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Biochem > Ch. 12: Bioenergetics and Regulation of Metabolism > Flashcards

Ch. 12: Bioenergetics and Regulation of Metabolism Flashcards

1
Q

why are biological systems often considered open systems?

A

because they can exchange both energy and matter with the environment

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2
Q

in the body, how is energy exchanged? how is matter exchanged?

A

energy is exchanged in the form of mechanical work when something is moved over a distance, OR as heat energy

matter is exchanged through food consumption and elimination, as well as respiration

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3
Q

at what level are most biochemical studies performed?

A

cellular or subcellular, NOT the entire organism

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4
Q

why are the cellular or subcellular studies considered closed systems?

A

there is no exchange of matter with the environment

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5
Q

defn: internal energy

A

the sum of all of the different interactions between and within atoms in a system (vibration, rotation, linear motion, and stored chemical energies all contribute)

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6
Q

how does the fact that the system is closed affect the change in internal energy?

A

it can come only in the form of work (changes in pressure and volume) or heat

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7
Q

why is heat the only quantity of interest in determining internal energy?

A

because pressure and volume (which together are work) are constant in most living systems

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8
Q

defn: bioenergetics

A

the term used to describe energy states in bilogical systems

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9
Q

what information do changes in free energy (G) provide? (2)

A
  1. info about chemical reactions
  2. can predict whether a chem reaction is favorable and will occur
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10
Q

in biological systems, what is the crucial role that ATP plays?

A

crucial role in transferring energy from energy-releasing catabolic processes to energy-requiring anabolic processes

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11
Q

what determines whether a chemical reaction proceeds?

A

by the degree to which enthalpy and entropy change during a chemical reaction

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12
Q

defn: enthalpy

A

measures the overall change in heat of a system during a reaction

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13
Q

what is true about change in enthalpy (H) and thermodynamic heat exchange (Q) at constant pressure and volume?

A

they are equal

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14
Q

defn: changes in entropy (S)

A

measure the degree of disorder or energy dispersion in a system

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15
Q

unit: entropy

A

J/K

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16
Q

eqn + func: Gibbs free energy equation

A

predicts the direction in which a chemical reaction proceeds spontaneously

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17
Q

char: spontaneous vs. nonspontaneous reactions vs. equilibrium

A

SPONTANEOUS = proceed forward, exhibit a net loss of free energy, have negative deltaG

NONSPONTANEOUS = would be spontaneous in reverse, have net gain of energy, positive deltaG

APPROACHING EQUILIBRIUM = free energy approaches zero, no net change in concentration of reactants or products

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18
Q

defn: change in free energy vs. change in standard free energy

A

CHANGE IN FREE ENERGY = predicts changes occurring at any concentration of products and reactants and at any temperature

STANDARD FREE ENERGY = the energy change that occurs at standard concentrations of 1 M, pressure of 1 atm, temperature of 25 deg C

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19
Q

how can change in free energy and change in standard free energy be related? (eqn)

A

where R is the universal gas constant
T is temperature
Q is the reaction quotient

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20
Q

biochemical analysis works well under all standard conditions except one, what is that one?

A

pH

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21
Q

values: modified standard state

A

ΔG°′ indicates that it is standardized to the neutral buffers used in biochem

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22
Q

what is the general trend of the relationship between deltaG and the ratio of products to reactants?

A

products > reactants tend to have more negative deltaG

reactants > products tend to have more positive deltaG

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23
Q

the human body can make use of different energy sources with roughly the same efficiency, so are all nutrient molecules created equally?

A

no (i.e fats are more energy-rich than carbohydrates, proteins, or ketones)

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24
Q

value of energy: complete combustion of fat vs. carbohydrates, proteins, or ketones

A

fat: 9 kcal/g of energy

others: 4 kcal/g

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25
Q

why are fats preferred for long-term energy storage?

A

fats are so much more energy-dense than other biomolecules

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26
Q

analogy: fats vs. carbs for storage

A

fats = 16 GB flash drive
carbs = 8 GB flash drive

they occupy the same amount of physical space, but fat holds twice as much data

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27
Q

what is the readily available form of energy fot the cell?

