Urinary System

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Urinary System
2012-07-25 12:52:07
Kidneys bladder urinary system

Urinary system
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  1. Kidneys function?
    Filtration of blood and production of urine
  2. Ureters function?
    Transportation of urine
  3. Urinary Bladder function?
    Storage of urine
  4. Urethra function?
    Excretion of urine
  5. Micturition (urination)
    • Stretch receptors signal spinal cord and brain
    • When VL exceeds 200-400ml
  6. Micturition center in sacral spinal cord triggers what reflex?
    • Parasympathtic fibers cause detrusor muscle to contract - squeezes urine out
    • external & internal sphincter muscles to relax and allow flow
  7. Desire to urinate before reflex occurs..
    • Conscious control of external sphincter
    • Cerebral cortex can initate micturition or delay it for a period of time.
  8. Kidneys: Renal corpuscle function?
    filtration ofblood plasma
  9. glomerulus
    Capillary with blood in Renal Corpuscle
  10. Bowmans Capsule
    Collects filtrate from blood in Renal Corpuscle
  11. Renal tubule
    • Proximal convoluted tubule
    • Descending & Ascending loop of Henle
    • Distal convoluted tubule
    • Collecting duct
    • Papillary duct
    • Minor & Major Calyx
    • Renal Pelvis
    • Ureter > Urinary bladder > Urethra
  12. Glomerular Filtration
    • Water & small soultes in blood plasma move across the wall of the glomerular capillaries into glomerular corpuscle and then renal tubule.
    • PCT > loop of henle > DCT > collecting duct
  13. Tubular Reabsorption
    As filtrate moves along tubule water and many useful solutes reabsorbed = returned to blood
  14. Tubular Secretion
    filtrate moves along tubule other molecules are secreted into fluid (wastes, drus & excess ions)
  15. What drives filtration?
    • Blood Pressure
    • 20% of plasma becomes filtrate
  16. Filtration Membrane: What is filtered?
    • Water, ions, small molecules & small proteins move through membrane :lucose, amino acids,
    • Becomes filtrate
  17. Fenestration of glomerular endothelial cell
    Prevents filtration of blood cells but allows all components of blood plasma to pass through
  18. Basal lamina of glomerulus
    Prevents filtration of larger proteins -Albumins
  19. Slit membrane between pedicels
    Prevents filtration of medium sized proteins
  20. Glomerular Blood Hydrostatic Pressure (GBHP)
  21. Capsular Hydrostatic Pressure (CHP)
  22. Blood Colloid Osmotic Pressure (BCOP)
  23. Net Filtration Pressure (NFP)
    GHBP - CHP - BCOP = 55mmhg - 15mmhg - 30 mmhg = 10mmhg
  24. Functions of Kidneys
    • Regulates ions in blood
    • - blood pH
    • - Blood Volume and Blood Pressure
    • - Blood Glucose levels
    • Maintains Blood Osmolarity
    • Produces Hormones
    • Excretion of wastes
  25. Regulation of pH in Kidneys
    • Removes H+ from blood
    • Maintains bicarbonate ions (HCO3-) in blood
  26. Regulation of Blood Volume and BP
    • Retention of water = increases BP
    • Elimination of water = decreases BP
  27. Production of Hormones in Kidneys
    • Calcitrol - Form of Vita. D (Active)
    • ---Calcium homeostasis
    • Erthropoietin (EPO) - RBC production
  28. Regulation of Blood Glucose levels in kidneys
    Can synthesize glucose from glutamine
  29. Excretion of wastes in Kidneys
    • Ammonia & Urea
    • Bilirubin
    • Creatine
    • Uric Acid (purine metabolism - A's & G's of DNA)
    • Drugs and Toxins
  30. Gout
    Arthritis - Excess uric acid
  31. Production of Urine
    • 1. Glomerular Filtration
    • 2. Tubular reabsorption
    • 3. Tubular secretion
  32. GFR -too high =
    useful substances are lost Urine
  33. GFR- too low =
    Not enough Waste products removed from body
  34. Mechanisms that maintain a constant GFR
    • Renal Autoregulation
    •  - 1. Myogenic Mechanism
    •  - 2. Tubuloglomerular feedback
  35. Renal Autoregulation
    2 ways kidneys help maintain a constant renal blood flow
  36. Myogenic Mechanism:
    • - Evalated BP cause Stretching of the afferent arteriole
    • - Smooth muscle contraction constricts afferent arteriole returning GFR to its previous level.
  37. Tubuloglomerular feedback :
    • Elevated BP raises the GFR so that fluid flows too rapidly through the renal tubule
    • - macula Densa Cells detect that filtrate is moving too fast.
    • - Inhibits the release of Nitric Oxide (NO)- a vasodilator
    • - Afferent arterioles constrict & reduce GFR
  38. Neural Regulation
    • Sympathetic neurons cause vasocontriction of afferent arterioles
    • - Decreases GFR = lowers urine output and permits blood flow to other tissues
    • -At rest, renal Blood vessels are maximally dilated because sympathetic activity is minimal. (Parasympathetic is maximal)
  39. Hormonal Regulation
    • - Angiotensin II = decrease GFR
    •      -low blood VL & low BP stimulates productoin of Angiotensin II
    •      - Potent vasoconstrictor that narrows bothafferent & efferent arterioles reducing GFR

