Download Liver Function - Groby Bio Page

What can you label?
 To
know the structure of the liver
 Describe
with the aid of diagrams and
photographs, the histology and gross
structure of the liver
 Know
about the function of the liver
 Describe
the formation of urea in the liver,
including an outline of the ornithine cycle
 Describe the roles of the liver in
detoxification
1. What is the functional unit of the liver called?
2. What are the main functions of the liver?
3. What is the triad?
4. What is the sinusoid?
5. What fills the bile canaliculi?
6. What is the name of the phagocytic cell in the liver and where
would we find it?
7. Name two products release from the hepatocytes into the blood
8. Name two products removed and metabolised from the blood by
the liver.
 Write
out the equations for:
 Deamination
 Formation of Urea
 Detoxification of alcohol
Vital role in maintaining blood glucose levels controlled by pancreas
FATS FOR ENERGY
•
•
•
Fats released from adipose tissue and released into blood.
Hepatocytes split triglyceride molecules into fatty acids and glycerol.
Fatty acids converted to acetyl coenzyme A  Kreb’s cycle.
CONVERTING XS PROTEIN AND CARBS TO FATS (TAG’S)
CHOLESTEROL
Transported in the blood as lipoproteins
Cholesterol is needed for:
-cell membranes
-Lipid and steroid based hormones such as sex hormones
FATS FOR ENERGY
•
•
•
Fats released from adipose tissue (GLUCAGON) and released into blood.
Hepatocytes split triglyceride molecules into fatty acids and glycerol.
Fatty acids converted to acetyl coenzyme A  Kreb’s cycle.
G
L
Y
C
E
R
O
L
COOH
Liver: break down of
the triglyceride
FA’s: acetoacetate to
blood
COOH
Absorbed by tissues
Acetyl coA
COOH
Used in Krebsproducing ATP
 Detoxification
can take place by the
oxidation, reduction or methylation of toxins
 Detoxification of alcohol, antibiotics, steroid
hormones etc
 Example
catalase
Hydrogen peroxide water and oxygen
2H2O2

2H2O +
O2
 Alcohol
is broken down into ethanoate by the
enzymes alcohol dehydrogenase and
aldehyde dehydrogenase.
 Ethanoate (acetate) combines with
coenzyme A and becomes acetyl coenzyme A.
 Hydrogen
ions are released and reduced NAD
is produced.
 Acetyl
coenzyme A enters the Krebs cycle
and is metabolised to produce ATP.
 NAD
is used to
oxidise and break
down fatty acids (for
use in respiration) in
the liver (by
hepatocytes)
If NAD is reduced (from already having to detoxify
alcohol, there is insufficient NAD to oxidise the fatty acids.
The fatty acids are converted back to lipids and are deposited
in the hepatocytes which then causes the liver to become enlarged
If it persists the liver tissue is converted to fibrous tissue and
can lead to cirrhosis
 Damaged
hepatocytes are replaced by
fibrous tissue
 Structure of blood supply is lost

Blood flows from hepatic artery into hepatic vein
without flowing through sinusoids
 Effects

Increase in ammonia concentration which can
cause major damage to the central nervous
system
What
type of reaction
will be involved in
converting glucose to
glycogen?
A
condensation reaction;
glycosidic bonds will be
formed between glucose
molecules.
 Describe
in three or four bullet points the
key features about the gross structure of
the liver.
 Describe and explain the important
differences in the liver’s blood supply
(compared to most organs of the body)
 Briefly describe the role of the following
structures in liver tissue:
1.
2.
3.
4.
Bile canaliculi
Phagocytic Kupffer cells
Central vein
Sinusoids
Proteins are made of long chains of amino
acids.
When amino acids are metabolised and
broken down during deamination, ammonia is
released;
This is a poisonous substance which must be
rapidly converted into something less
harmful.
In the liver, the ammonia is converted in
urea.
After the urea has been synthesized it is
carried in the blood to the kidneys, where it
is excreted in the urine.
The ornithine cycle
Oxygen is required,
and along with
ammonia, hydrogen
peroxide is
produced.
Ammonia is highly toxic and very soluble, so as
soon as the ammonia is made, it enters the next
stage of the process.
Urea is soluble
and can be
excreted from the
body in the form
of urine.
The ornithine cycle
was discovered by
Krebs 5 years before
the TCA cycle. The
first stages occur in
the mitochondria,
the second half of
the cycle occurs in
the cytoplasm.
Transamination – transferring an amino group
from one molecule to another.
Transaminase is the catalyst
 Explain
what deamination is and why it is so
important.
 Why should excess amino acids not be
excreted?
 What is the ornithine cycle?
 Why are there so many symptoms associated
with liver disease?
 Why might you want to include liver in your
diet?
 On
print out Ornithine Cycle
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Define the term excretion
What are the main 2 substances to be excreted by
humans?
Define the term deamination.
What can excess carbon dioxide in the blood cause?
Write down the chemical equation for formation of
urea from ammonia?
What is the scientific name for a liver cell.
Name the 2 blood supplies to the liver
What is the function of the Kupfer cell
Name the enzyme that initially breaks down alcohol
in the liver
What happens to the acetly co enzyme A that has
been produced by the break down of ethanol in the
liver?