MT 2 Flashcards
(97 cards)
1
Q
Metabolism
A
-Chemical processes in the body that provide energy in useful forms and sustain vital activities
-Encompasses all sequences of chemical reactions that occur in body
2
Q
Metabolic pathway
A
Group of biochemical reactions that occur in a progression from beginning to end
3
Q
Intermediates
A
Compounds formed in any step of the metabolic pathway
4
Q
Anabolic pathway
A
- uses small, simpler compounds to build larger, more complex compounds
- require energy
- use compounds like glucose, fatty acids, cholesterol, and amino acids to form new compounds like glycogen, hormones, enzymes, and other proteins
5
Q
Catabolic
A
- pathways that breakdown compounds into smaller units
- produces energy
6
Q
Catabolic
A
- pathways that breakdown compounds into smaller units
- produces energy
7
Q
Balance between catabolic and anabolic pathways
A
- body strives for balance
- growth: increased anabolism bc tissue is being synthesized
- weight loss or wasting disease (cancer): increased catabolism bc tissue is being broken down
8
Q
Converting food into energy
A
- energy used by all cells initially comes from cells
- from photosynthesis to plants which we then eat
9
Q
catabolic pathways of food conversion
A
- ATP, heat, water, and CO2
- the heat produced helps body temp regulation
- occurs from proteins, carbs, lipids, and alcohol
10
Q
Stages of food conversion
A
- digestion- the breakdown of complex molecules to their component building blocks; proteins become amino acids, carbs to monosaccharides, lipids to fatty acids and glycerol
produces CO2 and ATP and then are converted to acetyl coa except alcohol which is converted straight to acetyl coa - conversion of building blocks to acetyl coa or other intermediates
- metabolism of acetyl coa to CO2 and ATP before entering citric acid cycle
11
Q
use of ATP in metabolism
A
- function: synthesize new compounds, conduct nerve impulses, contract muscles, pump ions across membranes
- hydrolysis: breaks the high energy phosphate bonds in ATP and releases energy producing ADP and Pi and AMP if hydrolyzed twice
- is recyclable: add phosphate back ( happens more during exercise)
12
Q
Oxidation- reduction reactions
A
- synthesis of ATP from ADP and Pi forming water and releasing energy
- OILRIG: oxidation is loss, reduction is gain
- if something is oxidized, something else must be released
- controlled by enzymes called dehydrogenase
- antioxidants: donate electrons to oxidized compounds, making them more stable
13
Q
Niacin and riboflavin
A
- B vitamins that assist dehydrogenase in oxidation reduction reactions
- niacin: NAD coenzyme, reducer form is NADH
- riboflavin: FAD and FADH2 reduced coenzymes
14
Q
Cellular respiration
A
Oxidizes food molecules to produce energy/ ATP
15
Q
Aerobic respiration
A
- if oxygen present
- produces 30-32 ATP
16
Q
Anaerobic respiration
A
- if oxygen is not present
- produces 2 ATP and converts pyruvate to lactate
17
Q
States of ATP production from carbs
A
- glycolysis- converts glucose to 2 pyruvate; produces 2ATP
- transition reaction- using NAD and NADH converts pyruvate to acetyl coa producing CO2 and 2 ATP; irreversible step which is illustrated in individuals with deficiency of pyruvate dehydrogenase which leads to lactic acid acidosis and nervous system issues; requires 4-B vitamin coenzymes
- citric acid cycle
- electron transport chain- occurs in mitochondria, requires oxygen, where majority of ATP is produced, requires copper and oxygen and uses NADH and FADH2
18
Q
Cori cycle
A
- occurs during high intensity exercise where lactate is transported to liver where it is converted to glucose
19
Q
ATP production from fats
A
- begins with lyopolysis (breakdown of triglycerides into free fatty acids and glycerol)
- fatty acid oxidation: occurs in the mitochondria, donates electrons from fatty acids to oxygen
- high fat meals yield excess fat stored in adipose tissue
- low calorie intake or fasting result in triglycerides breaking into hormone sensitive lipase and are released into blood and then into a cells mitochondria by the carrier carnitine
20
Q
Steps of ATP production from fatty acids
A
- carbons are cleaved producing acetyl coa
- acetyl coa enters the citric acid cycle and produces CO2 (since there are more carbons in fatty acids than glucose, it can go through the citric acid cycle more times and 7 ATP per carbon are produced
there is NO pathway that converts fatty acids to glucose
21
Q
Carbs and fat metabolism
A
- as fatty acids create acetyl coa, carbs are needed to provide pyruvate for the production of oxoalacetate for the citric acid cycle
22
Q
Ketone bodies
A
- occurs mainly bc of hormonal imbalances
- incomplete breakdown of fat
- I.e decreased insulin production cannot balance glucagon and thus leads to ketosis
23
Q
Ketone formation steps
A
- Insufficient insulin production
