Chapter 25- Control of Internal Environment Ammonia Bowman’s capsule Collecting duct Countercurrent heat exchanger Dialysis Distal tubule Endotherms Estivation Excretion Exotherms Filtrate Filtration Glomerulus Hepatic portal vessel Hibernation Loop of Henle Nephrons Osmoconformers Osmoregulation Osmoregulators Proximal tubule Reabsorption Renal cortex Renal medulla Secretion Thermoregulation Torpor Urea Ureter Urethra Uric acid Urinary bladder

Thermoregulation Maintenance of internal temperature –Endotherm- organisms that derive body heat from metabolism –Ectotherm- absorb most heat from their surrounding 4 ways heat is gained/lost: –Conduction- direct transfer of heat through contact –Convection- transfer by movement of air or water past a body surface –Radiation- emission of electromagnetic E –Evaporative cooling- loss of heat from surface of a liquid that is transforming into gas

Maintaining Body Temperature Change rate of heat lost/gained by the 4 methods on previous slide Countercurrent heat exchanger- prevents heat loss, like it does to prevent O 2 loss in fish Behavior affects body temperature –Ex: migrate, bask in sun, huddling together

Maintaining Body Temperature Alter metabolic rate of heat production Reducing metabolic rate- saves E –Torpor- state of reduced activity, body temp and metabolic rate decrease, heart and respiratory system slows –Hibernation- long term torpor- live off E stored in body fat –Estivation- “summer torpor”- to survive long periods of high temp with little food or water

Osmoregulation Osmoconformers- aquatic animals that have solute conc. in body fluids = to seawater –* will need to expend E to keep ion conc’s maintained Osmoregulators- animals whose conc of solute is different from environment, they expend E to control water gain/loss –saltwater vs. freshwater fish Sweating- produces water loss, while trying to stay cool (thermoregulation)

Osmoregulation in fish

Waste disposal Animals need to dispose of nitrogen wastes (from protein and nucleic acid breakdown) or be at risk of poisoning –Aquatic animals- can dispose of ammonia because it’s very soluble in water, it readily diffuses into water environment –Most terrestrial animals- (ammonia can’t diffuse into air) body expends E to convert ammonia into less toxic urea/uric acid and is then released through excretory system

Carbs and fats- broken down into carbon dioxide and water

Human Excretory System

Parts of the excretory system Ureter - tube that leads to urinary bladder- where urine is stored until it is expelled through urethra Kidney- regulates chemical composition in blood, therefore chem composition of body fluids –Renal cortex, renal medulla, renal pelvis –Produces 180L of filtrate a day which is refined to produce 1.5L of urine!! –Nephron- extract filtrate and refine it, 1 million per kidney Bowman’s capsule- receiving end, around glomerulus, absorption takes place here Glomerulus- ball of capillaries in capsule, together they make up blood filtering unit Proximal tube, loop of Henle and distal tube- refine filtrate

4 functions of the Excretory System Filtration- water & molecules forces through capillary wall and enter nephron Reabsorption- water & valuable solutes (glucose, aa’s, salts)- reclaimed from filtrate and return to blood Secretion- certain molecules are moved to filtrate from blood –Ex: excess K+ and H+ (keeps blood from becoming acidic) Excretion- urine passes from kidney through ureters to bladder

–Gradient changes from cortex to inner medulla, helps with water absorption –Drugs that were processed in liver enter filtrate in proximal tubule –ADH (antidiuretic hormone)- signals nephron to reabsorb water Alcohol inhibits ADH = excessive urination

Dialysis Does the job of kidney, cleanses blood –Timely and costly unfortunately

The Liver More functions than any other organ!!! –Aids in digestion- produces bile –Prepares nitrogen wastes- synthesizes urea –Synthesizes plasma proteins- blood clotting –Regulates blood glucose- converts glucose to glycogen and stores it for later –Helps kidneys get rid of alcohol/drugs- converts them into inactive products that kidneys can remove –Hepatic portal vessel- conveys blood to liver to modify/detox – absorbs substances before blood is pumped to body

How the human kidney concentrates urine