Urinary

• Functions of the Urinary System

  • Waste excretion
  • Blood volume and pressure
  • Ion levels
  • pH
  • Erythopoietin production
• Urinary Structures

  • Kidneys
  • Ureters
  • Urinary Bladder
  • Urethra
• The kidneys are covered by:

  • Renal capsule
  • Adipose capsule
  • Renal fascia
• Renal Hilum

  • Entry: Renal artery
  • Exit: Renal vein, Ureter
  • Medial side of each kidney
• The outer layer of the kidney is the renal cortex.
• The inner part of the kidney, the renal medulla, consists of:

  • renal pyramids
  • renal papilla
  • renal columns
  • minor calyx
  • major calyx
  • renal pelvis
• 1. Nephron
  2. Papilla
  3. Minor calyx
  4. Major calyx
  5. Renal pelvis
  6. Ureter
  7. Urinary bladder
• Nephron

  • About a million in a kidney
  • Functional urine-forming unit
• Renal corpuscle is the site of the filtration of blood and the site of the reabsorption of water and solutes
• Renal tubule is a long tube that connects the renal corpuscle to the renal pelvis
• Glomerulus: a cluster of nerve endings, spores, or small blood vessels, especially a cluster of capillaries around the end of a kidney tubule.
• Bowman's capsule is a thin layer of epithelial cells that lines the glomerulus
• Proximal convoluted tubule: The tubule that collects urine from the nephron
• Nephron loop: The loop of the nephron that connects the renal corpuscle to the renal pelvis
• Distal convolute tubule: The tubule that collects urine from the distal convoluted tubule
• Collecting ducts are the tubes that collect urine from the nephrons and transport it to the renal pelvis
• Blood flow of the kidneys

  1. Aorta
  2. Renal artery
  3. Afferent arteriole
  4. Glomerulus
  5. Efferent arterioles
  6. Peritubular capillaries
  7. Venules
  8. Renal vein
  9. IVC
• Urea: by-product of protein digestion
• Creatinine: a compound which is produced by metabolism of creatine phosphate and excreted in the urine.
• Uric acid is a waste product from the digestion of RNA and is excreted in the urine
• Urine formation

  1. Glomerular filtration
  2. Tubular reabsorption
  3. Tubular secretion
• Glomerular Filtration

  • Glomerulus to Bowman's capsule
  • Filters water, glucose, amino acids, ions, uric acid, urea, creatinine
  • Remains in blood: blood cells, plasma proteins
• GFR

  • Glomerular Filtration Rate
  • Rate of filtrate formed in BOTH kidneys
  • 125mL per minute
  • 180L per day
• Tubular Reabsorption

  • Useful substances in filtrate are reacquired
  • Renal tubules to peritubular capillaries
  • 99% filtrate is reabsorbed, rest becomes urine
  • occurs in proximal convoluted tubule
  • 65% water
  • Glucose, amino acids, other nutrients, electrolytes
• Loop of Henle: A series of tubules that form the inner wall of the collecting duct; Thin descending limb - aborbs water, Thick descending limb - absorbs sodium and chloride
• Distal Convoluted Tubule and the Collecting Duct are hormonally controlled

  • ADH
  • Aldosterone
• Tubular secretion removes substances from the blood. It occurs from the peritubular capillaries to the renal tubules. It secretes H+, K+, Ammonia, Creatinine, Drugs, and Bile Salts.
• Urine Characteristics

  • Transparent
  • Yellow to amber
  • pH of around 6
• Urine Elimination - Structures

  1. Ureter
  2. Urinary Bladder
  3. Urethra
• Ureter: the smooth muscle duct by which urine passes from the kidney to the bladder through peristalsis.
• Urinary Bladder

  • 500mL storage
  • Rugae
  • Detrusor Muscle
  • Trigone
  • Internal Urethral Sphincter
• Urethra

  • Male: 8 inches
  • Female: 1.5 inches
  • Opening: External Urethral Orifice
• Urination

  • AKA micturition, voiding
  • Contraction of detrusor by ANS
  • Opening of internal urethral sphincter by ANS
  • Opening of external urethral sphincter by somatic nervous system