2B.Excretory products

• Blood vessels that enter the kidney: renal artery
• Blood vessels that exit the kidney: renal vein
• Renal pyramids are cone-shaped masses projected from the medulla of the kidney
• Renal pyramids contain Henle's loops of Juxta medullary nephrons and straight collecting ducts
• Renal papilla is the tip of the renal pyramid that opens into the pelvis
• Columns of Bertin are the projections of the cortex that separate the renal pyramids
• Structural and functional units of the kidney: nephron
• Two main types of nephrons: Cortical nephrons and Juxta medullary nephrons
• Each nephron consists of Bowman's capsule and renal tubule
• Cortical nephrons have renal corpuscle in the superficial renal cortex, short loop of Henle, but without vasa recta
• Juxta medullary nephrons are located near the renal medulla, have long loop of Henle and Vasa recta
• Glomerular filtration is the filtration of blood from the glomerulus into the lumen of Bowman's capsule
• Glomerular Filtration Rate (GFR) is the amount of filtrate formed by both kidneys in a minute, which is about 125ml/min
• Mandatory reabsorption: about 85% of the filtrate is reabsorbed in a constant unregulated manner by proximal convoluted tubule and Henle's loop
• Tubular epithelial cells of the nephron reabsorb water and substances
• Juxtaglomerular cells:

  • Present on the wall of afferent renal arteriole
  • Modified smooth muscle cells
  • Located at the place where afferent arteriole comes into contact with distal convoluted tubule
• Macula densa:

  • Group of modified epithelial cells of the distal convoluted tubule
  • Crowded at the place where afferent arteriole comes into contact with distal convoluted tubule
• Juxtaglomerular apparatus:

  • Formed by Macula densa and Juxtaglomerular cells
  • Regulates kidney function
• Renin:

  • Produced in the kidney
  • Converts angiotensinogen to angiotensin I
• Rennin:

  • Produced in the stomach
  • Converts casein to calcium para-caseinate
• Osmoregulation:

  • Process of maintaining a constant amount of water and dissolved salts in the body
  • Maintenance of homeostasis of an organism with respect to water in the body
• Atrial natriuretic peptide (ANP):

  • Causes vasodilation
  • Decreases blood pressure