[Unit 3.2] Gas Exchange Flashcards
Organisms exchange substances with their environment
what are the adaptations of alveoli to be efficient for gas exchange
squamous epithelial cells are flat to increase SA
network of capillaries maintains diffusion gradient
“wall” is one cell thick to reduce diffusion distance
“walls” contain protein called elastin to allow alveoli to return to original shape
they are moist to help gasses dissolve
define inspiration
breathing air in
what is the term for breathing air out
expiration
what happens to the involved muscles during inspiration
external intercostal muscles contract, ribs go up and out
diaphragm contracts going down and flat.
thorax volume increases, air pressure decreases. air rushes in
active process so requires energy
what happens to the involved muscles during expiration
external intercostal muscles relax, ribs go down and in
diaphragm relaxes, curving upwards
thorax volume decreases, air pressure increases. air rushes out.
passive process so doesn’t require energy
what is emphysema
caused by smoking or air pollution
pollution particles trapped in alveoli
inflammation. phagocytes break down elastin. alveoli lose shape
reduces SA
what is asthma
airways inflamed
due to allergic reaction
smooth muscles in bronchioles contract and produce lots of mucus
causes constriction of airways
inhalers bronchiole muscle to relax.
what is fibrosis
scar formation
due to infection of dangerous substances
lungs cant expand as much due to less elasticity
what is ventilation rate
number of breaths per minute
what is tidal volume
volume of air in each breath
how do you calculate pulmonary ventilation rate
ventilation rate x tidal volume
what is forced expiratory volume
maximum volume of air that can be breathed out in 1 second
what is forced vital capacity
maximum volume of air you can breathe out forcefully after a deep breath.
how does gas enter an insect
through spiracles. - to tracheal system
what is in the walls of trachea , and why
chitin, keep tubes rigid.
protects from getting compressed by surrounding tissue
what route does oxygen take from outside insect to cells. for resting insects
spiracle -> tracheae -> tracheoles -> fluid -> cells
state all the adaptations and advantages of an insects breathing system
- tracheoles have thin walls, short diffusion distance
- highly branched. short diffusion distance. larger surface area
- tracheae tubes full of air to maintain conc. gradient
- fluid can move during exercise so faster diffusion
-body can move to circulate air (in&out spiracles). maintains conc. gradient
what is the operculum
bony covering protecting gills, where water leaves after flowing through gills. acts as a lid
what part of the gills does the water flow through
opercular cavity
what is a counter current system
water flows in opposite direction to flow of blood. providing concentration gradient along entire length of gill plates
what would be bad about having a parallel exchange system in a fish’s gills
there is no concentration gradient after a while due to equilibration.
occurs quickly with max saturation of blood reaching only 50%.
what are the adaptations of gas exchange in fish
- Large SA in gill filaments and lamellae. lots of them
- Steep concentration gradient. maintained by ventilation mechanisms, providing the gill with air
- extensive blood supply and counter current system over gill surfaces maintains concentration gradient
- short diffusion path. capillary & lamellae walls are one cell thick each.
where is the main site of photosynthesis in a leaf
palisade layer
where is the main gas exchange surface in a leaf
spongy mesophyll cells
what adaptations of spongy mesophyll layer makes it a good gas exchange surface
high SA due to gap between cells, air spaces and low cell density
what do plants need gas exchange for
respiration and photosynthesis
what adaptation do leaves have for gas exchange
flat to increase SA
what adaptations do xerophytes have
- thick cuticle: increases diffusion distance
- rolling up leaves: traps water vapour, reduces water conc. gradient. protects from wind
- sunken stomata: in pits, traps water vapour, reducing ψ gradient.
- reduced SA:V: slower rate of diffusion, less water loss
- Hairy leaves: traps humid air, reduces conc. gradient.
- extensive roots: deeper roots for greater water uptake
- low stomatal density: fewer stomata for water to be lost from
