Exam 3 - Nutrition Flashcards
1
Q
Metabolism
A
- refers to the chemical processes and reactions involved in maintaining life
- enable us to release energy from carbohydrate, fat, protein, and alcohol
- permit us to synthesize new substance and excrete wast products
- a metabolic pathway is a group of reaction that occur in a progression
2
Q
what does the kidney excrete
A
urea in urine
3
Q
one liver function
A
converts ammonia to urea
4
Q
Adenosine Triphosphate
A
- ATP
- only energy in ATP can be used to make new compounds, contract muscles, conduct nerve impulses, pump ions across membranes
5
Q
ATP
A
made of adenosine bound to 3 phosphate groups, bonds contain energy
6
Q
Derivatives of niacin and riboflavin transfer…
A
hydrogens from energy yielding compounds to oxygen in metabolic pathways
7
Q
Ethanol metabolism
A
- High NADH leads to greater fatty acid synthesis which can lead to fatty liver
8
Q
Niacin
A
- nicotinic acid, vitamin B-3
- component of nicotinamide adenine dinucleotide
- NAD+: oxidized
- NADH: reduced
9
Q
Riboflavin
A
- vitamin B-2
- component of flavin adenine dinucleotide
- FAD: oxidized
- FADH2: reduced
10
Q
Job of lactate dehydrogenase
A
Requires the electron from NADH to convert lactate to pyruvate
11
Q
Aerobic cellular respiration
A
- molecules from food are oxidized to form ATP with O2 as the final electron acceptor
- creates 30-32 molecules of ATP per glucose
12
Q
Anaerobic metabolism
A
- insufficient O2 present
- incomplete breakdown of glucose
- creates 2 molecules of ATP per glucose
13
Q
Glycolysis
A
- glucose is oxidized to form: 2 pyruvate, 2 NADH+, 2 ATP
- occurs in the cytosol
- role is to break down carbohydrates to generate energy and produce building blocks for other compounds
- does not require oxygen
14
Q
Transition reaction
A
- synthesis of Acetyl-CoA
- Also makes: NADH and CO2
- occurs in mitochondria
- requires oxygen
- irreversible reaction
15
Q
Citric acid cycle
A
Acetyl-CoA enters the citric acid cycle
- per molecule of glucose: 6 NADH, 2 FADH2, 2 GTP, CO2
16
Q
Electron transport chain
A
- oxidative phosphorylation: energy carried by NADH and FADH2 is used to form ATp
- oxygen is the final electron acceptor: allows regeneration of NAD+ and FAD, oxygen combine with hydrogens to form water
17
Q
Anaerobic metabolism
A
- pyruvate is produced during glycolysis and converted into lactate
18
Q
Cori Cycle
A
- the absence of oxygen, muscle produces lactate from pyruvate
- Lactate leaves the muscle via blood and enters the liver
- liver enzymes convert lactate to glucose using ATP
- Glucose returns to the muscle
19
Q
Lipolysis
A
breakdown of triglycerides into free fatty acids and glycerol
20
Q
fatty acid oxidation
A
- breakdown of fatty acids for energy production
- fatty acids broken down with oxygen as electron acceptor
- occurs in the mitochondria
21
Q
ATP production from fats
A
- triglycerides stored in adipose
- during fasting, triglycerides are broken down into fatty acids by hormone-sensitive lipase: activity is increased by glucagon, growth hormone, and epinephrine, decreased by insulin
- fatty acids are taken up by cells and shuttled into mitochondria from cytosol by carnitine
22
Q
Beta-oxidation: ATP production from fats
A
- almost all naturally occurring fatty acids are made up of an even number of carbons ranging from 2-26
- to transfer energy from fatty acids: carbons are cleaved off in pair, NADH and FADH2 made, carbons are used to make acetyl-CoA that enters the citric acid cycle
23
Q
More beta-oxidation
A
- fatty acids contain many more carbons than glucose
- fatty acids also store more chemical energy per carbon than glucose (less oxygen)
- fats yield more energy than carbohydrates
24
Q
Carbohydrate aids fat metabolism
A
- some citric acid cycle compounds are used for other purposes
- cells can use pyruvate (from glucose) to replenish supply of oxaloacetate
- there is no pathway to make carbohydrates from fatty acids
- fats burn in a carbohydrate flame
25
26
Ketosis and Ketoacidosis
production of ketoacids results in metabolic acidosis: the depletion of bicarbonate
27
fasting ketosis
- acidosis is mild
- self limiting: ketosis increases insulin sensitivity, resulting in decreased fatty acid release and increased glucose uptake
