Aerobic Energy Systems Flashcards
(64 cards)
1
Q
What is the function of Hexokinase?
A
- Slow Glycolysis
- converts glucose to glucose-6-phosphate in the cell so it can be stored as glycogen
2
Q
What is the function of Insulin?
A
- Allows transport of glucose into the cells
- decreased activity during exercise
- stimulates glucose uptake into the tissues and glycogen storage
- stimulates fat cells to form fats from fatty acids and glycerol
- inhibits the liver/kidneys from making glucose from intermediate compounds of metabolic pathways
- stores nutrients right after a meal by reducing the concentration of glucose, fatty acids, and AA in the blood strew,
3
Q
What is the function of phosphorylase?
A
- Fast and Slow Glycolysis
- assists with breakdown of glycogen
4
Q
What is the function of Epinephrine?
A
- Increases Heart Rate
- Stimulates Phosphorylase, Hormone Sensitive Lipase
- activates glut 4
5
Q
What is the function of FAD?
A
-hydrogen carrier from the Krebs cycle to the ETC
6
Q
What is the function of Isocitrate Dehydrogenase? (IDH)
A
-rate controlling enzyme of the Krebs Cycle
7
Q
What is the function of Phosphofructokinase?
A
- enzyms that assists glycolysis
- stimulated by increased cell concentration of ADP and AMP
- inhibited by ATP and decreased pH
8
Q
What is the function of PDH?
A
-transforms Pyruvate to Acetyl CoA by removing carbon so it can be used in the Krebs Cycle
9
Q
What is the function of Lactate dehydrogenase muscle form?
A
- Fast Glycolysis - anaerobic
- recycles NAD in fast glycolysis and converts pyruvate to lactate
10
Q
What is the function of lactate dehydrogenase heart form?
A
- aerobic - slow glycolysis
- converts lactate to pyruvate
11
Q
What is the function of NAD?
A
-carries electrons and hyrdrogens to the Krebs cycle/ETC
12
Q
What is the function of ATP synthase?
A
ADP and Pi are joined together by ATP synthase to create ATP in the ETC
13
Q
What is the function of succinate dehydrogenase? (SDH)
A
- Aerobic enzyme used during the Krebs Cycle
- removes hydrogen from succinate
14
Q
What is the function of Cytochrome oxidase?
A
-accepts electrons from cytochrome c to be converted to water in the ETC
15
Q
What is the function of norepinephrine?
A
-increases blood pressure and heart rate when the body is put under stress
16
Q
What is the function of hormone sensitive lipase?
A
-breaks down fasts for utilization as fuel
17
Q
What is the function of cytochrome c?
A
-transports one electron at a time in the ETC
18
Q
What is the function of NADH Dehydrogenase?
A
-Removes H from NADHH and movie it to the inter membrane space of the ETC
19
Q
What is the function of Ubiquinone?
A
-electron carrier in the electron transport chain
20
Q
What is the function of Acetyl CoA
A
delivers carbons to the krebs cycle from glycolysis
21
Q
What is the function of oxaloacetate
A
combines with acetyl CoA to create a 6 carbon chain to be used in the krebs cycle to create energy
22
Q
What precautions should a diabetic take before exercising? Explain why these precautions are necessary.
A
- During exercise insulin decreases so glucose enters the cell through glut4 activation by calcium
- glut4 is activated by muscle contraction (Calcium and epinephrine)
- This increases glucose uptake into the cell which decreases blood glucose levels
- Could result in hypoglycemia
- Diabetics should check blood glucose levels before exercise and make sure insulin levels are not high prior to exercise
- high insulin and exercise = crash
- low blood glucose and exercise = crash
23
Q
Explain why refueling after hard or long workouts should be started within 30 minutes to 2 hours after the workout
A
- After exercise insulin is low, Glut4 remains active, and glycogen synthase activity increases due to low muscle glycogen levels
- Eating a 4:1 CHO:PR meal will restore muscle glycogen levels the most efficiently
24
Q
How is energy production via aerobic pathways limited by VO2?
A
- ability of the heart and blood vessels to transport oxygen to the active muscle tissues
- Cardiac output and redistribution of blood flow to active tissues (CO=SV x HR hence a person with a larger SV will have an advantage)
- Ability of muscle cell to take up and use oxygen (mitochondrial enzyme development)
- all are trainable to some degree
- Heart disease and respiratory disease have a negative impact on VO2
25
What is the function of Glycolysis?
Fast: provide ATP rapidly via partial breakdown of glucose and glycogen
- use when ATP resynthesis via O2 system is inadequate to meet the rate of ATP demand
- to extend ATP resynthesis beyond the ATP PCr system
Slow: provides substrates/reactant for the Krebs Cycle and ETC while providing a small amount of energy
26
What is the function of the Krebs Cycle?
