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Regulation (Homeostasis)

Afferent arteriole Efferent arteriole

Capillary showing pore Capillaries of the glomerulus
Podocyte
Filtration silts Squamous epithelial cells of

Basement membrane Bowman’s capsule
Glomerular filtrate
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Microvilli
Cells of proximal convoluted tubule
Basement membrane
Tight junction
Space between epithelial cells
Endothelium of
blood capillary Microvilli
BLOOD GLOMERULAR FILTRATE

Infolding of cell surface Epithelial cell of proximal
convoluted tubule
membrane forming base
channels
Reabsorption

Figure 7.8: Structure and function of renal corpuscle and proximal convoluted tubule

The loop of Henle acts as a counter current and numerous mitochondria to supply
exchange mechanism creating a low water energy for active transport.
potential (high solute content) in the
medulla of the kidney so that water can be Formation of urea in mammals
reabsorbed by osmosis. The descending
limb has a thin membrane which is freely Task 7.6
permeable to water and impermeable Use the internet sources to search for the
to salts and urea. The thick ascending simulation or videos / documentaries
limb has numerous mitochondria which on the mechanism of urea formation.
provide energy for active uptake of sodium
chloride and other ions from the renal Urea is the nitrogenous waste product of
fluids back into the interstitial regions of humans and other land living mammals.
the medulla. The body is unable to store excess
amino acids taken in the diet. Those not
The distal convoluted tubule and collecting immediately needed for protein synthesis
ducts are concerned with osmoregulation; or making sugar must be removed by
varying the amount of water reabsorbed the process called deamination, which is
into the blood. The cells of the distal followed by urea formation in the liver
convoluted tubule have a similar structure cells. The process of urea formation
to those of the proximal convoluted tubule, occurs in the urea cycle which is also
with microvilli lining inner surfaces to called ornithine cycle (Figure 7.9) and
increase the surface area for absorption, involves the following stages:

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