Exam 2 Flashcards
Carbs and Fats
1
Q
3 types of monosaccharides
A
glucose, fructose and galactose
2
Q
3 types of disaccharides
A
sucrose (glucose + fructose), maltose (glucose + glucose) and lactose (glucose + galactose)
3
Q
Sucrose
A
glucose and fructose
4
Q
Maltose
A
glucose and glucose
5
Q
lactose
A
glucose and galactose
6
Q
What are some examples of polysaccharides?
A
Starch and fiber. Remember that fiber ISN’T digestible
7
Q
During digestion, what are all CHO broken down into?
A
Monosaccharides
8
Q
In the _______ monosaccharides are converted into ______
A
Liver
Glucose
9
Q
How do we store glucose in the body?
A
Glycogen.
10
Q
AMDR for Carbs?
A
45-65%
11
Q
What should the Carb AMDR for Endurance athletes be?
A
for endurance athletes participating in events lasting 90+ minutes. For this type of performance, CHO intake could be 55-70% of total caloric intake.
12
Q
Athletes that are not strictly endurance athletes, but that have any type of endurance demand on their sport should get a minimum of ________ of CHO to maintain high levels of muscle glycogen.
A
5g/kg/day
13
Q
Endurance athletes should consume ____ g/kg/day of CHO.
A
7-10
14
Q
In reality, _____ CHO is usually adequate for most athletes. For some athletes with a very high kcal diet, this may mean a lower percentage of kcals coming from CHO.
A
~500-600 g
15
Q
How does digestion of CHO begin?
A
Always with salivary amylase in the mouth
16
Q
Step 1 of CHO Digestion?
A
- The majority of CHO digestion occurs in the small intestine through the enzymes pancreatic amylase and brush border disaccharidases.
17
Q
Step 2 of CHO digestion?
A
- All CHO is broken down to monosaccharides, which is absorbed in the duodenum of the small intestine.
18
Q
Step 3 of CHO digestion?
A
- Monosaccharides are transported into the blood stream. Fructose and galactose are metabolized in the liver to glucose.
19
Q
Step 4 of CHO digestion?
A
- Glucose is the monosaccharide absorbed by cells.
20
Q
Gastric emptying
A
the rate at which food is emptied from the stomach into the small intestine. CHO has the fastest rate of gastric emptying, and fat has the slowest rate. Gastric emptying is also determined by the meal components, the meal volume and the drink volume.
21
Q
What organ produces bile? What releases it?
A
Liver produces bile while the gallbladder releases it
22
Q
What is Glycemic Index?
A
A measurement of changes in blood sugar (glucose) due to consumption of different foods (all with equivalent levels of CHO). Foods with a high glycemic index cause the highest changes in blood sugar while foods low in glycemic index cause the lowest changes in blood sugar. It was developed to help diabetics regulate blood sugar and has some limited uses for the general population.
23
Q
Does Glycemic Index measure the rate at which glucose enters the blood stream?
A
As discussed in class, glycemic index does not measure the rate of glucose entering the blood stream. It only measures the changes in blood glucose, which is regulated by the rate of glucose entering the blood stream and the rate of glucose leaving the blood stream (entering cells).
24
Q
what was the example between corn flakes and bran flakes with glucose?
A
In the case of the corn flake/bran flake study discussed in class, the rate of glucose entering the blood stream was the same. The difference was that glucose from bran flakes were absorbed into the cells faster due to an earlier and higher insulin response.
25
Rank of Glycemic Index
High glycemic: >85
Medium glycemic: 60‐85
Low glycemic: <60
26
What are the 4 fates of glucose?
1. Immediately for energy
2. Stored as glycogen (liver and muscle)
3. Stored as fat in adipose tissue (only in small amounts and if in large excess of caloric needs)
4. Excreted in the urine (not typical, only if blood glucose levels remain high)
27
Where do we store glucose?
Liver and skeletal muscle
28
Why is CHO an optimal source of energy?
It can go through the lactate pathway or become fully oxidized through the TCA/electron transport chain to produce ATP.
CHO has greater ATP yield/oxygen consumed than fat.
29
What type of exercise intensity does CHO support?
Prolonged exercise- endurance events
| High intensity intermittent exercise
30
Depletion of CHO during exercise can cause what?