28
Diabetic ketoacidosis
- more serious metabolic acidosis
- seen in type 1 diabetics with absolute insulin deficiency
29
Diabetic ketoacidosis steps
- absolute or relative insulin deficiency
- hyperglycemia
- glucosuria: urinary loss of water and electrolytes
- dehydration and hypovolemia
- can lead to increased lactate
- can lead to acidosis
- increased counter regulatory hormones: glucagon, cortisol , growth hormone, and epinephrine
30
Protein metabolism
- amino acids being used for fuel must first be deaminated: requires vitamin B6, results in carbon skeleton that enters citric acid cycle or creates acetyl-CoA or pyruvate
31
Glycogenic amino acids
use carbons from carbon skeleton to form glucose
32
ketogenic amino acids
use carbons to form acetyl-CoA
33
Glycolysis review
- glucose to pyruvate
- occurs in cytosol of cells
- all organs do it
34
Transition reaction review
- pyruvate to acetyl-CoA
- occurs in mitochondria of cell
- occurs in all organs
35
Citric acid cycle review
- acetyl-CoA to CO2
- Occurs in mitochondria
- occurs in all organs except red blood cells, parts of the kidney, and brain
36
Gluconeogenesis
- begins in the mitochondria then moves to cytosol
- mostly liver, a lesser extent in the kidneys
37
Beta-oxidation
- fatty acid to acetyl-CoA
- occurs in mitochondria
- occurs in all organs
38
Glucogenic amino acid oxidation
- amino acids to pyruvate
- occurs in the cytosol
- liver and to a lesser extent kidneys
39
Non-glucogenic amino acid oxidation
- amino acids to acetyl-CoA
- occurs in mitochondria
- liver and to a lesser extent kidneys
40
Alcohol oxidation
- ethanol to acetaldehyde to acetyl-CoA
- It occurs in Cytosol and Mitochondria
- done by liver
41
regulation of energy metabolism
- the liver plays a major role in metabolic pathways
- regulation involves: ATP concentrations, enzymes, hormones
42
Insulin and metabolism
- low level of insulin promote: gluconeogenesis, protein breakdown, lipolysis
- increased insulin promotes synthesis of: glycogen, fat, protein
43
Fasting and feasting
- energy sources used during fasting vary depending on the length of the fast
- depletion of lean mass to about 50% is fatal
- other problemsL depletion of electrolytes due to diuretic effect of ketone bodies, buildup of urea due to protein catabolism
44
Postprandial fasting (0-6 hours)
order of digestion: 1. Carbohydrates, 2. Proteins, 3. Fats
45
Short term fasting (3 to 5 days)
carbohydrates are depleted
- order of digestion: 1. Protein (gluconegenesis), 2. fat/ketones
46
feasting
- excess energy intake from any source will result in fat storage
- excess dietary fat can be stored with minimal processing
- excess carbohydrates: maximize glycogen, use as energy, convert to fat (small amount), spare fat from lipolysis
- excess protein: mostly converted to glucose, very small amount storage, potentially increased muscles protein synthesis if combined with intense exercise
47
inborn errors of metabolism
- genetic conditions that affect a metabolic pathway
- often enzyme mutation leading to decreased activity
- symptoms are often not very specific. but in some cases management needs to start immediately
- newborn screening to look for 30+ conditions
48
Phenylketonuria
- insufficient phenylalanine hydroxylase activity
- cannot convert phenylalanine to tyrosine
- instead form toxic metabolites
49
Phenylketonuria management
- special formula at birth
- low-phenylalanine diet for life
- fruits, vegetables, and breads generally can be eaten
- dairy products, eggs, meats, nuts, and aspartame must be avoided
50
Galactosemia
- cannot convert galactose to glucose
- must switch to soy formula at infancy
- throughout life must avoid: dairy products, butter, organ meats, some fruits and vegetables
51
glycogen storage disease
- liver cannot convert glycogen to glucose
- leads to: poor physical growth, low blood glucose levels, liver enlargement
- management: must consume frequent meals and cornstarch in between meals
52
energy balance
- the relationship between energy intake and energy expenditure
53
energy equilibrium
when calories consumed matches the amount of energy expended
54
positive energy balance