A

ATP! (adenosine triphosphate)

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28
Q

what is ATP formed from?

A

substrate-level phosphorylation and oxidative phosphorylation

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29
Q

why do we want ATP to be a mid-level carrier and not a higher-level one?

A

think about your wallet – if you never had the ability to get change back after a purchase what type of bill would you want in abundance? one dollar bills!

similarly, ATP cannot get back the “leftover” free energy after a reaction, so it’s best to use a carrier with a smaller free energy

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30
Q

main source of production for ATP + 2 secondary sources

A

main: mitochondrial ATP synthase

secondary: 1. during glycolysis 2. indirectly from GTP in the citric acid cycle

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31
Q

structure + generated from + consumed by: ATP

A
  1. consists of an adenosine molecule attached to 3 phosphate groups
  2. generated from ADP and Pi with energy input from an exergonic reaction or electrochemical gradient
  3. consumed either through hydrolysis or the transfer of a phosphate group to another molecule
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32
Q

what results if one phosphate is removed from ATP? if 2 phosphates are removed from ATP?

A

1 phosphate –> adenosine diphosphate (ADP) is produced

2 phosphates –> adenosine monophosphate (AMP) produced

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33
Q

in a single day, what % of a person’s body weight does an average sized person use in ATP? how many grams of ATP are available at any given time?

what accounts for this discrepancy?

A

90%

50g

continuous recycling of ATP, ADP, and Pi more than 1000 times per day accounts for this discrepancy

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34
Q

func (2): ATP

A

to fuel energetically unfavorable reactions or to activate or inactive other molecules

it is the major energy currency in the body and is a mid-level energy carrier

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35
Q

what makes ATP such a good energy carrier? + how

A

its high-energy phosphate bonds

the negative charges on the phosphate groups experience repulsive forces with one another and the ADP and Pi molecules that form after hydrolysis are stabilized by resonance

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36
Q

is ATP more stable before or after hydrolysis? what thermodynamic value does this acccount for?

A

after, although its not UNSTABLE before hand

accounts for the negative value of deltaG

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37
Q

values: deltaGknot for

standard conditions

at pH 7 and with excess magnesium

ADP

AMP

A

standard conditions: - 55 kJ/mol

at pH 7 and excess magnesium: - 30.5 kJ/mol

ADP similar to above

AMP: -9.2 kJ/mol

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38
Q

in what reaction layout is ATP hydrolysis most likely to be in countered?

A

in the context of coupled reactions

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39
Q

how is ATP used in many coupled reactions?

A

as an energy source

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40
Q

defn: ATP cleavage

A

the transfer of a high-energy phosphate group from ATP to another molecule which generally activates or inactivates the target molecule

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41
Q

how is the overall free energy of the reaction determined with the phosphoryl group transfers that happen with ATP cleavage?

A

by taking the sum of the free energies of the individual reactions

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42
Q

how can we conceptualize the free energy of hydrolysis?

A

the transfer of the phosphate group to water

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43
Q

how can one determine the free energy of the phosphoryl group transfer to another biological molecule?

A

use Hess’s law and calculate the difference in free energy between the reactants and products

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44
Q

true or false: many key enzymes in ATP synthesis and other biochemical pathways have oxidoreductase activity

A

true

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45
Q

sign of delta G and E for spontaneous redox reactions

A

negative deltaG

positive E (electromotive force)

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46
Q

what are 6 molecules that act as soluble, high-energy electron carriers in the cytoplasm?

A
  1. NADH
  2. NADPH
  3. FADH2
  4. ubiquinone
  5. cytochromes
  6. gluatathione
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47
Q

what happens to electrons as they are passed down the electron transport chain?

A

they give up their free energy to form the proton-motive force across the inner mitochondrial membrane

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48
Q

are their electron carriers other than the soluble ones we have just discussed?

A

yes there are also membrane-bound electron carriers embedded within the inner mitochondrial membrane

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49
Q

what is an example of an inner mitochondrial membrane bound electron carrier

A

flavin mononucleotide (FMN), which is bonded to complex I of the ETC and can also act as a soluble electron carrier

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50
Q

proteins with prosthetic groups containing iron-sulfur clusters are particularly well suited for what

A

the transport of electrons

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51
Q

defn: riboflavin

A

a modified vitamin B2 contained in flavoproteins

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52
Q

defn: flavoproteins

A

nucleic acid derivatives

generally either flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN)

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53
Q

what are flavoproteins most notable for?

