UNIT 12 nutrition class
Eating can be triggered by signals other than hunger, even when the body does not need food which means that overriding satiety & satiation is far easier than overriding hunger. Influences on the signals that prompt us to seek out food and start eating include
psychological influences, sensory influence, and cognitive influences.
As the electrons are passed along the proteins, hydrogen ions are
pumped across the inner membrane of the mitochondria. Then the hydrogen ions rush back across the cell membrane and power the synthesis of ATP. ATP then leaves the mitochondria and enters the cytoplasm of the cell where it can power reactions.
In the presence of oxygen, glucose can become ______which then can be converted to______ which enters the TCA cycle and produces nearly ____ ATP per molecule of glucose. In the presence of oxygen, fatty acids can be oxidized to ______ to enter the TCA cycle. Proteins can be oxidized to provide energy as well when oxygen is available.
pyruvate acetyl CoA 40 acetyl CoA
During metabolism, these are further broken down into one of two molecules:
pyruvate or acetyl CoA.
You have _____ in your stomach that detect the 'stretch' caused by food gradually filling it up.
receptors This releases gastrointestinal hormones such as cholecystokinin and you will start to feel full. You will feel satiated and you will (hopefully) stop eating. After you are done with your meal, the sensation of satiety will keep you from eating again. Whereas satiation tells us to "stop eating," satiety reminds us to "not start eating again." Satiation and satiety are fairly easy to override, however, and we eat when present with favorite foods or some other situation.
The first step in amino acid metabolism for energy is to
remove the nitrogen-containing amino group through deamination or transamination. The amino acids can then be converted to pyruvate or acetyl CoA. Carbon skeletons from amino acids can also enter the TCA cycle at varying points depending on their structure. Amino acids used to make pyruvate can be used to make glucose instead, but any made into acetyl CoA cannot be used to make anything other than fat or ATP.
High-fat foods on the other hand do a better job at
satiety than satiation.
We can, however, influence satiation and satiety through the
size and composition of our meals. Balanced, varied and moderate meals and snacks do the best job of helping us not too eat to much and keeping us from eating again too soon. Meals and snacks that contain protein and that are high in fiber encourage satiation. High-fiber foods absorb liquid and fill the stomach faster. For this reason, eating a large vegetable salad as a first course can help you eat less during the meal.
Adipocytokines released by adipose tissue signals other cells to
store or feed. Ironically, when you try to lose weight, the fat tissue releases adipocytokines that tell your body to store fat rather than release it for energy.] Both undernutrition and overnutrition affect hormone levels and the neural circuitry controlling appetite, which makes losing or gaining weight a substantial physiological hurdle.
In contrast, in the "fed" state (when energy levels are high), extra energy from nutrients will be
stored. Glucose can be stored only in muscle and liver tissues. In these tissues it is stored as glycogen, a highly branched macromolecule consisting of thousands of glucose monomers held together by chemical bonds. The glucose monomers are joined together by an anabolic pathway called glycogenesis.
Metabolism is defined as the
sum of all chemical reactions required to support cellular function and hence the life of an organism. . The overall goals of metabolism are energy transfer and matter transport. Energy is transformed from food macronutrients into cellular energy, which is used to perform cellular work
Basal metabolism refers to those metabolic pathways necessary to
support and maintain the body's basic functions (e.g. breathing, heartbeat, liver and kidney function) while at rest. The basal metabolic rate (BMR) is the amount of energy required by the body to conduct its basic functions over a certain time period. The great majority of energy expended (between 50 and 70 percent) daily is from conducting life's basic processes.
Children born to mothers who were malnourished during pregnancy have greater risk of becoming obese as they age. True False
t correct Right! Good job! Scientists found that offspring born to mothers who experienced famine were more likely to be obese in adulthood than offspring born to mothers who were pregnant just after World War II who lived in the same geographical locations (1). Other studies have shown that the offspring of women who were overweight during pregnancy have a greater propensity for being overweight and for developing Type 2 diabetes. Thus, undernutrition and overnutrition during pregnancy influence body weight and disease risk for offspring later in life. They do so by adapting energy metabolism to the early nutrient and hormonal environment in the womb.
Human beings have a nearly limitless ability to store energy as fat. True False
t correct Right! Good job! From the image caption: the reason obesity is an issue is because human beings have an almost limitless capacity to store energy as fat for future use--something important for our hunter-gatherer ancestors but deadly in today's food-generous environment.
