Nutrition Physiology Flashcards
(84 cards)
1
Q
Nutrition
A
Science of the process of providing the food necessary for health and growth
2
Q
Nutrient
A
the element in food that is absorbed and utilized for cellular metabolism
3
Q
6 classes of nutrients
A
* Carbohydrate • Lipid • Protein • Vitamin • Mineral • Water: Males 3.7 L/d Female 2.7 L/d
4
Q
energy
A
Required to perform body functions. Generally expressed as the ATP produced by the catabolism of glucose, protein, lipids.
5
Q
Energy defined by nutrient
A
- Carbohydrate 4 kcal/g
- Protein 4 kcal/g
- Lipids 9 kcal/g
- Alcohol 7 kcal/g
6
Q
nutrient dense vs. energy dense foods
A
- Nutrient Dense food: provides large amount of nutrients for a small amount of kcal
- Energy dense food: comparison of the energy content of a food with the weight of that food; high in calories for amt of food
7
Q
DRI - Dietary Reference Intakes
A
general term for a set of reference values used to plan and assess nutrient intakes of healthy people; vary by age and gender; include the RDA, AI and UL
8
Q
Recommended Dietary Allowance (RDA)
A
average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people
9
Q
Adequate Intake (AI)
A
established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy
10
Q
Tolerable Upper Intake Level (UL)
A
maximum daily intake unlikely to cause adverse health effects
11
Q
Carbs source and production
A
- Sugars, starches and fibers
* produced by plants via photosynthesis (has light dependent stage and light independent stage)
12
Q
Carb structures
A
Monomer = monosaccharide (glucose, fructose, galactose)
Polymer = disaccharides (lactose, maltose, sucrose)
Starch = glucose polymers
Fibers (beta bonds; indigestable)
13
Q
insoluble fibers
A
- Seed and fruit structure
- seeds and skins of fruit, whole-wheat bread and brown rice
- Cellulose, hemicellulose
14
Q
soluble fibers
A
- Hold water, bind cholesterol and sugars, bulks stool
- Pectins, gums, mucilage, psyllium
- oatmeal, nuts, beans, apples, and blueberries
15
Q
GLUT - glucose transporter
A
- Facilitated diffusion
- Several types, tissue specific
- GLUT-4 on adipose and striated muscle is insulin dependent
16
Q
SGLT - sodium glucose transporter
A
- Sodium-glc cotransporter
- Secondary active transport
- SGLT1 present on enterocytes (GI cells) for glc absorption
- SGLT2 present on nephrons (PCT cells) for glc reabsorption
17
Q
Fxn of carbs
A
Cellular Energy Production • ATP: • Glycolysis • Oxidative phosphorylation • Pyruvate-lactate pathway
review each individual system
18
Q
explain carbs as a source of blood glucose
A
- brain consumes 20% of the body’s oxygen and 50% of glucose
- brain is unable to store ATP
- So BS is tightly maintained
- Hormonally regulated
- Insulin, glucagon, epinephrine, cortisol
19
Q
explain the protein sparing fxn of carbs
A
- prevent protein use as an energy source
* gluconeogenesis
20
Q
explain the function of preventing ketosis by carbs
A
• Ketones produced from FA by liver
• during fasting, starving, low carbohydrate diets,
prolonged exercise and DM
• 50 to100g of carbohydrates per day
21
Q
how do carbs provide organic structure
A
• Biological Recognition Processes: glycoprotein sequences are composed of amino acids linked to
carbohydrates.
• Also can serve as molecular source for production of other organiccompounds
22
Q
What are the flavor functions of carbs?
A
• provide sweetness to foods
• Receptors located at the tip of tongue bind carbohydrates, are
perceived as “sweet“
• different sugars vary in sweetness eg, fructose is almost twice as sweet as sucrose and sucrose is approximately 30% sweeter than glucose
23
Q
What are the carb functions of fiber?
