Gas exchange Flashcards
What is the gas exchange system in an insect called?
Tracheal system
What polysaccharide is an insect’s exoskeleton made of?
Chitin
What are the pores on an insect called through which air enters the body?
Spiracles
What are tracheoles and what do they do?
Tubes that extend through all the insect’s tissues, carrying oxygen directly to respiring cells, and removing carbon dioxide
What are the 3 things that cause movement of gases through the tracheal system?
- Concentration/diffusion gradients
- Contraction of muscles around tracheal system
- Ends of tracheoles filled with water
Explain the importance of the water in the end of tracheoles during intense activity
Muscle cells respire anaerobically
This produces lactic acid which lowers water potential, causing water to move into cells by osmosis
This speeds up diffusion of gases as gases diffuse faster through air than water
Insect adaptations to reduce water loss
- Small SA:V ratio
- Waterproof chitin exoskeleton
- Spiracles can close
Adaptations of leaves for gas exchange
- Flat: large SA:V ratio
- Stomata: every cell a short diffusion pathway away from a stomata
- Short diffusion distances: many interconnecting air spaces between stomata and mesophyll
Why are stomata mainly on the underside of leaves?
Often in the shade, so cooler, so less water lost
What are the two types of fish?
Cartilaginous: includes sharks and rays - have to keep swimming in order for oxygenated water to flow over their gills - parallel flow in gills
Bony fish: use a ventilation mechanism - countercurrent flow in gills
Why do fish have to have a more efficient gas exchange system?
- Concentration of gases in water lower than in air
- Fish are very active
- Relatively small SA:V ratio
- Outer surface waterproof and therefore gas tight
What are gills made up of?
Gill filaments with lamellae on their surface at right angles to the filaments - drastically increasing SA of gills
Path of water through gills
Mouth>over gills>out through opening on each side of body
What is counter current exchange?
Blood flows through gill lamellae opposite direction to water allowing gas exchange to occur over whole length of lamellae. Conc. gradient exists along whole length
What is the surface for gas exchange in humans? (specific)
The epithelium of the alveoli
