finals-urinary

• Urochrome/ Urobilin


  The pigment responsible with the color of urine
• Parts of the urinary system

  • Kidney
  • Ureter
  • Urinary Bladder
  • Urethra

  
• Kidney


  • Excretion of waste
  • Regulation of blood ionic composition
  • Regulation of blood pH
  • Regulation of blood volume
  • Maintenance of blood osmolarity
  • Production of hormones: calcitriol and erythropoietin
  • Regulation of blood glucose

  
• Urine is composed of nitrogenous wastes (urea, ammonia, uric acid & creatinine)
• Nitrogenous wastes come from metabolic reactions in our body
• Ionic compositions in our body

  • Calcium
  • Sodium
  • Phosphate
  • Potassium
  • Chloride ions
• External anatomy of the kidney

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

  
• Nephroptosis/ Floating kidney disease


  Inferior displacement or dropping of the kidney

  
• Internal anatomy of the kidney

  • Renal Medulla
  • Renal pyramids
  • Renal papilla
  • Renal Cortex
  • Renal columns
  • Parenchyma
  • Nephrons
  • Papillary ducts
  • Minor & major calyces
  • Renal pelvis
  • Renal sinus

  
• Kidney blood supply


  • Renal artery
  • Segmental arteries
  • Interlobar arteries
  • Arcuate arteries
  • Cortical radiate arteries
  • Afferent arterioles
  • Glomerular capillaries
  • Efferent arterioles
  • Peritubular capillaries
  • Peritubular venules
  • Cortical radiate veins
  • Arcuate veins
  • Interlobar veins
  • Renal veins

  
• Nephrons


  Basic structural and functional units of the kidney, consisting of a renal corpuscle and a renal tubule

  
• Histology of the nephron and collecting duct

  • Glomerular capsule
  • Visceral layer (podocytes)
  • Parietal layer
  • Glomerular capillaries

  
• Processes to produce urine

  1. Glomerular filtration

  2. Tubular reabsorption

  3. Tubular secretion

  
• Filtration membrane


  • Fenestration of glomerular endothelial cell
  • Basement membrane of glomerulus
  • Slit membrane between pedicels

  
• Net filtration pressure (NFP)

  The total pressure that promotes filtrations, determined by glomerular blood hydrostatic pressure, capsular hydrostatic pressure, and blood colloid osmotic pressure

  
• Glomerular Filtration Rate (GFR)


  The amount of filtrate in all renal corpuscles of both kidneys in each minute

  
• Renal autoregulation


  1. Myogenic mechanism

  2. Tubuloglomerular Feedback

  
• Macula densa


  A type of cell located in the distal convoluted tubule that acts as salt sensors to control kidney functions

  
• Tubuloglomerular feedback


  Increase in NaCl concentration at the macula densa constricts the glomerular afferent arteriole and decreases the single-nephron GFR

  
• Neural regulation of GFR


  Norepinephrine causes vasoconstriction through the activation of a1(alpha) receptors
• Hormonal regulation of GFR

  Angiotensin II and Atrial natriuretic peptide
• Tubular reabsorption


  Return of most of the filtered water and many of the filtered solutes to the blood stream, via paracellular and transcellular routes, using symporters and antiporters

  
• Tubular secretion


  Transfer of materials from the blood and tubule cells into glomerular filtrate

  
• Reabsorption and secretion in different parts of the nephron

  • Proximal Convoluted Tubule
  • Nephron Loop
  • Distal Convoluted Tubule
  • Collecting Duct

  
• Renin-Angiotensin-Aldosterone System


  1. Angiotensin II decreases GFR, enhances Na+ and water reabsorption, and stimulates aldosterone release

  2. Aldosterone stimulates Na+ reabsorption and K+ secretion in collecting ducts
• Antidiuretic hormone (ADH)


  Regulates facultative water reabsorption in the collecting ducts
• Atrial natriuretic peptide (ANP)

  Acts to increase the GFR within the kidney by dilating the afferent arterioles and constricting the efferent arterioles

  
• Parathyroid hormone (PTH)


  Reduces loss of calcium in urine
• Urine production


  1. Fluid consumption varies

  2. Urine concentration changes with ADH

  3. Increased fluid intake causes diluted urine

  4. Low fluid intake causes concentrated urine
• Formation of dilute urine

  1. Osmolarity in the tubule decreases

  2. Extensions of descending limb

  3. Diminished strength in the upward limb

  4. Greater reductions in the collecting duct

  
• Ascending limb


  Low water permeability, solutes leave but water stays in tubule

  
• Collecting duct


  Low water permeability in absence of ADH
• Formation of concentrated urine


  1. Collecting ducts become extremely porous to water when ADH is present

  2. Tubular fluid concentrates greatly

  3. Water movement transports urea into the medulla, increasing its osmolarity

  
• Tissue layers of the ureters

  • Mucosa (inner)
  • Muscularis (middle)
  • Adventitia (outer)
• Transitional epithelium


  Allows stretching, while peristalsis in the muscle layers propels urine
• Fluid consumption varies a lot
• The concentration of urine changes as ADH
• Increased fluid intake causes diluted urine to have a large volume
• Low fluid intake causes concentrated urine to have a large volume
• Formation of dilute urine

  1. Osmolarity in the tubule decreases

  2. Extensions descending limb

  3. Diminished strength in the upward limb greater reductions in the collecting duct