urinary & reproductivity

• Functions of Urinary System


  • Regulating plasma concentrations of Na, Cl, K, Ca
  • Regulating blood volume and blood pressure by adjusting volume of water lost, releasing erythropoietin, and releasing renin
  • Contributing to stabilization of blood pH
  • Conserving valuable nutrients by preventing their excretion in urine
  • Eliminating organic waste products especially nitrogenous waste such as urea and uric acid
  • Synthesizing calcitriol, a hormone derivative of vit D, that stimulates calcium ion absortion by intestinal epithelium
  • Assisting liver in detoxifying poisons and deaminating amino acids so that other tissues can break them down
• The Kidneys


  • Located inferior to diaphragm and the 12th rib
  • Right kidney lies lower because of the liver
  • Retroperitoneal
  • Protected by perirenal fat, renal fascia, and pararenal fat
  • Capped by Suprarenal glands
• Renal Fascia and Fat


  • Pararenal fat
  • Perirenal fat
  • Renal fascia - layer closest to Kidney, adipose Tissue, absorys forces, thin white line, dense spider web, anchors Kidneys outward, separates kidney from body wall

  
• Cross-section of the kidney

  1. Renal Pelvis

  2. Minor Calyx

  3. Major Calyx

  4. Renal Cortex

  5. Renal Columns

  6. Renal Pyramid

  7. Renal Papilla

  8. Renal Capsule

  9. Ureter

  
• Arteries of the Kidney


  • Renal Artery
  • Suprarenal Artery
  • Segmental Artery
  • Interlobar Artery And Vein
  • Arcuate Artery And Vein
  • Interlobular Artery And Vein

  
• The Nephron


  • The functional unit of the kidney
  • Filters blood from the Afferent arteriole
  • Blood enters via afferent arteriole
  • Blood is filtered by podocytes
  • Blood leaves via efferent arteriole

  
• Renal corpuscle


  1. Filtration occurs as blood pressure forces fluid and dissolved ions out of the glomerulus and into the capsular space

  2. Filtration must pass 3 barriers: Capillary endothelium, Basement membrane, Glomerular epithelium

  
• Proximal convoluted tubule


  1. First part of the renal tubule

  2. Actively absorb organic nutrients, ions, and plasma proteins

  3. Osmotic forces then pull water out of the filtrate and into the surrounding interstitial fluid (peritubular fluid)

  
• Loop of Henle (LOH)


  1. 2 parts - ascending / descending limbs

  2. Each of these divided into thin and thick segments

  3. Thick segments use active transport to move ions (Na, Cl) out of tubular fluid

  4. Thin segments are permeable to water but not ions. The high concentration of the peritubular fluid (due to the thick limb's active transport) causes osmotic pressure to force water out of the tubular fluid
• Distal convoluted tubule


  1. Active secretion of ions, acids and other materials

  2. Selective reabsorption of Na and Ca ions from tubular fluid (controlled by aldosterone secreted by adrenal cortex)

  3. Selective reabsorption of water
• Collecting system


  1. Consists of connecting tubules, collecting ducts, papillary ducts (which drain into minor calyx etc.)

  2. Collecting system makes the adjustments of the tubular fluid

  3. Regulatory mechanism involves changing the permeability of the collecting ducts to water

  4. ADH (antidiuretic hormone) responsible for controlling permeability of the collecting system (high ADH leads to more water reabsorbed which leads to more concentrated urine)
• Gonadal artery / vein
• Voluntary control