A

their presence in the mitochondria and chloroplasts as electron carriers

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54
Q

2 other funcs: flavoproteins

A
  1. involved in the modification of other B vitamins to active forms
  2. function as coenzymes for enzymes in the oxidation of fatty acids, the decarboxylation of pyruvate, and the reduction of glutathione
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55
Q

what is one of the key differences between general chemistry and biochemistry?

A

whether or not equilibrium is seen as a desirable state

biochemists: no

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56
Q

what do biochemists seek instead of equilibrium?

A

homeostasis

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57
Q

defn: equilibrium vs. homeostasis

A

equilibrium = a fixed state, thus preventing us from storing any energy for later use or creating an excitable environment

homeostasis = a physiological tendency toward a relatively stable stat that is maintained and adjusted, often with the expenditure of energy

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58
Q

what is the impact of the fact that most compounds in the body are actually maintained at a homeostatic level that is different from equilibrium?

A

we can store potential energy

reactions can proceed such that equilibrium is put off for a long time

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59
Q

what do the pathways that are operational in fuel metabolism depend on?

A

the nutritional status of the organism

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60
Q

what 2 things are very pronounced when going from the well-fed state to an overnight fast?

A
  1. shifts between storage and mobilization of a particular fuel
  2. shifts among the types of fuel being used
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61
Q

2 aka + defn: + char postprandial state

A

aka: absorptive state, well-fed state

occurs shortly after eating and generally lasts 3-5 hours after eating a meal

marked by greater anabolism and fuel storage than catabolism

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62
Q

defn: anabolism vs. catabolism

A

anabolism = synthesis of biomolecules

catabolism = breakdown of biomolecules for energy

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63
Q

what happens during the postprandial state?

A

nutrients flood fro the gut and make their way via the hepatic portal vein to the liver, where they can be stored or distributed to other tissues of the body

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64
Q

what happens just after eating? (4)

A
  1. blood glucose levels rise and stimulate the release of insulin
  2. insulin promotes glycogen synthesis in liver and muscle
  3. after the glycogen stores are filled, the liver converts excess glucose to fatty acids and triacylglycerols
  4. insulin promotes triacylglycerol synthesis in the adipose tissue and protein synthesis in muscle, as well as glucose entry into both tissues
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65
Q

what are the 3 major target tissues for insulin?

A
  1. the liver
  2. muscle
  3. adipose tissue
66
Q

after a meal, how are most of the energy needs of the liver met?

A

by the oxidation of excess amino acids

67
Q

what 2 types of cells are notably insensitive to insulin?

A
  1. nervous tissue
  2. red blood cells
68
Q

how do nervous tissue and red blood cells interact with glucose?

A

NERVOUS TISSUE derives energy fro oxidizing glucose to CO2 and water in both the well-fed and normal fasting states (only changes in prolonged fasting)

RED BLOOD CELLS can only use glucose anaerobically for all their energy needs, regardless of the individual’s metabolic state

69
Q

what 5 hormones oppose the actions of insulin? what and why are these hormones called?

A
  1. glucagon
  2. cortisol
  3. epinephrine
  4. norepinephrine
  5. growth hormone

called: counterregulatory hormones because of their effects on skeletal muscle, adipose tissue, and the liver which are opposite to the actions of insulin

70
Q

what happens after several weeks of fasting? (3)

A
  1. the brain derives approx. 2/3 of its energy from ketones and 1/3 from glucose
  2. the shift from glucose to ketones as the main fuel reduces the quantity of amino acids that must be degraded to support gluconeogenesis, which spares proteins that are vital for other functions
  3. cells that have few to no mitochondria like red blood cells continue to be dependent on glucose for their energy
71
Q

in a broad stroke: how is metabolism regulated best?