Fatigue
31
Exercise ability is enhanced when CHO availability remains ___ throughout the event.
high
32
CHO intake is most important for endurance type events lasting over ___ minutes. It becomes crucial in events lasting over ___ minutes.
45, 90
33
An increase in blood glucose causes what?
It causes insulin to be secreted from the pancreas
34
What is the mechanism of insulin action?
As glucose is absorbed into the blood stream from a meal, blood glucose increases (1). This causes insulin to be secreted from the pancreas into the blood stream (2), it then binds to receptors at muscle or liver cells (3). This causes GLUT4 to be moved to the cell membrane (4), which allows glucose to enter the cell (5), lowering the blood glucose levels.
35
A decrease in blood glucose causes what?
causes the release of glucagon from the alpha cells of the pancreas
36
What are the different responses that can increase blood glucose?
1. Glucagon
2. The fight or flight response results in increased circulating epinephrine (from the adrenal gland)
3. General stress can cause an increase in cortisol release (from adrenal gland)
37
What effect does exercise have on blood glucose?
It decreases blood glucose
38
What hormones cause glycogenolysis?
Epinephrine, glucagon
39
What hormones cause gluconeogensis?
Epinephrine, cortisol, glucagon
40
What hormones cause protein degradation?
Cortisol
41
Does exercise stimulate glucagon release?
No.
42
What is the recommended carbohydrate intake BEFORE exercise?
Depending on the timing of the event, intake 1g/kg CHO one hour before the event OR 2 g/kg CHO two hours before OR 3 g/kg CHO three hours before OR 4 g/kg CHO four hours before the event.
43
Recommendations for CHO intake pre exercise?
Choose foods lower in fiber for gastrointestinal comfort.
Choose foods with little or no fat and low levels of protein.
Choosing low glycemic index foods may be beneficial, especially if CHO intake will not be possible during the event. This research is not terribly conclusive yet.
Specialize to the athlete through trial and error- what foods/timing make them feel the best for the event?
44
Recommendations for CHO intake during exercise?
<30 minutes = NONE
30-90 minutes = 30-60 grams
90 min - 6 hours = 60-80 g/hr
45
Recommendations for CHO intake post exercise?
60-80 g/hr for 3-4 hours.
| Remember the 45-65% AMDR
46
How much CHO should we get daily?
1-3 g/kg/day
47
Foods with what type of CHO (Glc, frc, etc) are best for absorption?
It’s better to use foods with multiple CHO types (glucose, fructose) to facilitate better absorption. If using only glucose, 60g/h is the max amount that can be absorbed, but by using a mixture, over 100g/h can be absorbed.
48
Is the depletion stage of CHO loading necessary?
No. Many athletes found it difficult to tolerate with symptoms of GI distress, hypoglycemia, mood disturbances and stress over food preparation. A modified protocol was developed that results in similar levels of glycogen storage without the depletion stage.
49
Modified CHO loading protocol
recommends increasing CHO intake over several (2-6) days- starting with 50% and ending with 70-90% of total kcals as CHO. During this time, exercise should be tapered with a rest day the day before the event.
50
What are the common different types of lipids?
glycerides, phospholipids, sterols, fatty acids and triglycerides
51
What is a triglyceride composed of?
Triglycerides are composed of three fatty acids with a glycerol backbone
52
Are most fatty acids long chain or medium chain?
Long chain
53
What are saturated fatty acids?
All of the Carbons are single bonded
54
What is an unsaturated fatty acid?
There is at least one double bond in the molecule
55
Difference between mono- and poly- unsaturated fatty acids?
Monounsaturated fatty acids just have one double bond, whereas polyunsaturated have at least 2, if not more.
56
What are the fat soluble vitamins?
A, D, E, K
57
What is the relative percentage of the types of lipids we ingest?
~98% of ingested lipids are triglycerides and ~2% are phospholipids and cholesterol.
58
Where does digestion of fat occur?
Digestion of fat occurs in the small intestine where bile salts break up large droplets of fat into smaller droplets
59
What is the function of lipases?
Lipases release the fatty acids from the triglycerides and the fatty acids form micelles.
60
What is a micelle?
A small particle formed by aggregates of molecules with both polar and nonpolar segments (e.g., soap); the polar ends of these molecules point outward toward a polar solvent (e.g., water) while the non-polar ends will point inward toward a nonpolar solute (dirt/oil/grease). This allows the nonpolar substance to be washed away by the polar substance.
