Insects GE + Ventilation Flashcards
What is the respiratory system of insects called and what does it involve?
The tracheal system, involving the diffusion of oxygen directly from the atmosphere into air-filled sacs and tubes.
What are the spiralled in the tracheal system?
There are 10 pairs of spiracles laterally on bodies surface (2 thoracic, 8 abdominal) guarded by fine hairs that keep foreign particles out and valves that open and close spiracles to reduce water loss.
Spiracles open up into the tracheae
What are the tracheae?
Long, fine tubes of chitin rings that link to air sacs and have a wall of single layered epithelial cells.
The cells secrete cuticular thickenings around the tube that give support to the tube that prevent them from collapsing during inspiration.
What do tracheal tubes branch into?
Finer tracheoles that enter all the tissue and sometimes even penetrates cells of the insect.
The end of tracheoles that are in tissue are filled with fluid and lack cuticular thickenings.
When is fluid present on the tracheoles?
When the insect is resting, the fluid is present to slow down the rate of diffusion of oxygen into the cells, however when active, lactic acid is produced by cells which reduces water potential, so fluid moves into cells, increasing diffusion as it is faster by gas
What is the ventilation mechanism of larger insects?
Larger insects create a one-way airflow through main tracheae.
Air flows in through thoracic and first 2 abdominal spiracles.
Air flows out through remaining abdominal spiracles.
The air is moved by the contraction and relaxation of muscles in abdomen which change size of abdomen and cause pressure change.
How do insects inspire?
The thoracic and first 2 abdominal spiracles open, 6 other abdominal close.
The abdomen expands an increase in volume and a decrease in pressure, below the atmospheric.
Air flows in
How do insects expire?
Thoracic and first 2 abdominal spiracles close. Remaining abdominal spiracles open.
Abdomen contracts, causing a decrease in volume, and an increase in pressure, above the atmospheric pressure)
Air flows out
Are the air sacs compressible?
Yes, which increases the voile of air for gas exchange