A

through hormonal means

72
Q

func in metabolism:
water-soluble peptide hormones

vs.

fat-soluble amino acid-derivative hormones and steroid hormones

A

water-soluble peptide hormones (like insulin) able to rapidly adjust the metabolic processes of cells via second messenger cascades

fat-soluble amino-acid derivative hormones (like thyroid hormones) and steroid hormones (like cortisol) enact longer-range effects by exerting regulatory actions at the transcriptional level

73
Q

how are hormone levels regulated? (2)

A
  1. by feedback loops with other endocrine structures (such as the hypothalamic-pituitary axis)
  2. by the biomolecule upon which they act (i.e. insulin causes a decrease in blood glucose, which removes the trigger for continued insulin release)
74
Q

defn: insulin

A

a peptide hormone secreted by the beta-cells of the pancreatic islets of Langerhans

75
Q

func: insulin

A

a key player in the uptake and storage of glucose

76
Q

by what and how is glucose absorbed?

A

by peripheral tissues via facilitated transport mechanisms that utilize glucose transporters located in the cell membrane

77
Q

what 2 tissues require insulin for effective glucose uptake?

A
  1. adipose tissue
  2. resting skeletal muscle
78
Q

what are the 5 tissues in which glucose uptake is not affected by insulin?

what is a difference in these types of tissues?

A
  1. nervous tissue
  2. kidney tubules
  3. intestinal mucosa
  4. red blood cells
  5. beta-cells of the pancreas

difference:

some tissues that require insulin actively store glucose when it is present in high concentrations, while other tissues that do not require insulin must still be able to absorb glucose even when the glucose concentration is low

79
Q

how does insulin affect the metabolism of carbohydrates? (4)

A
  1. increases glucose uptake, 2. carbohydrate metabolism in muscle and fat and 3. glycogen synthesis in the liver
  2. decreases the activity of enzymes that promote glycogen breakdown
80
Q

func (2): increase glucose in muscle

A
  1. used as additional fuel to burn during exercise
  2. can be stored as glycogen
81
Q

how does insulin affect amino acid uptake by muscle cells?

A

it increases amino acid uptake by muscle cells, thereby increasing levels of protein synthesis and decreasing breakdown of essential proteins

82
Q

how does insulin affect metabolism of fats? sum + 5 specifics

A

sum: significant impact especially in the liver and adipocytes

insulin increases:
1. glucose and triacylglycerol uptake by fat cells
2. lipoprotein lipase activity, which clears VLDL and chylomicrons from the blood
3. triacylglycerol synthesis (lipogenesis) in adipose tissue and the liver from acetyl-CoA

insulin decreases:
1. triacylglycerol breakdown (lipolysis) in adipose tissue
2. formation of ketone bodies by the liver

83
Q

what is the most important controller of insulin secretion?

A

plasma glucose

84
Q

above what threshold is insulin secretion directly proportional to plasma glucose?

A

100 mg/dL OR about 5.6 mM glucose

85
Q

what must happen for glucose to promote insulin secretion?

A

glucose must not only enter the beta-cell but also can be metabolized, increasing intracellular ATP concentration

86
Q

what impact does increased ATP have on insulin?

A

increased ATP –> calcium release in the cell –> promotes exocytosis of preformed insulin from intracellular vesicles

87
Q

what else is insulin secretion affected by?

A

signaling initiated by other hormones, such as glucagon and somatostatin

88
Q

do patients with type 1 diabetes synthesize insulin or glucagon? what impact does this have?

A

they CANNOT make insulin, but DO make glucagon

this increases blood sugar much more than if an individual were to lose all pancreatic function or to develop insulin insensitivity

89
Q

defn: glucagon

A

a peptide hormone secreted by the alpha-cells of the pancreatic islets of Langerhans

90
Q

what is the primary target for glucagon action?

A

the hepatocyte

91
Q

what 5 affects does glucagon have as it acts through second messengers?

A

increased liver:
1. glycogenolysis

  1. gluconeogenesis

3.ketogenesis

  1. lipolysis

decrease: lipogenesis

92
Q

what are the most important physiological promoter and inhibitor of glucagon secretion?

A

PROMOTER = low plasma glucose (hypoglycemia)

INHIBITOR = elevated plasma glucose (hyperglycermia)

93
Q

do amino acids promote or inhibit the secretion of glucagon? which ones?

