Principles of Animal PhysiologyExcretory SystemExcretory System▪Primary functions:Introduction▪Primary functions:▸ Maintenance of proper internal levels of inorganic solutes (Na+ K+ Cl CO2 etc)solutes (Na+, K+, Cl-, CO2, etc)▸ Maintenance of proper plasma water volume▸ Removal of nonnutritive and harmful substances from metabolism (ammonia, urea, bilirubin, etc)▸ Maintenance of osmotic balancePrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Organ systems involved in excretion and retentionIntroductiongy▪ Respiratory system▸ Regulate O2and CO2▸Gills can remove ammonia and HCO3-Gills can remove ammonia and HCO3▸ Participate in acid-base balance▪ Digestive system▸R l f di t d f d d t▸Removal of undigested food and wastes▸ May regulate ion and water▪ Integumentory system▸ Can excrete organic wastes▸ May regulate salt and water uptake▪ Renal organsg▸ Filter body fluids▸ Regulate water, ions and organic substancesPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Nitrogenous products from nitrogen metabolismIntroductionNitrogenous products from nitrogen metabolism▸ Ammonia (NH3)♦ Most bony fishes, larval amphibians and most invertebratesy, p♦ They are called ammonotelic animals▸ Urea♦ Most adult amphibians and mammals♦ They are called ureotelicanimals▸Uric acid▸Uric acid♦ Insects, birds, most reptiles, tree frogs and desert toads♦ They are called uricotelicanimalsPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Excretion of nitrogenous wastesIntroductiongPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Renal organs modify body fluids by four basic renal processes:▸ Filtration♦ Movement through a semipermeable membrane♦ An ultrafiltration is produced▸Secretion▸Secretion♦ Specific solutes are transported into the tubule lumen for excretion▸ Reabsorptionp♦ Specific solutes are transported back into the body from the lumen▸ Osmoconcentration♦ Water is removed from the lumen leaving solutes behindPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Schematic of functions of tubular excretory organPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Schematic of functions of tubular excretory organPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Functions of the mammalian kidneyThe Mammalian Urinary System▪Functions of the mammalian kidney▸ Regulate major inorganic solutesRl l l▸Regulate plasma volume▸ Regulate harmful or un-needed organic molecules▸ Osmotic balance▸ Secretion of erythropoietinyp▸ Secretion of renin▸Conversion of vitamin D to its active formConversion of vitamin D to its active form▸ Excretion of pheromonesPrinciples of Animal PhysiologyExcretory SystemExcretory System▪The KidneysThe Mammalian Urinary SystemThe Kidneys▸ Located on either side of vertebrae, between T12 and L3▸Left kidney slightly superior to rightLeft kidney slightly superior to right▸ Adrenal glands sit on superior surface of each kidneys▸ Kidneys lie between dorsal body wall and the parietal yypperitoneum▸ Each kidney is protected and stabilized by:♦ The renal capsule - layer of collagen fibers♦ The adipose capsule - thick layer of adipose tissue♦The renal fascia dense outer layer of collagen fibers♦The renal fascia -dense outer layer of collagen fibersPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ The urinary system in a mammalThe Mammalian Urinary SystemyyPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Gross anatomy of the human kidneyThe Mammalian Urinary SystemPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Internal anatomy of the human kidneyThe Mammalian Urinary System▪Internal anatomy of the human kidneyPrinciples of Animal PhysiologyExcretory SystemExcretory System▪ Gross anatomy of the kidney▸ Renal hilus - prominent medial indentation and point of f l l d i f i f h entry for renal artery, renal nerves and point of exit for the renal vein▸ Renal sinus - internal cavity within the kidneyyy▸ Renal Cortex - superficial layer in contact with capsule▸ Renal Medulla - inner layer - consists of♦Rl id ti l t t♦Renal pyramids -triangular structures♦ Renal papilla - projects from the tips of pyramids to sinus♦ Renal columns - separate pyramidsRl lb l id d l i t▸Renal lobe -renal pyramids and overlying cortex▸ Minor calyx - ducts into which urine drains from papilla▸Major calyx -collection of two or more minor calycesMajor calyx collection of two or more minor calyces▸ Renal pelvis - funnel-shaped chamber from which urine leaves kidneyPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Structure of kidneys and urinary systemThe Mammalian Urinary System▪Structure of kidneys and urinary system▸ Paired kidneys, lie retroperitonealC d f b 1 200 000 f i l i▸Composed of about 1,200,000 functional units▸ The functional unit is the nephron▸ Each nephron is composed of a glomerulus and a tubulePrinciples of Animal PhysiologyExcretory SystemExcretory System▪Functional parts of a nephronThe Mammalian Urinary System▪Functional parts of a nephron▸ Nephron - the smallest functional unit capable of the kidney’s basic functionsthe kidney s basic functionsPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Functional parts of a nephronThe Mammalian Urinary System▪Functional parts of a nephronPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Functional parts of a nephronThe Mammalian Urinary SystemFunctional parts of a nephron▸ Bowman’s (Glomerular) capsule▸GlomerulusGlomerulus▸ Proximal tubule▸ Loop of Henlep♦ Descending limb (thick & thin)♦ Loop♦ Ascending limb (thin & thick)▸ Juxtaglomerular apparatus (complex)▸Di t l t b l▸Distal tubule▸ Collecting ductPrinciples of Animal PhysiologyExcretory SystemExcretory System▪Two types of nephrons in birds & mammalsThe Mammalian Urinary System▪Two types of nephrons in birds & mammals▸ Cortical nephrons♦Originate in cortex♦Originate in cortex♦ Glomeruli lie in outer layer of cortex♦ Hairpin loop only dips slightly into medullary regionppypgy yg♦ Only has peritubular capillaries▸ Juxtamedullary nephronsy♦ Originate in cortex♦ Glomeruli lie in inner layer of cortex♦ Hairpin loop dips plunges deep into medullary region♦ Peritubular