58: Macronutrition Flashcards
Role of dietary carbs
-major energy source for humans
-used to generate metabolic intermediates
excess carbs converted to
-glycogen
-triacyglycerol
Types of carbs
-simple (mono, di saccharides)
-complex (poly)
Simple carbs
-sugards
-fruits, veggies, milk
-mono and di saccharides
Monosaccharides
-single sugar molecules
-glucose, fructose, galactose
Disaccharides
-2 sugars combined
-sucrose, lactose, maltose
Polysaccharides
-complex
-many monos linked together
-glycogen in animals
-starch and fiber in plants
Glucose
-mono
-aka dextrose
-most important carb fuel for the body
-blood sugar
-di-sac or starch in food
Fructose
-fruits, veggies, honey
-does no inc blood glucose but inc blood lipids
-high-fructose corn syrup obesity
Digestion of carbs
-a-amylase
-enzymes on surface of small intestine
Only monosaccharides are
absorbed in the body
a-amylase
-hydrolyzes starch and glycogen to make maltose and maltotriose
-in saliva and pancreatic juice
small intestine enzymes
-maltase (m to glucose)
-sucrase (s to glucose and FRUCTose)
-lactase (l to glucose and GALACTOSE)
lactose intolerance caused by
-not enought lactase
Metabolism of indigetable carbs
-converted to monosac by bacterial enzymes
-anaerobic metabolism by bacteria
=production of short-chain fatty acids, lactate, H2, CH4, Co2
-may cause flatuelence and ab discomfort
Raffinose
-oligosaccharide in leguminous seeds (beans, peas)
-cannot be hydrolyzed by human enzymes
Glycemic index
-measure of how quickly individual foods will raise blood glucose levels
-ratio of area of blood glucose response curve to glucose curve
-100 is pure sugar
Dietary fibers
-cellulose and hemicellulose
-lignin
-pectin
Cellulose/Hemicellulose
-unrefined cereals, bran, wheat
-insoluble
-inc stool bulk and dec intestinal transit time
Lignin
-woody parts of veggies
-insoluble
-binds cholesterol and carcinogens
Pectin
-fruits
-soluble
-dec rate of sugar uptake and dec cholesterol
Dietary lipid function
-efficient source of energy
-provides satiety
-adds flavor and aroma
-carrier for fat-soluble vitamins
Dietary fat comp
-triacylglycerol is >90% of dietary fat
-phospholipids, cholesterol, esters, fatty acids 10%
Essential fatty acids
-used to synthesize eicosanoids in the body
-deficiency rare in US, needs to be added to baby formula
-omega 3 and 6
Ratio of omega 3 to 6 in the diet is important in
-regulating BP, blood clotting, and immune functions
Omega-3 fatty acids
-a-linolenic acid (18:3) in veg oil
-EPA (20:5) and DHA (22:6) in fish oils
Omega-6 fatty acids
-linoleic acid (18:2) in corn oil
-arachidonic acid (20:4) in meat and fish
Trans fatty acids
-higher melting point than cis
-raise blood cholesterol
-inc risk of heart disease
Hydrogenation
-converts unsaturated to saturated
-produces trans fats as byproduct
-hydrogenated oils for margarine and shortening
Digestion of Lipids
-fat needs to be solubilized for digestion
-dispersion of lipid phase into small droplets
-solubilization by bile acids
-gastric and pancreatic lipases
-esterase
gastric and pancreatic lipases
-hydrolyze triacylglycerol to fatty acids and monoacylglycerol
-produced fatty acids act as surfactantsE
Esterase
-hydrolyzes monoacylglycerol and cholesterol ester
Utililization of lipids
-used by muscles for energy
-excesss stored in adipose
-NOT used by brain
Chylomicron
delivers lipids to tissues
Ketone bodies
-conversion of fatty acids in liver
-used by muscle AND BRAIN
-acetone
Role of Proteins in diet
-essential structure component
-enzymes, hormones, plasma proteins, antibodies
Excess dietary protein
-source of energy
-glucogenic amino acids = glucose
-ketogenic amino acids = keto acids and fatty acids
-eventually converted to triacylglycerol in adipose tissue
Comp of human body by weight
-water 65%
-protein 20%
-fat 12%
Nitrogen balance
-intake of proteins vs excretion in urea and ammonia
Negative nitrogen balance
-inadequate dietary intake of protein
-trauma or illnessp
positive nitrogen balance
-net inc in body protein stores (less excretion)
-growing children, preg women, adults recovering from illness
Essential amino acids in the diet
-cannot be made by body in sufficient amounts
-if not in diet, new proteins cannot be made without breaking down other body proteins = results in negative nitrogen balance
-mix sources needed for vegetarians
Conditionally essential amino acids
-if phenylalanine is not enough, tyrosine cannot be made enough in the body
Digestion of proteins
-gastric
-intestinal by peptidases
Gastric digestion of proteins
-pH of gas juice <2
-low pH denatures proteins
-pepsins
Pepsins
-stable and active at acidic pH
-aspartic protease
Intestinal digestion of proteins by peptidases at LUMINAL SURFACE
-brush border
-produces free amino acids and di/tri peptides
Intestinal digestion of proteins by INTRACELLULAR peptidases
-amino acid and peptide transport systems
-intracellular hydrolysis of di/tri peptides
-practically only free amino acids are released to blood
Celiac Disease
-Celiac sprue
-gluten intolerance
-autoimmune genetic
-inflammed and damaged lining of small intestine (diarrhea, weight loss, malnutrition)
avg dietary consumption
-310g carbs
-94g fat
-100g protein
Energy content of macronutrition
-carbs 4 cal/g
-fat 9
-protein 4
-alcohol 7
Energy reserves of humans
-fat stored in adipose
-glycogen in liver to maintain blood sugar levels
-glycogen in muscle for exercise
-protein not preferred
Body in well-fed state
-insulin RELEASE
-glycoLYSIS
-glycogen synthesis
-CATabolism of amino acids
-fatty acid synthesis
-no gluconeogenesis (no cori cycle)
Early fasting state
-Glucagon RELEASE
-glycogen breakdown
-glucoNEOGENESIS (cori and alanine cycle)
-no catabolism of amino acids
Fasting state
-glucagon release
-gluconeogenesis
-protein used as major carbon and nitrogen source (alanine and glutamine)
-lipolysis in adipose tissue
-fatty acid oxidation
-ketogenesis
-reduced thyroid hormones (daily basal energy requirement drops by 25%
Caloric homeostasis
-constant availability of fuels in the blood
-glucose carefully regulated
Hyperglycemia
-dehydration, coma, diabetes complications
Glucose below 1.5
-coma and death
Energy for brain
-glucose
-uses more than 20% of total energy (100-120g/day)
-15-20% of total oxygen
-constant energy needed
Brain membrane potential
-na+/K+ ATPase
Brain energy storage
-NONE
-no glycogen storage
-brain doesn’t use fat
Brain adaptation to starvation
-ketone bodies made from acetyl-CoA in the liver
Protein-energy malnutrition
-common in developing countries in infants bc reduce ability to fight off infection
-Marasmus
-Kwashiorkor
Marasmus
-inadequate intake of both protein and energy
-thin, wasted appearance
-small for age
Kwashiorkor
-inadequate intake of protein with adequate energy intake
-mainly in kids 1-3
-deceptive plump appearance due to edema