- High amounts of fatty acid released by adipose cells
- Fatty acids flood into the liver and are broken down into acetyl coa
- High production from acetyl coa from beta oxidation slows citric acid cycle
- High amounts of acetyl coa unite in pairs to form ketone bodies
May also occur in low carb diets as decreased carbs mean a decreased amount of oxoalacetate which is needed for the citric acid cycle to function
Since ketones leave the body through the breath, an individual in ketosis may have fruity smelling breath
24
Q
Ketosis in diabetes
A
- decreased insulin yielding rapid lypolysis and production of ketone bodies
- called diabetic ketoacidosis
- blood becomes acidic
25
Ketosis in semi starvation or fasting
- ketone bodies used for fuel which leads to adaptation (need for glucose as fuel decreases)
- maintenance of body protein mass is key to make this work
26
Protein metabolism
- primarily takes place in liver (branched chain takes place in muscle)
- proteins become amino acids and are deaminated (removal of amino group which requires B-6 vitamin) yielding carbon skeletons that can either enter the citric acid cycle or form intermediates
27
Glucogenic amino acids
Can be converted into glucose via gluconeogenesis (bypasses the production of acetyl coa and enters the citric acid cycle directly)
28
Ketogenic amino acids
- Are converted into acetyl coa and can form ketone bodies if insulin levels are low enough
- Is determined depending on if part or all of the carbon skeleton can yield oxaloacetate
29
Gluconeogenesis
- glucose production from glucogenic amino acids
- present pathway in some kidney and liver cells
- starting material: oxaloacetate (alanine)
- begins in mitochondria and moves into cytosol
- requires ATP, coenzymes, and B vitamins
30
Urea cycle
- dispels excess a,into groups
- amino groups are converted to ammonia which is toxic to brain
- occurs from the liver
- steps:
1. urea forms in liver from 2 nitrogen groups (1 from amino acid and other from ammonia)
2. urea is transported to the kidneys via the bloodstream and is filtered and excreted
31
Alcohol metabolism
- occurs mostly in the liver but 10-30% occurs in the stomach
- directly forms acetyl coa and enters the citric acid cycle
- eventually stops citric acid cycle as the metabolism of it takes priority due to toxicity
- if acetyl coa is not used, leads to fatty acid accumulation in the liver called steatosis
32
Alcohol dehydrogenase pathway (ADH)
- main pathway
-steps:
1. cytosol: alcohol is converted to acetal aldehyde by dehydrogenase enzyme NAD+
2. coenzyme and dehydrogenase convert acetal aldehyde into acetyl coa and NADH
33
MEOS pathway
- used if alcohol consumption is moderate or excessive
- uses oxygen and NADP and forms acetalaldehyde and water
- also metabolizes drugs
- uses potential energy rather than producing potential energy
34
Liver regulation of energy metabolism
- key functions: nutrition storage, conversion between simple sugars, fat synthesis, production of ketones, amino acid metabolism, urea production, and alcohol metabolism
35
ATP concentrations regulating energy metabolism
- high levels of ATP: decreased ATP synthesis and energy yielding reactions, promotes anabolic reactions
- high levels of ADP: increased ATP synthesis and energy yielding pathways
36
Regulation of energy metabolism due to enzymes, hormones, vitamins, and minerals
- enzymes are key regulators in which synthesis and rates of activity are controlled by cells and products of reactions they participate in
- hormones: I.e. insulin and gluconeogenesis
- B vitamins most important
37
Fasting and feasting
Both affect metabolism
38
Fasting
- first hours: fuel from stored liver glycogen and fatty acids from adipose tissue
- nervous system and red blood cells can only use glucose as a fuel source leading the body to breakdown lean body mass and perform gluconeogenesis
- proteins break down rapidly which leads to increase urea levels in the blood
- slows metabolic rate
39
Feasting
- increased accumulation of body fat and insulin production
- energy cost of converting dietary protein to body fat is higher than dietary fat to body fat
- synthesis of fat from increased carb or proteins lead to lipolysis in the cytosol of liver cells
- increased enzyme activity needed in this pathway
- synthesizes triglycerides which enter the bloodstream and then adipose tissue via LDLs
40
Energy balance
- state in which energy intake, in the form of food and beverages, matches energy expenditure, primarily through basal metabolism and physical activity
41
Energy equilibrium
State in which intake equals energy use, and thus the body maintains a stable condition
42
Positive energy balance
- energy intake exceeds expenditure leading to weight gain
- desired during growth phases such as childhood, adolescence, pregnancy, and to restore weight after illness or injury
