Gas exchange in insects and single celled organisms

how do single-celled organisms exchange gases?

diffusion through the cell membrane

how are single-celled organisms adapted for gas exchange?

small so large SA:V ratio, one cell thick so short diffusion distance

which 3 structures do respiratory gases use to move around the tracheal system?

spiracles, trachea, tracheoles

what are spiracles?

pores on the surface of an insect’s body that can open and close to control water loss and gas exchange

which 3 ways to insects exchange respiratory gases?

diffusion gradients, mass transport, tracheoles + water

how does gas exchange occur with ends of the tracheoles + water?

anaerobic respiration occurs in muscle cells and produces lactate which is soluble and lowers the water potential of the muscle cell, causing water to move from tracheole into muscle cell by osmosis so air moves into the tracheole

why are the ends of the tracheoles filled with water?

so air can move in the gas phase

how does gas exchange occur with mass transport?

muscles contract and squeeze the trachea, forcing the air in and out so gas exchange happens quickly

how does the exchange of oxygen occur using a diffusion gradient?

o2 is used in respiration so the concentration is lower at the ends of the tracheoles so o2 diffuses down the concentration gradient into the cells

how does CO2 move along a diffusion gradient?

co2 is produced in muscle cells by respiration so higher conc in muscle cells so diffuses down the gradient into tracheoles

how is water loss balanced with gas exchange?

chitin, spiracles

how does chitin help manage water loss?

impermeable

how are spiracles adapted to control water loss?

they can close, have valves, and hairs around the opening

how are insects adapted for gas exchange? (tracheoles)

• tracheoles: highly branched so increase SA, lead directly into the cells so short diffusion distance, one cell thick so short diffusion distance

• muscle contractions maintain O2 conc grad