The Thermic Effect of Food is not actually part of energy needs calculations for an individual. True False
t correct Right! Good job! For most purposes, however, the thermic effect of food can be ignored when estimating energy expenditure because its contribution to total energy output is smaller than the probable errors involved in estimating overall energy intake and output.
Oxygen is required for the electron transport chain. True False
t correct Right! Good job! The ETC (and the Citric Acid Cycle) are both aerobic pathways which means that they require oxygen in order to work.
If pyruvate enters the anaerobic pathway—
that means that no oxygen is involved in the chemical reactions— pyruvate can accept the hydrogens produces during glycolysis (instead of them being carried off to the electron transport chain). In doing so, the pyruvate is converted to lactic acid which frees the co-enzymes that picked up the hydrogens to return to the glycolysis pathway to pick up more hydrogens.
electron transport chain video
the electron transport chain is a series of proteins that are embedded in the membrane of the mitochondria electrons captured from donor molecules are transferred to these complexes also there is the pumping hydrogen ions. this pumping generates the gradient used by ATP synthase complex to make ATP
although fat provides little satiation during a meal, it produces strong satiety signals once it enters
the intestine. When fat hits the small intestine, the hormone cholecystokinin is released which gives the brain the "do not start eating again" signal (satiety).
The process of digestion turns individual nurients into
their smallest intact components: carbohydrates → glucose (fructose, galactose), fats → glycerol and fatty acids, and protein → amino acids.
how amino acids can be used to make glucose gluconeogenesis
they are converted into pyruvate (minus the nitrogen and the "R" side chain) and then another pyruvate is added to make glucose (this process is called gluconeogenesis). Gluconeogenesis (abbreviated GNG) is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids.
The electron transport chain consists of a series of proteins that serve as
"electron" carriers. These carriers are mounted in sequence on the inner membrane of the mitochondria. As coenzymes deliver the hydrogens' electrons they picked up from glycolysis, fatty acid oxidation, and the TCA cycle, each carrier receives electrons and passes them along to the next carrier. The electron carriers continue to pass the hydrogens' electrons along the chain until they reach oxygen at the end of the chain. The oxygen accepts the electrons and combines with hydrogen to form water.
Since satiation is the signal to tell you to why harder to feel satiation with high fat meals
"stop eating", fat can be a problem since it is not very good at that job. Because they are so energy-dense, you can eat a large amount of high-fat foods (and therefore calories) before the signal to "stop eating" registers. Plus, fat promotes flavor and appetite which also influences you to eat more. So if you like to eat high fat foods but are also trying to control your portion size, you may feel unsatisfied by the small amount of food on your plate—visual portion size also influences satiation. Instead of eating small portions of high-fat foods and feeling deprived, a person can feel more satisfied by eating large portions of lower-fat, higher-fiber, and lower energy density foods.
The energy required for all the enzymatic reactions that take place during food digestion and absorption of nutrients is called the
"thermic effect of food" and accounts for about 10 percent of total energy expended per day. The other energy required during the day is for physical activity. Depending on lifestyle, the energy required for this ranges between 15 and 30 percent of total energy expended. The main control a person has over TEE is to increase physical activity.
Hunger can be influenced by a variety of different factors:
(1) the quantity of nutrients in the bloodstream (or lack thereof), (2) the quantity and type of foods you ate previously, (3) your normal eating habits, (4) how hot or how cold it is outside, (5) your exercise habits, (6) hormonal status, and (7) any physical or mental illnesses and/or conditions you may have
how to obese people still feel hungry
As nutrients dwindle satiety diminishes and hunger develops again, starting the cycle over. This cycle occurs no matter the state of your energy stores so people who have excess energy stored still get hunger and go through this cycle.
Each molecule of glucose produces ___ pyruvate, the reaction produces ---- ATP but because two ATP were used up to start the reaction, the net result is ____ ATP molecules.
2 4 2 Hydrogens produced by glycolysis are carried off to the electron transport chain where they are used to make more ATP.
The TCA cylce starts when 4-carbon oxaloacetate molecule joins with the
2-carbon acetyl CoA to make a 6-carbon compound. This compound is changed a little to make a new 6-carbon compound, which releases carbons as carbon dioxide, becoming a 5- and then a 4-carbon compound. Each reaction changes the structure slightly until finally the original 4-carbon oxaloacetate forms again and picks up another acetyl CoA—from the breakdown of glucose, glycerol, fatty acids, and amino acids—and starts the cycle over again.