A

PROMOTE

especially basic amino acids (arginine, lysine, histidine)

THUS, glucagon is secreted in response to the ingestion of a meal rich in proteins

94
Q

functional relationship: insulin and glucagon

A

INSULIN (associated with a well-fed, absorptive metabolic state) and GLUCAGON (associated with a postabsorptive metabolic state) usually oppose each other with respect to pathways of energy metabolism

enzymes that are phosphorylated by glucagon are generally dephosphorylated by insulin and enzymes that are phosphorylated by insulin are generally dephosphorylated by glucagon

95
Q

func + where/when do they come from: glucocorticoids

A

from the adrenal cortex

secreted with many forms of stress

responsible for part of the stress response

96
Q

why must glucose be rapidly mobilized from the liver? (2)

A
  1. in order to fuel actively contracting muscle cells while fatty acids are released from adipocytes
  2. in order to make a getaway in the “fight-or-flight” response
97
Q

defn: cortisol

A

a steroid hormone that promotes the mobilization of energy stores through the degradation and increased delivery of amino acids and increased lipolysis

98
Q

how does cortisol elevate blood glucose levels? what is the impact of this?

A

increases glucose availability for nervous tissue through two mechanisms

  1. cortisol inhibits glucose uptake in most tissues (muscle, lymphoid, and fat) and increases hepatic output of glucose via gluconeogenesis, particularly from amino acids
  2. cortisol has a permissive function that enhances the activity of glucagon, epinephrine, and other catecholamines
99
Q

impact of long-term exposure to glucocorticoids

A

causes persistent hyperglycemia, which stimulates insulin

this promotes fat storage in the adipose tissue, rather than lipolysis

100
Q

difference in what is produces by the adrenal cortex vs. the adrenal medulla

A

ADRENAL CORTEX produces steroid hormones (glucocorticoids, mineralocorticoids, and sex hormones)

ADRENAL MEDULLA produces catecholamines

101
Q

what secretes catecholamines? what 2 things are included in this group + their akas + diagram

A

secreted by the adrenal medulla

  1. epinephrine (aka adrenaline)
  2. norepinephrine (aka noradrenaline)
102
Q

func (3): catecholamines

A
  1. increase the activity of liver and muscle glycogen phosphorylase, thus promoting glycogenolysis (this increases glucose output by the liver)
  2. glycogenolysis also increases in skeletal muscle, but because muscle lacks glucose-6-phosphatase, glucose cannot be released by skeletal muscle into the bloodstream; instead, it is metabolized by the muscle tissue itself
  3. act on adipose tissue to increase lipolysis by increasing the activity of hormone-sensitive lipase
103
Q

func: epinephrine

A

acts directly on target organs like the heart to increase the basal metabolic rate through the sympathetic nervous system

this increase in metabolic function is often associated with an adrenal rush

104
Q

4 symptoms of hypothyroidism (insufficient thyroid hormone)

A
  1. cold intolerance
  2. fatigue
  3. weight gain
  4. depression

metabolism suffers

105
Q

4 symptoms of hyperthyroidism (excessive thyroid hormone levels)

A
  1. rapid weight loss
  2. anxiety
  3. jitteriness
  4. fever
106
Q

what does it mean that thyroid activity is largely permissive?

A

thyroid hormone levels are kept more or less constant, rather than undulating with changes in metabolic state

107
Q

func (3) + char (2): thyroid hormones

A

func: 1. increase the basal metabolic rate
2. accelerate cholesterol clearance from the plasma
3. increase the rate of glucose absorption from the small intestine

char: 1. increase in BMR is evidenced by increased O2 consumption and heat production when they are secreted
2. have primary effects in lipid and carbohydrate metabolism

108
Q

difference in increase in metabolic rate produced by thyroxine (T4) and triiodothryonine (T3)

A

T4: increase in metabolic rate occurs after a latency of several hours but may last for several days

T3: produces a more rapid increase in metabolic rate and has a shorter duration of activity

109
Q

what do the subscript numbers in T3 and T4 indicate?

