Overview of the Urogenital system: Urinary division

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Overview of the Urogenital system Urinary
division

• Kidneys
• Ureter
• Bladder
• Urethra

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The Urinary SystemThe mammalian Kidney
Macroanatomy of the Kidney
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Organs of the Urogenital system
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Kidney MacroanatomyFrontal Section

• Kidney Regions
• Cortex
• Medulla
• Pyramids
• papilla
• Renal Pelvis
• Minor calyces
• Major calyx
• Renal Artery and Vein
• artery branches and vein tributaries

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Location and structure of nephrons
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Kidney Function

• Excretory Function
• Filters blood plasma, eliminates waste, returns
  useful chemicals to blood
• Homeostatic Functions (Endocrine System)
• Osmoregulatory Function
• Regulates osmolarity of body fluids
• Regulates blood volume and pressure
• Secretes renin, activates angiotensin,
  aldosterone
• controls BP, electrolyte balance
• Secretes erythropoietin, controls RBC count
• Regulates PCO2 and acid base balance
• Gluconeogenesis

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Kidney Function
Excretory -- Formation of Urine
Filter and Excrete toxins, metabolic waste
products, excess ions, organic acids, and
nitrogenous wastes.
The main waste products excreted in urine are the
nitrogenous compounds.
Uric acid results from the catabolism of
nucleic acids
Urea derived from the breakdown of amino
acids Proteins ? amino acids ? NH2 removed ?
forms ammonia which the liver converts to urea
Creatinine derived from The breakdown of
creatine phosphate ( a molecule in
muscle that stores energy used in the synthesis
of ATP)
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Kidney Microanatomy
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Kidney Microanatomy

• Nephron (renal tubule)
• Glomerular capsule
• Proximal convoluted tubule
• Loop of Henle
• Decending limb
• Ascending limb
• Distal convoluted tubule
• Collecting Duct

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Kidney Urine FormationFiltration Reabsorption
Secretion
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Kidney Urine FormationFiltration
Blood with all materials enters the
glomerular capillaries Small molecules pass
from the capillaries into the
capsular space sodium (Na
) H2O glucose potassium (K)
nitrogenous wastes These molecules are
filtered by cell membranes based on size and
charge
Renal Corpusle
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Kidney Filtration Membrane

• Fenestrated endothelium
• of the glomerular capillaries
• 70-90nm pores exclude blood cells
• Basement membrane (main molecular filter)
• Proteoglycan gel, negative
• charge excludes molecules
• gt 8nm (ex. Proteins)
• Filtration slits
• Podocyte (cells of the viseral layer of the
  glomerular capsule) arms have pedicels
• with negatively charge
• filtration slits

Renal Corpusle
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The filtration slits
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The Juxtaglomerular apparatus senses BP in the
afferent arteriole
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Reabsorption in the Proximal Convoluted Tubule

• Mechanisms
• Leakage or Diffusion
• through tight junction
• Active transport
• Secondary active
• transport-- antiport
• Facilitated diffusion
• Diffusion through
• membrane channel
• Solvent Drag H2O absorb
• by osmosis and drags
• solute along with it

Peritubular capillary
Epithelial cells
Tubular Fluid
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Secretion into the Proximal Convoluted Tubule
and Nephron Loop
Additional waste materials enter the tubule from
the interstitial fluid by the same mechanisms
which facilitated reabsorption. Waste
removal urea, uric acid, bile salts, ammonia,
catecholamines, many drugs Acid-base
balance secretion of hydrogen and bicarbonate
ions regulates pH of body fluids Primary
function of nephron loop water conservation,
also involved in electrolyte reabsorption
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Summary of Molecules Reabsorbed and Secreted
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Urine

• Physical Characteristics
• Color due to urochromate (pigment released in
  hemoglobin catabolism)
• Odor Ammonia, due to bacterial metabolism
• pH 6.0 (acidic) that varies with diet
• Specific gravity more dense than distilled
  water
• Chemical Characteristics
• 95 water, 5 solutes
• Urea Nitrogenous wastes from catabolism of
  Amino Acids, creatine phosphate, etc.