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Therapeutics > Ex. 6 L1 - Macronutrients (L-58) > Flashcards

Ex. 6 L1 - Macronutrients (L-58) Flashcards

1
Q

Role of dietary carbohydrates

A

-Major energy source for humans
(4 kcal/g)
-Used to generate many metabolic intermediates

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2
Q

Excess carbohydrates are converted to

A

Glycogen
Triacylglycerol

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3
Q

Which organs can store glycogen

A

Liver and muscle
-Muscle can store glycogen

-All other carbohydrates will eventually make fat and then store it as a triacylgylcerol

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4
Q

Simple Carbohydrates

A

Sugars
Fruits, vegetable, and milk
Monosaccharides
-Single sugar molecules (C6H12O6)
Glucose, fructose, galactose
NOT COMMONLY OBSERVED IN FOODS - usually parts of disaccharides
Disaccharides
-Two sugar molecules combined
Glucose and fructose
-Sucrose lactose, maltose

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5
Q

Complex carbohydrates

A

-Polysaccharides
-Many monosaccharides linked together in chain
-Glycogen in animals and starch and fiber in plants

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6
Q

Glucose

A

AKA Dextrose
-The most important carbohydrate fuel for the body
-Frequently referred to as blood sugar
-Rarely occurs as monosaccharide in food; part of a disaccharide

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7
Q

Fructose

A

Found in fruits and vegetables, more than half the sugar in honey
-Does not cause as great a rise in blood glucose as other sugars, but causes an increase in blood lipids
-The dramatic increase in the use of high-fructose corn syrup has been suggested to be related in the increased incidence of diabetes and obesity

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8
Q

a-amylase

A

Hydrolyzes starch and glycogen to maltose and maltotriose
Exists in saliva and pancreatic juice

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9
Q

Enzymes on the luminal surface of small intestine

A

-Maltase (a-glycosidease): maltose and maltotriose -> glucose
-Sucrase: sucrose -> glucose and fructose
-Lactase: Lactose-> glucose and galactose
-Lactose intolerance occurs when lactase is not produced enough
Only monosaccharides are absorbed in the body

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10
Q

Indigestible carbohydrates

A

-Converted to monosaccharides by bacterial enzymes
-Metabolized anaerobically by bacteria
-Result in production of short-chain fatty acids, lactate, H2, CH4 and CO2
-May cause flatulence and abdominal discomfort

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11
Q

Raffinose

A

Oligosaccharide in leguminous seeds (beans and peas)
Cannot be hydrolyzed by human enzymes

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12
Q

Glycemic Index

A

Measure of how quickly individual foods will raise blood glucose levels
Defined as the ratio of the area of the blood glucose response curve to that of glucose

Lower GI = longer time to absorb in the body
When high GI = lots of insulin released

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13
Q

Dietary fibers

A

Cellulose and hemicellulose
Lignin
Pectin

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14
Q

Cellulose and hemicellulose

A

Unrefined cereals, bran, whole wheat
Insoluble
Increase stool bulk and decrease intestinal transit time

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15
Q

Lignin

A

Woody parts of vegetables
Insoluble
Binds cholesterol and carcinogens

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16
Q

Pectin

A

Fruits
Soluble
Decreases rate of sugar uptake and decreases serum cholesterol

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17
Q

Lipids in diet

A

Efficient source of energy (9kcal/g)
Provides satiety
Adds flavor and aroma to diet
Carrier for fat-soluble vitamins
Traicylglycerol is >90% of dietary fat
-Glycerol + three fatty acids
Phospholipids, cholesterol, cholesterol esters, fatty acids are <10% of dietary fat

18
Q

Essential fatty acids

A

Omega-3 (w3) fatty acids
a-Linolenic acid (18:3) in vegetable oils
-Eicosapentaenoic acid (EPA) (20:5) and docosahexaenoic acid (DHA) (22:6) in fish oils

-Omega-6 (w-6) fatty acids
Linoleic acids (18:2) in corn oil
Arachidonic acid (20:4) in meat and fish
-Used to synthesize eicosanoids in the body
-Deficiency is rare in US; need to be added to artificial infant formula
-The ratio of w-3 to w-6 acids in the diet is important in regulating processes like blood pressure, blood clotting, and immune function

19
Q

Trans fatty acids

A

Most unsaturated fatty acids found in nature have Cis double bond configuration
-Hydrogenation process to convert unsaturated fatty acids to sat fatty acids produces trans fatty acids as byproducts
-Hydrogenated or partially hydrogenated vegetable oils are a primary ingredient in margarine and shortening
-A trans fatty acid has a higher melting point than the same fatty acids in the cis configuration
-Tran fats raise blood cholesterol levels and increases the risk of heart disease

20
Q

Digestion of lipids

A

Fats need to be solubilized for digestion
-Dispersion of lipid phase into small droplets
-Solubilization by bile acids

Gastric and pancreatic lipases
-Hydrolyze triacylglycerol to fatty acids and monoacylglycerol
-Produced fatty acids acts as surfactants

Esterase
-Hydrolyzes monoacylglycerol and cholesterol ester

21
Q

Utilization of lipids

A

Chylomicron delivers lipid to peripheral tissues directly
-Muscle uses fat as energy source
-Excess fat is stored in adipose tissues
-Brain does not use fat as energy source
-When starved, liver converts fatty acid to ketone bodies (ketogenesis), which are utilized as energy source by brain and muscle

