pack 4 gas exchange Flashcards
(31 cards)
why does the volume affect the rate of gas production or use
bigger volume means more / bigger cells and therefore increases use of oxygen and production of co2 in more respiration
what does metabolic rate mean
rate at which chemical reactions in the body occur (respiration)
why do smaller mammals need a higher metabolic rate
smaller mammals have a larger SA: vol so lose heat faster, so they respire faster, releasing more heat and so replace the lost heat
equation for aerobic respiration - hard
c6 h12 6o2 + 6o2 = 6co2 + 6h2o + 38 atp
what is Ficks law
surface area * diff in conc /
thickness of exchange surface
adaptations for efficient gas exchange
- provides a large surface area
- maintains a high concentration gradient
- ensure that the exchange surface is as thin as possible
gas exchange in a single-celled organism
- these are organisms with no special exchange surfaces.
they rely on simple diffusion of gases across their outer surface membrane and this satisfies their respiratory needs - due to their small size, they have a larger surface area: volume ratio and a short diffusion pathway, so fast rates of diffusion can be achieved.
- continuous aerobic respiration will maintain concentrations gradients for o2 and co2.
what are gills
complex, fragile structures situated in between buccal cavity and operculum. the structure and function of the gills allows efficient gas exchange.
how do gills provide a large surface area
- each gill consists of many filaments each covered in many lamellae
- this gives a large surface area for diffusion
how do gills provide a short diffusion pathway
- there are many capillaries with thin/single layer of thin epithelium, close to the thin-walled lamellae ensures a short diffusion pathway between the blood and water
concentration gradient - fishiesss
- a continous flow of blood through capillaries ensures that freshly oxygenated blood is quickly removed from the gills and replaced with deoxygenated blood.
counter current flow
- water flows over the gill plates in the opposite direction to the flow of blood in the capillaries.
- blood always meets water with a lower concentration of oxygen.
- the concentration gradient is maintained so diffusion occurs across the entire surface of the gill
explain the ventilation mechanism of a fishieee
- water enters the fishs mouth and flows over the gills, leaving via an operculum.
- there is thus a constant flow of water over the gills
explain the body of an insect
- protected by an exoskeleton, made of a rigid substance called chitin
- it is waxy and waterproof which minimises water loss across the body surface but this prevents gas exchange across the surface.
insects gas exchange
- the tracheal system consists of many tracheae that open to the outside through small holes in the exoskeleton called spiracles
- these finer tubes are tracheoles are the site of gas exchange
- the large number of small tracheoles give a large surface area for diffusion, while their thin walls, extensive branching and close proximity to the cells provide a short diffusion pathwa
abdominal pumping
- flight requires more atp for increased muscle contraction
- ventilation by contraction of the muscles of the abdomen can force air in and out of the spiracles and tracheae to maintain a greater air flow and maintain steeper concentration gradients for fast diffusions
- the insects can also remove the fluid from the ends of the tracheoles to increase diffusion rates
where does gas exchange occur in plants
- spongy mesophyll layer of the leaf, with large air spaces and thin walled cells
why will there be steep concentration gradients for gases plant
- carbon dioxide will be lower in the leaf by day as it is used in photosynthesis
- reverse for oxygen
how does the leaf minimise water loss
- stomata mainly on underside
- thicker waxy cuticle on the under epidermis
action of guard cells can close stomata - all these reduce evaporation
large surface area - plant
- large number of stomata
- flat thin leaves
- air spaces in spongy mesophyll
thin exchange surface - plant
- flat thin leaves so short diffusion pathway
- mesophyll cells have thin cell walls
what is cilia and its role
- a short hair-like membrane beats regularly to move micro organisms and dust particles along with mucus
role of mucus
- traps micro organisms and debris helping to keep the airway clear
structure of human gas exchange
larynx - trachea - bronchus - bronchioles - alveoli
