Gas Exchange Flashcards
Purpose of gas exchange
- take in oxygen and nutrients
- remove waste products e.g. CO2
- heat loss / retain heat
Factors to have a good gas exchange
- large SA to V ratio
- a constant concentration gradient
- short diffusion pathway
- rich blood supply
- moist
- warm temperature
Structure of tracheal system in insects
- spiracles
- tracheae
- tracheoles
Functions of structure of tracheal system
- spiracles= open / closes to allow O2 and CO2 in or out of insects, close to prevent excess water loss
- tracheae = have rings around to strengthen it, enable gas transport smoothly
- tracheoles = extend through out all tissues to respiratory cells to deliver O2 to them and get waste CO2 out from cells
How do insects prevent water loss ? (3)
- have small SA exposed to outside air
- have waterproof exoskeleton
- spiracles open and closes to reduce excess water loss
Main Adaptations of insects gas exchange (3)
- tracheoles are highly branched = gives large SA for exchange
- walls of tracheoles are very thin = gives short diffusion pathway = faster diffusion rate
- spiracles open and closes = allow exchange of oxygen and CO2 efficiently = close to prevent excess water loss
Fish’s gas exchange structure
- stacks of gill filaments made up the whole gill
- gill lamellae lined right angle to the gill filament
- gill rackers
Functions of gill lamellae
- increase SA = maximum O2 can be intake
- maintain large SA to V ratio
- have thin walls and capillary provide rich blood supply = increase rate of diffusion
Describe counter current system in fish (3)
- when water flows over the gills in opposite direction to the flow of blood in capillaries in lamellae
- ensues equilibrium is not reached
- ensures a diffusion gradient is maintained across the entire length of gill lamellae
Features of xerophytic plants to reduce water loss
- sunken stomata
- curled leaves = reduce SA for evaporation
- waxy,waterproof thicker cuticles = prevent excess evaporation
- layer of hair on epidermis = trap moisture
- reduced number of stomata
- longer root hair network to reach more water = larger SA for reaching water
How does stomata reduce water loss
- sunken in pits to trap moist air, reduce concentration gradient between the leaf and the air
- less diffusion takes place
- turns turgid when water goes into the plants= stomata opens
- flaccid when water losing = stomata closes to prevent more water leaving
What do curled leaves do in plants ?
Keeps stomata inside = traps humid air and reduce exposed surface area
= protect them from wind as wind increase rate of diffusion and evaporation
How does the hair help reduce water loss in plants ?
- surface traps water, increase humidity of the plant = reduce conc. gradient for water evaporation
Why do mammals have lungs ?
- it has small SA:V ratio = need to have enough O2 to nourish all body cells
- in order to maintain constant body temperature
Why is lungs exist inside mammals’ body ?
- enable lungs to have constant moist condition to enable quicker diffusion rate
- so organs would not dry out de to loss of water
- air is not dense enough to support structure of gas exchange system = so needed bones inside body to protect
Structure to function of trachea
- supported by rings of cartilage = prevents trachea from collapsing as pulmonary pressure falls when inhaling = flexible airway
- made of ciliated epithelium cell = protects lungs from foreign particles and pathogens
Structure to function of alveoli
- have collagen and elastic fibres between alveoli = allows to stretch as they fill up with air when breath in and spring back to expel CO2 out
What happens during inspiration ?
- external I.M contracts + internal I.M relax
- causes rib cage to move upwards and outwards, diaphragm contract to flattens/ downwards
- leads to increase volume = decrease pulmonary pressure
- when pulmonary pressure is lower than atmospheric pressure= air is forced into the lungs following the pressure gradient
What happens during expiration ?
- internal I.M contract + external I.M relax
- causes rib cage move downwards and inwards, diaphragm relax to move upwards
- leads to volume of thorax decrease= pulmonary pressure increases
- when pulmonary pressure is greater than atmospheric pressure = air is forced out as following pressure gradient
Equation of measuring lung efficiency
Pulmonary ventilation (dm3/min-1) = tidal volume (dm3) x ventilation rate (min-1)
= Total amount of air move into the lungs in 1 minute
Tidal volume = Volume of air taken in one breath
Ventilation rate = number of breaths taken in 1 minute
What is the role of pleural membrane ?
- help lungs to be constantly moist = increase diffusion rate
- provides a layer to prevent lung dry out
Adaptations of lungs for efficient gas exchange (5)
1) alveoli continuously ventilated, always with air of higher conc of O2 = maintaining a steep conc grad of O2
2) large SA provided by alveoli = lots of gas exchange surface
3) short diffusion pathway = single layer of flattened cells of capillary endothelium and alveoli’s epithelium
4) each alveolus is right next to a capillary = shorter diffusion pathway = faster diffusion rate
5) continuous circulatory of blood = blood with higher conc of O2 constantly replace with blood of lower conc of O2 = always maintain a conc grad of O2
Adaptations of alveoli for gas exchange
- short diffusion pathway = (0.04-0.3 micrometre )one cell think walls of capillary and alveolar epithelium
- red blood cells are flattened against capillary walls = shorten distance for quicker diffusion
- steep conc. grad = constant ventilation + circulation of blood by action of heart = allow oxygen be used constantly for erotic respiration and CO2 made in reverse product
- red blood cells are slowed down when passing through capillary = allow more time for diffusion
How thick are capillary and alveolar epithelium ? (Numbers )
Thickness of Capillary = 0.04-0.2 micrometer
Diameter of capillary = 10 micrometer
Alveolar = 0.05-0.3 micrometer
