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Slide 1

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selective re-absorption
and ultra-filtration…read more

Slide 2

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Inside the kidney there are millions of tubules
called nephrons. These are so tiny that you can
only see them with the aid of a micro-scope.
The red area is where the nephrons are in the
Renal artery
Renal vein
ureter…read more

Slide 3

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Afferent blood vessel
Second coiled
Efferent blood tubule
glomerulus vessel
First coiled
Bowman's Collec
capsule ting
Two main processes take
place in the nephrons:
>Ultra filtration of blood
plasma from the glomerulus
into the Bowman's capsule
>Selective reabsorption
from the nephrons back
into the blood capillaries
around them. pelvis
Loop of henl…read more

Slide 4

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= little molecules, like water,
urea, ions and glucose.
= big molecules like protein and
red blood cells.
Blood in the glomerulus is
under high pressure. The
pressure pushes the small
molecules through the
microscopic holes in the
glomerulus wall and into the
holes in the lining of the
Bowman's capsule. The little
molecules then go through the
ultra filtration tubules and into the kidney.
The mixture is called
ultrafiltrate The big molecules
go back into the blood.…read more

Slide 5

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Selective reabsorption
Afferent blood vessel
Efferent blood
glomerulus vessel Normally, all the
First coiled substances that are in
tubule the ultrafiltrate would
eventually pass
through the nephron;
but this does not
happen because most
are reabsorbed
through the nephrons
walls into capillaries
from the efferent
blood vessel. 70% of
the water, all the
glucose, some mineral
Lining the nephron are tiny cells called
salts and amino acids
microvilli. These increase the surface area of the
are reabsorbed.
tubule without increasing the size of the cell.
Inside the Microvilli are mitochondrion, which
provide the energy for the reabsorption.…read more

Slide 6

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Concentration of substances
substance plasma ultrafiltrate urine
urea 0.03 0.03 3.00
water 91.00 99.00 (variable)
glucose 0.10 0.10 0.00
Mineral salts 0.40 0.70 (variable)
protein 8.00 0.00 0.00
This table shows the concentration (in g per dm) of different substances
throughout the ultra filtration and selective reabsorption processes. It shows how
the protein is left out by ultra filtration, and how a lot of mineral salts and glucose
are reabsorbed.…read more

Slide 7

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