Lecture 20

In birds and reptiles

Any epithelium exposed to the environment- combination of organs.
1. Gills
2. Kidneys- main organ for osmoregulation
3. Salt glands
4. GI tract from mouth to feces.

water uptake by osmosis.
Salt loss by diffusion
1. Active uptake of salts via gills
2. Don't drink water

Water loss by osmosis
salt gained by diffusion.
1. Active extrusion of salts via gills. (GI tract also involved)
2. Seawater animals drink water for salts and water ingestion.

Marine-gigantic chloride pump out
Freshwater- chloride pump comes in from outside.

1. Generates salt when needed. Marine birds have it; humans don't.
2. Extrude almost totally salt solution using urine. Terrestrial humans use Kidneys (require water-dehydrate) vs. birds use salt glands in base of eyes that generates salt solution without water (chloride pumps secretory tubule collects into duct extrude salty solution from blood- salty tears into the base of the beak)

normally secrete a biproduct of protein synthesis= urea- keep in tissues: extra addition of salts!
They keep the urea in tissues as a way of holding on to salts as a way of eliminating the water problem.

Gills= # of pumps changes/regulate activity of existing pumps.

If they are pumping in sea water- they move to freshwater, they have to pump in. Exchange the type of pumps or if keep same pumps they have to regulate activity pumps in new environment in gills.

Prevent exit of salts and water, gain salts and water from food/drinking.

Don't want to interact with environment at all!

Waxy cuticle impermeable to water: water loss is prevented.

Insecticide: melting wax at specific temperature- the insects dehydrate.

1. metabolic Water from dry seeds.
2. Limit activites to night (behavior)
3. Respiratory moisture in nasal passages- responsible for most of regulation
4. Kidneys- begins in smaller animals-

As air comes down, it increases in temperature, water droplets in nasal passages evaporate go into the gas stage and water vapor gets into air. It is humidified.

Air in lungs warmer than ambient air: fully loaded with water vapor.

Get OUT:
hot air heats walls of nasal passages humid air passes over cool surface condensing on walls.

protonephridium (pumps for inside) found in flat worms
-pumps in tube with flagella working as a motor creating movement of fluid to outside of animal.
excretes ions- beginning of kidneys flame cell.

nephrostomes- entry point into gigantic tube extending containing pumps for active transport of materials in metanephridium- into outside/inside.

nephrostome- has cilia that create vacuum suction, tube is long surrounded by capillaries allow for materials to go in and out from bloodstream into tubule. at end- accumulate in bladder, and thrown out through pore at the end.

line the middle of the GI tract- tubes facing the interior fluids of the animal. Insects have open circulatory system- malphigian tubules surrounded by fluid.
Stellate cells- water and chloride
Principal cells- all other ions.
expelling food, water, and ions- as approaching rectum giving another chance to regulate the ions.
(between midgut and hindgut)