22
Q

Role of dietary proteins

A

Essential Structural component
Enzymes, hormones, plasma proteins, antibodies

23
Q

Excess protein

A

Source of energy
Glucogenic amino acids -> glucose
Ketogenic amino acids -> keto acids and fatty acids
-Eventually converted to triacylglycerol in adipose tissue

protein = 20% of our body weight

24
Q

Negative nitrogen balance

A

Inadequate dietary intake of protein
Trauma or illness

25
Q

Positive nitrogen balance

A

Net increase in body protein stores
Growing children, pregnant women, or adults recovering from illness

26
Q

Essential amino acids

A

Cannot be synthesized by the body or synthesized but not enough (arginine, methionine, and phenylalanine)

If not in the diet, new proteins cannot be made w/o breaking down other body proteins -> negative nitrogen balance occurs

Mixed sources of protein necessary for vegetarian diet

Essential:
-Arginine
-Histidine
-Isoleucine
-Leucine
-Lysine
-Methionine
-Phenylalanine
-Threonine
-Tryptophan
-Valine

27
Q

Conditionally essential amino acids

A

If phenylalanine is not enough, tyrosine can not be made enough in the body

Conditionally:
Cysteine
Glutamine
Glycine
Proline
Tyrosine

28
Q

Gastric digestion of proteins

A

pH of gastric juice <2
Low pH denatures proteins
Pepsins - stable and active at acidic pH; aspartic protease

29
Q

Intestinal digestion of proteins - Peptidases at luminal surface

A

-Brush border - luminal surface of epithelial cells
-Rich in peptidases
-Produces free AA and di and tripeptides

30
Q

Intestinal digestion of proteins - intracellular peptidases

A

Amino acid and peptide transport systems
Intracellular hydrolysis of di and tripeptide s
Practically only free amino acids are released to blood

31
Q

Celiac disease

A

Celiac sprue
-Gluten intolerance
-~2 million ppl in US
-Autoimmune disorder in genetically predisposed individuals

Caused by exposure to gluten
-Major proteins contained in wheat, rye, and barley

The lining of the small intestine is inflamed and damaged
-Diarrhea, weight loss, malnutrition

-Life-long gluten-free diet

32
Q

Dietary Composition

A

Average consumption (US; Male)
-Carb - 310g
-Fat - 94g
-Protein - 100g

Energy content: 4kcal/g
Fat: 9kcal/g
Protein 4kcal/g
Alcohol 7kcal/g

33
Q

Energy reserves of humans

A

Excess energy is stored mostly as fat in adipose tissue
Glycogen in the liver to maintain blood glucose levels
Glycogen in muscle is used for exercise
Protein is not a preferred energy reserve

34
Q

Fuel reserves

A

Glycogen in liver:
70g; 280kcal

Glycogen in muscle
120g; 480kcal

Glucose in Body fluids
15,000g; 135,000kcal

Fat in adipose
15,000g; 135,000kcal

Protein in muscle
6,000g; 24,000kcal

35
Q

Well-fed state

A

Insulin release
Glycolysis
Glycogen synthesis
Catabolism of amino acids
Fatty acid synthesis
No gluconeogenesis ( = no Cori Cycle)

36
Q

Early fasting state

A

Glucagon release
Glycogen breakdown
Gluconeogenesis
-Cori cycle
-Alanine cycle
No catabolism of amino acids

37
Q

Fasting state

A

Glucagon release
Gluconeogenesis
-Protein is used as a major carbon and nitrogen source
-Alanine
-Glutamine
Lipolysis in adipose tissue
Fatty acid oxidation
Ketogenesis
Reduced thyroid hormones
-> the daily basal energy requirement drops by 25%

38
Q

Caloric homeostasis

A

Constant availability of fuels in the blood
Glucose is carefully regulated
If glucose is <1.5mM (27mg/dL), coma and death will follow shortly
Hyperglycemia -> dehydration, hyperglycemic coma, complications of diabetes

39
Q

Glucose ATP equivalents

A

Very well fed:
6.1mM
110mg/dL
313mM (ATP)

Postabsorptive 12h
4.8mM
86mg/dL
290 mM (ATP)

Fasted 3 days
3.8 mM
68mg/dL
380 mM (ATP)

Fasted 5 weeks
3.6 mM
65mg/dL
537mM (ATP)

40
Q

Energy for brain

A

Glucose as brain food
-Brain uses more than 20% of total energy
-100-120g of glucose per day (preferred fuel)
-Uses 15-20% of the total oxygen
-Constant energy need (awake or sleep)

Membrane potential
-Na+/K+ ATPase

No energy storage
-No glycogen storage
-Brain does not use fat

Adaptation to starvation
Ketone bodies made from acetyl-CoA in the liver

41
Q

Marasmus

A

Inadequate intake of both protein and energy
Thin, wasted appearance
Small for his/her age

-Infants and young children
-Reduced ability to fight off infection

42
Q

Kwashiorkor

A

Inadequate intake of PROTEIN WITH ADEQUATE ENERGY INTAKE
Mainly in children 1-3 years
Deceptive plump appearance due to edema

Therapeutics (61 decks)

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