understanding metabolism dr. ayisha qureshi assistant professor, mbbs, mphil
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UNDERSTANDING METABOLISM
Dr. Ayisha Qureshi Assistant Professor,
MBBS, Mphil
SIMPLIFYING METABOLISM
• Dietary fuel intake is intermittent, not continuous. • As a result excess energy from nutrients taken in
at meals must be stored and then released between meals.
• The food ingested meets one of three fates: 1. Energy2. Synthesis3. Storage
Stored Metabolic Fuel in the Body
ANABOLIC PATHWAYS:Pathways that synthesize larger molecules
from smaller ones. Usually energy in the form of ATP is required.
CATABOLIC PATHWAYS:Pathways that break large molecules into
smaller ones. Usually ATP is yielded.
FED/ ABSORPTIVE STATE:The period of time following a meal, when the products of digestion are being absorbed, used
and stored. This is an anabolic state in which energy of nutrients is transferred to larger mol.
FASTING/ POST-ABSORPTIVE STATE:The time period in between the meals when
nutrients are NOT present in the blood anymore & so NOT available for use by the tissues. Now the body taps into the stored
reserves. This is a catabolic state.
METABOLISMSum of all chemical
reactions in the body
Interconversions among Organic molecules
ALL FOOD EATEN (even CHO & Proteins) IS ULTIMATELY CONVERTED INTO FATS AND STORED IN THE ADIPOSE TISSUE.
MAINTAINING BLOOD GLUCOSE LEVELS DURING FASTING STATE
BLOOD GLUCOSE
LEVELS
PROTEINS serve as the last resort
for energy and providing glucose thru
Gluconeogenesis.
GLYCOGENthru Glycogenolysis
forms Glucose
FATS (TG) break down into
Glycerol (10%) & Fatty acids (90%). Glycerol
forms Glucose.
CARBOHYDRATE METABOLISM
The principal product of carbohydrate digestion & the principal circulating sugar is GLUCOSE.
• The breakdown of glucose to pyruvate or lactate (or both) is called Glycolysis.
• The conversion of non-glucose molecules to glucose is called Gluconeogenesis.
CARBOHYDRATE METABOLISM
• Glycolysis• Gluconeogenesis• Glycogenolysis• Glycogenesis
GLYCOGEN
• Glycogenesis: The process of glycogen formation is glycogenesis.
• Glycogenolysis: The process of glycogen breakdown is glycogenolysis.
Glycogen, the storage form of sugar, is present in most body tissues, but the major supplies are in the liver & skeletal muscles.
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