golmerular filtration , tubular secretion and tubular reabsorption

1. Basic Renal Process
Made by
Najam Ali

2. Basic Renal processes
• To produce urine, nephrons and collecting ducts perform three badic
functions.
• Glomerular filtration
• Tubular secretion
• Tubular reabsorption

3. Golerular filtration
• It is the first step of urine production.
• Water and most solutes in blood plasma move across the wall of
glomerular capillaries, where they are filtered and move into the
glomerular capsule and then into the renal tubule.
• The daily volume of golmerular filtrate in adults is 150 liters in females
and 180 liters in males.
• 99% of golmerular filtrate return to blood and 1 to 2 liters excreted as
urine.

4. Tubular reabsorption
• Substances moves from tubule to peritubular capillaries.
• Na+ moves from tubule to blood by Na/K pump and very small amount of
sodium moves through leaky channels.
• Others ions Mg+, Ca+, K+, Cl- moves easily across cells by leaky channels.
• Glucose, Amino acids and vitamins also reabsored.
• H20 are reabsored by osmosis and leaky channels.
• Lipid soluble substances moves across cells by diffusion.
• CO2 is excreted in form of bicarbonate.

5. Tubular secretion
• Substances moves from peritubular capillaries to tubule.
• K+ secreted into tubular cells by help of Na+/K+ pump.
• K+ also secreted into tubular cells by Na+ and K+ channels.
• Hydrogen ions are secreted into tubule cells by antiporter cells to balance PH.
• It eliminate undesired substances suchs as urea and uric acid.