energy exceeds energy expenditure and results in weight gain
- situations where positive energy balance is desired: pregnancy and childhood growth
55
negative energy balance
energy intake is less than energy expenditure and weight loss occurs
- desired if trying to lose weight
56
humans are not bomb calorimeters
- we don't digest all of the calories that we eat
- some energy is lost as heat or used for the digestive process
- the calories in/calories out rule of wight regulation is literally true but also an oversimplification
57
sources of energy expenditure
- basal metabolism
- physical activity
- thermic effect of food
- non-exercise activity thermogenesis (NEAT)
58
Basal Metabolism
- you may see the term resting metabolic rate, which is a similar idea but the person is not fasting
- BMR is approximately 0.9kcal/kg per hour for women and 1.0kcal/kg per hour for men
- various 25-30% amount individuals depending on: muscle mass, hormones, body surface area, several others
- declines 1-2% per decade after 30
59
basal metabolic rate
- minimum amount of energy expended in fasting to keep a resting, awake body alive in warm, quiet environment
- accounts for about 60-70% of total energy expenditure
- processes involved include beating of heart, respiration of lungs, and activity of other organs
60
Physical Activity
- calories burned from deliberate exercise
- can range from zero to several hundred per day
61
thermic effect of food
- energy used to digest, absorb, transport, store and metabolize
- accountants 5-10% of energy consumed (100-300 calories)
- influenced by food composition: TEF for protein rich meals is to 20-30%, TEF for carbohydrate rich meals is 5-10%, TEF for fat rich meal 0-3%
62
Non-exercise activity thermogenesis (NEAT)
- varies greatly, but can account for hundreds of calories burned per day
- includes ant physical activity that is not deliberate, sports-like exercise: examples: fidgeting, shivering, posture.muscle tone, taking the stairs, house/yard work
- brown adipose tissue: another source for NEAT, mainly in infants: heat generating tissue accounting for 5% of infant body weight, very tiny amount in adults
63
direct calorimetry
a method used to measure the amount of heat produced by a subject, typically to understand metabolic rates. It involves placing the subject (often a person or animal) in a sealed, insulated chamber that measures the heat given off by their body through processes like metabolism and physical activity. This heat is then quantified to determine energy expenditure
64
indirect calorimetry
estimating an individual's metabolic rate by measuring their oxygen consumption and carbon dioxide production. This approach is based on the principle that metabolic processes that produce energy (like the oxidation of carbohydrates, fats, and proteins) consume oxygen and produce carbon dioxide in predictable ratios. By analyzing the volumes of oxygen inhaled and carbon dioxide exhaled, researchers can estimate the rate at which the body is using energy, known as the metabolic rate
65
hunger
physiological drive to find and eat food
66
appetite
psychological drive to eat
67
hypothalamus
- communicates with endocrine and nervous system
- integrates internal clues of blood glucose levels, hormone secretions, and sympathetic nervous system
68
eating behavior regulations
- hypothalamus
- if internal signals stimulate satiety center, we stop eating; if they stimulate feeding centers, we eat more
69
Satiety process
many factors contribute to feelings of satiety:
- sensory aspects of food
- knowledge that food has been eaten
- chewing
- expansion of stomach and intestines
- effects of digestion, absorption, and metabolism
- hormones
70
Leptin
- hormone produced by adipose
- helps monitor stored energy
71
body weight and composition
- weight and fat percentage are indicators of health and disease risk
- several methods exist to assess whether these are in the healthy range
72
Body mass index
- weight-for-height standard
- convenient
- used for both males and females
- body weight (kg) / heightˆ2
73
underweight BMi
18.5
74
Heathy BMI
18.5-25
75
Overweight BMI
- 25-30
- health risks may be seen
- not necessarily a marker of excess fat
76
obese BMI
> 30
77
