Compare the endocrine and nervous systems HW: -Read 32.3 and 32.4 Turn in: -Test corrections if haven’t already

Osmoregulation Process by which animals control solute concentrations in interstitial fluid and balance water gain and loss Breakdown of nitrogenous compounds creates ammonia (toxic) Excretion- process that rids the body of toxic metabolites

Osmosis and Osmolarity All animals need to balance water uptake and loss Osmosis? Osmolarity= total solute concentration expressed as molarity (moles of solute per liter of solution) milliOsmoles per liter (mOsm/L)

Situations Isoosmotic Hyperosmostic Hypoosmotic

Osmoregulatory Challenges and Mechanisms Osmoconformer- *All are marine animals Osmoregulator-? Allows animals to live in environments uninhabitable to osmoconformers

Consider Marine vs. Freshwater Marine environment very dehydrating- what should happen to the fish What about freshwater?

Nitrogenous Wastes Most metabolic wastes need to be dissolved in water to be excreted through the body Ammonia (NH 4 + ) is toxic because it interferes with oxidative phosphorylation Some animals are able to excrete it directly Others have to convert it to other forms before excretion Urea and uric acid

Ammonia, Urea, or Uric Acid? Ammonia needs lots of water to be tolerated when released Aquatic Most vertebrates need to use urea so as not to lose the amount of water required to release ammonia Very low toxicity Uric acid- paste, requires very little water loss Lizards, snails, birds Much more energetically expensive than urea!

Excretory Process Most osmoregulation and removal of nitrogenous wastes use transport epithelia Kidney in vertebrates- water balance and blood pressure

Homeostatic Regulation of Kidneys Nervous and hormonal systems help control Key hormone: Antidiuretic hormone (ADH) ADH release increases number of aquaporins in kidney cells Increase reabsorption of water

ADH and Dehydration Blood osmolarity rises from sweating or eating salty foods Increase in ADH Increase in aquaporins Increase in water reabsorption Concentrated urine bc losing less water

RAAS Renin-Aldosterone- Angiotensin System Deals with blood volume when lose a lot