the urinary system glen hookey eric kolker justin loeb michael ross uston—period 5
TRANSCRIPT
The Urinary System
Glen Hookey Eric Kolker Justin Loeb Michael Ross
Uston—Period 5
Overview
Animals and Waste
• Filter body fluid for toxins and unnecessary substances
• Kidneys (bp, activation of vitamin D, erythropoietin, wastes)
• Nitrogenous waste
Transport Epithelium
• Manage solute levels
• Line many channels inside the body
• Comprised of special epithelial cells
• Can move solutes against gradient
Nitrogenous Wastes
• Three types: Ammonia, Urea, Uric Acid• Ammonia
– Highly toxic, diluted with large supplies of water
• Urea– Low toxicity, energy cost (used by mammals)
• Uric Acid– Low toxicity, water insoluble, excreted as a paste
Excretory Processes
• Filtration– One layer of transport epithelium (large molecules removed);
filtrate
• Reabsorption– Active transport (glucose, amino acids, etc.)
• Secretion– Materials added to excretory tubule
• Excretion– Expelled as urine
Filtrate/Urine Pathway
Kidney
• Filters substances form blood
• Adjusts filtrate’s composition
• Returns most substances to blood
Nephron
• Functional unit
• Packed tubules
• Surrounded by capillaries
• Filters blood
Bowman’s Capsule
• Start of Nephron• Glomerulus• Filtration into
lumen:– Water, salts
bicarbonate, hydrogen ions, urea, glucose, amino acids
Proximal Tubule
• pH maintained• Reabsorption• Reabsorbs Na+
osmosis
Loop of Henle
• Descending– Water
• Ascending– Thin & Thick
– Passive & Active
Distal Tubule
• pH regulation• Sodium, calcium,
potassium
Collecting Duct
• Subject to hormonal controls
• Diseases• Concentration of
filtrate
Urine Composition
• Excess water and solutes• Ions• Urea• Neurotransmitters• Histamine• Drugs/toxins
Osmoregulation
• Solute gradient• Bends in nephron• Membrane selective
permeability• Diffusion• Active transport• Salt
Solute Gradient
• Membrane selective permeability
• Interstitial fluid• Filtrate• Active transport• Diffusion
Nephron Overview
ProximalTubule
DescendingLoop of the henle
AscendingLoop of the henle
DistalTubule
Collectingduct
Gradient Overview
Gradient #1: Proximal tubule• Blood
– ~300 mosm/L• Interstitial fluid:
– ~300 mosm/L• Filtrate:
– ~300 mosm/L– In:
• Hydrogen ions• Ammonia
– Out:• Bicarbonate• Salt• Water• Nutrients• Potassium ions
• In cortex• Volume decreased• Osmolarity stays constant
Gradient #2: Descending Loop of the Henle
– Interstitial fluid• 300 - 1200 mosm/L
– Filtrate• 300 - 1200 mosm/L
• In– N/A
• Out– Water
– Membrane permeable only to water
– Salt concentration increases
– Water diffuses out
Gradient #3: Ascending Loop of the Henle
• Ascending loop– Interstitial fluid
• 1200 - 300 mosm/L
– Filtrate• 1200 - 200 mosm/L• In
– N/A
• Out– Salt
– Membrane permeable only to Salt
– Salt concentration decreases– Filtrate osmolarity lowered to
increase osmolarity of interstitial fluid
Gradient #4: Distal tubule
• Interstitial fluid– 300 mosm/L
• Filtrate– 100 mosm/L
– In• Potassium ions
• Hydrogen ions
– Out• Salt
• Water
• Bicarbonate
• Filtrate at lowest osmolarity
• Key role in determination of pH of urine
Gradient #5: Collection duct• Interstitial fluid
– 300 - 1200 mosm/L
• Filtrate– 300 - 1200 mosm/L– In
• N/A
– Out• Salt• Urea• Water
• Final stage• Controls final salt output• Low salt• Water diffuses• Concentrated filtrate
Regulation #1: ADH
• Antidiuretic hormone• Hormone• Activated by
hypothalamus at high blood osmolarity
• Decreases water loss– More permeability to
water
Regulation #2: RAAS
• Renin-angiotensin-aldosterone system
• Angiotensin II• Activated at low blood
pressure/volume• Decreases water loss
– Constricts capillaries– More reabsorption of
salt
Regulation #3: ANF
• Atrial natriuretic factor• Opposite of ADH and
RAAS– Triggered by high blood
pressure/volume– Inhibits NaCl absorption– Increased water loss
through urine
• Disables ADH
Ureter
• Lining of ureter
• Smooth-muscle cells contractions
• Ureter crosses bladder wall
• Ureter in Micturition
Urinary Bladder• Storage organ
• Bladder in micturition
• Brain cells
• Structure
Urethra
• Function and location
• Cells of Urethra
• External Meatus
Abnormalities of the Renal System
• Acute
• Chronic
• Congenital
Congenital Problems
• Horseshoe kidneys– Functions as one kidney
• Has to be cautious of rigorous activity
Acute Problems
• Usually reversible• Examples: stones, infections, tumors,
inflammation, acute renal failure• Detected by urinalysis or by pain and fever
Urinary Tract Infection (UTI)
• Occurs anywhere along the urinary tract (kidneys, bladder)
• Women more prone than men; shorter urethra
• Pain and fever• Treated with antibiotics
Tumors and Stones• Most tumors in kidneys
and bladder are malignant
• Smokers are prone to bladder tumors
• Stones- intensely painful• Can be passed but some
require surgery or ultrasound
Trauma
• Kidneys damaged by physical trauma
• People with one kidney have to avoid potentially dangerous activities
• Blood in urine
Chronic Kidney Failure• Dialysis (3 days a week; 4 hours)
– Cleans blood
• Only cure is transplantation