Gas exchange - insects Flashcards
(18 cards)
What’s a transport system?
Systems that move substances around the organism or facilitate exchange, such as blood vessels, lungs and gills.
What’s the relationship between transport systems and concentration gradient?
Transport systems allow a higher concentration gradient to be maintained.
A steeper concentration gradient increases the rate of transport.
What are gas exchange surfaces?
Parts of the body that are specialised for gas exchange
What do single-celled organisms exchange gas with?
Their direct environment
What gas exchange surface do insects use?
Tracheal system
What does the insect gas exchange system consist of?
A network of small tubes (trachea) that carry oxygen directly to the tissues
How do tracheae and tracheoles improve an insect’s gas exchange system?
They increase surface area which increases rate of diffusion
and tracheoles are lined with a single layer of cells to minimise diffusion distance.
Tracheae provide tubes full of air which means fast diffusion into insect tissues.
How are insects adapted to reduce water loss?
1) small surface area to volume ratio reduces water loss
2) waterproof waxy cuticle which inhibits water being lost from the surface by evaporation
3) spiraces can be closed to reduce water loss (spiracles are how air moves into tracheae)
4) there are tiny hairs around the spiracles which reduces evaporation
What are spiracles?
Holes in the insects exoskeleton
which can open to let air move in and out of the body
and closed to prevent water loss by evaporation
What do insect water loss adaptations mean for gas exchange?
They cannot use their body surface to diffuse respiratory gases in the way a single-celled organism can
What’s the tracheae and how are they supported?
Main tube that runs from insect’s body surface to tissues and divided into smaller dead-end tubules called tracheoles.
Tracheae are supported by strengthened rings to prevent them from collapsing.
What’s the advantage of the fluid-filled ends of the tracheoles?
During exercise the water moves into cells by osmosis due to the cells carrying out anaerobic respiration, producing lactate (soluble) This lowers the water potential of muscle cells.
This means that there is a larger surface area for gas exchange
and the final diffusion pathway is in gas rather than liquid state so its more rapid.
What are the steps for gas exchange in insects?
1) air moves into the tracheae through spiracles
2) oxygen travels down the concentration gradient towards the cells
3) the tracheae branch into smaller tracheoles which go to individual cells. Oxygen diffuses directly into respiring cells (oxygen isn’t carried in circulatory system)
4) carbon dioxide moves down its own conc grad towards the spiracles to be released.
How do gases in an insect diffuse along diffusion gradient?
Respiring cells use oxygen so its concentration towards end of tracheoles falls
This creates a concentration gradient for oxygen to diffuse from the atmosphere along the tracheae and tracheoles to cells
Carbon dioxide is a product of respiration so a diffusion gradient is created in the opposite direction
Carbon dioxide diffuses along the tracheoles and trachea from the cells to the atmosphere
Is diffusion quicker in air or water?
Air
How do insects move gases by mass movement?
It’s enabled by the contraction of muscles which can squeeze the trachea, enabling mass movement of air in and out, which speeds up the exchange of respiratory gases.
What’s a disadvantage of the ends of the tracheoles being filled with water and gas exchange?
Greater water evaporation
What’s the effect of temperature on the rate of carbon dioxide release in insects?
Enzyme activity and metabolic rate increases which means there’s a higher rate of respiration and carbon dioxide release so spiracles open more open to get rid of carbon dioxide and get more oxygen. This means increased water loss
