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Physio - E2 - Lecture Slides > L-7 Energy Balance and Metabolism II > Flashcards

L-7 Energy Balance and Metabolism II Flashcards

1
Q

how is ATP generated?

A

by the combustion of:

  • carbs
  • fatty acids
  • proteins
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2
Q

what does ATP energize?

A
  • synthesis of cellular components
  • muscle contraction
  • active transport across membranes
  • glandular secretion
  • nerve conduction
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3
Q

what does phosphocreatine function as?

A
  • an accessory storage depot for energy

- ATP buffer

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4
Q

describe phosphocreatine

A
  • has a high energy phosphate bond (13,000 cal)
  • is 3-8 times more abundant than ATP
  • cannot participate directly in energy transfer
  • can transfer energy interchangeably with ATP
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5
Q

what do non-essential amino acid formation depend on?

A

alpha-keto acid precursors

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6
Q

what amino acid is present in the body in large quantities?

A

glutamine; serves as an amino radical storehouse

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7
Q

what are aminotransferases derivatives of?

A

pyridoxine (vitamin B6)

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8
Q

describe protein synthesis in regards to energy consumption

A
  • one of the most energy expensive processes

- different peptide linkages require anywhere from 500 to 5000 calories per mole

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9
Q

how many phosphate bonds are needed to form one peptide linkage?

A

4

- each peptide bond only stores 500-5000 calories

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10
Q

what happens to excess amino acids in the body?

A

they are degraded and used for energy

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11
Q

what is one of the end products of deamination?

A

ammonia

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12
Q

what helps form urea? where?

A

in the liver; two molecules of ammonia + one molecule of CO2 are combined; this is the urea (ornithine) cycle

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13
Q

where in the liver cells does the ornithine cycle occur?

A

in mitochondria and in cytoplasm

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14
Q

describe process in mito

A

ammonia + CO2 –> carbamoyl phosphate

carbamoyl phosphate + ornithine –> citrulline

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15
Q

describe process in cytoplasm

A

citrulline + aspartate –> argininosuccinate

argininosuccinate –> arginine + fumarate

arginine –> urea + ornithine

*fumarate can enter CAC

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16
Q

what is the rate of the overall chemical reaction determined by?

A
  • concentration of enzyme

- concentration of substrate

17
Q

in regards to reaction rate, what happens when substrate concentration is high

A
  • reaction rate is determined almost entirely by concentration of enzyme
18
Q

give an example

A

diabetes mellitus and glucose:

  • large quantities of glucose enter renal tubules
  • glucose is in great excess in the tubules
  • transport enzymes become saturated
  • further incr in gluc concen in tubules have little effect on gluc reabsorption
  • glucose reabs rate is limited by concen of transport enzymes
19
Q

what about when enzyme conc is high

A
  • reaction rate becomes directly proportional to concentration of substrate enzyme
20
Q

give an example

A

absorption of substances from intestinal tract and renal tubules when concentrations of the substrate are low compared to transport enzymes

21
Q

EXAM: what is the major rate-limiting factor for almost all energy metabolism in the body?

A

ADP

22
Q

elaborate

A
  • cellular concentrations of ADP are low
  • chemical reactions that depend on ADP as one of the substrates are very slow
  • ATP is converted to ADP during cellular activity; thus, ADP concen incr during cell activity
  • incr ADP = incr reaction rates
23
Q

what are some examples of ADP substrate dependence

A

all oxidative metabolic pathways

other pathways for the release of energy

24
Q

how much of the energy in foods becomes heat during ATP formation and how much of it is used by functional systems?

A

35% and 27%

25
Q

what are factors that influence metabolic rate?

A
  • arousal vs sleeping
  • skeletal muscle
  • age
  • thyroid activity
  • testosterone
  • growth hormone
  • fever
  • sleep
  • malnutrition
26
Q

what is the best known stimuli for increasing the rate of thyroid stimulating hormone?

A

the cold

27
Q

describe basal metabolic rate

A

95% of energy expended by body is dervied from oxidative phosphorylation involving different kinds of foods

28
Q

how can whole-body metabolic rate be calculated ?

A

from rate of oxygen utilization

29
Q

what do you metabolize 1 L of O2 with?

A
  • glucose: 5.01 C
  • fat: 4.7 Cal
  • Protein: 4.6 Cal
30
Q

how many Cal are liberated per liter of oxygen with average diet?

A

averages to about 4.825 Cal = energy equivalent of oxygen

31
Q

give some averages and random numbers on basal metabolic rate

A
  • avg 70kg man, inactive: 1650 Cal/day
  • 70kg man, inactive, reasonable diet: 1850 Cal/day
  • 70 man, sitting in chair, psychologically active, no exercise: 2000 Cal/day
  • walking upstairs requires 17x the energy as sleeping in bed all day
32
Q

what is the BMR average per hour?

A

65-70 Cal per hour

33
Q

How is BMR measured?

A

TEXT

34
Q

what are some factors affecting BMR?

A
  • thyroxine and basal metabolic rate
  • malnutrition and basal metabolic rate
  • testosterone and basal metabolic rate
35
Q

describe the thyroxine and basal metabolic rate

A
  • thyroxine incr rate of chem reactions in cells and incr metabolic rate
  • max secretion may incr metabolic rate 50 to 100 percent above average
  • loss of thyroid secretion decr met rate to 40-60% of normal
36
Q

describe malnutrition and basal metabolic rate

A
  • malnutrition results in reduced food substances in the cells
  • this results in a marked reduction in metabolic rate
  • this process may accompany final stages of many disease conditions
37
Q

describe testosterone and basal metabolic rate

A
  • T can incr met rate 10-15 %

- mainly related to anabolic effect of incr in skeletal muscle mass

38
Q

what is the minimal level of energy required for a person to just exist?

A

60% - basal metabolic rate

39
Q

what is much of the decline in BMR with increased age?

A

probably related to loss of muscle mass and replacement with adipose tissue with a lower rate of metabolism

Physio - E2 - Lecture Slides (8 decks)

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