TT2: Carbohydrates

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TT2 Flashcards
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Glycaemic Index ranking of the effect on blood glucose of a food of a certain carb content relative to an equal amount of carb from a reference food such as white bread or glucose
Refining processes which change or remove various components of food
Bran layers protective outer layer of whole grains; good source of vitamins and fibres
Germ embryo or sprouting portion of a kernel of grain; good source of vegetable oils and vitamin E
Endosperm largest portion of kernel of grain; mostly starch (some proteins) serves as a food supply for the sprouting seed refined grains such as corn flakes/rice krispies are made of endosperm & are mostly starch
Enriched Vs. Fortified Fortified or enriched grains are grains to which specific amounts of thiamin, riboflavin, niacin and iron have been added; since 1998 folic acid has also been added to enriched grains
Photosynthesis chlorophyll in plant leaves use energy from sunlight to combine CO2 from the air + H20 from the ground to form glucose + release oxygen
Simple Carbohydrates - sugars; mono- and di- saccharides - sometimes refined/high GI
Complex Carbohydrates glycogen, starch and fibre; monosaccharides linked together in straight or branching chains; sometimes starchy foods or sugars in their "natural" state such as whole fruit
Oligosaccharides 3-9 sugar units
Polysaccharides ≥ 10 sugar units: starch + dietary fibres
Major dietary monosaccharides Glucose: fruits, vegetables, HFCS Galactose: not present in foods Fructose: fruits, vegetables, HFCS
Hydrolysis Rxn Vs. Condensation Rxn a large molecule broken into two smaller molecules by addition of water vs. two molecules joined to form a larger molecule and water is released
Major Dietary Disaccharides Sucrose (glucose-fructose); fruits, vegetables + table sugar Maltose (glucose-glucose); germinating seeds formed during starch digestion Lactose (glucose-galactose); milk + milk products
Types of Polysaccharides Glycogen Starches (Amylose + Amylopectin) Fibre (Cellulose)
Carbohydrate storage in animals (100-200g) in liver released into bloodstream; (200-400g) in muscle for muscle's own use; stored w/ water (1 g carries 5-10 g of H20); not found in foods
Raw starch in plants packed in granules: semi-crystalline structures, resistant to digestion
Gelatinization cooking in moist heat; (starch granules swell w/ water, crystalline structure disrupted, molecules disperse + become entagled (viscous), gelatinized starch is rapidly digested)
Retrogradation cooling cooked starch; molecules partially re-associate; formation of resistant starch
Dietary Fibre polysaccharides + lignin not digested by human enzymes found intact in plant foods
Functional Fibre isolated indigestible carbohydrates shown to have beneficial physiological effects in humans
Total Fibre sum of dietary fibre + functional fibre
Soluble Fibre dissolves in water or absorbs water to form viscous solutions; usually is readily broken down (fermented) by colonic microorganisms; includes pectins, gums + some hemicelluloses
Insoluble fibre does not dissolve in water; usually is incompletely fermented in the colon; includes cellulose, some hemicelluloses + lignin
Digestibility available CHO (absorbed in small intestine) unavailable CHO (enters the colon)
What causes Lactose Intolerance? - low levels of intestinal lactase; needed to digest lactose (sugar found in milk) - more common in non-Caucasian populations
What are the symptoms of lactose intolerance? if lactose is not digested in small intestine, passes through to large intestine -> gas, pain and diarrhea
What is the treatment for lactose intolerance? reduce/eliminate dietary lactose (cheese low in lactose, lactose-free milk and non-dairy milk substitutes)
How does one get CFG's recommended 2-3 servings of milk + alternatives per day if lactose intolerant? - if not too severe; divide milk servings into smaller portions and spread them throughout the day - consume foods like tofu, fish and vegetables; - consume calcium-fortified foods, milk treated with enzyme lactase and lactase tablets
Cellular Respiration/Aerobic Metabolism glucose metabolized to generate energy 38 molecules of ATP/glucose molecule
How many calories in each gram of carbohydrate? each gram of carbohydrate = 4 kcal
How do RBC get their energy supply? they rely ONLY on glucose
Why CHO for intense exercise? oxidation of carbohydrates produces 6.3 ATP per oxygen whereas oxidation of fat only produces 5.6
Gluconeogenesis synthesis of glucose from simple, noncarbohydrate molecules; amino acids from protein are the primary source of carbons for glucose synthesis
Regulation of Acute Glycaemic Response (Internal + External Factors) Internal Factors: nature of monosaccharide, amount consumed, rate of absorption External Factors: liver, hormones secreted by pancreas
Glycaemic Load an index of the glycemic response that occurs after eating specific foods, calculated by multiplying a food's glycemic index by the amount of available carbs in a serving of the food
Glycaemic Index Vs. Glycaemic Load GI = 100 X F/G; qualitative (independent of amount of CHO) GL = g x GI/100; quantitaive; relects CHO quality + quanttiy (glycaemic impact of 1g glucose)