61
Function of micelles?
Free fatty acids are taken in to micelles. Micelles are absorbed into the intestinal cell and made into chylomicrons (a type of lipoprotein). The chylomicrons are then taken up into the lymph system.
62
Chylomicron function
After traveling through the lymph system, the chylomicrons are deposited into the blood stream where they are transported to the liver for further metabolism.
63
VLDL
Very Low density Lipoprotein
How Triglycerides are transported to adipocytes (fat cells) and muscle cells
Mainly transport fatty acids and glycerols
64
What is a lipoprotein?
any of a group of soluble proteins that combine with and transport fat or other lipids in the blood plasma.
65
How long does it take for fats to be ready to be used as an energy source?
It takes 3-4 hours after consumption for fatty acids to become available as an energy source. It’s not recommended to eat fat right before or during exercise because it causes gastric distress and it won’t be available as an energy source during the exercise.
66
Which chain of fatty acids can be absorbed directly into the bloodstream?
Medium chain fatty acids
67
Function of bile salts?
Bile salts serve as emulsifiers, breaking up the lipid droplets into smaller segments that may be hydrolyzed by the lipids enzymes, pancreatic lipases and cholesterases
68
When do we normally use fats for energy?
During lower intensity exercise.
In fact, sitting/laying quietly burns the highest percentage of fat of any activity).
Also As exercise duration increases, more fatty acids are released into the blood stream and the reliance on fat increases (the intensity of exercise also decreases).
69
Who is able to use more fat during exercise? Why?
Women have a lower RER and are also able to use more fat during exercise than men, which spares glycogen stores.
Children are also able to use more fat during exercise than adults.
70
What effect does training have on fat utilization?
Trained individuals develop adaptations to use more fat during exercise, resulting in glycogen sparing and delayed fatigue.
71
Exercise training's effect on fatty acid uptake?
Trained individuals are able to uptake more fatty acids into their cells than untrained individuals. This adaptation occurs through upregulation of FATCD36. This allows them to increase their fat uptake into muscle cells.
72
Exercise training's effect on fatty acid on triglyceride stores?
Trained individuals also have higher intramuscular triglyceride stores in the muscle. This allows them to have a higher reliance on fatty acids during exercise.
73
Exercise training's effect on CPT1 activity
Trained individuals have higher CPT1 activity
74
What is CPT 1 and CPT 2?
CPT: Carnitine palmitoyl transferase
Becomes a fatty acyl carnitine at CPT-1
Gets back to a fatty acyl CoA at CPT-2
75
Exercise training's effect on fatty acid oxidation?
Trained individuals rely more heavily on fat oxidation than untrained individuals when exercising at similar VO2 percent (ex. Both groups exercise at 65% of individual VO2 max).
76
Exercise training's effect on fat use and fatigue?
Trained individuals also upregulate β-oxidation enzymes and are better able to burn fat during prolonged exercise which allows them to spare their glycogen stores and delay fatigue.
77
What is the ultimate factor for weight loss?
A common misconception is that fat must be burned during exercise to result in fat weight loss. It is not necessary to burn fat while exercising to lose weight. The overall energy expenditure in relation to kcal consumption is the largest factor that will determine weight loss (or gain).
78
Is a ketogenic diet recommended for athletes? Why or why not?
This diet, while it can be effective, is not recommended for athletes because low carbohydrate levels won’t be adequate for replenishing glycogen stores.
79
What do high density lipoproteins transport
Mainly protein; delivers cholesterol from cells to liver
80
What do low density lipoproteins transport
Mainly cholesterol; delivers cholesterol to cells
81
What hormone activates hormone sensitive lipase?
Epinephrine
82
In which state do we oxidize more fats?
In a fasted state.
83
What is ACC? What does it do?
Acetyl coA carboxylase
Adds a carboyxl group to a Acetyl CoA, which forms Malonyl CoA. Malonyl CoA inhibits carnitine and as such slows fat metabolism
84
How were researchers able to find increased muscular levels of carnitine? Why did this certain way work?
By taking carnitine twice a day with large amounts of carbohydrate, researchers were able to observe increased muscular levels of carnitine. This occurred because carbohydrate causes an insulin response, which also increases amino acid (including carnitine) uptake into the muscle.
