structure and function of nephron

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Describe the structure and function of mammalian
nephron

• By Domnic Otieno
• Senior Biology and chemistry teacher
• St. Annes Sega Girls

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Diagram of the nephron
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Cross section of the kidney
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The nephron

• It has renal tubule and glomerulus/network of
  blood capillaries for ultrafiltration due the
  difference in diameter of blood vessels serving
  it/Afferent vessel wider than efferent vessel
• Bowmans capsule for passage of glomerular
  filtrate into the proximal convoluted tubule
• Proximal convoluted tubule extends from Bowmans
  capsule

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• Ultra filtration

Blood from renal artery enters wide capillary
Blood travels through narrow capillary towards
renal vein
Ultra Filtration
Glomerular filtrate
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Cont.

• The filtrate flows flows through the proximal
  convoluted tubule where useful substances such as
  glucose, amino acids salts are selectively
  reabsorbed into blood stream by active transport
  by diffusion/ active transport and some water by
  osmosis.
• The loop of Henle/ descending and ascending arms
  ascending arm for reabsorption of water.
  Descending for reabsorption of mineral salts. The
  filtrate the flows to distal convoluted tubule

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Cont.

• The distal convoluted tubule is where is where
  more water is reabsorbed into blood stream by
  osmosis under the influence of antidiuretic
  hormone/ vassopresin. More mineral salts are
  reabsorbed by diffusion/active transport under
  the influence of aldosterone hormone.
• The filtrate then flows into collecting
  duct/tubule where more water are reabsorbed

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ADAPTATIONS OF THE PROXIMAL AND DISTAL CONVOLUTED
TUBULE.

• a)The lumen wall has villi and microvilli which
  increase the surface area for reabsorption.
• b)The tubule is long and highly coiled to
  increase surface area and slow down movement of
  filtrate/ creating more time for efficient
  reabsorption.
• c)It is one cell thick/has thin epithelium to
  reduce the distance travelled by substances hence
  faster reabsorption of materials.

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Cont.

• The tubule is well vascularized/ well supplied
  with blood capillaries for transportation of
  reabsorbed materials/ create a steep
  concentration gradient for efficient transport of
  reabsorbed materials.
• The cells lining the tubule have numerous
  mitochondria which provide energy for active
  transport/ reabsorption of substances.

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adaptationsLoop of Henle

• It is long to increase the surface area for
  re-absorption of mineral salts and water.
• It has a counter current flow established between
  the filtrate flow and the large supply of blood
  in capillaries. This creates a large/steep
  diffusion gradient for efficient re-absorption.

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Factors that promote re-absorption of water in
the distal convoluted tubule.

• The active uptake of mineral salts at the loop of
  Henle this raises the osmotic potential of
  blood.
• Secretion of Antidiuretic hormone/vasopressin
  (ADH) from the pituitary gland which increases
  permeability of the tubules and blood capillaries
  to water.

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End Thank you