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111: Anatomy/Phys 2 > 10.1 Nutrition Metabolism and Body temp regulation > Flashcards

10.1 Nutrition Metabolism and Body temp regulation Flashcards

1
Q

what is a nutrient

major nutrieds

micronutrients

A

Nutrient - a substance that promotes normal growth, maintenance, and repair

Major nutrients - carbohydrates, lipids, and proteins

Other nutrients (micronutrients) - required insmall amounts (vitamins and minerals)

*Technically water is a nutrient as well (60% of our diet by volume)

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2
Q

what are essential nutrients

A

must be eaten because body cannot synthesize these from other nutrients

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3
Q

Nonessential nutrients

A

vital to life, but if not enough is available, liver can usually convert another nutrient into one needed

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4
Q

what is a calorie

A

amount of heat (energy) needed to raise

temperature of 1 kg H2O by 1°C

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5
Q

what are teh types of carbohydrates

A

(CH2O)2

  • Monosaccharides: Simple sugars with multiple OH groups.

* Name depends on the number of carbons (3C-triose, 4C-tetrose, 5C -pentose or 6C-hexose

  • Disaccharides: 2 monosaccharides covalently linked
  • Oligosaccharides: a few monosaccharides covalently linked (up to 9 or 10)
  • Polysaccharides: polymers consisting of chains of monosaccharide or disaccharide units
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6
Q

how are polysaccharides stored

A
  • Starches
    • glucose polymers that have alpha linkage bonds (alpha 1,4)
      • amylose: linear chian of >10 glucose mol
      • Amylopectin (~80%) is a branch molecule made of >1000gluclose units
      • digested by amylases
  • Glycogen: polysaccharide found in animals and is composed of a branched chain of glucose residues
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7
Q

structural polysaccharides

A
  • Cellulose
    • structural component of plants with repeated glucose untis bonded by beta linkages
      • humans cant break the beta linkages (dietary fiber)
      • ruminants & termintes can digest
  • Chitin
    • one of most abundant natural materials
      • has long unbranched chains of glucose similar to celluclose
      • compentne tof cell walls of exoskeletons of crustaceans, plants and insects
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8
Q

how are carbohydrates used in the body

A
  • neurons and RBC rely almost entirely on glucose
  • excess glucose is conv to glycogen for fat and stored
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9
Q

what are the dietary requirements for carbohydrates

A
  • need about 100g/day (<50g leads to tissue breakdown)
  • carbs should be 45-65% of total calorie intake
  • strachy foods and milk have nutrients like vitmains and minerals plus complex carbohydrates
  • Refined carbohydrate foods (candy and soft drinks) provide an energy source ONLY and are referred to as “empty calories”
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10
Q

dietary sources of lipids

A
  • saturated fats:
    • meat, dairy food and few tropical plants (coconut)
    • hydrogenated oils (trans fats) like margarine and solid shortening
  • Unsaturated fats
    • seeds, nuts, olive oil, and vegetables oils
  • Cholesterol
    • egg yolk, meats, shellfish, and milk
    • liver produces 85% of req cholesterol
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11
Q

essential fatty acids

A

linoleic (omega-6 FA) and linolenic acid (omega-3 FA) are found in most vegetables, fish and shellfish

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12
Q

why are fats important for yout body (uses)

A
  • Fats:
    • help the body to absorb vitamins
    • major energy fuel of hepatocytes
    • heart, skeletal muscle
    • component of myelin sheaths and all cell membranes
  • Cholesterol
    • stabilizes membrnaes and is a precursr of bile salts and steroid hormones

*lipids stored as triglycerides

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13
Q

dietary requriements for lipids

A
  • Fats represent over 40% of the calories in our diets
  • should be less than 30% of caloric intake
  • saturated fats limit to <10% of total fat intake
  • daily cholesterol intake should not exceed 200mg/dl (amoung in one egg yolk)
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14
Q

what subsititudes are available for lipids

A
  • modified starches and gums, and/or milk whey protein (Simplesse)
  • Olestra
    • ​fat-based product made from cottonseeds and sucrose
    • not metabolized bc tis not digested or abs
  • Drawbacks
    • Destroyed by the intense heat needed to fry foods
    • cramping, flatus (gas, or diarrhea
    • interfere w/ abs of fat solube drugs vitmains( A,D,E and K) and phytochemicals like beta carotene, a precursor of vitamin A
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15
Q

dietary sources of protiens

A

Eggs, milk, fish, and most meats have all the body’s amino acid (AA) requirements