While around_________ calories is the amount of energy stored in 1 pound of fat, the equation of energy in and weight is not quite so simple.
3500 Different people can eat the same amount of excess calories and yet gain differing amounts of weight However, the fat stores of even normal weight adults represents about 50,000 to 200,000 calories ].
At the beginning of exercise, ATP is produced anaerobically. Once stored ATP and creatine is exhausted (after about _____seconds), the next step in the pathway to replenish ATP stores
8 is anaerobic glycolysis. This is the lactic acid pathway described above and is the anaerobic pathway provides the majority of fuel for short-duration, high-intensity exercise. In this pathway, energy is released from glucose without the presence of oxygen. The major by-product of this reaction is lactic acid and this pathway can only last for physical activity about 60-120 seconds.
This is why fatty acids produce so much more energy than carbohydrates or amino acids. A glucose only produces 30-32 ATP during the entire metabolic process.
A 16-carbon fatty acid can produce 35 ATP through the hydrogens that are carried to the electron transport chain. Additional ATP will be made when the eight total acetyl CoA molecules produced during fatty acid oxidation hit the TCA cycle: 96 ATP will be generated totaling 129 ATP from one 16-carbon chain.
influence energy expenditure during exercise
A particular activity's duration, frequency, and intensity also influence energy expenditure. The longer, the more frequent, and the more intense the activity (all three combined), the more calories are expended. Increases in physical activity over time result in elevated metabolic rate after exercise—another benefit of regular physical activity.
The sole purpose of metabolism is to release food energy as
ATP or adenosine triphosphate.
Which of the following hormones is most responsible for signaling satiety? a. Gastrin b. Adipokines c. Insulin d. Cholecystekinin
Cholecystekinin correct Right! Good job! . GI hormones are also highly involved in regulating energy intake signals. They are involved in initiating and terminating feeding, bringing on sensations of hunger & satiety. When fat hits the small intestine, the hormone cholecystokinin is released which gives the brain the "do not start eating again" signal (satiety).
a person is also in negative-energy balance between meals.
During this time, blood-glucose levels start to drop. In order to restore blood-glucose levels to their normal range, the anabolic pathway, called gluconeogenesis, is stimulated. Gluconeogenesis is the process of building glucose molecules from certain amino acids and it occurs primarily in the liver. The liver exports the synthesized glucose into the blood for other tissues to use
***********Starting again notes
Energy Out: Glycolysis
many societal factors influence the number of calories burned in a day.
Escalators, moving walkways, and elevators (not to mention cars!) are common modes of transportation that reduce average daily energy expenditure. Office work, high-stress jobs, and occupations requiring extended working hours are all societal pressures that reduce the time allotted for exercise of large populations of Americans. Even the remote controls that many have for various electronic devices in their homes contribute to the US society being less active.
genetics certainly play a role in body fatness and weight and also affects food intake.
However, overweight and obesity that manifests in millions of people is not likely to be attributed to one or even a few genes, but to rather the interactions of hundreds of genes with the environment. In fact, when an individual has a mutated version of the gene coding for leptin, they are obese, but only a few dozen people around the world have been identified as having a completely defective leptin gene.
If plenty of oxygen is available and the cells need energy, then pyruvate enters the mitochondria of the cell for
If plenty of oxygen is available and the cells need energy, then pyruvate enters the mitochondria of the cell for aerobic metabolism. There, a carbon group (COOH) on the pyruvate molecule is cleaved, leaving a 2-carbon compound that binds with the coenzyme molecule CoA to form Acetyl CoA. The leftover COOH group becomes carbon dioxide which enters the blood and then is expired through the lungs. The conversion from pyruvate to acetyl CoA is irreversable, the cleaved COOH group cannot be added back.
Electrochemical energy.
In the body, electrical impulses travel to and from the brain encoded as nerve impulses. Once the brain receives an electrical impulse it causes the release of a messenger chemical (glutamate, for example). This in turn facilitates electrical impulses as they move from one neuron to another.
Chemical energy.
In your body, blood sugar (glucose) possesses chemical energy. When glucose reacts chemically with oxgen, energy is released from the glucose. Once the energy is released, your muscles will utilize it to produce mechanical force and heat.
helping lose weight with sedentary lifestyle
International Journal of Behavioral Nutrition and Physical Activity reports that even breaking up sitting-time with frequent, but brief increased energy expenditure activities, such as walking for five minutes every hour, helps maintain weight and even aids in weight loss (2). Americans partake in an excessive amount of screen time, which is a sedentary behavior that not only reduces energy expenditure, but also contributes to weight gain because of the exposure to aggressive advertising campaigns for unhealthy foods.
