Gas Exchange in Insects

What are the tiny holes on the surface of an insect’s body called?

Spiracles

What do spiracles allow the movement of?

They allow air to flow in and out of the insect

What is the name of the tubes that spiracles are connected to?

Trachea

What do trachea branch into?

Tracheoles

What do the tracheoles extend into?

Insect’s muscle tissue

What is the name of the liquid found at the end of each tracheole?

Tracheal fluid

What are the trachea and tracheoles supported by?

Spirals of chitin

What is the role of the spirals of chitin supporting the trachea and tracheoles?

Prevent the tubes from collapsing when the insect moves

What are four differences between the trachea found in humans and the trachea found in insects?

• Human tracheae are larger in diameter and length

• Humans only have one trachea, insects have many

• Human tracheae branch into bronchi, insect tracheae branch into tracheoles

• Human tracheae are supported by cartilage, insect tracheae are supported by chitin

What must oxygen do before it diffuses from the tracheoles into the muscle tissues?

Dissolves from the air into the tracheal fluid

How is the insect gas exchange system adapted to have a large surface area?

Large number of tracheoles

How is the insect gas exchange system adapted to give a short diffusion pathway?

• The tracheoles extend into the muscle tissue

• Tracheole walls are one cell thick

Why does absorbing tracheal fluid into surrounding muscle tissue increase the rate of diffusion?

Diffusion takes place faster in gases than in liquids

What are insects able to do if their demand for oxygen increases?

Tracheal fluid can be absorbed into surrounding muscle tissue

Why are insects at risk of more water loss than other animals?

They have a high surface area to volume ratio

In which two ways are insects adapted to reduce water loss?

• They have a waterproof outer layer on their exoskeleton

• Their spiracles can be closed