Lecture 8 Volume composition of extracellular fluid is regulated by the excretory system Solute concentration The number of moles per actively solute liter Osmosis osmolarity Filtration reabsorption secretion Nephron Urine Most animals water based Osmoconformers equilibrate with their environment osmoregulators do not Isotonic Sharks rays use urea Use urea to match salt concentration Specific tissue Osmoconformer Sea monkey Conforms to the environment by maintaining an internal environment relatively similar to the external environment in which its living in Sharks skates rays Match osmolarity Osmoregulator Physically maintains an internal environment completely different form its external environment Almost all marine vertebrates Except cartilaginous fishes Some animals regulate ion concentrations Ionic regulators Regulate ion concentrations Active transport Using ATP Water follows and rinses salt out in little droplets Pumping chloride ions into tubes and sodium follows Nasal salt glands Regulate salt in body Remove salt by active transport Ionconformer Matches ion concentration Sea squirts tunicates Nitrogenous wastes are toxic and need to be excreted Ammonia urea uric acid Ureotelic Secrete urea Mammals most amphibians cartilaginous fishes Uricotelic Secrete uric acid Conserves a lot of water Birds insects reptiles Ammonotelic Secrete ammonia Aquatic invertebrates and most bony fishes Water solubility Ammonia is very soluble in water Uric acid is not very soluble in water Network of tubules Each tubule ends with a flame cell Small blunt ended tube with cilia in it Flame cells Cilia Pressure differences Moves wastes out Using protonephridia Extracellular fluid moves in by filtration Cilia beats and creates a slightly negative pressure Make urine less dilute that extracellular fluid Protonephridia Flatworms freshwater planaria metanephridia malpighian tubules process nitrogenous wastes Protonephridia metanephridia malpighian tubules process nitrogenous wastes Annelids Earthworms leeches Each segment is a fluid filled ceolome Use muscle to constrict fluid to move forward Nephrostome Opening that has cilia surrounding it Coelomic fluid is flowing in from the blood into the coelom and is swept by the cilia into the nephrostome Nephridopore Collect and process coelomic fluid Absorbs things that need to be maintaned Dilute urine Released through nehpridopore Protonephridia metanephridia malpighian tubules process nitrogenous wastes Insects Malpighian tubues Open circulatory system Active transport Blunt ended projections between midgut and hindgut Cannot generate a pressure difference due to open system Must be used to generate pressure difference Osmosis occurs Creates concentration gradient Vertebrate groups are found in many environments Marine vs freshwater Marine fish water wants to leave body water hypertonic to body Concentration is 1 3 to the concentration of sea water Cannot produce urine that is more concentrated that extracellular fluid Excrete excess salt actively across gills Osmoregulate extracellular fluid Freshwater fish water wants to go into body water hypotonic to body Sharks skates rays conform to match concentration using urea Take nitrogenous wastes and put back into the body Amphibians vs reptiles Live in or near fresh water Amphibians avoid losing too much water Make dilute urine and conserve salts Some live far away from water Coat body with waxy substance stopping water from leaving skin Reptiles adapted to both wet and dry environments Scales help prevent losing water Aren t tied to water Amniotes Don t need water for reproduction Secrete uric acid as waste Birds water is heavy Secrete uric acid Mammals habitat variety Only group of animals that can produce urine that is more concentrated that their extracellular fluid Use kidney and more specifically the nephron Vertebrates use the nephron for excretion Glomerulus Not of capillaries Inside bowman s capsule Empties into bowmans capsule Blood going into glomerulus is at a very high pressure With pressure water and filtrate comes with it Moves through tubule system becomes concentrated and leaves as urine Bowman s capsule podocytes Bowman s receives the glomerular filtrate Podocytes are the start of the renal tubule system Alter composition of glomerular filtrate through reabsorption and filtration Selective permeability of the tubules Comes into the kidney Surrounds the tubule system so everything being pulled out can go back into the blood Final product of nephron Kidneys produce urine and the bladder stores urine Renal tubule Blood flow Urine Adrenal glands Within kindey Cortex Medulla Ureter Urethra Transports urine from kidney to bladder Transports urine from bladder to toilet Nephrons have a specific arrangement Proximal convoluted tubule PCT Closer to glomerulus In cortex Distal convoluted tubule DCT Farther away from glomerulus In cortex Loop of henle In medulla Capillary bed Collecting duct In medulla Glomerulus In cortex Nephrons concentrate urine using gradients Medulla loop of henle concetrantion gradient Becomes concentrated by removing a lot of water Countercurrent multiplier Fluid and concentration gradient are opposite Multiplier ascending loop is extracting salts which increases water retention in later fluid Permeability to water PCT descending loop of henle DCT collecting duct are permeable to water Ascending loop is IMPERMEABLE to water Lose NaCl Active transport Used in PCT Remove molecules that you want to retain in body Descending loop of Henle Osmosis Urine concentration depends on the length of the loops of henle Relative to kidney size Desert and terrestrial animals Loop of henle extends into renal pelvis Increased size Kidneys regulate the pH balance of the extracellular fluid Regulates proton hydrogen ion concentration NH4 Ammonium transporter RHCG Used to buffer the pH in the blood Excretes excess protons in the form of ammonium NH4 Antiporter Symporter Dialysis is used to treat kidney failure High blood pressure salt and water retention low pH Filter out waste from blood and put clean blood back in Glomerulus filtration rate is regulated by enzymes and hormones Renin Arteriole dilation Causes a cascade Angiotensinogen becomes angiotensin 1 Angiotensin 1 becomes angiotensin Angiotensin Stimulates thirst Stimulates adrenal cortex to Aldosterone Afferent comes in Efferent exiting ADH Hormonal control increases blood pressure and water reabsorption Rise Blood osmolarity