Osmoregulation

OsmoregulationThe process by which animals control solute concentrations and balance water gain and loss.

Osmoconformers-isoosmotic with their environment, most marine invertebratesOsmoregulators-regulate internal osmolarity by releasing or taking in water, many marine animals, all freshwater animals, terrestrials animals, and humansWater BalanceMost metabolic wastes must be excreted from the body.Nitrogenous wastes come from the breakdown of proteins and nucleic acids.Excretion the removal of nitrogenous wastes from the bodyNitrogenous WastesAmmonia- very water soluble and toxic. Generally only produced in aquatic animals where water loss is NOT a problem.Urea Produced in the liver of most vertebrates by combining ammonia with carbon dioxide. Requires energy but urea is less toxic.Uric Acid Requires more energy to produce than urea; it is insoluble in water and can be excreted as a paste or crystals. Produced by birds and reptiles and can be stored in the egg.Types of Nitrogenous Wastes

Protonephridia/Flame-bulb system Flat worms (Platyhelminthes)Metanephridia Annelida (Earthworms)Malpighian tubules Insects and terrestrial arthropodsKidneys Vertebrates FishAmphibiansReptilesBirdsMammalsExcretory SystemsVariations on a Tubular Theme

Functional similarities of all excretory systemsFiltration of body fluidsmodification of that filtrate by: selective secretion of solutes and selective reabsorption of some of those solutesExcretory SystemsKidney

Excretory SystemsFunctional similarities of all excretory systemsFiltration of body fluidsmodification of that filtrate by: selective secretion of solutes and selective reabsorption of some of those solutesKidney made of nephronsnephron-single long tubule and associated capillariesthree processes occur: filtration, secretion, and reabsorption

Functional Unit of the Excretory System of Mammals-Nephron

This is the pressure-filtering of body fluids, removing water and solutes. Cells, proteins, and large molecules remain in the body fluid.Occurs in the glomerulus of the kidney.

FiltrationReabsorption reclaims valuable substances from the filtrate such as glucose, vitamins and hormones.Occurs in the proximal and distal tubules as well as the loop of Henle. Water continues to be reabsorbed.*** The flow of filtrate in the loop of Henle is an example of a countercurrent system.

Reabsorption17Adds other substances such as toxins and excess ions to the filtrate by active transport.Occurs in the proximal tubule.SecretionOccurs when the altered filtrate leaves the body.Carried by the collecting tubules to the ureters, then to the bladder, then out the urethra.ExcretionRegulation of Kidney FunctionADH-antidiuretic hormone, enhances fluid retention by increasing the water permeability of the tubules, produced by hypothalamus, but released from the posterior pituitaryRAAS-renin-angioltensin-aldoserone system cooperates with ADH and is opposed by ANFVideos and Websiteshttp://www.biologymad.com/resources/kidney.swf