3.3.2 gas exchange Flashcards
why do fish need a specialised gas exchange system
multicellular - they have a small SA:V, large diffusion distance and an impermeable surface.
they can not exchange gases across their surface
structure of a fish gas exchange system
gills - many gill filaments and lamellae providing a large surface area
gills - constant blood supply to maintain steep diffusion gradients
lamellae - thin walls providing a short diffusion distance
countercurrent flow principle
blood and water flow over the lamellae in opposite directions.
blood flows next to water with a greater concentration of oxygen, maximising diffusion of oxygen from water to the blood.
maintaining a concentration gradient
how do fish exchange gases
water flows in through the mouth.
water passes over the gills and lamellae.
oxygen diffuses from the water to the blood via countercurrent flow, maintaining a steep concentration gradient.
CO2 will diffuse into the water and flow out of the fish
why do insects need a specialised gas exchange system
multicellular - small SA:V, large diffusion distance , impermeable barrier
how do insects exchange gases
air moves into the tracheae through pores called spiracles.
oxygen travels down the concentration gradient towards the tracheoles.
the tracheoles branch through the body transporting oxygen to the cells.
carbon dioxide diffuses down the concentration gradient out of the cell into the tracheoles.
contraction of muscles in the trachea allow for movement of gases
air is carried to the spiracles via the trachea and released from the body.
structure and adaptation of the insect gas exchange system
trachea - many trachea to increase surface area
tracheoles - connected directly to tissues to reduce diffusion distance, highly branched to increase surface area,.
spiracles - open and close to control gas exchange and water loss
how do plants limit water loss
waterproof waxy cuticle
guard cells which close the stomata
xerophyte adaptations
thick waxy cuticle - reduces evaporation
folded leaves - encloses the stomata reducing evaporation
hairs on leaves - trap air around the stomata reducing diffusion
sunken stomata - reduce evaporation and air flow
structure of a leaf
upper epidermis with waxy cuticle - reduces water loss
air spaces - allow for gas exchange
mesophyll cells - large surface are for gas exchange
stomata - where gases enter and leave
guard cells - close and open the stomata to minimise water loss
what is the function of the lungs
site of gas exchange in mammals
allow oxygen to get into the blood for respiration
order of structures in the body needed for gas exchange
nose - trachea - bronchus - bronchioles - alveoli
structure of the trachea and bronchi
rings of cartilage which keeps airway open
lined with ciliated epithelial cells and goblet cells which produce mucus and push it up out of the lungs
structure of bronchioles
no cartilage allowing them to change shape
smooth muscle to contract and relax
how are alveoli adapted for gas exchange
1 cell thick - short diffusion distance
large surface area - increases rate of gas exchange
elastic tissue - allow the walls to stretch and recoil when breathing
constant blood flow - maintains a steep concentration gradient of oxygen and carbon dioxide
