insects and adaptations in lungs Flashcards
What is tissue fluid?
the environment around the cells of multicellular organisms
How does a flattened shape help with exchange
no cell is ever far from the surface
Describe how having a compact shape or a less compact shape is an adaptation for exchange
more compact = small SA: V = minimises heat loss
less compact = large SA:V = increases heat loss
Why do animals with a large surface area to volume ratio have a higher rate of respiration?
to maintain body heat as large SA : V means lots of heat is lost
Describe how gas exchange happens in a single-celled organism
due to being small, these organisms have a large SA: V. Oxygen is absorbed by diffusonacross their body surface, which is only covered by a cell-surface membrane.
CO2 from respiration diffuses out across their body surface
Describe the Tracheal system in insects
Trachea = supported by strengthened rings to prevent them from collapsing
Trachea divide into smaller dead-end tubes = tracheoles
tracheoles extend throughout all the body tissues of the insect = oxygen brought directly to respiring tissues = short diffusion pathway fro the tracheole to any body cell
Describe gas exchange in insects when they are at rest
- cells respire= oxygen used up, so concentration towards the ends of the tracheoles falls
- when oxygen enters through the spiracles, it diffuses from the atmosphere, along the tracheae and tracheoles,
dissolves in the fluid in the tracheoles, and diffuses down the concentration gradient maintained by respiration into the cells
- CO2 travels down the concentration gradient in the opposite direction
Describe gas exchange when insects need more air
contraction of muscles in insects squeezes = increase the pressure inside
= CO2 forced out down a pressure gradient, and due to the spiracles being closed for a moment there is a higher pressure of oxygen on the outside
= mass movements of air in and out= fast gas exchange as oxygen diffuses down pressure gradient
Describe gas exchange when insects are doing vigorous activities. If this is so efficient, why doesn’t it happen so often?
- some muscle cells around tracheoles respire anaerobically = produces lactic acid, which lowers water potential in the muscles, which means there is now a higher water potential at the tip of the tracheoles than muscles
- water moves down the concentration gradient (from high water potential to low) from tracheoles to muscle cells by osmosis = ends of tracheoles decrease in volume, so it draws air further into them
- when oxygen reaches ends of tracheoles, it no longer needs to dissolve in liquid before diffusing down concentration gradient = more rapid diffusion
- It doesn’t happen all the time because there’s not enough energy to sustain this
What are the limits of insects’ tracheal system?
- relies mostly on diffusion to exchange gases between the environment and the cells
- diffusion pathway needs to be short = so insects need to be small
Describe the structure of gills and how is it adapted for gas exchange
- made up of gill filaments, which are covered with lamellae, which increase the SA of gills
- lamellae have lots of blood capillaries and a thin surface layer of cells to speed up diffusion
Describe the counter-current in fish and what is its purpose?
blood and water flows in opposite direction =maintains the concentration gradient between the water and the blood
ensures the maximum amount of the oxygen passes into the blood flowing through the gills =
always higher oxygen concentration in the blood, which flows past water= concentration gradient maintained across the whole of the lamellae
Describe the ventilation mechanism in fish
the fish’s mouth opens and the operculum shuts as the floor of the mouth is lowered
water enters the mouth due to a decrease in pressure and an increase in volume.
the mouth then closes and the operculum opens
the floor of the mouth is raised resulting in an increase in pressure in the mouth and a decrease in volume.
this increase in pressure forces water over gills
Why is air moved constantly in and out of the lungs?
to maintain diffusion of gases across the alveolar epithelium
What is ventilation?
breathing (air being moved constantly in and out of the lungs)
