Thursday, January 1, 2015

Explain how the kidneys produce urine in the simplest terms possible.

Human kidney is an organ which performs many vital
functions of the body. The most important of this is the production of urine. This
involves separation of and removal of various waste material from the blood. There are a
pair of kidneys that lie below the middle of the back on each side of the
spine.


The human kidney consists of three layers. In order
of their location from outside to inside these are called cortex, medulla, and pelvis.
The blood to be purified enters the medula. In medula and cortex the blood arteries
carrying the blood branch into increasingly smaller arteries. These arteries lead the
blood to tiny blood filtration units called nephrons located at the end of each branch
of the arteries. In a normal adult there are about 2 million nephrons capable of
filtering about 190 liters of blood daily.


A nephron
consists of various parts including parts - a network of tiny blood vessels, the
glomerulus, Bowman's capsule surrounding the glomerulus, convoluted tubule, and
collecting tuble.  Pressure forces much of the fluid portion of the blood (blood plasma)
through the glomerulus and into Bowman's capsule.  The resulting fluid called tubular
fluid, which contains water and dissolved chemicals, then passes into the convoluted
tubule.  The remaining blood in the glomerulus flows into small vessels called
capillaries, which surround the convoluted tubule.  As the tubular fluid flows through
the tubule, substances needed by the body are absorbed by the cells of the tubule wall. 
These substances rejoin the blood in the capillaries.  The capillaries return the blood
to the heart by way of the renal vein.


Substances not
absorbed in the tubule are wastes that the body needs to get rid of.  These are secreted
into the tubular fluid by the tubular cells of the kidney.  These various substances,
which include ammonia, urea, uric acid, and excess water, make up urine.  The urine
passes from the convoluted tubules into larger collecting tubules and then into the
pelvis layer of the kidney.This urine collects in the bladder to be passed out
periodically.

No comments:

Post a Comment

Comment on the setting and character of "The Fall of the House of Usher."How does setting act as a character?

Excellent observation, as it identifies how the settings of Poe's stories reflect the characters of their protagonists. Whet...