UNITIII Ketosis Ketosis Ketosis simply means that - PowerPoint Presentation

Slide1

UNITIII

Ketosis

Ketosis

Ketosis simply means that

ketones

are present in body fluids in elevated

concentrations

K

etone

bodies are

acetoacetic

acid,

beta-

hydroxybutyric

acid and acetone

Ketosis is frequently associated with

ketoacidosis

Ketosis is a normal response to low glucose availability

Ketogenesis

take pace in lever

Aetyl

CoA

is precursor of

ketone

bodies

Mechanism of development

Occurs

during

fasting

, starvation, carbohydrate restriction,

prolonged

exercise

Trace

levels of

ketones

are always present in the

blood

Increase

when blood glucose reserves are low

Liver

 shifts from primarily metabolizing carbohydrates to metabolizing fatty

acids

Mechanism of

development…..

When the liver rapidly metabolizes fatty acids into acetyl-

CoA

, some acetyl-

CoA

molecules can then be converted into

ketone

bodies

These

ketone

bodies can function as an energy

source

The

liver itself cannot utilize these molecules for energy, so the

ketone

bodies are released into the blood for use by peripheral tissues including the

brain

Acetyl-

CoA

can be metabolized through the TCA cycle in any

cell

It can also undergo ketogenesis

in the mitochondria of liver

cells

When

glucose availability is low,

oxaloacetate

is diverted away from the TCA cycle and is instead used to produce glucose via 

gluconeogenesis

Excess of Acetyl-CoA synthesize ketone bodiesUncontrolled production of ketones leads to keosis

Mechanism of

development…..

Biochemical alteration

K

etonemia

-

the

presence of an abnormally high concentration of

ketone

bodies in the

bloodHypoglycemia- decrease in blood glucose levelKetonuria- presence of ketone bodies in urineRothera's 

test-

Detection of

ketone

bodies in urine

Types of ketosis

Alimentary ketosis

Fasting Ketosis

Diabetic

Ketosis

Ketosis Associated with Pregnancy and

Lactation

Bovine ketosis- Cattle Pregnancy toxemia- SheepPostexercise Ketosis

Alimentary ketosis

A

limentary

ketosis occurs when cattle have been fed spoiled silage that contains excessive amounts of butyric acid

Ketogenesis

can occur from

Volatie

Fatty acid

Propionate is the major gluconeogenic precursor and is not an important precursor of ketonesButyrate is converted to 3-hydroxybutyrate by the rumen epithelium Rumen epithelial cells possess high activities of butyryl-CoA

synthetase

, which can convert butyrate to

butyryl-CoA

During fasting, hormonal changes occur that promote lipolysis

Plasma

glucose concentrations will

decrease (hypoglycemia)

Low plasma insulin concentrations high plasma

glucagon concentrations

These

hormonal changes will increase

cAMP concentrations in adipose cells, which leads to the activation of hormone sensitive lipaseLong chain fatty acid released from adipose tissueFasting Ketosis

More frequently in dogs and cats than other domestic species

Diabetes is accompanied by hyperglycemia, whereas most other

ketotic

syndromes occurring in domestic animals are usually accompanied by

normoglycemia

or hypoglycemia

The

ketonemia in diabetes is due to increased lipolysis in adipose plus accelerated hepatic gluconeogenesisDiabetic Ketosis

Post exercise ketosis

During

exercise long chain fatty acid bodies is utilized by muscles

Ketone

bodies formed from long chain fatty acid is utilized

by muscle

Trained athlete have high activity of enzyme related to fatty acid and

ketone bodies utilizationAfter exercise ketone bodies is still synthesizing which leads to accumulation of ketone bodies (Ketosis)