A
• Dietary Fiber: passes undigested, degraded into acids and gases by coliforms, SCFA can be absorbed
bulks stools and increases mucus production.
fiber also absorbs glucose, cholesterol and bile for elimination
increases the bulk of meal w/o yielding energy
24
Q
Dietary requirements of carbs and fiber in males vs. females
A
MALES:
carbs: 130
fiber: 38
FEMALES
Adult: 130 25
Pregnant: 175 28
Lactating:210 29
25
FA structure
* Hydrocarbon chain, carboxyl end
* Basic subunit of triglycerides and phospholipids
* Insoluble in water
Chain length (short, med, lg)
• SCFA 6 or fewer carbons
• MCFA 7-12 C
• LCFA 13-21 C
26
Saturated fatty acids
* No double bonds
• Fully saturated with H
• more solid at RT, stable
• Animal fats
27
Unsaturated fatty acids
• One or more double bond in chain
* Monounsaturated (MUFA)
* Polyunsaturated (PUFA)
28
Monounsaturated (MUFA)
* Single double bond
* More fluid
* Canola and olive oils
29
Polyunsaturated (PUFA)
* 2 or more double bonds
* Omega-3: First dbl bond at third carbon
* Omega-6 :First dbl bond at sixth carbon
30
Cis FA
* H are on same side of dbl bond
| * Bends chain
31
Trans FA
• H are on opposite side of dbl bond
• Straight chain
• Typically result of hydrogenation in food industry to increase shelf
life
32
What effect does trans FA have on cholesterol?
effects cholesterol levels by raising LDL cholesterol and lowering HDL cholesterol
increasing triglycerides and Increased coronary heart disease.
33
Essential FA
* Must be provided in diet
* Source for production of eicosanoids:
* Prostaglandins
* Prostacyclins
* Thromboxane
* Leukotrienes
34
Omega-3 PUFA
• Alpha-linoleic acid
• EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid)
• tend to decrease inflammation
sources: flaxseed, broccoli, spinach, cauliflower, walnuts, canola oil, eggs.
35
Omega-6 PUFA
• Linoleic acid
• Plant oils: corn, soy and sunflower oils,
nuts and seeds
• Tend to increase inflammation
36
Essential FA DRIs
MALES
Linoleic: 17
ALA: 1.6
FEMALES
Linoleic: 12
ALA: 1.1
37
omega-6 omega-3 ratio
* typical American diet has a ratio 20 omega-6 to 1 omega-3, about 20:1
* best ratio of omega-6 to omega-3 is about 2:1 and 4:1
38
explain FA as energy source
• Catabolism of FA provides ATP:
• Lipolysis of TG in adipose
when insulin is low
• FA released to circ and uptaken by most cells via FA transporter then shuttled to mitochondrion
• Beta-oxidation is FA cleavage to release 2C acetate units
• Combined with cofactor A to form acetyl-CoA to enter oxidative phosphorylation
• Liver can release ketones to be used in TCA also
Gluconeogenesis
• Liver can catabolize fats to provide glucose
• released to circulation
39
Structure of TGs
* Glycerol plus three FA
| * Typical structure of fats and oils in diet
40
TGs as energy storage
* Light weight and energy dense form of energy
* Adipose cells store TG
* Uptaken from lipoproteins as FA and formed into TG in cell
41
TG as energy source
* Low BS, glucagon and NE can stimulate release FA from adipose to circulation
* FA serve as energy source for cells
* Glycerol can be converted to pyruvate and enter Krebs
42
TG for insulation and protection
* Adipose tissue under skin forms a layer of insulation
* Around organs forms protective cushion
* Sex characteristics
43
Transport of fat-soluble vitamins by TGs
* during SI absorption into lacteal with chylomicron
* In circulation in lipoproteins
* Storage in adipocytes
44
satiety and flavor by TGs
* Feeling of fullness and satisfaction in a meal
* Many spices dissolve in oils providing flavor to foods
* Pleasing texture
45
dietary recommendations of TGs
* limit dietary fat to 20–35% of total calories
* average American diet contains 35–40% of calories as fat
* Diets containing as little as 5–10% of total calories as fat appear tobe safe and well tolerated
46
Structure of phospholipids
glycerol, phosphate group and a polar organic group (choline)
47
phospholipid fxn as membrane
i.e. phospholipid bilayer
48
fat emulsification of phospholipids
* Forms monolayer in lipoproteins and chylomicrons
| * Bile (3%)
49
signal transduction fxn of phospholipids
* G protein couple receptor (GPCR)
* activation of phospholipase C (PLC) cleaves phosphatidylinositol phosphate (PIP3) to DAG and IP3 (soluble) to increase intracellular Ca2+ conc
50
myelination fxn of phospholipids
myelin sheath production
51
structure of cholesterol
ringed structure - no FA base.