  • Legumes (beans & peas), nuts, and cereals are protein- rich but are low in one or more of the essential AA
  • Leafy green vegetables are well balanced in all essential AA except methionine, but contain only small amounts of protein
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16
Q

what are the 8 essetail amino acids required in our diet

A

tryptophab

methionine (those above two better found in corn and grains)

valine

threonine

phenylalanine

leuine

isoleucine (bottom two better found in legumes)

lysine

histidine and anrginine (infants)

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17
Q

how much protein do we need

A

depends on age, size, metabolic rate, and current state of nitrogen balance

  • recommend daily intake of 0.8g/kg body weight
  • prolonged high protein consmptom may lead to bone loss
  • > metabolizing sulfur continaing AA makes blood more acidic and bone Ca2+ used to buffer acids
18
Q

what are vitamins

A

most not made in the body, except Vit D made in skin, Vit B &K made in small amounts by intestinal bacterial

  • body can convert beta-carotene, the orange pigment in carrots and other foods, to vitamin A(beta-carotene is a provitamins)

* No one food contains all the required vitamins

19
Q

what are the two main classes of vitamines

A
  • Fat soluble vitmains
    • A,D,E and K (ADEK)
    • bind to ingested lipids anda re abs with their digestion products
    • Except for vitamin K, fat-soluble vitamins are stored in the body
  • Water soluble
    • B-complex (8 types) and C)
    • absorbed in the GI tract
    • B12 must bind gastric intrinsic factor to be absorbed
    • ingested amounts not used within an hour or so are excreted in urine
  • Vitamins A,C and E act in an antioxidant cascade
20
Q

role of vit B1

B2

B3

B5

A

B1 (thiamine) imp for removing CO2

B2 (riboflavin) compentnts of FAD and FMN

B3 (Niacin): component of NAd and NADP+

  • B5 (pantothenic acid): component of Coenzyme A
21
Q

role of vit

B7

B9

B12

Vit C

A

B7 (biotin); synthesis of fat, glycogen and aa

B9 (folic acid): nucleic acid and amino acid metabolism

B12: nucleic acid metab, maturation of RBC

Vit C (ascorbic acid): collagen synthesis, antioxidant

22
Q

Role of Vit A

D

E

and K

A

A (retinol): syn visual pigments, maintenance of epithelial tissues, antioxidant

D: aids in abs of calcium and phosphorous

E (tocopherol): antioxidant

K (phylloquinone): imp for formation of blood clotting

23
Q

what are minerals

A

Dozens are required and some in trace amounts

  • make up 4% of body weight, monsyl from Ca2+ and phosphorous (as bone slats

*those account for 75% of body weight

  • Minerals work with nutrients to ensure proper body functioning
  • Uptake and excretion must be balanced to prevent toxic overload
24
Q

anabolism vs catabolism

A

Anabolism = larger molecules are built from smaller ones

Catabolism = all processes that break down complex structures

25
Q

general roe of ATP and phosphorylation in metbaolism

A

ATP: erves as the “chemical drive shaft” links energy- releasing catabolic reactions to cellular work

*ATP is never hydrolyzed directly but instead enzymes shift its high-energy phosphate groups to other molecules

  • Phosphorylation primes mol to change in way that increases activity, produces motion or does work
26
Q

what are the stages of nutrient processing

A
  1. Digestion and abs in GI tract
  2. delivered nutrients are build into lipids, proteins and glycogen by anabolic pathways OR broken down yb catabolic pathways to pyruvate and acetyl CoA
  3. Almost entirely catabolic required O2 producing CO2, water and ATP
27
Q

role of oxidation reducation reaction

A

-involve the gain of oxygen or loss of hydrogen atoms (and their electrons)

  • in Redox reactions
    • Oxidized substances lose electrons and energy (LEO)
    • Reduced substances gain electrons and energy (GER)
    • catalyzed by enzymes vit B usually coenzyme
      • ​dehydrogenases involve removal of hydrogen
      • Oxidases catalyze transfer of oxygen
28
Q

how are carbohydrates metabolism

A

Oxidation of glucose is shown by the overall reaction:

C6H12O6 + 6 O2 —> 6 H2O + 6 CO2 + 36 ATP + heat

glucose is catabolized in 3 pathways: glyolysis, krebs cycle and ETC and ox phosphoylation

29
Q

what is glycolysis

A
  • 3 phase pathway: 2 NAD reduced -> NADH + H+

Products: Net 2 ATP and pyruvic acid

*pyruvic acid -> Kerbs cycle in aerobic pathway OR -> lactic acid via anaerobic pathway

30
Q

what are teh 3 phases of glycolysis

A

phase 1: sugar activation: glucose -> fructose 1,6 bisphosphate

Phase2: fructose 1,6 bisphosphate -> Glyceraldehyde phoshpate

phase 3 sugar oxidation and formation of ATP: -> 2 pyruvate

31
Q

what is the Krebs Cycle

A

aka citric acid cycle

  • pyruvate enters mitochondira and conv to acetyl CoA

Starting material: glucose + 2 acetyl CoA

Products: 3 NADH + H+, 1 FADH2, 2 CO2, 1 ATP (for each acetyl CoA, so x2)

32
Q

how is glucose oxidized

overview

A
  • last step of glucose metabolism
  • ETC is only pathway that directly uses oxygen

* CA cycle will notrun is oxygen not rpesent- but does not directly use oxygen

  • overview:
    • NADH+ + H+ and FADH2 (from glycolysis and Krebs cycle) deliver H+ taken from glucose to ETC proteins
    • ETC uses engery from e- and hydrogen to pump H+ across memrbane creating proton gradient
    • some H+ combines with O2 -> water
33
Q

what carrier proteins are involved in the ETC

A

*ETC harvests energy of food fuels a little bit at a time to avoid damage to cell (e.g. from ROS)

  • carrier proteins are in iner mitochondiral membrane, contain metal atoms (cofactors)
  • Flavins: proteins from riboflavin (vit B2) and ETC complexes I and II
  • Cytochromes: proteins with iron containing pigment compelxes (III and IV)
  • neighboring compelxes cluster together forming respiratory enzyme complexes
  • each protein complex alternatively reduced and oxidized as picks up/passes electorn
34
Q

describe step 1 of ETC

A
  1. complexes I and II accept hydrogen from NADH and FADH2 respectively
    - > NAD+ and FAD+ can now return to glycolsus and krebs cycle
35
Q

describe step 2 of ETC

A
  1. Hydrogen atoms are split into H+ (proton) and electorns (e-)
    - > electrons passed down chain
    - > each complex reduced when gets e-, then ox when passes on e- to next coplex
    - coenzyme Q and cytochrome c act to shuttle electron between complexes
    - very little energy releaed/transfre
    - energy released used by complexes I, III and IV to pump H+ out into intermembrane space of mitochondria creating an H+ concentration gradient (proton gradient)
36
Q

describe step 3 of ETC

A
  • at complex IV e- pairs combine with some H+ and a molecule of oxygen to form water

2H+ +2e- —> 1⁄ 2 O2 →H2O

37
Q

Describe ATP synthase complex steps to make ATP

A
  1. protons flow down electrochemical gradient thru stationary stator
  2. each prton binds a subunit of rotor -> changes shape and making rotor spin
  3. spinning rotor turns the connecting rod
  4. as rod spins, it activates catalytic sites in kob, joing Pi to ADP to make ATP

*PRODYCT: NADH ox -> 2.5 ATP, FADH2 ox -> 1.5 ATP

38
Q

how efficeint is the body at metabolizing glucose

A
  • of 686 kcal in 1 mole glucose, 262 kcal captured at ATP
  • rest lost as heat

38% efficient

39
Q

what is the net gain from compelte oxidation of 1 glucose molecule

A
  1. Substrate level phosphorylation: Net 4 ATPs
    • 2 from glycolysis and 2 from citric acid cycle
  2. Oxidattive phos: Net 28 ATPs
    • each NADH/H+ = 2.5
      • 10 NADH/H so 25 ATP
    • Each FADH2 = 1.5 ATPs
      • 2 FADHs amde = 3 ATPS

TOTAL 32 ATPs BUT energy to move NADH/H from glycolysis into mitochonrida uses 2 ATPS

FINAL TOTAL IS 30

40
Q
A

111: Anatomy/Phys 2 (31 decks)

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