Regulation of Blood Glucose (Insulin Vs. Glucagon) steady supply of glucose necessary for cells; concentration regulated by liver + hormones secreted by pancreas; increase in blood glucose levels = insulin decrease in blood glucose levels = glucagon
Insulin produced by Beta cells of pancreas; increases glucose uptake by liver + muscle; stimulates storage of glucose as glycogen in liver + muscle; overall effect of lowering blood glucose
Translocation of GLUT4 Transporter SEE TEXTBOOK
Glucagon produced by alpha cells of the pancreas; stimulates breakdown of glycogen to glucose; stimulates gluconeogenesis (production of glucose from AA); overall effect = raises blood glucose
Blood glucose response elicited by 80g HFCS plasma glucose removed as quickly as half and hour after intake, even undershoots baseline (we can't regulate insulin as quick as we want)
Fuel Use: Fasting SEE TEXTBOOK
Fuel Use: Postprandial SEE TEXTBOOK
Availability of Carbs + Fatty Acid Metabolism When carbohydrates are unavailable, fatty acids are converted to ketones which are used for energy, excreted urine or accumulate in blood
Abnormal Blood Glucose 1. Low blood glucose (hypoglycaemia) 2. High blood glucose (diabetes)
Symptoms of Hypoglycaemia - irritability, nervousness - sweating - anxiety, shakiness, rapid heart beat - hunger, weakness - headache - seizure, coma
Diagnosis of Hypoglycaemia must demonstrate low blood glucose in presence of symptoms
Types of Hypoglycaemia Overtreatment of diabetes (imbalance b/w insulin/medication & food/exercise) Reactive hypoglycaemia (in response to consuming CHO/treatment is small frequent meals, low sugars, high protein/fibre) Fasting hypoglycaemia (insulin secreting tumour)
Symptoms of Diabetes - excessive thirst - frequent urination (glucose in urine) - blurred vision - frequent infections (skin, vagina, urinary tract) - poor wound healing - pain or numbness in feet/legs
Type 1 Diabetes insulin deficiency due to destruction of insulin-secreting cells by the body's own immune system; usually develops in children & adolescents; accounts for 5-10% of all cases of diabetes; requires insulin injections
Type 2 Diabetes reduced insulin sensitivity/secretion; usually occurs in middle-aged/elderly people (most are obese); account for 90-95% of all cases of diabetes; due to inability to produce sufficient insulin to overcome insulin resistance
Gestational Diabetes high blood glucose first occurring during pregnancy
Diabetes Diagnosis diagnose by high blood glucose levels by fasting or by after eating
Diabetes Complications: Micro-vascular disease - retinopathy (eye damage) - nephropathy (kidney failure) - neuropathy (nerve damage - pain/numbness)
Diabetes Complication: Macro-Vascular Disease - heart attack (MI)/heart failure - stroke - poor circulation in legs/feet - infection
Is tight control of blood glucose necessary? SEE TEXTBOOK
What is intensive insulin therapy? 3-4 injections per day or insulin pump (combination of long- and short- acting insulins) insulin dose based on carb counting, blood glucose monitoring 3-4 times per day
Endocrinological Feedback Loop
Causes of Type 2 Diabetes
What is Gestational Diabetes? Prevalence? high blood glucose first occurring during pregnancy; due to placental hormones which causes insulin resistance; higher prevalence in Aboriginal populations; all pregnant woman screened for GDM
Risks associated with Gestational Diabetes (Maternal) Caesarean delivery; pre-eclampsia; birth trauma; diabetes after delivery
Risks associated with Gestational Diabetes (Infant) stillbirth, birth defects; macrosomia, shoulder dystocia; diabetes in adulthood
Treatment of GDM INSULIN
Diabetes Treatment goal is to reduce risk for complications by controlling blood glucose, lipids & BP + managing body weight treatment includes combination of diet, exercise and if necessary medication (oral or injected) + regular examination of eyes, kidney function and feet
What is a diabetes diet? - normal "healthy" diet" - use of a divided plate to control portions - advice to limit simple sugars & choose starchy goods, whole grains, milk, fruit & low fat meat & dairy products
Recommendations for CHO - RDA for carbs is 130g/day for adults + children; minimum amount of glucose used by the brain - AMDR for carbs is 46-65% of energy - sources should be unrefined + no more than 25% carbs consumed should come from added refined sugars - CFG recommends Canadians choose foods w/ little or no added sugar
Nutritive Sweetners contains 4 kcal energy per gram; sugar, fructose, honey, brown sugar, sugar alcohols, high fructose corn syrup
Non-nutritive Sweetners provide little or no energy; acceptable daily intakes (ADI) have been established by HC for saccharine, acesulfame-K, aspartame, sucralose
Soluble Fibre pectin, gums, mucilages found in legumes, fruit, oats, barley increase/decrease metabolic effects
Insoluble Fibre lignin, cellulose, hemicellulose; fibrous vegetables, wheat, rye, corn increase/decrease stool bulking
Medical uses of fibre - laxative - irritable bowel - diverticular disease - lowering cholesterol - lowering blood glucose
Actions of fibre in GI tract
Dietary fibre adequate intake (AI) for fiber is 14 grams for every 1000 kcal in diet (38g for men, 25g for women) most canadians eat only 14-21 grams of fiber eating whole grain foods, fruits, vegetables, and legumes daily will increase your fibre intake

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