```
-produces NADH and FADH for use in the electron transport chain while releasing some ATP
For every glucose:
-2 ATP
-10 NADH
-2 FADH
```
27
What is the function of the electron transport chain?
-the create of ATP via hydrogen/electron gradient
28
What is the function of Beta Oxidation?
-to cleave 2 carbon from free fatty acid and continues until you are left with 2 pairs
29
How many ATPs are produced from each NADH+H in the ETC?
-cost of each= appx 0.5 ATP
| 3 ATPs from NADHH - 0.5 = 2.5ATPs
30
How many ATPs are produced from each FADHH in the ETC?
-cost=appx 0/5 ATP
| 2 ATPs from FADHH - 0.5 = 1.5 ATPs
31
What is the function of H in the electron transport chain?
increases gradient in the inter membrane space which allows for the flow of electrons
32
What is the function of electrons in the ETC
transfer of electrons provide energy for H pumping by creating a gradient
33
What is the function of oxygen in the ETC?
Final electron receptor forming H2O`
34
Define Oxidative Phosphorylation
- The process of producing energy via the ETC
| - Oxidation process producing ATP
35
After free fatty acids are broken down to Acetyl-CoA in beta-oxidation, what happens to the Acetyl-CoA
it enters the Krebs cycle
36
Which is more effective for the clearance of lactate, active recovery or passive recovery? Why?
- Active Recovery
- It allows blood to keep moving to clear lactate
- Clearance mechanisms
- Lactate Shuttle: Muscle cell to muscle cell in same muscle, lactate consumed in mitochondria
- Muscle cell to blood: from muscle to heart, liver, or other muscles, heart consumes lactate
37
Given similar lactate thresholds, why do athletes with high VO2 max values perform better in endurance events than those with low values?
- lactate is expressed as a percentage of VO2 max
| - the person with a higher VO2 max will be able to exercise at higher steady state than the person with a lower VO2 max
38
Given similar VO2 max values, why do individuals with higher lactate thresholds perform better in endurance activities than those with lower values?
- lactate thresholds are expressed as a percentage of VO2max
| - those with higher lactate threshold are able to exercise longer before fatigue
39
What factors determine lactate threshold?
- mitochondrial mass/capillary density
- LDH
- muscle fiber makeup
-can train factors to shift lactate threshold to the right
40
Explain 2 reasons why lactate begins to rise rapidly at lactate threshold?
- ATP demand is greater than what can be made
- recruit more type II muscle fibers
- lactate production exceeds clearance
41
What are the two primary determinants of VO2max? Explain how training enhances the function of each.
- Cardiac output: SV increases, HR decreases, CO increases which allows body to work less to transport oxygen throughout body
- A-VO2 Difference: Mitochondrial Function: the greater the difference the more oxygen you are able to take up
42
During the initial stage of aerobic exercise, before reaching steady state, we contract and oxygen deficit.
Where do we gain the energy needed to sustain exercise during this period?
energy for exercise is met by the smooth blending and overlap of the body's three energy systems
43
During the initial stage of aerobic exercise, before reaching steady state, we contract an oxygen deficit.
Explain oxygen deficit. What are the implications for performance?
- oxygen needs that are met anaerobically instead of aerobically
- training to decrease the time of the O2 deficit will increase cardiac output, increase mitochondrial mass, increase oxygen transport, increase VO2 max, and increase capillary density
44
Explain how lactate threshold training may be beneficial for people recovering from a myocardial infarction, cancer, or even a sedentary person
- if able to work more aerobically, more oxygen will be in the blood and the heart will work less
- increases function capacity to do daily work/activities
45
Margaret and Nicole are endurance athletes of the same age and training background. Maggie weighs 58 kg and her VO2max is 3.2 L/min. She can sustain exercise at about 82% of her VO2max. Nicole weighs 59 kg and her VO2 max is 3.2 L/min. She can sustain exercise at about 65% of her VO2 max.
Based on the info provided, would you expect Maggie or Nicole to perform better in an endurance event lasting 45 min or longer?
- they have the same VO2max so a difference in endurance activity would be determined by lactate threshold
- Maggie has a lactate threshold of 82% of her VO2max and Nicole has a lactate threshold of 65% of her VO2max.
- Maggie can run at a faster speed than Nicole and remain at steady state
- Maggie is likely to perform better in an endurance event lasting over 45 min or longer
46
Explain the effect of intensity of exercise on fuel selection utilization.
