5.4 The respiratory system

Question 1

What does the respiritory system consist of?

4 points

Answer 1

• 10 pairs of spracles leading to
• the trachea connected directly to
• the tracheal sacs and
• the tracheoles which lead to all [parts of the body particularly the muscles, glands and tissues where respiration takes place

Question 2

What is the finction of the respiritory system?

Answer 2

• To provide a supply of O2 in order to release energy by respiration
• To rid the system of Co2 (waste product of energy production)

This gaseous exchange is acheived paertly by diffusion and mainly by muscular action of the abdominal segments where inergy is being used at a high rate.

Question 3

Where are spiracles and what do they do?

External respiratory orifices in insects

Answer 3

1. 10 pairs in total on T2, T3, A1 and A2 to A8
2. A8 cannot be seen as it is hidden in the sting chamber
3. All have valves except T3 which is small
4. The valve on T2 cannot be fully closed (remember 2 wide) - n.b: acarine and is concealed below a flat lobe part of T1. The edge of the lobe is covered in dense hairs
5. A1, the 3rd spiracle is the largest one of all (0.23mm to 0.6mm)
6. There are two types of valve, the one on T2 and those on A1 to A8

Question 4

What to the trachea do?

passages through which air is conveyed through the body of an insect

Answer 4

• major highways from the tracheal sacs
• a continuation of the ingrowths of the body wall and are fored of a thin epitheliom of flat cells which is lined with a cuticular intima
• The cuticular intima is ribbed with ckiseky set thickenings called taenidia which provide rigidity to the tracheal walls and prevents their collapse
• they provide the major outlets fro the tracheal sacs and provivde the distribution network in a branched formation of tubules that become smaller and smaller eventually terminating in the tracheoles