Electron transport chain (ETC) is the last step in the production of ATP.
It occurs in the inner membrane of the mitochondria of cells and requires the presence of oxygen. The ETC uses electrons produced from the TCA cycle, glycolysis, and fatty acid oxidation and the end result is the synthesis of ATP.
oregon and energy expenditures
Liver 27% Brain 19% Heart 7% Kidneys 10% Skeletal muscle (at rest) 18% Other organs 19%
Eating can also be suppressed by signals other than satiety, even when a person is hungry.
Mental health conditions were mentioned above as an influence on appetite. People suffering from the mental condition of anorexia nervosa use extraordinary willpower to override the influence of hunger. Others simply do not feel like eating when stressed or nervous.
metabolism
Metabolism is the final step in which actual energy is released to power all the chemical reactions that go on in living cells including all reactions from which the body obtains and expends energy from foods.
undernutrition and overnutrition during pregnancy influence body weight
One of the first scientific investigations of prenatal control over energy balance was conducted in Germany. In this observational study, scientists found that offspring born to mothers who experienced famine were more likely to be obese in adulthood than offspring born to mothers who were pregnant just after World War II who lived in the same geographical locations (1). Other studies have shown that the offspring of women who were overweight during pregnancy have a greater propensity for being overweight and for developing Type 2 diabetes. Thus, undernutrition and overnutrition during pregnancy influence body weight and disease risk for offspring later in life. They do so by adapting energy metabolism to the early nutrient and hormonal environment in the womb.
Socioeconomic status has been found to be inversely proportional to weight gain.
One reason for this relationship is that inhabitants of low-income neighborhoods have reduced access to safe streets and parks for walking. Another is that fitness clubs are expensive and few are found in lower-income neighborhoods. The recent and long-lasting economic crisis in this country is predicted to have profound effects on the average body weight of Americans. The number of homeless in this country is rising with many children and adults living in hotels and cars. As you can imagine neither of these "home spaces" has a kitchen, making it impossible to cook nutritious meals and resulting in increased economically-forced access to cheap, unhealthy foods, such as that at a nearby gas station.
Why is it so difficult for some people to lose weight and for others to gain weight?
One theory is that every person has a "set point" of energy balance. This set point can also be called a fat-stat or lipostat, meaning the brain senses body fatness and triggers changes in energy intake or expenditure to maintain body fatness within a target range. Some believe that this theory provides an explanation as to why after dieting, most people return to their original weight not long after stopping the diet.
It is probably no surprise to you that eating can be triggered by signals other than hunger, even when the body does not need food.
Some of us eat when we are bored, some of us eat when we are stressed. Some people crave certain foods during certain situations. People who tend to eat more when stressed and who then experience chronic stress may overeat and gain weight. Many people respond to external cues such as the time of day ("It's time to eat") or the availability, sight, and taste of food
While each of the energy-yielding nutrients may follow different pathways, once they are converted to Acetyl CoA, then they enter the This cycle occurs in the The TCA cycle uses any substance that can be converted to
TCA cycle (also know as: Kreb's cycle or citric acid cycle). inner compartment of the mitochondria and breaks down acetyl CoA through a series of reactions to carbon dioxide and hydrogens. acetyl CoA: fatty acids, glycerol, glucose, fructose, galactose, amino acids.
Fatty acids are converted directly to acetyl CoA by a chemical reaction which takes off two carbons at a time.
The ATP adds a CoA molecule to the fatty acid chain and two hydrogens are carried off to the electron transport chain. The fatty acid is cleaved two molecules of carbon in the line from the COOH end leaving a fatty acid chain that is now two carbons shorter and a molecule of acetyl CoA. Another CoA molecule is attached the remaining fatty acid and the process starts over. A 16-carbon fatty acid can produce 35 ATP through the hydrogens that are carried to the electron transport chain. Additional ATP will be made when the eight total acetyl CoA molecules produced during fatty acid oxidation hit the TCA cycle: 96 ATP will be generated totaling 129 ATP from one 16-carbon chain. This is why fatty acids produce so much more energy than carbohydrates or amino acids. A glucose only produces 30-32 ATP during the entire metabolic process.
bomb calorimeter
The calorie content of food is measured by a burning foods in a device called a bomb calorimeter. When the food burns, energy is released in the form of heat and the amount of heat given off provides a direct measure of the food's energy value. However, while the bomb calorimeter can accurately measure the direct energy available in a particular food, it actually overestimates the amount of energy the human body can actually extract from it. So scientists have come up with some calculations that help us to more precisely identify the actual amount of energy a human will give from food. It is actually impossible to know exactly how much energy a person expends or how much energy they extract from food (but we are able to estimate
Humans are not designed to eat only once a day.
