gas exchange Flashcards
how does an organisms size relate to their surface area to volume ratio?
- the larger the organism, the lower the surface area to volume area .
how does an organisms surface area to volume ratio relate to their metabolic rate ?
- the smaller the surface area to volume ratio, the higher the metabolic rate .
how might a large organism adapt to compensate for its small surface area to vol ratio ?
- changes that increase surface area (folding, body parts become larger - elephant ears) developing a specialised gas exchange surface .
why do multicellular organisms require specialised gas exchange surfaces ?
- 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
explain the adaptions to control body temp.
- 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
name 3 features of an efficient gas exchange surface .
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 .
why can’t insects use their bodies as an exchange surface ?
- they have waterproof chitin exoskeleton and small surface area to vol ratio in order to conserve water
name and describe the 3 main desires of an insects gas transport system
- 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
explain the process of gas exchange in insects .
- 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 .
why can’t fish use their bodies as an exchange surface?
- they have waterproof , impermeable outer membrane + a small surface area to vol ratio.
name and describe the two main features of a fish’s gas transport system.
- 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)
explain the process of gas exchange in fish.
- 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.
how does the countercurrent exchange system maximise oxygen absorbed by the fish?
- 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
name and describe 3 adaptations of a lead that allow efficient gas exchange .
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.
how do plants limit their water loss while still allowing gases to be exchanged ?
- 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 )
how are xerophytes adapted to prevent excess water loss?
- 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 .
describe the pathway taken by air as it enters mammalian gaseous exchange system.
- nasal cavity —> trachea —> bronchi —> bronchioles —> alveoli
describe the function of the nasal cavity in mammalian gaseous exchange system.
- good blood supply warms + moistens air entering lungs.
- goblet cells in membrane secrete mucus
describe the trachea and its function in the mammalian gaseous exchange system .
- 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
describe the brochi + their function in mammalian gaseous exchange system .
- 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 .
describe the bronchioles and their function in mammalian gaseous exchange system .
- 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
describe the alveoli and their function in mammalian gaseous exchange system .
- 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.
describe the gas exchange process in respiratory system .
- 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 .
define what’s meant by pleural membrane .
- 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
explain the process of inspiration and the changes that occur through the thorax .
- 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 .
explain the process of expiration and the changes that occur throughout the thorax.
- 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.
what are the adaptations of the alveoli .
- 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
to get firm inside of alveolus into bloodstream, an oxygen molecule has to pass through WHAT 3 cells?
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 .
describe what’s meant by a spirometer
- 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
what is tidal volume ?
- the volume of air we breathe in and out during each breath at rest
what’s forced vital capacity ?
- the max volume of air a person can expel from the lungs after a max inhalation
what is breathing rate ?
- the number of breaths we take per minute
how do you calculate pulmonary ventilation rate ?
- tidal volume x breathing rate.
- can be measured using spirometer, - records volume changes onto graph as person breathes .
what’s the diff between oxygen consumption and forced expiratory volume?
- oxygen consumption - the volume of oxygen used by the body .
- forced - the max volume of air breathed out in one sec .
how do lung diseases occur ?
- 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 .
how does tuberculosis occur ?
- 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
describe how fibrosis occurs ?
- 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
describe how asthma occurs .
- 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