Body roundness index
- relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model
- primarily uses height and waist circumference
78
Pros of body roundness index
- might be better at assessing risk in different body types
- visceral adipose tissue is strongly associated with disease risk (diabetes, cardiovascular, etc)
79
Cons of body roundness index
- measuring waist is harder than you may think
- needs more validation
80
Desirable amounts of body fat:
men: 8-24%
women: 21-35%: need more body fat to support pregnancy/lactation
81
measurement methods of body fat
- dual energy x-ray absorptiometry (DEXA) is most accurate
- water or air displacement
- skin fold
- bioelectrical impedance
82
factors affecting body weight and composition
- children has one parent with obesity, risk increase to 40%
- if child has 2 obese parents, risk increases to 80%
83
Role of genetics
- even when identical twins are raised apart, they show similar weight gain patterns
- genes account for 40-70% of weight differences: body type, metabolic rate, factors that affect hunger and satiety
- thrifty metabolism: some people may use energy more frugally, store fat more readily
84
Role of genetics: set-point theory
- the body appears to have a genetically predetermined body weight or fat content that is closely regulated
- when energy intake is reduced: thyroid hormone secretions fall, slowing metabolism, body becomes more efficient at storing fat
- body is also somewhat resistant to weight gain, but mechanism is much weaker
85
Roles of environment
- little change to gene pool over the last 50 years, but obesity has drastically increased
- couples and friends tend toward similar weights
- many factors play a role in food intake: cultural, economic
- genes and environment both matter
86
Treatment of overweight and obesity
- commercial diets: only 5% have lasting weight loss
- most return to original weight within 3-5 years
87
characteristics of successful diets
- rate of loss
- flexibility
- intake
- behavior modification
- overall health
88
Control of energy intake
- adipose tissue contains 3500 kcal/lb: to lose 1 pound a week, net energy intake must be decreased by 5000 kcal/day, calories restriction, physical activity or combination
- caveats: weight loss is not pure adipose, weight loss will often plateau due to metabolic changes
- low-energy density approaches are the most successful long-term
89
Regular physical activity
- does not need to be high intensity
- good to add some resistance/higher impact exercise
90
Behavior change
- advice for an individual trying to lose weight (or change any behavior):
- reflect on why you might eat too much or choose unhealthy foods
- think about changes of behavior, avoid starting the chain, or recognize when you are in the early steps of the chain and break it
- don't go through life on autopilot. Change what you have the power to change, in order to get what you want
91
Behaviors of people who maintain a healthy weight
- eat a low-fat, high-carbohydrate diet: 25% fat intake, 56% carbohydrate intake from fruits, vegetables and grains
- eat a healthy breakfast: may cause body to burn more fat, less tendency to overeat due to hunger
- self-monitor: regularly weigh yourself, keep a food journal
- physical activity: about 1 hour/day
92
Professional help for weight control
- get medical exam first: test for/treat underlying health problems, possible referral to registered dietitian or exercise physiologist
- interventions beyond diet/exercise: weight-loss drugs, surgery
93
Weight loss drugs: lorcaserin (Belviq)
- acts on a specific type of serotonin receptor in the hypothalamus
- though to activate satiety pathways
- weight loss in clinical trials was modest (about half loss >5% body weight)
- controlled substances because very high does can cause hallucinations
94
Weight loos drugs: orlistat: mechanism
mechanism: works by inhibiting pancreatic and gastric lipases, orlistat prevents about 30% of the fat consumed from being absorbed by the body, fat is excreted in feces
95
Benefits of orlistat
- When combined with a reduced-calorie diet, orlistat has been shown to lead to moderate weight loss, especially in individuals with a BMI over 30.
