gas exchange in single cells, insects and fish

• Gases cannot exchange through the exoskeleton of insects because it's hard and waxy.
• Insects have small pores along their bodies called spiracles.
• A tube called a trachea comes from the spiracle and branches out into tracheoles that contain a fluid which delivers oxygen to the cells in the insect.
• The trachea of insects is supported by rings of chitin to keep them open.
• Tracheoles run between cells into muscle fibres where gas exchange occurs.
• Very active flying insects need lots of oxygen.
• Flying insects close the spiracle using abdominal muscles to create a pumping movement for ventilation.
• During flight, the fluid is drawn into the respiring muscles of insects.
• gas exchange in insects

  A) spiracle

  B) air sac

  C) trachea

  D) tracheoles