    • - atrial natriuretic peptide (ANP)
    •    -strecthing of the atria due to an increase in blood volume causes release of ANP
    •    - increases capillary suface area by relaxation of mesangial cells
    •    - Increases GFR
  40. Glomerular Filtration Rate must remain
    Constant - homeostasis requires GFR to remain constant
  41. Angiotensin II
    Decreases GFR

    • -low blood volume and low BP stimulates production of Angiotensin II
    • -Potent Vasoconstrictor that narrows both afferent & efferent arterioles reducing GFR
  42. Atrial Natriuretic Peptide (ANP)
    increases GFR

    • Stretching of the atria due to an increase in blood VL causes release of ANP
    • increase in capillary surface area by relaxation of mesangial cells
  43. What is the Renal Hilum? 5 specific structures?
    Indentation of kidneys

    • 1. lymphatics
    • 2. nerves
    • 3. ureters
    • 4. renal vein
    • 5. renal artery
  44. What are renal Columns?
    columns of tissue that are identical to the tissue found in the renal cortex but located in the medulla between renal pyramids.
  45. What are renal pyramids?
    Cone-shaped arrangement of tubules in renal medulla
  46. Who has a loner urethra males or females?
  47. Internal urethral sphincter is voluntary or involuntary?
  48. external urethral sphincter is voluntary or involuntary?
  49. Tubular Reabsorption along the Nephron
    • 180L of filtrate produced
    • 99% must be reabsorped by Nephron
    • Water + Solutes move tubules to Peritubular Capillaries
  50. Peritubular Capillaries (PCT)
    • Has Microvilli- does the reabsorption
    • Solutes are reabsorbed by Active Transport and Passive Diffusion - GLucose, amino acids, urea, and ions

    65% of water follows by osmosis
  51. Reabsorption in the PCT
    -Solutes reabsorption
    100% of: Glucose, amino acids, lactic acid, water soluble vitamins and other nutrients are Completely areaborped in the 1st half of the PCT
  52. Reabsorption of NA+ in PCT produces what?
    Produces electrical gradient that caused Cl- to follow by passive transport
  53. What helps "pull" water out of the tubule in PCT?
    Accumulation of NaCl outside tubule produces an osmotic gradient?
  54. Reaborption  at the descending Loop of Henle
    • 15% of filtered water ir reabsorbed
    • High solute content of medulla "pulls" water out -By Osmotic gradient
    • Impermeable to solutes = Little reabsorption of more solutes
  55. Reaborption  at the Ascending Loop of Henle
    • Variety of transporters reclaim more ions by diffusion
    • Impermeable to water = little reabsorption of water
  56. Reabsorption  at the Distal Convoluted Tubule
    • Reabsorption of Na+ and Cl- continues
    • 10-15% of water reabsorption by Osmosis
    • Serves as the major site where Parathyroid hormone stimulates reaborption of Ca+2
  57. What Serves as the major site where Parathyroid hormone stimulates reaborption of Ca+2?
    The Distal Convoluted Tubule
  58. Collecting Ducts cells
    • 95% of solutes & water have been reabsorbed by the end of DCT
    • Principal Cells & Intercalated cells make the final adjustments
  59. Principal Cells
    • Target 2 hormones that promote reabsorption of more water and Ions
    • 1.ADH-anti-dieuretic, Targets principal cells in collecting duct
    • ----Increases water reabsorption

