BIOD33H3 Lecture Notes - Lecture 12: Osmotic Pressure, Circulatory System, Hemolymph
Insects have a diff system for producing urine and getting rid of nitrogenous waste. Get some reabsorption in the hind gut for things it wants to keep and doesn"t want to excete in waste. Th lining of the rectum sets up a local osmosis phenomenon. That allows for the concentration of the content of the gut (urine) by allowing for the reabsorption of water. Greater osmolarity inside the rectum than outside in the hemolymph. Osmotic pressure is greater in the rectum which should cause water to go into the rectum, but instead you get it going the other way. This is bc theres a microgradient set up by the anatomical structure of the rectal pad. Apex of the rectual pad is pointing towards the rectal lumen. Within the rectal pad theres epithelial cells lining, but theres 2 sets of spaces.