Chapter 44- Osmoregulation and Excretion

OSMOREGULATION The regulation of solute concentrations [ ] with the balance of the gain/loss of water. - Water will enter/leave cells through osmosis which will create difference in osmolarity.

Solutions for Osmoregulation: 1. Osmoconformer- The internal environment matches the outside environment - Many marine invertebrates

Solutions 2. Osmoregulators- The animal controls its own osmolarity. - High energy cost because of active transport - Most vertebrates

Osmoregulation in Specific Examples of Animals: 1. Marine animals (fishes, but not including sharks) - There is a strong threat of dehydration by water exiting body - Drink LOTS of saltwater but have special cells to extract excess NaCl - Very small amounts of water in the urine *very concentrated uric acid

Animals 2. Freshwater fishes - Constantly gain water from osmosis and lose salts by diffusion - Excrete large amounts of water in the urine 3. Land animals - Have to regulate water loss

Nitrogenous Wastes Excretion of Nitrogenous Wastes (from metabolism) - Nitrogen is removed in the form of ammonia (highly toxic) or converted to less toxic forms and then excreted.

Production of Wastes Excretory systems all have tubular theme Production of Wastes (4 steps) 1. Filtration- creates filtrate 2. Reabsorption- Essential, small molecules need to be recovered through active transport 3. Secretion- Active transport of other molecules/toxins/ions not already filtered out 4. Excretion of urine

Excretory Systems in Specific Examples of Animals: 1. Annelids (earthworms)- Metanephridia- Has internal openings that collect body fluids and then waste is excreted through pores all over body.

Excretory Systems 2. Arthropods (insects, spiders, etc…)- Malpighian Tubules- Tubules collect waste and the tubules connect to the digestive tract.

Excretory Systems 3. Vertebrates (we are going to look specifically at mammals)- Kidneys - Blood enters the kidneys through the renal artery and exits the renal vein Waste exits the kidney through tubes called ureters and collects in the urinary bladder. Bladder is drained through the urethra.

Kidney Structure Nephrons (and Blood Vessels) are the functional units. Parts of the nephron: - Glomerulus- Ball of capillaries - Bowmans Capsule- Surrounds glomerulus - Loop of Henle- Where most filtration and reabsorption of water takes place Path of flow through the nephron: Proximal tubule  Loop of Henle  Distal tubule  Collecting duct  Out

Urine Urine is highly concentrated waste - How do we conserve so much water (up to 99%)? Concentration gradients (mainly using NaCl to cause the gradient) The longer the Loops of Henle, the greater the concentration of solutes becomes in the urine.