Metabolism Flashcards
1
Q
Def of metabolism:
A
sum of all chemical reactions in the body
2
Q
Metabolism can be…
A
- anabolic
- catabolic
3
Q
Metabolism is used to…
A
- extract energy from nutrients
- use energy for work
- store excess energy
4
Q
What is the basal metabolic rate (BMR)?
A
lowest rate of reactions needed to keep body going
5
Q
How do you find the total body energy?
A
energy stored + energy intake - energy output
6
Q
What is energy intake?
A
energy in nutrients that we absorb
7
Q
What is energy output?
A
work + heat
8
Q
Work is used to…
A
- transport molecules
- cause movement
- growth
- body maintenance
- store information
- store energy
9
Q
Regulation of energy intake comes from…
A
- hunger
- satiety
10
Q
What is the difference between hunger and satiety?
A
- hunger: desire for food in general
- satiety: desire for specific food
11
Q
Where is hunger and satiety regulated?
A
hypothalamus
12
Q
Two types of neurons in the hypothalamus that regulates appetite and energy expenditure:
A
- pro-opiomelanocortin neurons
- orexigenic neurons
13
Q
Pro-opiomelanocortin neurons release…
A
alpha-MSH and CART (cocaine and amphetamine regulated transcript
14
Q
Pro-opiomelanocortin neurons’ effect on hunger and satiety:
A
- decrease in food intake
- increase in energy expenditure
15
Q
When are pro-opiomelanocortin neurons specifically activated?
A
- severe infections
- cancer
- uremia
- can also be activated the same way as orexigenic neurons
16
Q
Orexigenic neurons release…
A
- neuropeptide Y (NPY)
- agouti-related protein (AGRP)
17
Q
Orexigenic neurons effect on hunger and satiety:
A
- increases food intake
- reduces energy expenditure
18
Q
What influences the activation of hunger and satiety centers?
A
- higher brain control
- endocrine regulation
- sensory feedback from GI
19
Q
Examples of sensory feedback from GI that influences activation of hunger and satiety centers:
A
- stretch receptors for fullness and CCK, which increases with food
- insulin and PPY from GI and leptin from adipocytes, which decreases feeding when food is present
- ghrelin from oxyntic cells of empty stomach
- endocannabinoids made by the NS, which increases feeding behavior
20
Q
Glucostatic theory of regulation:
A
feeding behavior results from glucose metabolism
- high blood glucose decreases hunger and increases satiety
21
Q
The glucostatic theory of regulation is regulated by…
A
- insulin
- glucagon
22
Q
Lipostatic theory of regulation:
A
- body fat stores will regulate weight
- leptin protein hormone helps regulate (made by adipocytes)
23
Q
According to the lipostatic theory of regulation, an increase in fat leads to…
A
increase in leptin -> signal to hypothalamic centers
- can lead to decrease in NPY -> decrease in hunger
- or increase in alpha-MSH -> increase in CRH
- increase in SNS
- decrease in insulin
24
Q
Thermoregulation of food intake:
A
- cold = increased feeding
- hot = decreased feeding
25
T/F: stress can't affect food intake
F, it can and it's not consistent from person to person
26
Both long term and short term mechanisms help to regulate...
immediate feeding behavior and long term body weight
27
Example of short term mechanism:
- fullness and CCK (increases)
| - ghrelin (decreases)
28
Example of long term mechanism:
- hyperglycemia
- leptin
- heat
- cold
29
Energy content is expressed as...
heat units Calorie
| - 1 kilocalorie heat to raise 1 L h2o 1 degrees C
30
How do you measure how many Calories are in food?
burn it in a bomb calorimeter
- amount of heat released is measured
- doesn't take into account food ingested but not absorbed
31
How much of each macronutrient is recommended?
- 30% fat
- 10-15% protein
- 55-60% carbs
32
You can measure energy produced from food by measuring...
- oxygen used to metabolize it
| - CO2 produced when it's metabolized
33
What is respiratory quotient (RQ)/respiratory exchange ratio (RER)?
rate of CO2 produced to O2 consumed
34
What is the RQ for each macronutrient?
