insects ventilations

spiracles

small openings on the surface of insects that allow for the exchange of gases with their environment

sphincters

rings of muscles which surround the openings to spiracles. They control the size of the opening to maintain a balance between gas exchange and water loss

How does gas exchange

They have a rigid exoskeleton, which is waterproof to prevent the insects drying out, but it also prevents gas exchange. Insects increase their rate of gas exchange by having openings in the exoskeleton called spiracles, which lead to a network of tubes called tracheae, which branch into many smaller tracheoles that carry air directly to the cells. These tracheae and tracheoles are held open by rings of hard chitin (a polysaccharide). The tracheoles penetrate deep into the insects tissues, carrying air quickly and directly to every cell. At the ends of the tracheoles oxygen diffuses directly into the cells, and carbon dioxide diffuses out, down their concentration gradients.

1. spiracles in exoskeleton

2. spiricals

3. trachea

4. rings of chitin

5. air sac

6. tracheoles

7. muscle cell

How does ventilation differ between small insects and larger

Small insects can rely entirely on diffusion through the tracheoles to obtain enough oxygen for respiration, but larger and more active insects, like houseflies and grasshoppers, ventilate their tracheal system by using muscles to squeeze their abdomen and so suck air in and out of the spiracles. This increases the concentration gradient and so the rate of gas exchange

what are some issues that open spiracles cause

water loss

how do you counter the problem of water loss

To counteract problems of water loss insects can close their spiracles using a muscular valve. The opening and closing is controlled by the nervous system, which detects a build-up of CO2 in the tracheae. Some insects also have spines or hairs around the spiracles to increase humidity and so reduce evaporation.

1. closed

2. open

what is the role of air sacs

supply’s / store / reservoir of oxygen

so respiration can occur in ( large active )locusts.

also means spiracles can close preventing water loss

enhance ventillation

flight buoyancy control

how are the insects gas exchange organs adapted

air / oxygen into spiracles to trachea to tracheoles

by diffusion

there thin offering a short diffusion pathway

Insects have short diffusion distances because their tracheal system has extremely fine, highly branched tracheoles that extend directly to individual cells

• Tracheae & Tracheoles: Tracheae (main tubes) branch into numerous, fine tracheoles that permeate tissues, maximizing surface area and minimizing diffusion distance to cells.

• Chitin Lining: Tracheae are reinforced with chitin rings, preventing collapse but remaining impermeable to gases, directing flow to the permeable tracheoles.

tracheoles contain fluid to allow oxygen to dissolve

air sacs provide store of air oxygen

abdominal movements move air in to maintain a conc gradient

explain why 80 % humidity is used 

a standard for comparison 

to prevent water loss and dehydration 

as this is the highest humidity they can tolerate 

compare the gas exchange system between may fly (insect) and baby mayfly (tadpole)

similarities= 1. large surface area 2. thin exchange surface or small diffusion distance

differences= baby have gills adults have spiracles babies have an external system adults internal