The stomach prefers to handle periodic amounts of food and since it usually takes about four hours for a meal to leave the stomach, most people eat around every four hours. In general, most people do not feel like eating again if there is still food in the stomach and some people may not feel hungry again for a while even after food has left the stomach
The catabolism of nutrients to energy can be separated into three stages, each containing individual metabolic pathways.
The three stages of nutrient breakdown are the following: Stage 1. Glycolysis for glucose, β-oxidation for fatty acids, or amino acid catabolism Stage 2. Citric Acid Cycle (Kreb's cycle[/TCA Cylce]) Stage 3. Electron Transport Chain and ATP synthesis
calorie
The unit of measurement that defines the energy contained in a energy-yielding nutrient is called a calorie [A calorie is simply the amount of heat energy needed to increase the temperature of 1mL of water by 1 degree Centigrade while a kilocalorie is actually 1000 calories and is actually what we see on food labels and when we calculate our energy needs.
Pyruvate
The use of glucose for energy starts with the breakdown of glucose into two pyruvate molecules is called glycolysis. Pyruvate is basically one-half of a glucose molecule and can be put together with another pyruvate molecule to make glucose.
ATP
This molecule is the energy currency of our cells. It may help to think of ATP as a rechargeable battery—capturing and releasing energy as it does the body's work. Energy is released when a high-energy phosphate bond in ATP is broken. Just as a battery can be used to provide energy for a variety of uses, the energy from ATP can be used to do most of the body's work—contract muscles, transport compounds, make new molecules, and more.
Thermal (heat) energy.
We can say that a cup of hot tea has thermal energy. Thermal energy is defined as the collective, microscopic, kinetic, and potential energy of the molecules within matter. In a cup of tea, the molecules have kinetic energy because they are moving and oscillating, but they also possess potential energy due to their shared attraction to each other.
All cells are in tune to their energy balance.
When energy levels are high cells build molecules, and when energy levels are low catabolic pathways are initiated to make energy.
Thermic Effect of Food (TEF).
When you eat, your gastrointestinal tract begins the work of digesting and absorbing your food. Your intestinal muscles will start moving, nerve cells will signal, fluids will be secreted and so forth. It even requires energy for some nutrients to be brought across the walls of the small intestine (remember active transport?). Digestion and absorption require energy which is called the Thermic Effect of Food (TEF).
During glycolysis,
a phosphate molecule is attached to the glucose molecule and this requires the use of one ATP molecule. Then, the glucose-6-phosphate is rearranged by an enzyme, another phosphate is added, one more ATP molecule is used and makes the compound fructose-1,6-diphosphate (this is where fructose can enter the metabolic pathway). Fructose-1,6-diphosphate breaks in half making two different 3-carbon compounds which go through a series of reactions to turn them into two pyruvate molecules. Each molecule of glucose produces 2 pyruvate, the reaction produces 4 ATP but because two ATP were used up to start the reaction, the net result is 2 ATP molecules. Hydrogens produced by glycolysis are carried off to the electron transport chain where they are used to make more ATP.
The amount of energy needed for any activity (activity thermogenesis and NEAT) is impacted by which of the following factors? [mark all correct answers] a. muscle mass b. body weight c. the activity being performed including its duration, intensity, and frequency. d. the amount of protein consumed prior to the activity
abc correct Right! Good job! The amount of energy needed for any activity depends on these factors: muscle mass, body weight, and activity. The larger the muscle mass and the heavier the weight of the body part being moved, the more energy is expended. Also, the amount of physical activity that can be accomplished (thus influence total caloric expenditure) is dependent on the person's cardiorespiratory fitness which is the ability of the respiratory system to provide oxygen for metabolic processes.