    • 2. Aldosterone- increases reabsorption of Na+ and Cl- (water's reabsorbed)
    • ----Secretion of a varible amount of K+
  60. What does ADH do in the collecting duct?
    -anti-dieuretic, Targets principal cells in collecting duct----Increases water reabsorption
  61. What does Aldosterone do in the collecting duct?
    • - increases reabsorption of Na+ and Cl- (water's reabsorbed)
    • -Secretion of a varible amount of K+
  62. Intercalated Cells:
    • Help regulate pH of body fluids
    • Proton pumps (H+ATPases) secrete H+ into tubule (prevents accumulation of blood)
    • Reabsorption of bicarbonate ions (buffers blood pH)
  63. What do proton pumps do in Intercalated cells? What does this prevent?
    • Proton pumps (H+ATPases) secrete H+ into tubule
    • Prevents accumulation of blood
  64. What is the function of bicarbonate ions in Intercalated cells?
    • When reabsorbed they buffer blood pH
    • (so you dont urinate acid)
  65. ADH Feedback System
    • -Simulus: High osmolarity of body fluids (low water, dehydration)
    • -Receptor: Osmoreceptors of hypothalamus
    • -Control: Hypothalamus/Post. Pituitary release ADH
    • -Effectors: Principal cells of collecting ducts
    • -Responses:
    • 1. insertion of aquaporin-2 channels into the tubule
    • 2. h20 molecules move out of collectging duct and into bloodstream
    • 3. Conservation of water results in concentrated urine (yellow urine)
  66. ADH Feedback: Stimulus
    -Simulus: High osmolarity of body fluids (low water, dehydration)
  67. ADH Feedback: Receptors
    -Receptor: Osmoreceptors of hypothalamus
  68. ADH Feedback: Control Center
    -Control: Hypothalamus/Post. Pituitary release ADH
  69. ADH Feedback: Effectors
    Effectors: Principal cells of collecting ducts
  70. ADH Feedback: Responses (3)
    • 1. insertion of aquaporin2 channels into the tubule
    • 2. h20 molecules move out of collecting duct and into bloodstream
    • 3. Conservation of water results in concentrated urine (yellow urine)
  71. Renin-Angiotensin-Aldosterone (RAA)
    • 1.Low BV/BP causes Renin to be release from kidneys
    • 2.Renin stimulates release of angiotensinogen converts to angiotensin 1
    • 3. Angiotensin 1 converts ACE into Angiotensin 2
    • 4. Angiotensin 2 causes aldosterone to retain Na+ & water and vasoconstriction of Afferent arterioles which lowers GFR. (Both raise BV then BP), and vasoconstriction of arterioles which raise BP
  72. Atrial Natriuretic peptide does what?
    • 1.Inhibits secretion of aldosterone & ADH
    • 2.Suppresses reabsroption of Na+ which increases urine output and decreases blood volume
    • 3.increases GFR by increasing permeability of glomerulus
  73. Angiotensin 2 stimuli & effects
    • Stimuli: low BV/BP
    • Effects: Increases reaborption of Na+ & other solutes, Increases BV
  74. Aldosterone stimuli & effects
    Effects: Increases secretion of K+ and reabsorption of Na+, Cl-; increases reabsorption of water = Increase in BV

    Conserves water
  75. ADH stimuli, mechanism & effects
    • Stimuli: increased osmolarity, decreased BV, released from post. pituitary gland
    • Mechanism: insertion of aquaporin 2 channels.
    • Effects: Increases facultative reaborption of water

    Conserves Water
  76. Atrial Natriuretic Peptide (ANP) effects
    • Natriuresis- increased excretion of Na+ in urine
    • Diuresis- Increased urine output
    • Decreases BV
    • Gets rid of water
  77. What is Natriuresis?
    Natriuresis- increased excretion of Na+ in urine
  78. What is Diuresis?
     Increased urine output
  79. Parathyroid Hormone site of action & effects
    • Site of action: Distal tubule cells
    • Effects: Increases reabsorption of Ca2+
  80. What hormones Increase BV?
    Angiotensin 2, Aldosterone
  81. Tubular Secretion does what?
    Transfers materials from blood into filtrate/urine
  82. Tubular Secretion is located where?
    At various locations along tubules
  83. Tubular Secretion eliminates what?
    excess K+, ammonia, urea, creatinine - depends on diet
  84. Tubular Secretion & Penicillin
    Penicillin gets metabolized by liver or kidneys secrete it
  85. Where does H20 get reabsorbed?
    • 65% Proximal convoluted tubule (osmosis)
    • 15% Loop of Henle (osmosis in descending limb)
    • 10-15% Early Distal Convoluted Tubule
    • 5-9% Late DCT & collecting duct (insertion of h20 channels stimulated by ADH)
  86. Where does glucose get reabsorbed?
    100% Proximal convoluted tubule
  87. Where do amino acids get reabsorbed?
    100% proximal convoluted tubule (symporters and facilitated diffusion)
  88. Diuretics
    • Promote diuresis
    • -Most potent- loop diuretics- inhibits transporters (Na-K-Cl symporter) in the ascending loop of henle
    • Drug: LASIX - congestivie heart failure, edema, hypertension
  89. What are some substances that slow the renal absorption of h20 and cause diuresis?
    • Caffeine - inhibits Na+ reabsorption
    • Alcohol- inhibits ADH secretion
    • Prescription meds- can act on the PCT, loop of henle or DCT
  90. Abnormal Urine