| esterified cholesterol has big FA attached to it
52
cholesterol fxns in hormone production
```
Sex hormones:
• Estrogen
• Progesterone
• testosterone
Mineralocorticoids:
• aldosterone
Glucocorticoids:
• cortisol
```
53
Other fxns of cholesterol
cell membrane structure
bile acid production
vit. D precursor
54
sources of cholesterol
liver:
• Synthesis starts with the mevalonate pathway: two molecules of acetyl CoA condense to form acetoacetyl-CoA which forms HMG-CoA
• reduced to mevalonate by the enzyme HMG-CoA reductase
* Produce about 800-1000 mg/d
* Average American diets contain approximately 450 mg/d
* 300 mg or less per day is recommended.
55
What is the basic structure of a protein?
amino acid:
amine (-NH2) and carboxyl (-COOH) functional groups, along with a side-chain (R group) specific to each amino acid
• 20 appear in the genetic code
56
essential vs. non essential amino acids
• Non-essential amino acids:
Those that can be synthesized by cells
• Essential amino acid:
Must be provided by diet
57
complete proteins
* all 20 aa present
| * nearly all animal foods contain the essential amino acids in sufficient quantity
58
incomplete proteins
* All present however often insufficient proportion of aa
* many plant foods are lower in one or more essential amino acids than animal sources, especially lysine, methionine and threonine
59
protein synthesis
transcription and translation - how you go from DNA code to amino acid sequence
60
protein structure and denaturation
primary to secondary to tertiary 3D structure then goes to its function.
denaturation: protein rendered useless - renaturation is not common. pH can denature proteins.
61
protein functions in cell components
* cytoskeleton: microtubules, microfilaments, actin and myosin.
* cytosolic binding and transport proteins
* cell membrane: receptors, signaling proteins and transporters
* cell adhesion proteins
* nuclear pores
* dna structural proteins for binding and packaging
62
protein cellular functions
* secretions: cytokines, paracrines
* enzymes: anabolism, catabolism
* protein synthesis
* DNA replication
* mitosis
63
Protein functions in providing body structure and function
connective tissue: collagen, elastin, fibrin, cartilage, tendons, ligaments
Blood proteins: Hgb, clotting factors, transport proteins, albumin
Muscle fibers
Digestive enzymes
Visual pigments
64
Explain proteins role in maintaining fluid balance
* Oncotic (colloid) pressure created by different concentrations of proteins on two sides of a membrane or compartment influences osmosis
* CVS fluid volume is grossly maintained by the return of fluid leaked to tissues to the blood
65
What is the role of proteins in acid base balance?
acid base balance is a protein buffer system. In cells, tissues and blood. proteins can accept or donate protons.
66
Protein function in immune system
* Immunoglobulins
* Complement
* Perforins
67
Protein function in hormones
* Peptide and protein hormones
| * Thyroid, insulin, glucagon, releasing hormones, etc
68
How to proteins contribute to energy ?
They are an energy source by providing ATP and glucose
69
define nitrogen balance
a measure of nitrogen indicative of protein metabolism
Nitrogen Balance = Nitrogen intake - Nitrogen loss
70
nitrogen intake vs. losses
* nitrogen intake: meat, dairy, eggs, nuts and legumes, and grains and cereals.
