Animal osmoregulation

waste movement

-waste material is usually concentrated

—water is reabsorbed before defecation

—-liquid waste—> kidneys

—-solid waste—> colon

-most vertebrates have a single urogenital opening for both liquid and solid waste

—cloaca: reptiles, birds, monotreme

—rectum, urethra, and separate genital openings: mammals

to maintain osmotic balance the animals body has to:

-be able to take H2O from environment

-excrete excess H2O into environment

—ex) change solutes to maintain homeostasis

—-including inorganic ions (salts) and toxins (nitrogenous waste)

-solutes: small ionic molecules (Na+, Cl-)

-solvent: liquid into which solutes go (H2O—> H+ OH-

osmotic pressure

-amount of pressure needed to rebalance after changes in pressure from the movement of H2O

Higher osmolarity = ? pressure

-higher pressure

—moles of solute in a solution

—1 mol glucose= 1 osmole (covalent bond), 1 mol NaCl = 2 osmoles (ionic bond)

-this leads to changes in tonicity

tonicity:

-measure of a solutions ability to change the volume of a cell by osmosis

hypertonic:

-has greater ability to use osmosis to change volumes

—sets up where there is less water, direction of osmosis

hypotonic:

-lesser ability to use osmosis to change volume

osmoconformers:

-organisms that are in osmotic equilibrium (isotonic) with their environment
—most marine invertebrates and chrondrichthyes

osmoregulators:

-maintain a constant blood osmolarity different than their environment (hypertonic/hypotonic)

—most vertebrates, all terrestrial animals

—-if not they would dry out

osmoregulation contributes to nitrogenous waste by:

-osmoregulation is important for dealing with metabolic waste

-produced when amino acids and nucleic acids are broken down

—amino group is removed—> (NH3)

—only safe in dilute concentration, must be eliminated

-Chondrichthyes, adult amphibians and mammals convert ammonia into urea which is dissolved in H2O

-Birds, reptiles and insects convert ammonia into water insoluble uric acid, this uses more carbon but does NOT require H2O

-Bony fishes and immature amphibians eliminated ammonia by diffusion via gills.

what do nephrons do in the kidney?

-filter: fluid from blood water and solutes

-reabsorption: retaining important macromolecules

-secretion: removal of concentrated waste from the body (urine)

where is blood carried into in the kidneys

glomerulus

-plasma is filtered as it is forced through porous capillary walls

-results of this is filtrate

where does the filtrate and unfiltered blood enter

-filtrate enters bowmans capsule

-unfiltered blood drain out (cells and large proteins stay behind)

where does the filtrate move through

-renal tubules

blood plasma is filtered out of ____ into the ___ system

-renal tubules

-tubule

loop of henle exhibits _____ current water concentrations

counter

descending loop of henle

-filtrate has high H2O/solute ratio

-blood vessels lower H2O/solute ratio

-osmosis from descending henle to renal venules

ascending loop of henle

-filtrate has low H2O/solute ratio

-blood vessels lower H2O/solute ratio

-osmosis from ascending henle to renal arterioles