Why do organisms need to regulate their internal conditions? Osmoregulation Why do organisms need to regulate their internal conditions?

PLANTS Since plants can’t move, they are osmocomformers That means that they must remain isosmotic with their surroundings. What does the prefix iso- and the word osmotic mean?

OSMOREGULATORS Organisms that can regulate their internal osmolarity. They can live in many different environments Marine fish can gain water and ions from food and excrete salt ions through gills Freshwater fish can gain water and ions from food and uptake salt ions through gills Salmon can tolerate both freshwater and saltwater (Euryhaline) Most animals can only tolerate narrow ranges of external osmolarities (stenohaline) Anhydrobiosis- when animals such as tardigrades can live in temporarily hydrated environments. When conditions are dry, they go dormant

Osmoregulation, osmolarity and excretion Animals regulate their osmolarity by controlling the amount of SOLUTE that they retain in their bodily fluids Intake of water, excretion of fluid, and dissolved solute is the major way that animals control internal osmolarity

Can I drink saltwater if I’m stranded in the ocean? Not unless you’re an albatross

Nitrogenous waste Waste molecules produced by cells from the breakdown of proteins and nucleic acids Ammonia: Most toxic. Only produced by aquatic animals Urea: Formed by combining ammonia with carbon dioxide. Not as toxic, so it can be tolerated at higher concentrations than ammonia, and released with less water (mammals, amphibians, sharks) Uric acid: Least soluble. Can be excreted with the least amount of water. More energetically expensive to produce than urea. (reptiles, insects, snails)

EXCRETORY SYSTEM All excretory systems involve 4 major processes (FRSE): Filtration- Initial movement of fluids and solutes from the body to the system (filtrate) Reabsorption- Water and desirable solutes are reclaimed by transport epithelim Secretion- Excess waste solute is sent to the filtrate Excretion- the modified filtrate (urine) is expelled from the body All excretory systems use tubules for collection of filtrate

Protonephridia: Platyhelminthes Interstitial fluid moves into the protonephridia The filtrate is produced through the action of ciliated “flame bulb” cells Filtrate then leaves the animal through openings in the body wall

Malpighian tubules: Arthropods Filtrate moves from the hemolymph into the malpighian tubules From the tubules, filtrate is combined with undigested food and eliminated from the body through the rectum

THE VERTEBRATE EXCRETORY SYSTEM

KIDNEY AND NEPHRONS The kidney is the main organ in charge of filtering and producing urine The nephron is the interface between the circulatory system and the excretory system responsible for filtration, reabsorption and secretion.

KIDNEY TUBULES AND FRSE

When blood osmolarity increases, the pituitary gland releases ADH, which increases water reabsorption in the collecting duct of the nephron. ADH also triggers a thirst response in the animal. These effects decrease osmolarity

THE RAAS SYSTEM

Watch these videos for a recap https://www.youtube.com/watch?v=FN3MFhYPWWo https://www.youtube.com/watch?v=qfWx8msgHqM

EXAM 3 CHAPTERS: Endocrine Nervous Immune Digestive Circulatory and Respiratory Osmoregulation Watch more of Bozeman science for a review of these chapters