URINARY need to edit pa

• Urinary system


  System that produces, stores, and eliminates urine from the body
• Major organs of the urinary system


  • Kidneys
  • Ureters
  • Urinary bladder
  • Urethra
• Kidneys

  • Excrete toxins and nitrogenous wastes
  • Regulate levels of many chemicals in blood
  • Maintain water balance
  • Help regulate blood pressure via secretion of renin
  • Secrete erythropoietin (EPO)

  
• Nephron


  Microscopic unit of the kidney that filters blood and produces urine

  
• Parts of a nephron


  • Renal corpuscle
  • Renal tubules

  
• Renal corpuscle

  Consists of Bowman's capsule and glomerulus

  
• Renal tubules

  • Proximal convoluted tubule
  • Nephron loop (Henle's loop)
  • Distal convoluted tubule
  • Collecting duct

  
• Glomerular filtration

  • Fluid entering the glomerular capsule is called filtrate
  • Glomerular filtration rate (GFR) is 115-125 ml/min for both kidneys

  
• Reabsorption

  Return of filtered molecules to the blood
• 180 L of water is filtered per day, but only 1-2 L is excreted as urine
• Countercurrent multiplier system


  Mechanism that helps concentrate urine by creating a solute gradient in the renal medulla

  
• Antidiuretic hormone (ADH)

  Secreted from the posterior pituitary gland, decreases the amount of urine by making the collecting ducts permeable to water
• Aldosterone

  Secreted by the adrenal cortex, stimulates the tubules to reabsorb sodium at a faster rate
• Atrial natriuretic hormone (ANH)

  Secreted from the heart's atrial wall, stimulates kidney tubules to secrete more sodium and thus lose more water

  
• Abnormalities of urine volume

  • Anuria (absence of urine)
  • Oliguria (scanty amount of urine)
  • Polyuria (unusually large amount of urine)
• Tubular secretion

  Transfer of materials from peritubular capillaries to the renal tubular lumen, opposite of reabsorption

  
• Juxtaglomerular apparatus

  Specialized structure that regulates blood pressure and glomerular filtration rate

  
• Decrease in plasma Na+

  Juxtaglomerular apparatus secretes renin, which converts angiotensinogen to angiotensin II to increase blood pressure
• Urinalysis

  Physical, chemical, and microscopic examination of urine to detect signs of disease
• Micturition


  Passage of urine from the body, also called urination or voiding
• Urinary control mechanisms

  • Internal urethral sphincter (involuntary)
  • External urethral sphincter (voluntary)

  
• Emptying reflex

  1. Initiated by stretch reflex in bladder wall

  2. Bladder wall contracts

  3. Internal sphincter relaxes

  4. External sphincter relaxes, and urination occurs
• Urinary disorders

  • Urinary retention
  • Urinary suppression
  • Urinary incontinence

  
• Parts of Urinary system for elimination of urine

  .

  A) kidney

  B) bladder

  C) ureter

  D) urethra