renal final

• Renal system consists of:

  • 2 kidneys
  • 2 ureters
  • 1 urinary bladder
  • 1 urethra
• General functions:

  • filter blood
  • keep necessary fluid and components
  • excrete wastes
• 1. right kidney
  2. right renal vein
  3. right renal artery
  4. right ureter
  5. left adrenal gland
  6. abdominal aorta
  7. inferior vena cava

  
• Kidneys:

  • size of a fist

  Location:

  • lateral to T12-L3
  • right kidney is slightly lower
• Kidney Tissue Layers

  • Renal fascia
  • Adipose capsule
  • renal capsule
• Renal Fascia:

  • anchor kidney to surrounding structures and posterior abdominal wall
• adipose capsule:

  • protection
  • holds kidney in place
• Renal capsule:

  • protection from trauma and infection
  • maintenance of shape
  • continuous with ureter
• Renal blood supply:

  • 25% of cardiac output (1.2 L/min)
  • 2 arterioles (afferent and efferent)
  • 2 capillary beds (glomerular and peritubular)
• order of blood supply of kidneys:

  1. renal artery (delivers blood into kidney)
  2. afferent arteriole (delivers blood into glomerulus)
  3. glomerular capillaries
  4. efferent arteriole (delivers blood away from glomerulus
  5. peritubular capillaries (surrounds renal tubule, collects filtered blood)
  6. renal vein (delivers blood away from kidney)
• Nephron:

  • functional unit of the kidney
  • consists of: renal corpuscle and renal tubule
  • filters blood and produces urine
• renal corpuscle:

  includes: glomerulus and bowman's capsule

  what happens here?

  • site of blood filtration

  filtrate: blood that passed through the glomerular capillary to the space of bowman's capsule
• renal tubule:

  includes:

  • proximal tubule
  • loop of henle
  • distal tubule

  what happens here?

  • passage of filtrate
• Ureters:

  ~10 inches long

  transport urine from kidney to bladder
• kidney functions:

  1. Regulation of blood ionic composition
  2. Regulation of blood pH
  3. Regulation of blood volume
  4. Regulation of blood pressure
  5. Maintenance of blood osmolarity
  6. Regulation of blood glucose level
  7. Production of hormones
  8. Excretion of wastes and substances
• 5 key ions of blood ionic composition:

  • Sodium ions
  • Phosphate ions
  • Chloride ions
  • Calcium ions
  • Potassium ions
• kidney regulating blood pH:

  • excretion: hydrogen ions into urine
  • conservation: bicarbonate ions
• kidney releases glucose into blood by process of gluconeogenesis
• kidney hormone production

  • calcitriol
  • erythropoietin

  where?

  adrenal gland
• kidney excretion of wastes:

  • metabolic reaction wastes (ammonia, urea, bilirubin, creatine, uric acid)
  • drugs and toxins
• Excretion = filtration + secretion - reabsorption

  filtration occurs in the glomerulus
• major processes in the nephron:

  • filtration
  • reabsorption
  • secretion
  • excretion
• Filtration:

  • movement of water and solutes from the blood plasma across the wall of the glomerular capillaries, into the glomerular capsule and into the renal tubule
• pressures driving filtration:

  1. glomerular blood hydrostatic pressure
  2. capsular hydrostatic pressure
  3. blood colloid osmotic pressure (BCOP)

  Net filtration pressure = GBHP - CHP - BCOP

  GFR (glomerular filtration rate): volume of plasma filtrate that passes through the glomeruli every minute
• Reabsorption:

  • movement of substances from the renal tubule to the blood stream through the peritubular capillaries and vasa recta
  • Cells reabsorb 99% of the filtered water and solutes
  • Water and solutes return to the blood as it flows
• secretion:

  the removal of a substance from the blood and into the renal tubule
• Proximal tubule:

  • Largest amount of solute and water reabsorbed
  • reabsorbs: water, Na, Cl, K, glucose, amino acids, bicarb ions
  • secrets: H ions and drug residues
• Loop of henle

  Descending limb:

  • reabsorbs water, secretes NaCl

  Ascending limb:

  • water impermeable
  • reabsorbs NaCl
• Distal tubule:

  • secretion of K and H+ ions
  • reabsorbs:
  • Na if aldosterone
  • water if ADH
  • and Cl

  inhibited by ANP
• RAAS:

  Aldosterone causes reabsorption of Na & Cl and secretion of K in the collecting duct
• ADH:

  increases permeability to water in cells of the distal tubule and collecting duct causing higher water reabsorption
• ANP:

  decreases Na and water reabsorption; inhibits aldosterone and ADH release