A

the number of iodine atoms in the hormone

110
Q

relationship between T4 and T3

A

T4 can be thought of as the precursor to T3

111
Q

defn + func: deiodonases

A

enzymes that remove iodine from a molecule

located in target tissues and convert T4 to T3

112
Q

what does epinephrine require of thyroid hormones?

A

to have a significant metabolic effect

113
Q

what are the 4 major sites of metabolic activity in the body?

A
  1. the liver
  2. skeletal and cardiac muscles
  3. brain
  4. adipocytes
114
Q

what type of cells are the primary secretory cells?

A

epithelial cells

115
Q

what role do epithelial cells have with metabolism?

A

they are involved in the regulation of metabolism because they are the primary excretory cells, but they do not make major contributions to the consumption of energy

116
Q

what are the 2 major roles of the liver in fuel metabolism?

A
  1. maintain a constant level of blood glucose under a wide range of conditions
  2. synthesize ketones when excess fatty acids are being oxidized
117
Q

how does the liver act in the well-fed state?

between meals and during prolonged fasts?

A

WELL-FED: the liver derives most of its energy from the oxidation of excess amino acids

BETWEEN MEALS/PROLONGED FASTS : liver releases glucose into the blood; the increase in glucagon promotes both glycogen degradation and gluconeogenesis

118
Q

what 3 things provide carbon skeletons for glucose synthesis?

A
  1. lactate from anaerobic metabolism
  2. glycerol from triacylglycerols
  3. amino acids
119
Q

what 2 places does insulin trigger fatty acid release from?

A
  1. VLDL
  2. chylomicrons
120
Q

where does the glycerol phosphate required for triacylglycerol synthesis come from?

A

glucose that is metabolized in adipocytes as an alternative product of glycolysis

121
Q

what happens to fatty acids during the fasting state? why?

A

fatty acids are released into circulation

why? decreased levels of insulin and increase epinephrine activate hormone-sensitive lipase in fat cells

122
Q

what are the 2 major fuels of skeletal muscle? 2 minor?

A
  1. glucose
  2. fatty acids

minor:
1. excess glucose
2. amino acids

123
Q

why is skeletal muscle the body’s major consumer of fuel?

A

because of its enormous bulk

124
Q

what does insulin do to skeletal muscle after a meal?

A

insulin promotes glucose uptake in skeletal muscle, which replenishes glycogen stores and amino acids used for protein synthesis

125
Q

what happens to resting muscle in the fasting state?

A

resting muscle uses fatty acids derived from free fatty acids circulating in the bloodstream (ketone bodies may also be used if the fasting state is prolonged)

126
Q

what does the primary fuel used to support muscle contraction depend on?

A

the magnitude and duration of exercise as well as the major fibers involved

127
Q

func: creatine phosphate

A

transfers a phosphate group to ADP to form ATP

provides a very short-lived source of energy (2-7 seconds)

128
Q

what 2 things does skeletal muscle have stores of?

what 2 things may also be used?

A
  1. glycogen
  2. some triacylglcyerols

secondary:
1. blood glucose
2. free fatty acids

129
Q

how are short bursts of high-intensity exercise supported?

A

by anaerobic glycolysis drawing on stored muscle glycogen

130
Q

how is moderately high-intensity, continuous exercise supported? + what happens after 1-3 hours of this

A

oxidation of glucose and fatty acids are important, but after 1-3 hours of exercise at this level, muscle glycogen stores becomes depleted and the intensity of exercise declines to a rate that can be supported by oxidation of fatty acids

131
Q

what do cardiac myocytes use for fuel?

A

they love fatty acids! even in the well-fed state

(or ketones if they are present during prolonged fasting)

132
Q

what other type of muscle do cardiac myocytes most closely parallel in terms of energy usage?

A

skeletal muscle during extended periods of exercise

133
Q

what happens in a failing heart? (2)

A
  1. glucose oxidation increases
  2. beta-oxidation falls
134
Q

what is the brain’s primary fuel?

A

glucose

135
Q

why are blood glucose levels tightly regulated?

A

to maintain a sufficient glucose supply for the brain

136
Q

what does normal brain function depend on?

A

a continuous glucose supply from the bloodstream

137
Q

what happens to the brain during hypoglycemic conditions (<70 mg/dL)?