Which of the following may influence someone to ignore the sensations of satiation and satiety? [mark all correct answers] a. Seeing the dessert table after consuming Thanksgiving dinner. b. Smelling popcorn upon entering a movie theater. c. Using a small plate instead of a large plate at a meal. d. Going to your favorite buffet restaurant.
abd correct Right! Good job! We can be prompted to eat even if we're not hungry. You may have just finished up Thanksgiving dinner and couldn't eat another bite of turkey (savory) but could certainly make room for pie (sweet). Different flavors of food affect our ability to detect satiation/satiety. This is why a buffet causes us to eat more than we intend do, if we get tired of one flavor there's plenty more dishes for us to move on to. Smelling or seeing a favorite food (like popcorn) can also cause us to override our body's natural ability to sense when we're full. Using a small plate is actually more likely to cause someone to eat less and pay better attention to their internal signals of fullness.
Fatty acids are converted directly to
acetyl CoA by a chemical reaction which takes off two carbons at a time. One ATP is required to start the process (but it means a loss of 2 ATP due to the way the ATP molecule is broken down). The ATP adds a CoA molecule to the fatty acid chain and two hydrogens are carried off to the electron transport chain. The fatty acid is cleaved two molecules of carbon in the line from the COOH end leaving a fatty acid chain that is now two carbons shorter and a molecule of acetyl CoA. Another CoA molecule is attached the remaining fatty acid and the process starts over.
The Institute of Medicine has devised a formula for calculating your Estimated Energy Requirement (EER). It takes into account your
age, sex, weight, height, and physical activity level (PA).
A kilocalorie (Calorie) is the
amount of heat generated by a particular macronutrient that raises the temperature of 1 kilogram of water 1 degree Celsius. A kilocalorie of energy performs one thousand times more work than a calorie. On the Nutrition Facts panel, the calories within a particular food are expressed as kilocalories, which is commonly denoted as "Calories" with a capital "C" (1 kcal = 1 Calorie = 1,000 calories).
ar
arobic respiration is the most important to producing energy it involves glycolysis, pyruvate oxidation, citric acid cycle and electron transport chain. various fats, carbs and proteins are broken down and enter the cycle to produce energy
catabolism of food molecules begins when food enters the mouth,
as the enzyme salivary amylase initiates the breakdown of carbohydrates. The entire process of digestion converts the large polymers in food to monomers that can be absorbed. Carbohydrates are broken down to monosaccharides, lipids are broken down to fatty acids, and proteins are broken down to amino acids. These monomers are absorbed into the bloodstream either directly, as is the case with monosaccharides and amino acids, or repackaged in intestinal cells for transport by an indirect route through lymphatic vessels, as is the case with fatty acids and other fat-soluble molecules. Once absorbed, blood transports the nutrients to cells.
What fraction of the day's energy expenditure of the average person is represented by the basal metabolism? a. About 1/10th b. Up to 1/2 c. About 2/3rds. d. Over 9/10ths.
c correct Right! Good job! About two-thirds of the energy the average person expends in a day supports the body's basal metabolism.
Which of the following would NOT affect your basal & physical activity energy expenditure? a. The amount of lean body mass you have. b. The amount of adipose tissue you have. c. The amount of carbohydrates you consume. d. Your genetics.
c correct Right! Good job! Carbohydrate intake does not affect basal metabolic rate nor physical activity expenditure.
Which of the following breakfasts would likely delay the onset of hunger (e.g. cause the most satiety) for the next meal? a. 1 cup of fat-free milk with 1 1/2 cup of fruit loops; 1 cup of orange juice; 1 mug black coffee b. 1 cup of oatmeal made with milk; served with 1 tablespoon chopped walnuts, 1 tablespoon brown sugar, and 1 tablespoon margarine mixed in c. 1 16-oz expresso frappucino from Starbucks d. 1 16-oz smoothie made with orange sherbert and cranberry juice
b correct Right! Good job! The oatmeal breakfast contains fiber, protein, and fat. Protein and fiber contribute to satiation ("stop eating") while the fat contributes to satiety ("do not start eating again"). The rest of the meals only contain either protein or fat but not both and are high in simple carbohydrates and/or added sugars which would not contribute to satiety and satiation.
Our energy expenditure consists of three main categories:
basal metabolic rate, thermic effect of food, and physical activity (or activity & non-exercise thermogenesis)
According to the video, why is physical activity alone not the best way to lose weight? [mark all correct answers] a. Most Americans already exercise a lot and are still overweight or obese. b. Calories burned during physical activity do not equal those consumed. c. People tend to eat more when they become physically active. d. Exercise alters thyroid function which in turn, lowers metabolism.
bc correct Right! Good job! According to the video, physical activity does burn calories but in today's high-calorie, high-fat, high-sugar food environment, any gains in calorie expenditure can be quickly erased by a single meal or snack. People also experience an increase in appetite when physically active and weight loss results in a lowered metabolic rate which can further reduce energy expenditure (the thyroid has nothing to do with it). Most Americans do not meet even the minimum 2008 Physical Activity Recommendations of 150 minutes of moderate intensity physical activity per week.
