Download Deamination in the Liver PPT File

EXCRETION
Excretion
There are many chemical reactions taking place in
the body – these produce by-products, some of
which are able to be used by the body, while others
are wastes.
Most wastes are toxic and would be harmful if
allowed to accumulate.
The removal of metabolic wastes from the body is
called Excretion
Removing wastes also allows the body to maintain
equilibrium within the body (this is called
Homeostasis)
Organs of Excretion
• Kidneys – filter blood to
maintain a constant
concentration of materials in
the body fluids, excrete/remove
nitrogenous wastes like urea,
uric acid & creatinine
• Liver – deamination &
synthesis of urea
• Lungs – CO2
• Skin – sweat glands secrete
sweat (contains salts, urea &
lactic acid)
The Liver
&
its role in excretion and other
functions
FUNCTIONS
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Deamination
Blood glucose regulation
Fat conversion
Bile formation
Plasma protein production
Production of blood-clotting factors
Storage
Toxin and hormone breakdown
Heat production
Deamination occurs in the
liver
Wellcome Foundation - Miles Kelly Art Library
Deamination is the stripping of
nitrogen from amino acids and
nitrogen bases
Some of the amino acids absorbed
during digestion are taken in by
cells and used to make proteins.
Excess of amino acids cannot be
stored, but is converted in the liver
into carbohydrates
The deamination process
• The conversion first involves the removal of
the amino group (-NH2) from the amino
acid
• The amino group is converted to Ammonia
(NH3)
• As ammonia is toxic to the body, so is
quickly converted to urea
• Urea is removed from the blood by the
kidneys and excreted as urine.
• Amino acid → ammonia +
organic compounds (used for
respiration)
The amino
group
• Ammonia (very toxic) + CO2 →
urea (H2NCONH2)
Other Functions
2. Blood Glucose Regulation & 3. Fat
Conversion
– after a meal = hepatic portal vein contains a large quantity
of absorbed glucose
– Liver cells take in this glucose and may use for own
energy requirements = convert it into glycogen, or convert
it to fat
– Glycogen, is the form in which the carbohydrate is stored
– Liver stores as an energy reserve for the body
– So between meals when blood glucose falls, the liver is
able to recover glycogen to glucose and pass it into the
blood - releasing glucose into the blood = regulating blood
glucose
4. Bile Formation
• Liver produces bile which is involved in the
mechanical breakdown of fat
5. Plasma Protein Production
• The liver produced most of the proteins
found in the blood plasma
6. Production of Blood-clotting factors
• Many of the substances required for blood
clotting are produced here
7. Storage
• Stores glycogen, but also stores iron, the fatsoluble vitamins A & D
8. Toxin & Hormone breakdown
• Toxins and compounds that naturally occur in
the body or are introduced with food or form
of drugs = are broken down to harmless
substances in the liver
• Hormones that circulate in the blood are also
inactivated by the liver
9. Heat production
• A great deal of chemical reactions take
place here = heat energy is released as a
by-produced
• Liver is important source of heat & assists
in the maintaining a constant body
temperature