Gas Exchange and Ventilation in Insects

Question 1

What is Gas exchange and ventilation like in insects?

Answer 1

• they have high demands for oxygen
• have a hard exoskeleton - prevents gas exchange occuring across the body
• they have a open circulatory system
• no blood or blood vessels
• oxygen is delivered directly to the cells
• CO2 removed directly from the cells

Question 2

How does this occur in insects?

Answer 2

• Insects have spiracles: small openings where air enters and leaves the insects.
• tubes lead to TRACHAE: carrying air into the body
• tubes have CHITIN around them - which provide flexible support (keeping the tubes open)
• smaller tubes (TRACHEOLES) - it is a single elongated with no chitin
• walls are permeable and very thin

Question 3

What are spiracles?

Answer 3

small openings where air enters and leaves the insects.

Question 4

What does the trachea do?

Answer 4

tubes lead to TRACHAE: carrying air into the body

Question 5

What is chitin?

Answer 5

provide flexible support (keeping the tubes open)

Question 6

What are tracheoles ?

Answer 6

smaller tubes, it is a single elongated with no chitin

Question 7

How are insects adapted for gas exchange?

Answer 7

• Tracheoles: site for gas exchange. (large SA)
• Single layer of cells - short diffusion pathway
• steep concentration gradient
• good ventilation

Question 8

What are the limits to the diffusion of oxygen?

Answer 8

• end if the tracheole is the tracheal fluid - limits air getting to the end of the tracheoles
• can be overcome when the insects is very active
• insect activity increases, cell respiration increases, some anareobic respiration occurs producing lactic acid in cells

Question 9

What is Active ventilation in insects?

Answer 9

• tracheal system are expanded and have flexible walls.
• Repetitive expansion and contraction of these sacs ventilate the tracheal system
• movement of wings alter the volume if the thorax.
• when the thorax increases in volume, the pressure inside drops and air is pushed into the tracheal system from outside
• locusts can alter volume of their abdomen by specialized breathing movements.
• They coordinate and closing valves in the spiracles
• as the abdomen reduces in volume, the spiracles at the rear end of the body open and air can leave the tracheal system.

Question 10

How can this reduces the volume of fluid in the tracheoles?

Answer 10

• contains the tracheal fluids: flooding the tracheoles and limits air penetration.
• Increase in lactic acid
• water potential decreases.
• tracheal fluid enters muscle cells
• moves out by osmosis
  CO^2 produced in muscle cells -> tracheoles and out of spiracles

Question 11

why are there sphincter around the spiracles of an insect?

Answer 11

• This so air can enter and leave the cells when it needs to depending on their activity. They need to conserve water