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Overview of the Urogenital Overview of the Urogenital system: Urinary divisionsystem: Urinary division
KidneysKidneys UreterUreter
BladderBladder UrethraUrethra
The Urinary SystemThe Urinary SystemThe mammalian KidneyThe mammalian Kidney
Macroanatomy of the Kidney
Kidney MacroanatomyKidney MacroanatomyFrontal SectionFrontal Section
Kidney RegionsKidney Regions
Cortex
Medulla
Pyramids
papilla
Renal PelvisRenal Pelvis
Minor calycesMinor calyces
Major calyxMajor calyx
Renal Artery and Renal Artery and VeinVein
artery branches artery branches and and vein vein tributariestributaries
Kidney FunctionKidney Function
Excretory FunctionExcretory FunctionFilters blood plasma, eliminates waste, Filters blood plasma, eliminates waste, returns useful chemicals to bloodreturns useful chemicals to blood
Homeostatic Functions Homeostatic Functions (Endocrine System)(Endocrine System)
Osmoregulatory FunctionOsmoregulatory FunctionRegulates osmolarity of body fluidsRegulates osmolarity of body fluids
Regulates blood volume and pressure Regulates blood volume and pressure Secretes renin, activates angiotensin, Secretes renin, activates angiotensin, aldosteronealdosterone
• controls BP, electrolyte balancecontrols BP, electrolyte balance
Secretes erythropoietin, controls RBC countSecretes erythropoietin, controls RBC count
Regulates PRegulates PCO2CO2 and acid base balance and acid base balance
GluconeogenesisGluconeogenesis
Kidney FunctionKidney FunctionExcretory -- Formation of Excretory -- Formation of UrineUrine
Filter and Excrete toxins, metabolic waste products, Filter and Excrete toxins, metabolic waste products, excess ions, organic acids, and nitrogenous wastes.excess ions, organic acids, and nitrogenous wastes.
Uric acid: Uric acid: results from results from the catabolism the catabolism of nucleic acidsof nucleic acids
Urea: Urea: derived from derived from the breakdown the breakdown of amino acidsof amino acids
Proteins Proteins amino acids amino acids NH NH22 removed removed forms ammonia which the forms ammonia which the liver converts to urealiver converts to urea
Creatinine: Creatinine: derived from derived from The breakdown of creatine The breakdown of creatine phosphate ( a molecule in phosphate ( a molecule in muscle that stores energy used in muscle that stores energy used in the synthesis of ATP)the synthesis of ATP)
The main waste products excreted in urine are The main waste products excreted in urine are the nitrogenous compounds.the nitrogenous compounds.
Kidney MicroanatomyKidney Microanatomy
Nephron (renal tubule)
Glomerular capsuleProximal convoluted
tubuleLoop of Henle
Decending limbAscending limb
Distal convoluted tubule
Collecting Duct
Kidney Urine FormationKidney Urine FormationFiltration – Reabsorption – Filtration – Reabsorption –
SecretionSecretion
Kidney Urine FormationKidney Urine FormationFiltrationFiltration
Blood with all materials Blood with all materials entersenters the glomerular the glomerular capillariescapillaries Small molecules pass from Small molecules pass from the the capillaries into the capillaries into the capsular capsular spacespace sodium (Na sodium (Na ++))
HH22OO glucoseglucose potassium (Kpotassium (K++)) nitrogenous wastesnitrogenous wastes
These molecules are These molecules are filtered by cell membranes filtered by cell membranes based on size and chargebased on size and charge
Renal Renal CorpusleCorpusle
Kidney Kidney Filtration MembraneFiltration Membrane
Fenestrated endotheliumFenestrated endotheliumof the glomerular of the glomerular
capillariescapillaries70-90nm pores exclude 70-90nm pores exclude
blood cellsblood cells
• Basement membrane Basement membrane (main (main molecular filter)molecular filter)
Proteoglycan gel, negativeProteoglycan gel, negative charge excludes charge excludes molecules molecules > 8nm (ex. Proteins)> 8nm (ex. Proteins)
Filtration slitsFiltration slitsPodocyte (Podocyte (cells of the viseral cells of the viseral
layer of the glomerular capsulelayer of the glomerular capsule) ) arms have pedicelsarms have pedicels
with negatively chargewith negatively charge filtration slitsfiltration slits
Renal Renal CorpusleCorpusle
The Juxtaglomerular apparatus: The Juxtaglomerular apparatus: senses BP in the afferent arteriolesenses BP in the afferent arteriole
Reabsorption in the Proximal Reabsorption in the Proximal Convoluted TubuleConvoluted Tubule
MechanismsMechanisms
Leakage or Diffusion Leakage or Diffusion through tight through tight junctionjunction
Active transportActive transport
Secondary active Secondary active transport-- transport--
antiportantiport
Facilitated diffusionFacilitated diffusion
Diffusion through Diffusion through membrane membrane channelchannel
Solvent Drag: Solvent Drag: HH22O O absorbabsorb by osmosis and drags by osmosis and drags solute along with itsolute along with it
• PinocytosisPinocytosis
Peritubular capillary
Epithelial cells
Tubular Fluid
Additional waste materials enter the Additional waste materials enter the tubule from the interstitial fluid by the tubule from the interstitial fluid by the same mechanisms which facilitated same mechanisms which facilitated reabsorption.reabsorption.
Waste removalWaste removalurea, uric acid, bile salts, ammonia, urea, uric acid, bile salts, ammonia,
catecholamines, many drugscatecholamines, many drugsAcid-base balanceAcid-base balance
secretion of hydrogen and secretion of hydrogen and bicarbonate ions bicarbonate ions regulates pH of body regulates pH of body fluidsfluids
Primary function of nephron loop Primary function of nephron loop water conservation, also involved in water conservation, also involved in
electrolyte electrolyte reabsorptionreabsorption
Secretion into theSecretion into theProximal Convoluted Proximal Convoluted Tubule Tubule and Nephron Loopand Nephron Loop
UrineUrine
Physical CharacteristicsPhysical Characteristics– Color: due to urochromate (pigment released Color: due to urochromate (pigment released
in hemoglobin catabolism)in hemoglobin catabolism)– Odor: Ammonia, due to bacterial metabolismOdor: Ammonia, due to bacterial metabolism– pH: ~6.0 (acidic) that varies with dietpH: ~6.0 (acidic) that varies with diet– Specific gravity: more dense than distilled Specific gravity: more dense than distilled
waterwater Chemical CharacteristicsChemical Characteristics
– 95% water, 5% solutes95% water, 5% solutes– Urea: Nitrogenous wastes from catabolism of Urea: Nitrogenous wastes from catabolism of
Amino Acids, creatine phosphate, etc.Amino Acids, creatine phosphate, etc.