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Negative energy balance
- energy intake is less than expenditure
- desired in adulthood when weight exceeds healthy levels
44
Bomb calorimeter
- directly measures calorie content
- determines grams of carb, protein, fat, and alcohol in food and multiplies these values by the physiological fuel values
45
3 main purposes of energy expenditure
1. Basal metabolism
2. Physical activity
3. Digestion, absorption, and processing of ingested nutrients
Minor- thermogenesis
46
Basal metabolism
- Represents minimum amount of energy expended in a fasting state to keep resting, awake body alive in a warm, quiet environment
- For sedentary person, accounts for 60-70% of total energy expenditure
- includes beating of heart, respiration of the lungs, and other organ activity, but does not include physical activity or digestion
47
Resting metabolic rate (RMR)
-If the individual is not fasted or completely rested
- typically 6% higher than BMR
48
BMR
-women: 0.9 kcal/ kg per her
- men: 1 kcal/kg per hour
- example calculation for 130 lb women: 130/2.2= 59kg, 59 * 0.9= 53 kcal/ hr and 53* 24 hrs= 1272 kcal/ day
49
Factors that increase BMR
- greater muscle mass
- larger body surface area
- male biological sex
- increased secretion of thyroid hormones
- aspect of nervous system activity
- growth stages of life cycle
- caffeine and tobacco increase metabolism
- recent exercise
50
Factors that decrease BMR
- lower than normal secretions of thyroid hormones (hypothyroidism)
- restricted calorie intake (decreases 10-20%)
- fasting and starvation
- less body surface area and muscle mass
- aging after 30 years (deceases 1-2% every decade past 30; physical activity helps prevent this)
51
Thermic effect of food
- energy the body uses to digest, absorb, transport, store, and metabolize nutrients
- uses 5-10% of energy each day and is also influenced by meal composition and size
52
Adaptive thermogenesis
- process of heat production
- occurs for non voluntary physical activity triggered by extreme cold
- shivering
- brown adipose tissue plays a role
53
Direct calorimetry
- estimates energy expenditure by measuring amount of heat released by body
- 60% of energy leaves body as heat
- placed in insulated room surrounded by water
- expensive and complex
54
Indirect calorimetry
- most common
- collects expelled air over given time period
55
Estimated energy requirements (EERs)
Formula based on weight, height, age, sex, and activity levels
56
Factors driving desire to eat
- hunger: physiological drive to eat regulated by internal mechanism
- appetite: psychological drive to eat regulated by external factors
- satiety: no longer a desire to eat/ satisfaction which is regulated by the hypothalamus and sympathetic nervous system
57
Satiety process
1. Flavor of food
2. Knowing meal was eaten and chewing (histamine)
3. Influence of stomach and intestinal expansion and activity
4. Influence of nutrient use in liver and related communication with hypothalamus and brain
5. Conscious thinking in brain cortex can overcome hunger and satiety signals
58
Ghrelin
Hormone produced by the stomach that increased food intake
59
Leptin
Hormone made by adipose tissue that decreases body fat
60
Signal to eat
Macronutrient concentration decreases and body uses energy states leading to decreased satiety and increased appetite endorphins
61
Body mass index
= body weight/ height squared
healthy= 18-25; anything beyond 25 increases health risks
this does not apply to children, teens, old adults, and pregnant or lactation women
62
Body fat content
- men: 8-24%
- women: 21-35%
63
Methods for measuring body fat content
- underwater weighing (2-3% error)
- air displacement (2-3% error)
- skinfold thickness (3-4% error)
- bio electrical impedance (3-4% error)
- DXA *most accurate method but expensive and not widely available
64
Upper body obesity
Associated with cardiovascular disease and hypertension, regulated by testosterone and more common in men
65
Lower body obesity
More common in women and estrogen regulated
66
Factors affecting body weight and composition
- if neither parent is obese, 10% chance
- if one parent is obese, 40% chance
- if both parents are obese, 80%
67
Role of genetics in body composition
- studies with twins argue for nature over nurture
- account for 40-70%
68
Set point theory
- genetically predetermined body fat percentage which body regulates
- new set points can be established
69
Settling point theory
- opponents of set point that argue that weight is not constant throughout adulthood and environment and stress factors affect things
70
Role of environment in body composition
- learned behaviors are supported by the fact that the gene pool has stayed relatively consistent but obesity is on the rise
71
Genetic and environmental synergy
