Wildlife Physiology ecology exam 4

osmoregulation

keeping water and salt balanced in the body

water always moves from an area of _______ to _________

low osmotic pressure to high osmotic pressure

Problems for Freshwater Fish in Osmosis

freshwater fish don't have a lot of salt, but the freshwater is constantly coming through their gills, so they can breathe

solutions for freshwater fish

dilute urine and pump salts across gills

problems for marine fish

they have a high ion concentration and water leaves the body

solutions for marine fish

pump salts out of the body

marine birds and mammals problems

get liquid from prey which is a lot of saltwater
no freshwater source

marine birds and mammals solutions

salt glands for birds and kidneys for mammals

osmotic pressure

the pressure of water to enter, given the solute concentration
depends on the number of solutes per unit volume and not their chemical identity

isosmotic

osmotic pressure is equal

hyperosmostic

higher osmotic pressure (more solutes)

hyposmotic

lower osmotic pressure (less solutes)
Water moves to higher solute concentration

osmosis

movement of water from an area with lower osmotic pressure to higher osmotic pressure
salts move down in concentration gradient

osmolarity

concentration of solutes in a solution

osmolarity vs molarity

osmolarity is concentrations of solute without regard to chemical identity whereas molarity is the number of moles of solute per liter of solution

solute

dissolved particle in a solution

osmoconformer

An organism that allows its internal concentration of salts to change in order to match the external concentration of salts in the surrounding water
(invertebrates)

Osmoregulator

an animal that controls its internal osmolarity independent of the external environment

Freshwater Fish

hyperosmotic to environment
problem is that they gain water and lose salt

How do freshwater fish osmoregulate?

produce dilute urine
actively move salt into blood
active uptake of Na+ and Cl-

what do chloride cells do in freshwater fish

help in active uptake of ions across the gills

How do amphibians osmoregulate?

hyperosmotic to environment
gain water and lose salt
produce dilute urine
pump salt into body, but no gills so main osmoregulator organ is skin
active transport of Na+ into animal and Cl- follow passively through electric gradient

Jawless Fish

osmoconformers and ionoconformers

sharks and rays

osmoconformers and ionoregulators

bony fish, marine reptiles, marine birds, marine mammals

osmoregulators and ionoregulators

cartilagenous fish

there is less Na and Cl because they put urea in their blood
this helps them loose less water by matching seawater osmolarity

teleosts

regulate their osmolarity severely

marine teleosts

slimehag is the only ional conformer and the rest are ionoregulators
they are osmoregulators and are hypoosmotic to environment

marine teleost problems and solutions

lose a lot of water and gain a lot of salt
solution is that they produce little urine and when they do it is isosmotic to environment since they can't concentrate it
they also excrete salt across the gills by actively pumping ions out

marine reptiles and birds osmoregulation

salt gland; hypoosmotic body fluids; less exposed to salt water because of lack of gills, everything they eat has salt in it, so they raise their salt content
reptiles can't concentrate urine
marine birds can concentrate urine a little bit
use urea in blood, so they don't lose water

salt glands of marine birds and reptiles

transport epithelia that excretes water saltier than the ocean, allowing birds to drink ocean water with a net gain of water
they secrete a higher concentration of salt than they get in
salt is excreted outside of the body (birds through nose)
mechanism is the same in reptiles, but the salt gland is in many diff places

How do marine mammals osmoregulate?

kidneys
some groups can only produce isosmotic or hyposmotic urine relative to plasma

glomerulus

A ball of capillaries surrounded by Bowman's capsule in the nephron and serving as the site of filtration in the vertebrate kidney.

Bowman's capsule

cup-shaped strucutre of the nephron of a kidney which encloses the glomerulus and which filtration takes place.
1st part of nephron

nephron

The tubular excretory unit of the vertebrate kidney.

mammals

can produce hyperosmotic urine
no water pumps in our body, so we must use channels that rely on higher solute concentration

making concentrated urine

loop of Henle pumps Na+ out of filtrate and into extracellular fluid
sets up osmotic gradient in kidney ECF
as filtrate passes through the collecting duct, it loses water to ECF