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

2. 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?

3. 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

4. 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

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

6. 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)

7. 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

8. 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

9. 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

10. THE VERTEBRATE EXCRETORY SYSTEM

11. 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.

12. KIDNEY TUBULES AND FRSE

14. 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

15. THE RAAS SYSTEM

16. Watch these videos for a recap

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