Both nature and nurture play a role in body composition
72
Marfan syndrome
- affects fat storage
- characterized by tall height with long arms and little fat
73
Prayer Willi syndrome
- uncontrolled appetite resulting from dysfunction of the nervous system leading to obesity
- characterized by shortness and obesity
74
A good weight loss program should include
1. Control of energy intake
2. Regular physical activity
3. Control of problem behaviors
75
Control of energy intake in weight loss
- to lose 1 lb of fat, once must decrease intake by 500 kcal/ day or increase physical activity by 500 kcal
- increase water content of food which will decrease energy density of foods
- eat smaller portions
76
Regular physical activity in weight loss
- duration and regular performance are more important than the intensity of the exercise
- resistance training should be included
77
Control of problem behaviors in weight loss
- chain breaking: separates link between behaviors that tend to occur together (eating chips while watching tv)
- stimulus control: alter environment ti decrease stimuli (out of sight, out of mind)
- cognitive restructuring: change frame of mind regarding eating (substitute food for another reward)
- self monitoring: use diary to track when and why foods are ate and how it feels (reveals habits)
78
Weight loss stats
- only 5% of people following commercial diets lose weight
- 1/3 of the weight loss is regained in 1 yr and close to all weight is regained in 3-5 yrs
- surgery shows most consistent success
- negative health consequences of weight cycling
79
Weight loss maintenance
- eat a low fat and high carb diet
- eat breakfast
- self monitor by weighing and keeping a food journal
- have a physical activity plan
80
Fad diets
Promote rapid weight loss resulting mostly from losing water weight; they are not designed for permanent weight loss
81
Restricted carb diets
- reduces glucagon synthesis and reduces water weight
- forces liver to use gluconeogenesis (body proteins)
82
Low fat diet
- result in high carb diets
- are not harmful to adults but are difficult to follow
- mostly made up of grains, fruits, and veggies
83
Novelty diets
Emphasize single food group and exclude all others
84
Disordered eating
Mild and short term changes in eating patterns that occur in response to stressful events/ illnesses or the desire to modify diet for personal/ appearance reasons
85
Prevalence and susceptibility of eating disorders
- 6-10x more common in females
- 85% develop in adolescence or early adulthood
- frequently occur with other psychological disorders
86
Anorexia nervosa
- psychological denial of appetite characterized by extreme weight loss, distorted body image, and extreme fear of obesity
- 20% of individuals die from related health complications
- restrict/ limit food intake and increase exercise
- 10% are male and are most commonly gay or an athlete
87
Physical effects of anorexia nervosa
- decreased weight, body temperature, metabolic rate, heart rate, iron level, white blood cell count, potassium levels
- less of periods in female and hair loss
- increased risk of tears and fracture of bone
88
Treatment of anorexia
- composed of a multi disciplinary team
- often takes place at a treatment center
- can involve hospitalization in extreme cases
- average recovery time= 7 yrs
- involves both nutrition and psychotherapy
89
Bulimia nervosa
- characterized by episodes of binge eating followed by induced vomiting
- use food as a coping mechanism
- most cases go undiagnosed
- individuals understand that their behavior is abnormal
- mostly successful females at or just above average weight
- binges often occur at night and last from 30 min to 2 hrs
- 33-75% of energy is still absorbed before vomiting
- 90% of energy is absorbed if using laxatives
90
Physical effects of bulima nervosa
Tooth decay and stomach ulcers
91
Treatment for bulimia nervosa
- both nutrition and psychotherapy
- high risk of depression and suicidal
- 50% never recover
92
Binge eating disorder
- binge eating sessions not followed by vomiting
- 8% of obese individuals have a binge eating disorder
- stress trigger and frequent dieters are more susceptible
- treatment focuses on expression and coping with emotions instead of eating
93
Other specified eating disorders
Patients meet some but not all of the criteria for the other disorders
94
Muscle dysmorphia
Excessive concern that one has underdeveloped muscles and is most commonly seen in body builders
95
Orthorexia
Eating healthy and unprocessed foods to an extreme
96
Pregorexia
Women excessively attempting to control weight during pregnancy
97
Prevention of eating disorders
- caregivers play very important role
- should discourage restrictive eating and encourage eating when hungry, promote good nutrition and exercise, and build respectful and open relationships about food