A

hypothalamic centers in the brain sense a fall in blood glucose level and the release of glucagon and epinephrine is triggered

138
Q

why are fatty acids not used as an energy source by the brain?

A

they cannot cross the blood-brain barrier

139
Q

what does the brain use for energy between meals?

A

the brain relies on blood glucose supplied by either hepatic glycogenolysis or gluconeogenesis

140
Q

what does the brain use for energy during prolonged fasting?

A

the brain gains the capacity to use ketone bodies for energy, and even then still, the ketone bodies supply 2/3 of the fuel, but the rest is still glucose

141
Q

levels of what 6 things can be measured in the blood of humans to analyze metabolic control?

why can these all be used as indicators of metabolic function?

A
  1. glucose
  2. thyroid hormones and thryoid-stimulating hormone
  3. insulin
  4. glucagon
  5. oxygen
  6. carbon dioxide

because they have a predictable effect on metabolism

142
Q

func: respirometry

A

allows accurate measurement of the respiratory quotient

143
Q

what does the respiratory quotient differ depending on?

A

the fuels being used by the organism

144
Q

eqn + how is it determined: respiratory quotient (RQ)

A

measured experimentally

for the complete combustion of a given fuel source

145
Q

value: respiratory quotient for

carbs

lipids

resting individuals

A

carb: 1.0

lipids: 0.7

resting: 0.8 (indicates that both fat and glucose are consumed)

146
Q

what 3 conditions change the respiratory quotient?

A
  1. high stress
  2. starvation
  3. exercise
147
Q

func: calorimeter

A

can measure basal metabolic rate (BMR) based on heat exchange with the environment

148
Q

what 4 things can BMR be estimated by?

A
  1. age
  2. weight
  3. height
  4. sex
149
Q

what 4 things contribute to body mass? what 1 thing doesnt?

A

does:
1. water
2. carbs
3. proteins
4. fats

doesn’t:
1. nucleic acids

150
Q

how do carbs, protein, water, and lipids change in the body mass/composition?

A

overall mass of carbs and proteins tend to be stable over time (modified slightly by starvation or muscle-building)

WATER –> very quickly adjusted by the endocrine system and the kidneys (so does not factor into obesity and weight regulation), however it is the primary source of frequent minor weight fluctuations

LIPIDS (stored in adipocytes) –> the primary factor in the gradual change of body mass over time

151
Q

defn: basal metabolic rate

A

the amount of energy required for one sedentary day

152
Q

how does BMR change as individuals increase in mass? what impact does this have on body mass?

A

the BMR increases

a caloric excess will cause an increase in body mass until equilibrium is reached between the basal metabolic rate and the existing intake

153
Q

true or false: larger changes must be made to lose weight than to gain it

A

true

154
Q

what are 5 factors that all have key roles in weight control?

A
  1. diet (energy intake)
  2. exercise (energy expenditure)
  3. genetics
  4. socioeconomic status
  5. geography
155
Q

what 5 hormones are critical to the integration of metabolism?

A
  1. thyroid hormones
  2. cortisol
  3. epinephrine
  4. glucagon
  5. insulin
156
Q

what 3 hormones control hunger and satiety?

A
  1. ghrelin
  2. orexin
  3. leptin
157
Q

what causes it to come out + func: ghrelin

A

secreted by the stomach in response to signals of an impending meal

sight, sound, taste, and smell all act as signals for its release

increases appetite and stimulates secretion of orexin

158
Q

func: orexin

A

further increases appetite and is also involved in alertness and the sleep-wake cycle

hypoglycemia is a trigger for its release

159
Q

defn: leptin

A

a hormone secreted by fat cells that decreases appetite by suppressing orexin production

160
Q

genetic variations in which hormone: ghrelin, orexin, or leptin; and its receptors have been implicated in obesity? + diagram of mouse

A

a knockout mouse unable to produce leptin

161
Q

equation: body mass index (BMI)

A

mass (kg)
height (m)

162
Q

values: normal, underweight, overweight, obese BMIs

A

underweight: <25
normal: 18.5-25
overweight: 25-30
obese: >30

Biochem (12 decks)

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