2. • When there is a adequate balance bet. Lipid and
carbohydrate metabolism, most of the acetyl CoA
produced from the B-oxidation pathway is
further processed through the citric acid cycle.
• The first step of the citric acid cycle involves the
reaction between oxaloacetate and acetyl CoA.
Sufficient oxaloacetate must be present for the
acetyl CoA to react with.
3. • Certain body conditions upset the lipid-carbohydrate balance
required for acetyl CoA generated by fatty acids to be processed
by the citric acid cycle. These condition include
dietary intake high in fat and low in carbohydrates
Diabetic condition where the body cannot adequately
processed glucose even though it is present
Prolonged fasting condition, including starvation, where
glycogen supplies are exhausted.
Under these conditions, the problem of adequate oxaloacetate
supplies arises, which is compounded by the body’s using
oxaloacetate that is present to produce glucose through
gluconeogenesis.
4. • Ketone body is one of the three substances
( acetoacetate, B- hydroxybutyrate and
acetone) produced from acetyl CoA when
an excess of acetyl CoA from fatty acid
dergadation accumulates because of
triacylglycerol- carbohydrate metabolic
Imbalances. The structural formulas for the
three ketone bodies, two of which are C4
molecules and the other a C3 molecule.
5. • Ketogenesis
`is the metabolic pathway by which
ketone bodies are snythesize from acetyl
CoA. Items to consider about this process
prior to looking at the actual steps in this
four step process are:
6. • 1. the primary site for the process is liver mitochondria.
• 2. the first keyone body to be produced is acetoacetate.
This production occurs in step 3 of ketogenesis.
• 3. some of these acetoacetate produced in step 3 is
converted to the second ketone body, B- hydroxybuterate.
In step 4 of ketogenesis.
• 4. the acetoacetate and B-hydroxybutyrate synthesized by
ketogenesis in the liver are released to the blood stream
where acetone, the third ketone body is produced.
7. • 5. acetoacetate is somewhat unstable and can
sponteously or enzymaticallylose its carboxyl group to
form acetone. Thus, the ketone body acetone is not
actually a product of the metabolic pathway
ketogenesis.
• 6. the ketone body acetone present in the blood stream
is a volatile substance that is mainly excreted by
exhalation. Its sweet odor is detectible in the breath of
a diabetic.
• 7. the amount of acetone present is usually small
compared to the concentrations of the other two ketone
bodies.
8. • Steps in the process of Ketogenesis:
step 1: first condensation:
Ketogenesis begins as two acetyl CoA molecules
combine to produce acetoacetate CoA, a reversal af the step
of the B- oxidation.
Step 2: second condensation:
Acetoacetyl CoA then reacts with a third acetyl CoA
and water to produced 3-hydroxy-3-methlglutary CoA and
CoA-SH
9. • Step 3: Chain cleavage.
HMG-CoA is then cleaved to acetyl CoA and
Acetoacetate.
• Step 4: Reduction:
Acetoacetate is reduced to B-hydroxybutyrate. The
reducing agent is NADH.
10.
11. • The over all accumulation of ketone
bodies in the blood and urine. And it is
often detectable by the smell of acetone
on a person’s breath; acetone is very
volatile and is excreted through the
lungs.
13. • KETONURIA
At level of 70 mg/ 100 mL, the renal threshold is
exceeded, and ketone bodies are extracted in
the urine.
14. • The symptoms of the mild ketosis that
occurs as the result of such dieting
include headache, dry mouth, and
sometimes foul- smelling breath.
15. • Two of the three ketone bodies, acetoacetate,
B-hydroxybutyrate are acids. Their presence
in blood causes a slight but significant
decrease in blood pH. This can result in
acidosis.
16. • In severe ketosis, the symptoms include heavy
breathing and increased urine output that can
lead to dehydration. Ultimately, the condition
can cause coma and death.