- High intensity short term: PCr to produce ATP fast
- Muscle glycogen used during longer intensity activities both aerobically and anaerobically
- fatty acids used during longer intensity to produce a lot of ATP
- Fuel sources are recruited based on the rate of need of ATP
47
Explain why several days of high (70%) carbohydrate may be beneficial for an endurance activity
- muscle and liver glycogen depletion during exercise
| - Can double muscle glycogen stores by carboloading which will increase endurance
48
Explain mobilization of fatty acids
- Mobilization from fat cells
- have to break acid chains off of glycerol (hormone driven)
- epinephrine and norepinephrine decrease insulin which activate hormone sensitive lipase (HSL breaks off first fatty acid)
- Diglyceride Lipase, Monoglyceride lipase act on 2nd and 3rd Fas
- FAs bind to PR carrier albumin to be transported to muscle
49
Explain uptake of fatty acids
- uptake into muscles in concentration dependent
- FFAs released from albumin in cytosol
- once in cell must be activated by Acetyl CoA using 2 ATPs each
50
Explain translocation of Fatty Acids
- Translocation into mitochondria
- FFAs diffuse into mitochondria using CPT1 and CPT2 (carnatine translocase)
- Aerobic training increases mitochondrial mass and CPT therefore increases FFA oxidation
51
Explain Beta Oxidation of fatty acids
- Beta Oxidation: breakdown of FFA to Acetyl CoA, NADH, FADH
- Purpose: to cleave 2 carbon units off of FFA chain to be converted to Acetyl CoA
- For every time through bOx you get 1 NADH and 1 FADH for the ETC
52
Explain oxidation of fatty acids
-Oxidation of AcetylCoA in Krebs and ETC
53
The body has ample fat stores, so what is the importance of adequate carbohydrate stores for endurance performance? Why can't the endurance athlete just depend on fat metabolism?
- Fat burning does not occur until at least 45 minutes of moderate intense exercise
- Carbohydrate (Muscle Glycogen stores) must be used until this point
- the use of fat burning for fuel must be trained
54
What is the effect of exercise on post-exercise metabolic rate (EPOC) and why is an elevated metabolic rate beneficial?
- EPOC: Excess Post Exercise Oxygen Consumption
- EPOC increased with increased intensity and duration
- Increased caloric cost of exercise---weight loss or control
- Exercise 5xs a week for 40-60 min for weight loss ---200-300 min of exercise per week is optimal
55
Under what conditions is protein metabolism (breakdown) increased?
when CHO stores are low
56
Discuss protein needs for endurance trained people
- For endurance athletes activities lasting longer than 90mins, small amount of PR is used as fuel
- Replace AAs used for energy and repair post exercise
- 1.2-1.4 g/kg BW/day
57
Discuss protein needs for power trained people
- Strength athletes need more to repair muscle and increase mass
- 1.4-1.8 g/kg BW/day
58
What is meant when we say that aerobic metabolism is glycogen sparing (especially fat burning)?
- same amount of fuel used differently
| - more aerobic/fat burning spares the glycogen to be used later
59
From a performance perspective, why are low carbohydrate diets a poor idea?
- carbohydrates provide muscles with glycogen stores that provide fuel for activity
- low carbohydrates would result in low glycogen stores and a reduced time to fatigue
60
What are the probable causes of fatigue during endurance activities lasting 14-30 min and lasting 90 min to 3 hours?
14-30: decreased pH inhibits hemoglobin
90-3h: muscle glycogen depletion: decreased oxaloacetate slows krebs cycle
-liver glycogen depletion: source of glucose for blood, decrease causes CNS fatigue
-Dehydration: increased blood viscosity, decreased oxygen transport, increased body temperature
61
What physiological adaptations occur as a result of training for fat metabolism?
- increased sensitivity of hormone sensitive lipase
- greater number (mass) of mitochondria
- Increased CPT1 and CPT2
- Increased Beta Oxidation enzymes
62
What physiological adaptations occur as a result of training for lactate threshold?
- LDH converts lactate to pyruvate to go into the Krebs cycle
- increased mitochondrial mass
- increased capillary density
- increased Krebs/ETC enzymes
- increased A-VO2 difference
63
What physiological adaptations occur as a result of training for VO2 max?
- possible increase in cardiac output based on increased stroke volume
- increased mitochondrial mass
- increased capillary density
- increased myoglobin
- increase in Krebs and ETC enzymes
- Improved A-VO2 difference
64
What type of exercise is most beneficial for weight loss? Exercise at a low HR for 45min to ensure a greater percentage of fat burning, resistance training to increase muscle because it increases metabolic rate, or high intensity exercise?
- EX at low HR is not effective unless done for a very long time (moderate intensity more effective 70-75%)
- Resistance: muscle is always metabolically active and increase muscle mass also increases amount of food intake
