BIOC 2300 Lecture Notes - Lecture 25: Basal Metabolic Rate, Bile Acid, Emulsion
3 May 2018
School
Department
Course
Professor
Nutrition
April 1, 2016
Macronutrients:
• Carbohydrates
• Proteins
• Lipids
Micronutrients: *no energy
• Minerals (electrolytes and trace elements)
• Vitamins (water/fat soluble)
Energy in different nutrients:
• Fat 9 kcal/g
• Carbohydrate 4 kcal/g
• Protein 4 kcal/g
• Ethanol 7 kcal/g
1 cal = energy to heat 1g of water by 1C
1 kcal = 1000 cal = 1 Cal
Energy requirements:
• Basal metabolic rate:
o Energy expenditure at rest, warm, awake, several hours following a meal
o Higher in males than females
o Decreases with age after adulthood
▪ Decreases after age 18
• BMR of organs and tissues:
o Brain and heart are high and constant
o Liver is high due to …
• Total energy expenditure: BMR + thermic + activity
Protein and Carbohydrate Digestion *see diagram
• Amylase in saliva breaks down starch
• Pancreatic amylase then breaks it down further
• In small intestine they are broken down to monosaccharides
• Cellulose doesn’t get digested
Lipid Digestion
• Triacylglycerols
o Cannot cross membranes by simple diffusion
o Not soluble in water
o Present in diet in big droplets
• Stomach breaks lipids down emulsification by bile salts *small droplets
o Big fat globules are broken down into small droplets
o Bile acids act as detergents
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Document Summary
Micronutrients: *no energy: minerals (electrolytes and trace elements, vitamins (water/fat soluble) Energy in different nutrients: fat 9 kcal/g, carbohydrate 4 kcal/g, protein 4 kcal/g, ethanol 7 kcal/g. 1 cal = energy to heat 1g of water by 1c. Protein and carbohydrate digestion *see diagram: amylase in saliva breaks down starch, pancreatic amylase then breaks it down further, cellulose doesn"t get digested. In small intestine they are broken down to monosaccharides. *glucose is used by most tissues; insulin-stimulated uptake of glucose into muscle and adipose. In type 1, glucagon is also high even when dietary glucose is present catabolism even in the presence of nutrients. Insulin resistance: fa, inflammatory cytokines, and other molecules trigger other signalling cascades that interfere with insulin signalling. Insulin resistance is a key characteristic of type 2 obesity. Positron emission tomography image: pet visualized activity following injection of glucose tracer. It is phosphorylated by hexokinase but not further broken down accumulates in cells that take up glucose.
