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.Energy 2.Synthesis 3.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. METABOLISM Sum 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. GLYCOGEN thru 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.