Gas exchange in insects Flashcards
what do insects have in terms of their skeleton ?
an exoskeleton made of hard fibrous material (chittin) for protection
what layer of skin do they have and what is it for ?
a lipid layer
- to prevent water loss
what do insects have instead of lungs ?
a tracheal system
how is water lost from an insect ?
water evaporates off the surface of terrestrial insects
what provides ideal conditions for gas exchange ?
adaptations of gas exchange surfaces
what are the adaptations of insects that prevent water loss?
- insects have a small surface area to volume ratio where water can evaporate from
- insects have a waterproof exoskeleton
- spiracles, where gases enter and water can evaporate from so they can open and close to reduce water loss
what do insects use to exchange gases ?
a trachea, tracheoles and spiracles
what are spiracles ?
round, valve like openings that run along the length of the abdomen. oxygen and carbon dioxide enter and leave via the spiracles. and the trachea attatch to these openings
what is the trachea ?
a network of internal tubes which have rings within them to strengthen the tubes and keep them open
what does the trachea branch into ?
tracheoles
what are tracheoles ?
smaller tubes with thin permeable walls which are deep into the abdomen and extend throughout all tissues in the insect and terminate at individual cells to deliver oxygen to all respiring cells
what does the circulatory system in insects NOT do ?
transport oxygen
what happens to carbon dioxide in an insect ?
CO2 diffuses from cells and into the spiracles as it travels down its own conc gradient out of the insect
what do some larger insects have ? and what does it do ?
muscles in their abdomen which contract rhythmically to move air in and out of the spiracles
what is the exoskeleton made out of and what is its properties ?
made from chittin
- strong, waterproof and airtight
explain the movement of oxygen into the gas exchange system of an insect at rest ? (3)
air firstly moves into the insects trachea through the spiracles which are pores on the insects exoskeleton. The air then moves into tracheoles which have thin permeable walls that terminate at each cell and so the oxygen will diffuse directly into the cells. Oxygen is used in aerobic respiration and oxygen moves along a concentration gradient
What are the 3 methods of moving gases in the tracheal system ?
- Gas can exchange by diffusion as when cells respire they use up oxygen and carbon dioxide creating a concentration gradient from the tracheoles to the atmosphere
- Mass transport, in which an insect contracts and relaxes their abdominal muscles to move gases on mass
- When an insect is in flight the muscle cells start to respire anaerobically to produce lactate. This lowers the water potential of the cells and therefore water moves from the tracheoles into the cells by osmosis. This decreases volume in the tracheoles and as a result air moves in .