The three components of energy expenditure are: [mark all correct answers] a. Total energy expenditure b. Thermic Effect of Food c. Basal metabolism d. Physical Activity e. Lean body mass
bcd correct Right! Good job! Our energy expenditure consists of three main categories: basal metabolic rate, thermic effect of food, and physical activity (or activity & non-exercise thermogenesis).
Which of the following nutrients are catabolized by the body to provide energy? [mark all correct answers] a. Minerals b. Carbohydrate c. Proteins d. Lipids (fats)
bcd correct Right! Good job! This question also reviews Unit 1, the sections on macro & micronutrients. The energy-yielding nutrients are carbohydrate, fat, and protein and therefore can be catabolized into energy. Minerals cannot be broken down by our body nor are they used directly for energy.
Lactic acid eventually accumulates within the
blood lowering the pH in the body to the point where enzymatic function is interfered with and fatigue sets in. This is a relatively inefficient pathway and relies on glucose from the blood and glycogen from the muscle.
BMR is dependent on
body size, body composition, sex, age, nutritional status, and genetics--because, once again, all of those things influence the amount of lean body mass (LBM) a person has. People with a larger frame size have a higher BMR simply because they have more mass. Muscle tissue burns more calories than fat tissue even while at rest and thus the more muscle mass a person has, the higher their BMR.
Basal metabolic rate (BMR) is the required to maintain the
body temperature, keep the lungs inhaling and exhaling air, the bone marrow making new red blood cells, the heart beating 100,000 times a day, and the kidneys filtering wastes. The BMR supports all the most basic processes of life and accounts for 2/3rd of all of our energy expenditure.
The use of glucose for energy starts with the
breakdown of glucose into two pyruvate molecules is called glycolysis. Pyruvate is basically one-half of a glucose molecule and can be put together with another pyruvate molecule to make glucose.
Intermediates in the catabolic pathways of energy metabolism are sometimes diverted from ATP production and used as
building blocks instead. This happens when a cell is in positive-energy balance. For example, the citric-acid-cycle intermediate, α-ketoglutarate can be anabolically processed to the amino acids glutamate or glutamine if they are required.
The energy released by catabolic pathways powers anabolic pathways ([anabolism]) in the
building of macromolecules such as the proteins RNA and DNA, and even entire new cells and tissues. Anabolic pathways are required to build new tissue, such as muscle, after prolonged exercise or the remodeling of bone tissue, a process involving both catabolic and anabolic pathways. Anabolic pathways also build energy-storage molecules, such as glycogen and triglycerides.
What is the Estimated Energy Requirement (EER) for a 22 year old man weighing 160 pounds who is five foot, ten inches tall and is active (walks about 7 miles per day)? a. less than 2,000 calories b. between 2,000-2,500 calories c. around 3,000 calories d. between 4,000-4,500 calories
c correct Right! Good job! Depending on which formula you use (the one from the lecture or the one from the reading), the answer is around 3,000 kcals give or take.
One of chemical found in our brain is neuropeptide Y, which causes
carbohydrate cravings, initiates eating, decreases energy expenditure, and increases fat storage—all factors favoring a positive energy balance and weight gain.
catabolism and anabolism
catabolism, referring to all metabolic processes involved in molecule breakdown, or catabolic processes release energy anabolism, which includes all metabolic processes involved in building bigger molecules. anabolic processes consume energy
When the stomach is empty it
contracts, producing the characteristic pang and "growl." The stomach's mechanical movements relay neural signals to the hypothalamus, which relays other neural signals to parts of the brain. This results in the conscious feeling of the need to eat. [All those sensations are prompted by our body's physiological response to the lack of nutrients in our bloodstream. Nerve signals and chemical messengers (hormones) both originate from and act on the brain, notably the area called the hypothalamus, to let it know that the body requires sustenance.
The hypothalamus in the brain appears to be the
control center, integrating messages about energy intake, expenditure, and storage from other parts of the brain and from the mouth, GI tract, and liver. Some of these messages influence satiation, which helps control the size of a meal; others influence satiety, which helps determine the frequency of meals.