- pure carbs: 1
- pure protein: 0.8
- pure fat: 0.7
35
What is the average dietary RQ?
0.82
36
When do you measure resting metabolic rate?
after 12 hour fast
37
Skeletal muscle accounts for how much of BMR?
20-30%
38
What factors affect metabolic rate?
- genetics
- hormones (+)
- diet (+)
- SNS activity (+)
- activity level (+)
- lean muscle mass (+)
- age (-)
- females have less lean muscle than men
- fever (+)
- climate
39
Examples of hormones that increase metabolic rate?
- TH
- epi/norepi
- testosterone/GH
40
Nutrient pools of building blocks are used in what three ways?
- metabolized to make ATP
- used as building blocks to make things for growth and maintenance
- stored
41
Most tissues use ____ as energy source
glucose
42
What is glycolysis?
breakdown of glucose for energy
43
Def of essential nutrients:
nutrients that can't be made and have to be consumed
44
Energy can be stored as...
- fat in adipose
| - glycogen in liver and skeletal muscle
45
What is lipogenesis?
storage of glucose as fats
| - FA + glycerol -> triglyceride
46
What is lipolysis?
breakdown of fats to use for energy
| - triglyceride -> FA and glycerol
47
What is glycogenesis?
storage of glucose as glycogen
| - glucose -> glycogen
48
What is glycogenolysis?
conversion of glycogen to glucose for use
49
What is gluconeogenesis?
AA -> glucose and FA
50
What is the fed state?
- absorptive state
| - follows ingestion of nutrients
51
T/F: fed state is catabolic
F, is anabolic
| - nutrients used for energy, synthesis, and storage
52
What is proteogenesis?
AA -> proteins
| - in muscle
53
What is proteolysis?
proteins -> AA
| - in muscle
54
What is the fasted state?
- postabsorptive state
| - between meals
55
T/F: fasted state is catabolic
T b/c body taps into stored reserves
56
Fate of carbs in the fed state metabolism:
- glucose is main source of energy and used to make ATP
- some used by liver for lipoprotein
- some stored as glycogen or fat
57
Glucose enters the cell via what transporter?
GLUT
58
Fate of amino acids in the fed state metabolism:
- used for protein synthesis
- liver goes first
- cells uptake amino acids
- in muscle: some get stored as phosphocreatine for energy
59
What does the liver make with amino acids during the fed state metabolism?
- lipoproteins
| - plasma proteins (albumins, clotting factors, angiotensinogen
60
What do cells make with amino acids during the fed state metabolism?
- structural proteins
- enzymes
- hormones
- neurotransmitters
61
What happens to excess amino acids in the fed state?
- broken down to make ATP
| - stored as fat
62
Fate of fats in fed state metabolism:
- travels as chylomicrons
- gets converted to free FA and glycerol by lipoprotein lipase
- usually used to make ATP by most cells
- metabolized by liver
63
Examples of chylomicrons:
- cholesterol
- triglycerides
- phospholipids
- apolipoproteins
64
Where do fats get converted to free FA and glycerol during the fed state metabolism?
capillary endothelium of muscles and adipose
65
What happens to fats when they are metabolized by the liver during the fed state metabolism?
- cholesterol -> steroids
- some excess cholesterol -> bile salts
- other excess cholesterol -> lipoprotein complexes
66
Examples of lipoprotein complexes made from fats in the liver:
- VLDL: mostly triglycerides
- LDL: large amounts of cholesterol
- HDL: less fat and more protein
67
VLDL is used for...
lipoprotein and eicosanoid synthesis
68
LDL info:
- bad cholesterol
- apoprotein B promotes its absorption into blood vessels
- causes atherosclerosis
69
HDL info:
- good cholesterol
- apoprotein A promotes uptake into cells
- promotes cellular use in steroids and cell membranes
70
Function of liver, muscle, and adipose tissue in the fasted state metabolism:
- liver: releases glucose for brain
- muscles: burn stored energy
- adipose: releases FA for use by muscle
71
Fate of carbs in the fasted state:
- glycogenolysis of glycogen to glucose 6 PO4
- used for energy in liver and muscle
- converted to glucose by liver and released for energy for CNS
72
Fate of proteins in the fasted state:
- broken down into AA
- AA used to make glucose in liver via gluconeogenesis
- gets deaminated: loss of amino group
73
How does deamination of proteins in the fasted state occur?
