7.3 Ventilation In Insects

Question 1

why do insects need to have a specialised ventilation system

Answer 1

they have a tough waxy exoskeleton which is impermeable to gases
and are very active so have a high metabolic demand

Question 2

what opens and closes spiracles and why

Answer 2

sphincters so to minimise water loss and allow air to flow into the tracheae

Question 3

what are spiracles

Answer 3

small openings along the thorax and abdomen of an insect when the air enters

Question 4

what holds the tracheae open

Answer 4

spirals of chitin

Question 5

what’s the tracheal system like in insects

Answer 5

air enters through the spiracles into the tracheae which is held open by spirals of chitin, the tracheae then leads into smaller trachioles they run in between tissues and muscle fibres this is where gas exchange takes place

Question 6

where does gas exchange take place in insects

Answer 6

in the trachioles

Question 7

what’s the ventilation mechanism is very active insects

Answer 7

very active insects need a large supply of oxygen so they draw a mass flow of air into the tracheal system they do this by closing the spiracles and making a pumping movement in the abdomen by using the abdomen muscles for ventilation
during flight the fluid at the narrow end of the trachiole is drawn to the respiraring muscles so gas diffuses across quicker as it’s a shorter distance

Question 8

what is tracheal fluid

Answer 8

it’s fluid found at the end of the trachioles which limits the penetration of air for diffusion

Question 9

how do insects increase the levels of gaseous exchange

Answer 9

• mechanical ventilation of the tracheal system pumping movements in the thorax/abdomen cause pressure changes
• collapsible enlarged tracheae or air sacs they act as air resivours increasing the amount of air moved through the tracheal system

Question 10

why are trachioles permeable to gases

Answer 10

they have no chitin lining