vol of thorax decreases
  • air pressure inside lungs is thus higher than air pressure outside, so air moves out to rebalance.
27
Q

what are the adaptations of the alveoli .

A
  • larger surface area = 700 mil alveoli in lungs with combined SA of 70 squared meters
  • good blood supply = lots capillaries during each alveolus .
  • short diffusion distance = walls of both alveoli and capillaries just one cell thick
  • moist surfaces = liquid on surface of alveoli dissolved gases and facilities diffusion
  • steep conc gradient = there’s high conc of O2 and CO2 between alveoli and capillaries . = maintained by blood flow and ventilation
28
Q

to get firm inside of alveolus into bloodstream, an oxygen molecule has to pass through WHAT 3 cells?

A

1) alveolar epithelium = single layer of cells that form the alveolar walls

2) capillary endothelium = single layer of cells that form the capillary walls

3) red blood cells = once inside RBC = oxygen molecule binds to haem group on haemologbin .

29
Q

describe what’s meant by a spirometer

A
  • used to investigate the vol of air that individual is capable of breathing in and out.
  • consists of chamber filled with oxygen and has lid which moves up and down as person breathes
  • attached to a pen - moves whenever lid moved to draw a spirometer trace

trace used to find tidal vol and forced viral capacity

30
Q

what is tidal volume ?

A
  • the volume of air we breathe in and out during each breath at rest
31
Q

what’s forced vital capacity ?

A
  • the max volume of air a person can expel from the lungs after a max inhalation
32
Q

what is breathing rate ?

A
  • the number of breaths we take per minute
33
Q

how do you calculate pulmonary ventilation rate ?

A
  • tidal volume x breathing rate.
  • can be measured using spirometer, - records volume changes onto graph as person breathes .
34
Q

what’s the diff between oxygen consumption and forced expiratory volume?

A
  • oxygen consumption - the volume of oxygen used by the body .
  • forced - the max volume of air breathed out in one sec .
35
Q

how do lung diseases occur ?

A
  • involve impaired gas exchange so less oxygen moves from lungs into bloodstream
  • less oxygen delivered to cells so less energy released by aerobic respiration + patient experiences fatigue .
36
Q

how does tuberculosis occur ?

A
  • caused by infection with mycobacterium tuberculosis bacteria .
  • immune cells build wall around bacteria forming hard lumps called tubercles
  • tissue death damages alveoli and reduces tidal volume .
  • ventilation rate increases to compensate reduced tidal vol
  • symptoms = cough, chest pain, tiredness and shortness of breath
37
Q

describe how fibrosis occurs ?

A
  • formation os scar tissue due to infection or exposure to irritants
  • compared to normal tissue = scar tissue thicker and less elastic .
  • less elasticity reduces tidal vol and forced vitals capacity
  • thicker scar tissue increase diffusion distance - gas exchange less effiecient
  • ventilation rate increases to compensate for reduced tidal vol
    -> cough, chest pair , tiredness and shortness breath
38
Q

describe how asthma occurs .

A
  • inflammation of airways due allergic reaction to pollen/ dust
  • contact moon of smooth muscle in bronchioles constricts airways and reduces amount air breathed out in one sec

-> shortness of breath, wheezing and tight chest

  • drugs delivered by inhalants relive symptoms > stimulate smooth muscle in bronchioles to relax

BIOLOGY (14 decks)

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