1. Glycogenesis
    • Increased glycogen levels possible through physical training and dietary manipulations although limited energy source
    • Fat storage: conversion of glucose to fat is irreversible
  2. Carbohydrate Digestion
    • Carbohydrates from food tend to be disaccharides (sugars) or polysaccharides (starches) which must be broken down into monosaccharidesfor absorbtion
    • Begins in the mouth and ends in the small intestine where intestinal enzymes and pancreatic amylase complete the conversion to monosaccharides
    • Enzymes:
    • Lactase: lactose
    • Sucrase: sucrose
    • Maltase: maltose
  3. Carbohydrate Metabolism
    • Primary aspect is maintenance of blood glucose homeostasis  (70-100 mg/dL)
    • Blood glucose sources may be CHO and non-CHO Dietary starches and simple CHO provide blood glucose after digestion and absorption
    • Glycogenolysis: process of converting glycogen stored in liver and muscle back to glucose
    • Gluconeogenesis: process of producing glucose from fat and protein
    • Results in formation of ketones which can lead to acid base imbalances
  4. Blood Glucose Regulation: Hypoglycemic hormones
    • Insulin
    • Pancreas: beta cells
    • Lowers blood glucose
    • Eases glucose absorption into cells increases glucose use as energy
    • Enhances glycogenesis: conversion of excess glucose to glycogen
    • Stimulates lipogenesis: conversion of excess glucose to fat
    • Inhibits breakdown of fat and protein
    • Promotes amino acid uptake in skeletal muscle, increasing protein synthesis
    • Influences glucose oxidation
  5. Blood Glucose Regulation: Hyperglycemic Hormones
    • Glucagon
    • Pancreas: alpha cells
    • Raises blood glucose
    • stimulates conversion of liver glycogen to glucose
    • Stimulates breakdown of lipids for energy
    • Somatostatin
    • Released from the Pancreas and Hypothalamus
    • Inhibits glucose and glucagon
    • Epinephrine
    • Raises blood glucose
    • Enhances conversion of liver glycogen to glucose Glucocorticoids
    • Promote gluconeogenesis and inhibit insulin
    • Thyroid hormone Increases insulin breakdown, increases glucose absorption, causes releas  of epinephrine
  6. Glycemic Index
    • Measure of the effect of a carbohydrate-containing food on blood glucose level: ranking of how much the food raises glucose levels
    • ranking of 100 highest; < 50 low
    • Low glycemic index is good!
    • Factors affecting glycemicindex
    • Physical form such as apple juice compared with apple
    • Fat and protein content in addition to CHO, which slows digestion
    • Ripeness such as in fruits and vegetables, which increases glucose content
    • Fiber content, which slows digestion
    • Botanic variety of a food, such as the different glycemic indexes of rice species
  7. Simple Carbohydrates
    • Monosaccharides
    • Glucose
    • Often called blood sugar,is the simple CHO that circulates in blood
    • Found in fruits and honey
    • Main energy source for central nervous system and brain
    • Rapidly absorbed into bloodstream from intestine, but needs insulin to enter cells
  8. Sugar: a special disaccharide
    • Sugar refers to simple CHO, sucrose, white table sugar, and numerous sweetening agents
    • refined white sugar, brown sugar, dextrose, crystalline fructose, high fructose corn syrup (HFCS), glucose, corn sweeteners, concentrated fruit juice, honey, maple syrup, molasses, sorbitol, mannitol, xylitol 
    • Concerns about sugar focus on (1) sources in the food supply, (2) consumption levels, and (3) health effects
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