- Orlistat can help reduce cholesterol levels, blood pressure, and potentially lower the risk of type 2 diabetes by improving insulin sensitivity in some individuals
96
Side effects of orlistat
- gastrointestinal issues: oily stool, poop problems
- fat-soluble vitamin deficiency: ADEK
- Rare liver injury
97
GLP-1 Agonists
- Ozempic
- produce up to 20% weight loss
- nausea, vomiting, diarrhea are common side effects
- can cause hypoglycemia
- warning about thyroid cancer (rare)
98
GLP-1 on liver
decreases gluconeogenesis and steatosis
99
GLP-1 on Intestine
decrease in gastric emptying and gastrointestinal motility
100
GLP-1 on brain
- decreases food intake, reward behavior, and palatability
101
Muscle
increase in insulin sensitivity and glucose uptake
102
GLP-1 on Pancreas
- increased insulin secretion, insulin synthesis, beta-cell survival
- decreased in glucagon secretion and apoptosis
103
gastroplasty
- can be very effective: 75% of patients lose >50% of body weight
- requires significant lifestyle changes
- carries risks of major surgery
104
Risks associated with low BMI
- health risks associated with BMI below 18.5: loss of menstrual function, loss of bone mass, complications with pregnancy and surgery, slow recovery after illness, can interfere with normal growth in children and teens
- can be caused by disease, stress/depression, genetics
105
Eating disorders
- affect up to 5% of females
- may be more susceptible because of: genetics, psychological reasons (depression, substance abuse, anxiety disorders)
- physical reasons
- family/social problemsa
106
anorexia nervosa
- DSM-5 criteria:
- restriction of energy intake relative to requirements leading to a low body weight
- intense fear of gaining weight or persistent behaviors that interfere with gaining weight
- disturbance in the way a person's weight or body shape is experienced or a lack of recognition about the risks of low body weight
107
Bulimia nervosa
- DSM 5 criteria:
- recurrent episodes of binge eating, An episode of binge eating is characterized by both of the following: eating in a desecrete period of time, an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances, a sense of lack of control over eating during the episode
- Recurrent inappropriate compensatory behavior in order to prevent weight gain, such as self-
induced vomiting, misuse of laxatives, diuretics, or other medications, fasting, or excessive
exercise
- the binge eating and inappropriate compensatory behaviors both occur, on average, at least
once a week for three months
- self-evaluation is unduly influences by body shape and weight
- symptoms not necessarily visible: may be at or above normal weight
108
Prevention of eating disorders
- discourage restrictive dieting, meal skipping, and fasting in children and adolescents
- focus on moderation, not restriction and perfection
- encourage children to each only when hungry
- promote good nutrition and regular physical activity
- promote regularly eating meals as a family
- provide information about normal changes during puberty
- weight is a component of health but don't overemphasize
109
A to Z weight loss study
- atkins: very low carb/ketogenic (5% carb during induction)
- zone: moderate low crb (40%), 30% protein, 30% fat
- ornish: very low fat (10% or less of calories)
- learn: low fat, high carb (55-60% based on national guidelines)
110
Ketogenic diets
- induction phase with very low carbohydrates <20g/day, fast 3-5 pound loss from glycogen depletion
- need to avoid fruit, bread, pasta, starchy vegetables, sweets
- studies have shown increased weight loss. compared to other diets however: not sustainable, can lead to eating excess fatty foods and meat
meatbolic effects of spending years in ketosis are mostly unknown: conflicting evidence on cholesterol levels
- may lead to better blood sugar control in type 2 diabetics
111
The DIETFITS Trial
- examined weight loss on a "healthy low-fat" versus a "healthy low-carb diet"
- looked at genotype and insulin responsiveness
112
Preliminary studies of DIETFITS trial
- showed that some individuals might have a low-fat or low-carb genotype
- there was also some evidence that insulin-resistant individuals might benefit from a low-carb diet
113
DIETFITS study design
- first 8 weeks: total far or carbs were restricted to 20 g/day
- after that: allowed to increase intake to an amount that the participants felt could be sustained indefinitely
114
-Both diet groups of DIETFITS were instructed to
1) maximize vegetable intake
2) minimize intake of added sugars, refined flours, and trans fats
3) focus on whole foods that were minimally processes, nutrient dense, and prepared at home whenever possible
115