85
What is the AMDR for fats? What is the g/kg/day?
20-35% of total Kcals
| 1 g/kg/day
86
For athletes with a high kcal diet, what should be the g/kg/day to meet the kcal requirement?
Pretty high on fats, up to 3g/kg/day
87
Is fat intake recommended before exercise? Why or why not?
Fat takes 3-4 hours to reach the blood stream after it has been consumed. Because of this, fat intake is not recommended in the hours right before or during exercise. In addition to not being available for use, it causes GI distress.
88
Is fat recommended during exercise?
No
89
Post exercise meals and fat?
Post exercise meals can contain larger amounts of fat- especially to compensate for large caloric needs. Getting adequate CHO for glycogen replenishment is more important.
90
Where is glycerol metabolized and what is it used for?
It is metabolized by the liver and used in gluconeogenesis (glucose formation).
91
Function of Hormone sensitive lipase (HSL).
| Activated and inhibited by what?
Hormone sensitive lipase (HSL): mobilizes stored fatty acids from the adipose tissue to the blood stream. It is activated by epinephrine and inhibited by insulin.
92
What transports triglycerides in the bloodstream?
VLDLs
93
What cleaves fatty aids from triglycerides?
Lipoprotein Lipase (LPL)
94
What facilitates the transport of fatty acids across the membrane?
FATCD36 and FABP facilitate transport of the fatty acids across the membrane (fatty acids can cross the membrane without transporters, but at a slower rate).
95
What is the fatty acid molecule converted to once it's inside the cell?
What can it be used for?
Once inside the cell, a CoA molecule is added to the fatty acid to form fatty acyl CoA. The fatty acyl CoA can be formed into intramuscular fat stores (IMTG) or transported to the mitochondria to be oxidized for energy.
96
How do fatty acids enter the mitochondria?
Fatty acids enter the mitochondria via two Carnitine Palmitoyl Transferases: CPT1 and CPT2. The CoA is released from the fatty acid and carnitine is bound to it during transport. Carnitine is released once inside the mitochondria and the fatty acid binds to a CoA molecule again forming fatty acyl CoA. Medium chain fatty acids do not go through CPT1/2 and are therefore not under regulation by carnitine.
97
What happens to the Fatty Acyl CoA once it is in the mitochondria?
The fatty acyl CoA goes through β-oxidation and is broken down into several two carbon acetyl CoA molecules. During this process, electron carriers are reduced.
It results in an acetyl CoA
98
What does malonyl CoA do in fatty acid metabolism?
Malonyl CoA inhibits CPT1. Without CPT 1 being active, fatty acids are unable to enter the mitochondria.
99
What activates ACC?
ACC is activated by insulin and thus inhibits fatty acid transport into the mitochondria and fatty acid oxidation.
100
What inhibits ACC?
ACC is inhibited by AMPK (which is activated by exercise), meaning fatty acids are transport into the mitochondria for oxidation.
101
What can lactate be used for?
It can further be oxidized by going into mitochondria Or it can be exported from the muscle and used by other muscles:
For energy
Goes back to liver for gluconeogenesis
Lactate can be used by the liver to make new glucose
The heart and the brain also use lactate to create energy
102
What is the precursor to Acetyl CoA?
Pantothenic Acid
103
What is NADH derived from?
Niacin
104
What is FADH2 derived from?
Riboflavin
105
Does protein really provide us any energy?
No
106
Can fats be oxidized anaerobically?
No
107
Fats are more oxidized/reduced than carbs
REDUCED
108
What is the predominant end product of glycolysis?
Lactate
109
How many ATP do you get from NADH?
3
110
How many ATP do you get from FADH2?
2
111
RER values?
```
RER values depend on the substrate
being utilized
Range: 0.7 (fat only) to 1.0 (CHO
only).
Resting RER on mixed diet: 0.82-0.87
High intensity exercise: approaching
1.0
```
112
What is RER?
This is done through measuring the amount of oxygen consumed and the amount of carbon dioxide produced.
The resulting ratio of CO2 and O2 is known as the respiratory exchange ratio (RER). RER=VCO2VO2 where V indicates the volume of gas.
113
Why does it make sense that fat is used more at rest and carbohydrate more during exercise?
Because at rest you are able to breathe in a lot more oxygen
