Functions of the kidney

3 major steps

Ultrafiltration

Reabsorption

Tubular
secretion

Ultrafiltration

the blood flows through the glomerulus under great pressure

it is because the efferent arteriole is
narrower than the afferent arteriole

this filtration under extraordinary force is called ultrafiltration

During ultrafiltration almost all liquid part plasma comes out of the glomerulus

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reabsorption

Tubular seceation

The glomerular filtrate is not urine

It is dilute solution containing a lot
of useful materials such as glucose and salts

In the tubule , much of water and
other useful substances are reabsorbed

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But their reabsorption is upto certain extent that the normal concentration of blood is not disturbed This is called selective absorption

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Foreign chemicals such as penicillin
are secreted back in the renal
tubule

Urea, uric acid ammonia etc are also secreted

This fluid entering in renal tubule is called glomerular filtrate

Certain substances like potassium

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this pressure causes the liquid part or waste part of the blood to enter in the Bowman’s capsule

The thicker part of the blood
carried by efferent arteriole arteriole