* nitrogen losses: urine, feces, sweat, hair, and skin
71
Nitrogen equilibrium
Intake=loss, nitrogen balance achieved
72
Positive nitrogen balance
* intake is greater than loss
| * associated with periods of growth, hypothyroidism, tissue repair, and pregnancy
73
Negative nitrogen balance
• nitrogen loss is greater than amount ingested
• associated with burns, serious tissue injuries, fevers,
hyperthyroidism, wasting diseases, and during periods of fasting
• can be used as part of a clinical evaluation of malnutrition
74
how to measure nitrogen balance
via urea levels. (Urea is formed by liver to detoxify amine wastes, a function of
protein catabolism)
Blood urea nitrogen (BUN) lab value can be used in estimating nitrogen balance, as can the urea concentration in urine
75
Increase BUN levels vs. low BUN levels
• Increased BUN levels: impaired kidney function; kidney disease or decreased blood flow to the kidneys; excessive protein catabolism, increased protein in diet, or GI bleed
• Low BUN levels: may be seen in severe liver disease, malnutrition, and sometimes
overhydration
76
serum albumin
• tests for the diagnosis of undernutrition
• Most patients with severe protein depletion will have low serum albumin levels
• nonnutritional conditions can also reduce serum albumin—particularly liver disease and
severe illness in general
77
general requirements for protein
45-55 g/day
78
how to calculate protein requirements
Weight(kg) X 0.8g/kg = g protein/d required
* Convert pounds to kg
* Weight in pounds divided by 2.2 = weight in kg
when less active, use lower g/Kg number
if under stress, pregnancy, weight/endurance training - use higher number (b/w 1-1.8)
79
high protein diet
* Once daily protein and cal needs are met, extra protein converted to fatty acids and stored in adipose
* excess protein may displace other nutritious foods
* those with impaired renal function should avoid excess protein
* elevated dietary protein may be associated with renal cancer or kidney stones
* excess protein intake may affect insulin sensitivity and development of diabetes
80
Protein-energy undernutrition
* Undernutrition can result from:
* inadequate ingestion of nutrients
* malabsorption, impaired metabolism
* loss of nutrients due to diarrhea
* increased nutritional requirements (as occurs in cancer or infection
• Treatment consists of correcting fluid and electrolyte deficits with IV solutions, then gradually replenishing nutrients, orally if possible
81
primary PEU
Starvation;
Marasmus:
• weight loss and depletion of fat and muscle in developing
countries
• most common form of PEU in children.
• immunity is impaired, increasing susceptibility to infections.
• hunger, weight loss, growth retardation, and wasting of
subcutaneous fat and muscle.
• Ribs and facial bones appear prominent.
• Loose, thin skin hangs in folds.
82
Secondary PEU most commonly results from what?
* Disorders that affect GI function
* Wasting disorders: AIDS, cancer, COPD, renal failure, anorexia, etc.
* Conditions that increase metabolic demands: infections, hyperthyroidism, burns etc
83
Symptoms of PEU
* Apathy and irritability • weakness • Cognition and sometimes consciousness • Diarrhea is common • amenorrhea in women and loss of libido in men and women • Wasting of fat and muscle
* skin becomes thin, dry, inelastic, pale, and cold • hair dry becoming sparse • Wound healing impaired • In elderly patients, risk of hip fractures and decubitus ulcers increases • heart size and cardiac output decrease; pulse slows and BP falls • RR and vital capacity decrease • Edema, anemia, jaundice, and petechiae can develop • Liver, kidney, or heart failure may occur. • Total starvation is fatal in 8 to 12 wks
84
Sarcopenia
* progressive loss of lean body mass
* common with aging even without disease or dietary deficiency
* Causes of sarcopenia include the following:
* Decreased physical activity • Decreased food intake • Decreased levels of growth hormone • In men, decreasing androgen levels • decreased basal metabolic rate
