Gas exchange Flashcards
example - volume increases a lot more than surface area
surface = 6 ( 10 x 10 ) = 600 um2
volume = 10 x 10 x 10 = 1000 um3
surface area / volume = 600 / 1000 = 0.6
what is Fick’s law ?
surface area and conc gradient is directly proportional
thickness of membrane is inversely proportional
explain the key features to allow gas exchange in the alveoli to occur quickly and efficiently
- large surface area - faster diffusion
- one cell thick - shorter pathway
- large network of capillaries - shorter diffusion distance
- moist lining - gases to dissolves
function of stomata
- oxygen diffuses out of the stomata
- carbon dioxide diffuses in through the stomata
- to reduce water loss by evaporation stomata close at night when photosynthesis occurs
guard cells
when turgid their curved shape means the stomata opens and when they lose turgor and straighten the pores close - allows leaf to maximize gas exchange in the ight when photosynthesizing and limit water loss
do fish have a large or small surface area to volume ratio ?
small surface area to volume ration as there bodies are not adequate to supply and remove the respiratory gasses therefore they have a specialized gas exchange surface - gills
gill filaments
fingerlike projections through which gases enter and leave the blood system - used for respiration and they are stacked up in a pile
gill lamellae
at right angle to gill filaments which increase the surface area of the gills
gas exchange in gills
they have thin walls - large surface area
capillaries have only one cell thick and carry blood with large number of red cells
what is it called when water and blood water in opposite directions ?
countercurrent flow
Why does the opposite flow of blood and oxygen maintain a concentration gradient?
Blood that is well loaded with oxygen meets water
Water has a maximum concentration of oxygen
Therefore diffusion of oxygen from water into the blood takes place along a concentration gradient
Blood with little oxygen meets water which has the most but not all oxygen removed
Again diffusion of oxygen from water to blood takes place
Therefore diffusion concentration of oxygen is maintained across the entire width of the gill lamellae
Explain how the relationship between the direction of flow of the water and of the blood is useful to the fish
as there is a countercurrent flow which maintains the concentration gradient across the whole gill so MORE oxygen will enter the blood so there is MORE aerobic respiration
Explain how the gills of a fish are adapted for efficient gas exchange?
Gills have lamellae which increase surface area for increased diffusion of oxygen
Thin epithelium walls which decreases diffusion distance into capillaries which increases the rate of diffusion
Water and blood flow in opposite directions which maintains a concentration gradient as blood always has a lower oxygen concentration
Circulation of blood by capillaries replaces saturated blood with oxygen
Concentration of oxygen is higher in the surface waters than it is in water close to the seabed. Explain Why?
As there is mixing of air and water on the surface water and air has a higher concentration of oxygen than water so oxygen diffuses into water
Plants/seaweed near surface photosynthesize which produces oxygen
counter current exchange principle
- when water flows over the gills in the opposite direction to the flow of blood in the capillaries
- counter current flow ensures that equilibrium is not reached -> this ensures that a diffusion gradient is maintained across the entire length of the gill lamellae
