Please enable JavaScript.
Coggle requires JavaScript to display documents.
Kidney: Structure and Working (Excretory system: Part 2) - Coggle Diagram
Kidney: Structure and Working
(Excretory system: Part 2)
Microscopic view: Cross section of a kidney
Kidneys
are
oval structures
and are present at the
back of the abdominal cavity
.
A kidney is seen to have a
dark
, outer region called the
cortex
and a
lighter
, inner zone called the
medulla
.
Where the
ureter joins the kidney
there is a
space
called the
pelvis
.
The
renal artery divides into many arterioles and capillaries, mostly in the cortex.
This
capillary is repeatedly divided and coiled,
making a knot of vessels known as
glomerulus
.
Each glomerulus is surrounded by a cup- shaped organ called a renal capsule
which leads to a coiled renal tubule.
This tubule, after a series of coils and loops,
joins a collecting duct, which passes through the medulla to open into the pelvis.
A
nephron
is a
single glomerulus with its renal capsule, renal tubule and blood capillaries.
Nephron
is the place where all the
purification occurs.
Function of kidneys:
Filtration:
The
blood pressure in the glomerulus
causes the part of
blood plasma to leak though the capillary walls
. T
he glucose, salts, minerals, and urea come out of the capillaries
. This filters out in the capsule and the nephron tubule.
Absorption:
At the
proximal convoluted tubule
,
glucose
, which was moving in the nephron tubule moves back
is reabsorbed into the capillaries by active transport.
This is
selective reabsorption
and
needs energy
(by mitochondrion).
At the loop of henle, salts are reabsorbed back into the blood by diffusion and water is reabsorbed by osmosis back in the blood.
After the
loop of henle
, whatever remains in the filtrate (fluid- urine) is
drained into the collecting tubule and into the ureter.
The main steps are:
Filtration, Reabsorption and Secretion (salts go back to the blood).
This
filtration is important
. The blood optimises the levels of sodium, potassium and other substances
to carry out proper transportation of nutrients.
Ultrafiltration is the filtration of ultra (fine) molecules.