Gaseous Exchange Flashcards
What is the diffusion equation?
Diffusion is proportional to (SA X [difference]) divided by length of diffusion pathway
Describe the gaseous exchange system in insects
Tracheal system- many tubes that branch to dead ended tracheoles
Diffusion occurs down conc gradient, conc gradient maintained by respiring cells using oxygen (CO2 gradient opposite)
They can contract muscles to push air through
Anerobic respiration produces lactate which lowers the osmotic potential meaning water moves into cells, decreases volume hence brings in more air
Trachea have spiracles that can open or close
Why can insects with their tracheal system not get to a large size?
The trachea have to get to every respiring tissue, in a large organism this would be impossible
Describe the structure of the fishes gills
Gills made up of many gill filaments so high SA:V
Gill lamalle perpendicular to the filaments
Describe the counter current principle in fish gills
Blood and oxygen flow in opposite directions
Blood with high [O2] meets water with high [O2] so diffusion occurs
Blood with low [O2] meets water with low [O2] so diffusion occurs
This way exchange occurs across the whole surface, because the gradient is maintained
Give three adaptations of a plant leaf cell for gaseous exchange
Large SA:v of mesophyll cells
Has stomata surrounded by guard cells, open and close to prevent water loss
Lots of open air in the leaf so more contact with O2
Describe adaptations of a xerophyte
Thick waxy cuticle
Leaf inward rolling, covers stomata which traps air
Hairy leaves to trap air
Describe the ultrastructure of the respiratory system
Trachea - airway supported by cartilage which divides into two bronchi one for each lung which produce mucus
Further subdivide into bronchioles which have muscle to contract,
These lead to alveoli,
Describe the adaptations of the alveoli
Many of them so v large SA:V
Thin epithelial cells - short pathway
Large number of capillaries - maintain gradient
Capillaries are thin which slows blood movement meaning greater time for diffusion
Constant ventilation keeps gradient also
What happens in inspiration
External intercostal muscles contract (internal relax)
Ribs pulled upwards and outwards = increased volume
Diaphragm muscles contract (moves up) increases volume
Increased volume = reduced pressure
Atmospheric pressure greater than pulmonary pressure so air moves in
Describe what happens in expiration
Internal intercostal muscles contract (external relax)
Diaphragm rleaxes
Both decrease volume hence increase pressure
Atmospheric pressure lower than pumanory so air moves out
Define with an equation the pulmonary ventilation rate
Tidal volume (air in per breath) X ventilation rate (breaths taken in per minute) = pulmonary ventilation rate ( air taken in per minute)