NH3 converted to NH4
- both are converted to urea by liver
- urea gets excreted by kidney
74
Fate of lipids in the fasted state:
- converted to FA and glycerol by lipases via lipolysis
| - glycerol used for glycolysis
75
In order for FA to be used for energy, it needs to undergo...
beta-oxidation in liver
76
What happens during beta-oxidation of FA?
1. FA -> 2 carbon acyl units
2. acyl units -> acetylCoA
3. acetylCoA used to make cholesterol and in glycolysis
4. excess acyl units (ketone bodies)
77
What happens to the excess acyl units during beta-oxidation of FA?
- used for E by brain
| - too many ketone bodies = ketosis, which lowers body pH
78
What is the main concern when it comes to the availability of glucose?
making sure there is enough for CNS metabolism
79
What is the normal resting blood glucose?
90mg/dL
80
Glucose is regulated by...
pancreatic islet hormones insulin and glucagon
81
What kind of cells make insulin?
pancreatic beta islet cells
| - due to high blood glucose
82
Insulin dominates in the ____ state and causes an increase in...
fed state and causes an increase in:
- glucose oxidation
- glycogen synthesis
- fat synthesis
- protein synthesis
83
What kind of cells make glucagon?
pancreatic alpha islet cells
| - due to low glucose levels
84
Glucagon dominates in the _____ state and causes an increase in...
starved state and causes an increase in:
- glycogenolysis
- gluconeogenesis
- ketogenesis
85
Regulation of glucose is a function of...
insulin to glucagon ratio
86
Both insulin and glucagon have ____ half lives
short, and are secreted constantly
87
Insulin is a _____ hormone
anabolic
88
Insulin is turned on by...
- increase in blood glucose and plasma AA
- feedforward GI hormones like GLP-1 and GIP
- CCK and gastrin
- PNS stimulation to beta cells
89
Insulin acts on what receptor?
tyrosine kinase receptor
90
Effects of insulin on the body?
- increases glucose uptake into cell via GLUT-4 transporters in membrane
- promotes phosphorylation of glu to glu-6-PO4 and fat synthesis
- activates enzymes of glycolysis, proteogenesis, and lipogenesis
- inhibits effects of glucagon
- enhances use of AA
91
Glucagon is turned on by...
- low glucose
- acts on liver to stimulate glycogenolysis and gluconeogenesis
- high AA from eating protein without carbs (stimulates formation of ketone bodies)
92
What other hormones affect metabolism?
- stress reactions
| - thyroid hormone
93
What are the effects of stress reactions on metabolism?
- increase in cortisol and circulating norepi
| - synergistic (opposing) w/ insulin effects
94
What are the effects of the thyroid hormone on metabolism?
associated with cold stress so should increase metabolism
95
What is metabolic disorder?
combination of type 2 diabetes, atherosclerosis, and high blood pressure
96
In order to have a metabolic disorder, you must have at least 3 of the 5 criterias:
- central obesity (waist > 40" women, 35" men)
- BP > 130/85
- elevated fasting triglycerides
- low plasma HDL
- fasting glucose > 110 mg/dL
97
Metabolic disorder is associated with...
PPARs (proliferator-activated receptors) for lipid and carb metabolism
98
T/F: body temp rises with decreased metabolism
F, increased metabolism such as during exercise or after meals
99
Thermoregulation is controlled by...
thermoregulatory centers in the hypothalamus
| - signals come from thermoreceptors in the skin
100
How does heat get lost?
- vasodilation of blood vessels in the skin under sympathetic control
- sweating
101
How does the body thermostat get reset?
- hot flashes: due to low estrogen
- fever: due to pyrogens, fever producing cytokines
- inflammatory: due to interleukins
- genetics: malignant hyperthermia due to defective Ca2+ channels in skeletal muscle -> overcontraction
