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DEMS unit 2 > Metabolism/Pathways intro > Flashcards

Metabolism/Pathways intro Flashcards

1
Q

Concept of energy balance

A

Energy in = Energy Out

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2
Q

Weight gain

A

Energy in > Energy Out

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3
Q

weight loss

A

Energy in

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4
Q

components of Total energy expenditure (TEE)

A

Resting metabolic rate, Thermic effect of food, energy expended in physical activity

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5
Q

Resting metabolic rate

A
  • about 75% TEE in sedentary ppl

- primary determinant = free fat mass (lean body mass)

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6
Q

measure resting metabolic rate

A

indirect calorimetry – device measures respiratory gas composition and flow rates to estimate O2 consumption/CO2 production

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7
Q

Why is oxygen used in indirect calorimetry

A

energy mostly from oxidation of nutrients (oxygen final electron acceptor in oxidation of nutrients, so rate of oxygen consumed = indirect measure of energy expenditure)

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8
Q

Estimate RMR

A

formula based on age, sex, height, weight, and lean body mass if known fo rmore accuracy

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9
Q

Thermic effect of food (TEF)

A
  • normally about 8% of TEE
  • energy cost of digestion/distributing nutrients from diet to body tissues
  • protein has highest energy cost, then carbs then fat
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10
Q

Measure Thermic effect of food

A
  • indirect calorimetry - determine increment of energy expenditure above RMR following ingestion of defined test meal
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11
Q

Energy costs of nutrients

A

Protein > Carbs > Fat

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12
Q

Energy expended in physical activity

A
  • most variable component of energy expenditure

- 30-40% for those exercising regularly

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13
Q

non-exercise activity thermogenesis (NEAT)

A

refers to energy consumed in movement that is unplanned/unconscious; i.e. fidgeting or other random movements

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14
Q

efficiency

A

ratio of work to total energy expenditure during activity (total includes that lost as heat/lost to environment)

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15
Q

measure total energy expenditure

A

doubly labeled water – measures O2 consumption in free living individuals over weeks then subtract RER and TEF

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16
Q

Energy intake regulated by

A

brain makes decisions about eating (how much, how often)

- get signals from senses, organs, internal signals (blood nutrient levels/hormones)— all regulated in brain pathways

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17
Q

3 key nutrient molecules

A

glucose, fatty acids, amino acids

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18
Q

Stores of which nutrient has largest energy

A
  • Fat (about 9 kcal/g) – large storage pool
  • Carbs: 4 kcal/g – stored as glycogen in muscle and liver
  • Protein: 4 kcal/g but no true storage
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19
Q

what happens to excess protein

A

oxidized to carbohydrate or fat

- if in protein balance, carbs preferentially oxidized and fat stored

20
Q

why do we accumulate body fat

A
  • smaller capacity to store excess carbohydrates, so they will be preferentially oxidized while fat is stored
  • can also convert carbs into fat for more efficient storage
21
Q

What happens in fasting

A
  • glycogen broken down, protein in muscle –> amino acids to convert to glucose
  • eventually lack essential amino acids, essential fatty acids and micronutrients and get organ dysfunction/disease
22
Q

what happens in positive energy balance

A
  • assimilate ingested nutrients and fill storage pools

- may remake polymers from monomers –> anabolic

23
Q

Forms of energy currency in cell

A

ATP, NADPH, GTP/UTP, NADH/FADH2

24
Q

catabolic vs anabolic processes

A

catabolic = breakdown of complex molecules into simpler ones

anabolic - building complex molecules from simpler ones

25
Q

Glycolysis

A
  • in cytoplasm
  • Breakdown of glucose (6C) to pyruvate (2 3-carbon molecules)
  • pyruvate converted to lactate when no oxygen or cell doesn’t have mitochondria
26
Q

TCA cycle

A
  • Tricarboxylic acid cycle
  • Pyruvate –> oxaloacetate
  • produces CO2, GTP, NADH, FADH2
27
Q

Electron transport

A
  • series of protein in inner mitochondrial membrane
  • take NADH/FADH2 –> produce ATP from ADP
  • consume O2 and produce water – oxidative phosphorylation
28
Q

Gluconeogenesis

A

produce glucose from other nutrients

- uses lactate, carbon skeletons of amino acids

29
Q

Glycogen

A

storage of glucose; mostly in liver and skeletal muscle

30
Q

Urea cycle

A

disposes of nitrogen left over from amino acid conversion to glucose
- produces urea that enters blood as BUN–excreted by kidneys as urea nitrogen

31
Q

Main point of glycolysis

A

breakdown glucose to produce a little ATP and NADH

- ends with pyruvate in oxygen-containing tissues or converted to lactate if no oxygen/mitochondria

32
Q

Purpose of TCA cycle

A
  • requires O2 and mitochondria
  • extract energy from pyruvate
  • produce CO2, GTP, NADH, FADH2
33
Q

Electron transport chain purpose

A
  • oxidative phosphorylation– - consume oxygen to produce water
  • takes all the NADH/FADH2 from TCA to produce ATP from ADP
  • NEED OXYGEN and ADP!
34
Q

purpose of gluconeogenesis

A
  • when not enough glucose (negative energy balance)–> create glucose from lactate/amino acids
35
Q

where does gluconeogenesis take place

A

liver, some kidney

36
Q

what is glycogen

A

storage form of glucose

  • liver - 100 g
  • 400 g in skeletal muscle
37
Q

Pentose Phosphate Pathway

A
  • Hexose Monophosphate Shunt
  • When excess glucose, generates NADPH and ribose
  • NADPH used for fatty acidt/steroid hormones Ribose -5- phosphate is a key step in nucleotide synthesis
38
Q

purpose of NADPH

A
  • provides energy for synthesis of fatty acids and steroid hormones
  • important in defending cells against oxidative stress and in pathogen killing by WBC
39
Q

Triacylglycerol (triglyceride synthesis)

A
  • De novo lipogenesis
  • with excess glucose, rise in Acetyl-CoA that can be used to make fatty acids for storage
  • chains of 3 fatty acids plus glycerol can make triglyceride to store in adipose tissue or secreted from liver
40
Q

What is stored better, carbohydrate or fat?

A

Fat

41
Q

Triacylglycerol degradation

A

if negative energy balance (fasting/exercise), stored fat can provide energy to oxidizing tissues (sk.muscle/liver)

42
Q

can fat be converted to glucose

A

No, but its breakdown can provide energy for gluconeogenesis in the liver

43
Q

Beta oxidation

A

breakdown of fatty acids 2 carbons at a time to get Acetyl-CoA

44
Q

Ketogenesis

A

Process of breaking down fatty acids to ketone bodies when very low insulin and high counter regulatory hormones

45
Q

Brain food

A

glucose; can use ketone bodies when fasting/uncontrolled type I diabetes

46
Q

Functions of amino acids

A
  • structural components of proteins
  • precursors for other molecules (NT and hormones)
  • substrate for gluconeogenesis
  • nitrogen carriers
47
Q

Urea cycle

A

disposal of Nitrogen from metabolism of amino acids

  • produces urea (BUN in blood)
  • BUN excreted by kidneys in form of urine area nitrogen

DEMS unit 2 (4 decks)

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