One year results of DIETFITD
- both diet groups reduced energy intake by 500-600 kcal/day compared to baseline
- both groups lost about 13 pounds
- no interaction between diet type and genotype or insulin secretion
- no difference in adverse events
116
benefits of fitness
- the physical activity guidelines for Americans set 3 goals:
- adults should be physically active
- each week adults should engage in 150 minutes of moderate intensity aerobic exercise or 75 minutes of vigorous intensity exercise
- adults should perform muscle-strengthening activities 2 or more days per week
117
ways to measure exercise intensity
- heat rate
- metabolic equivalents (METs): baseline (rest), 1jkcal/kg/hr, 3.5 ml O2/kg/min
118
VO2max
- maximum O2 consumption during exercise
- no additional O2 uptake despite increasing effort-bodu shifts to anaerobic metabolism
- measured as ml O2/kg/min
- exercise intensity can be expressed as % of VO2max
119
Glucose - skeletal muscles (anaerobic)
- no oxygen required
- only extracts a fraction of the energy stored in the glucose molecule
- rapid fatigue
120
Glucose - skeletal muscle (aerobic)
- efficient conversion of chemical energy to ATP
- preferred energy source of moderate intensity exercise
- lasts for 30 minutes to 3 hours depending on intensity
121
fatty acids - skeletal muscle
- supply a large amount of chemical energy that can be converted to ATP
- metabolism requires more oxygen compared to glucsoe
- provide hours of energy for low-intensity activities
- do not have a process analogues to anaerobic glycolysis - can only supply energy when adequate oxygen is present
122
ATP - energy storage
- stored in all tissues
- used all the time
- sprinting (0-3 seconds)
123
Phosphocreatine (PCr) - energy storage
- stored in all tissues
- used during short bursts
- shot put, high jump, bench press
124
carbohydrate (anaerobic) - energy storage
- stored in muscles
- high intensity lasting 2- seconds to 2 minutes
- 200 meter sprint
125
carbohydrate (aerobic) - energy storage
- stored in muscle and liver
- exercise lasting 2 minutes to 3 hours or more
- jogging, soccer, basketball, swimming, gardening, or car washing
126
fat (aerobic) - energy storage
- stored in muscles and fat cells
- exercise lasting more than a few minutes; greaater amounts are used at lower exercise intensities
- long-distance running, marathons, ultra endurance events, cycling, day-long hikes
127
Glycogen use during exercise
- glycogen is storied in live and muscle
- during exercise: liver glycogen is used to maintain blood glucose levels, muscle glycogen supplies glucose to working muscles and is used for short events
- when muscle glycogen stores are depleted, muscles begin to take up blood glucose for energy
- when blood glucose is depleted, you hit the wall/bonk - supplement with carbs if exercise is greater than one hour
128
After class, you leave and walk across campus at a leisurely pace, Most of the ATP powering your muscle contractions come from
beta-oxidation of fatty acids
129
Changes in muscles with endurance training
- increased ability of muscles to store glycogen (high carbohydrate diet increases this even further)
- increased triglycerides storage in muscle
- increased mitochondrial size and number
- increased myoglobin content
- increased cardiac output
130
Advantages for muscles with endurance training
- more glycogen fuel available for the final minutes of an event
- conserves glycogen by allowing for increased fat use
- conserves glycogen by allowing for increased fat use (even at high exercise outputs)
- increased oxygen delivery to muscles and increased abiity to use fat for fuel
- increased blood flow to promote adequate delivery of oxygen and nutrients to muscles
131
Nutrition for athletes
- moderate to high carb probably best, specifically for those who exercise more than an hour per day
- carb loading 2-3 days before a competition can increase glycogen stores 50-80%
132
Sports drinks
- more important for events lasting longer than 60 minutes because they supply: glucose to muscles as they become depleted, electrolytes to help: maintain blood volume, enhance absorption of water and carbohydrates, stimulate thirst
- avoid beverages with alcohol, caffeine, carbonation, and sugar content above 10%
133
supplements
- protein can come from real food; bars/shakes are convenient but offer no real benefit
- creatine does boost performance in very short, high intensity exercise
- caffein can provide modest benefits across a variety of exercises
134
Caffeine can provide modest benefits across a variety of exercises
* May increase cardiovascular performance and mobilize fat
* Mechanism not fully understood
* Wide variation in response between individuals
