Gas Exchange - Insects Flashcards
What is the tracheal system of terrestrial insects?
Spiracles → Tracheae → Tracheoles
What are spiracles?
openings/pores in the body surface (abdomen) that leads to tracheae → allows diffusion of oxygen, O2 +CO2 enter and leave via spiracles
What are tracheae?
network of internal tubes that carry air directly to cells for gas exchange → rings of cartilage to strengthen tubes and hold them open
What are tracheoles?
branch of tracheae → walls are permeable to oxygen → extend throughout all the tissues to deliver oxygen to all respiring cells
How are insects tracheal system adapted for gas exchange?
- large number of fine tracheoles/ highly branched → large SA for exchange
- walls of tracheoles are thin → short distance between spiracles and tracheoles → short diffusion distance
- use of oxygen and production of carbon dioxide → sets up steep diffusion gradient
How are insects adapted to limit water loss?
- exoskeleton has lipid layer/ impermeable
- muscular sphincter opens/closes spiracles which prevents water evaporating
- spiracles are sunken = conc of water is equal on inside and outside which prevents osmosis
- tiny hairs around spiracle trap water vapour and reduce rate of evaporation
- small SA:Vol where water can evaporate from
What happens when an insect is very active/in flight?
the cells start to respire anaerobically so lactate will be produced as a waste product which lowers the water potential of fluid in the muscles so water from the base of the tracheoles move by osmosis into the muscles - decreases volume in tracheoles so air from atmosphere is drawn in
How are gases moved?
- diffusion when cells respire they use up O2 and produce CO2 making a conc gradient from the tracheoles to the atmosphere
- mass transport = rhythmic abdominal movements causes insect to contract/relax abdominal muscles to move gases on/move air in and out of spiracles and speed up rate of diffusion from the tracheae into body cells