Lactate can be transported to the liver where it can be
converted back into glucose once the need for energy slows down. Liver enzymes can convert lactate to glucose, but this reaction requires energy. The process of converting lactate from the muscles to glucose in the liver that can be returned to the muscles is known as the Cori cycle.
Fatty acids are clipped off _____carbon molecules at a time to form Acetyl CoA. (this is a numerical answer, enter the numeral only)
correct 2 Right! Good job! Fatty acids are clipped off two carbons at a time to form Acetyl CoA. Review the video on fatty acid oxidation.
A molecule of ______ is the substance that enters the Citric Acid Cycle and is used to form ATP.
correct Acetyl CoA Right! Good job! The TCA cylce starts when 4-carbon oxaloacetate molecule joins with the 2-carbon acetyl CoA to make a 6-carbon compound.
______ metabolism can be carried out without the use of oxygen while _________ metabolism requires the use of oxygen.
correct Anaerobic correct aerobic Right! Good job! Anaerobic = metabolism that can be carried out without the use of oxygen. Any high-intensity, short-term activity uses anaerobic metabolism. Aerobic = metabolism that requires the use of oxygen. Any activity lasting longer than about 120 seconds requires the use of oxygen--the intensity of the activity must decline at this point.
______ is what prompts a person to eat or not eat while__________ is the physical sensation of discomfort brought on by a lack of nutrients in the bloodstream.
correct Appetite correct hunger Right! Good job! Appetite prompts a person to eat (or not to eat) while hunger as an irritating feeling that prompts thoughts of food and motivates them to start eating.
_______ is the signal that tells you to stop eating while ________ is the signal that keeps you from eating again.
correct Satiation correct satiety Right! Good job! As you are eating, food is entering your gastrointestinal system and the hunger signals that prompted you to eat in the first place start to level off. This is called satiation. After you are done with your meal, the sensation of satiety will keep you from eating again. Whereas satiation tells us to "stop eating," satiety reminds us to "not start eating again."
____is the energy expended during sports for fitness exercises while_____ is the energy expended during activities of daily living.
correct activity thermogenesis correct non-exercise activity thermogenesis Right! Good job! Activity thermogenesis is the energy expended during sports for fitness exercises and can vary per person between 100 kcal/day up to 3,000 kcal/day. Non-exercise activity thermogenesis (NEAT) is the energy expended during activities of daily living and even includes chewing gum and fidgeting.
The process of is used to help build muscles.
correct anabolism Right! Good job! Anabolic pathways are required to build new tissue, such as muscle, after prolonged exercise or the remodeling of bone tissue, a process involving both catabolic and anabolic pathways.
The ______ is the amount of energy the body expends to meet its basic physiological needs.
correct basal metabolic rate Right! Good job! . About two-thirds of the energy the average person expends in a day supports the body's basal metabolism. Metabolic activities maintain the body temperature, keep the lungs inhaling and exhaling air, the bone marrow making new red blood cells, the heart beating 100,000 times a day, and the kidneys filtering wastes—in short, they support all the basic processes of life.
Once your muscles and liver have stored all the glycogen possible, any excess glucose will be stored in the form of .
correct fat Right! Good job! Once glycogen stores are maxed out, leftover glucose will be converted into fat.
A(n) ______molecule is necessary to form a derivative of called oxaloacetate which drives the Kreb's cycle (TCA cycle/Citric Acid Cycle).
correct glucose (carbohydrate) Right! Good job! A glucose molecule is necessary to form a derivative of pyruvate called oxaloacetate which drives the Kreb's cycle (TCA cycle/Citric Acid Cycle). Acetyl CoA molecules (made from either fat, carbohydrate, or protein) enter metabolism here. If there is no glucose available to make oxaloacetate, metabolism comes to a grinding halt.
Receptors in the --------- control the sensation of satiation.
correct stomach Right! Good job! During the course of a meal, as food enters the GI tract and hunger diminishes, satiation develops. As receptors in the stomach stretch and hormones such as cholecystokinin become active, the person begins to feel full. The response: satiation occurs and the person stops eating.
The short-term re-synthesis of ATP is facilitated by
creatine kinase, an enzyme which can carry out this reaction without the presence of oxygen. The limiting factor of this reaction is the amount of creatine available in the muscles which is only enough to support an all-out effort of a few seconds such as a power lift or sprint.
Which of the following may increase the caloric cost of the Thermic Effect of Food? a. Consuming regular meals. b. Consuming spicy foods. c. Consuming meals containing carbohydrate and protein. d. All of these increase the energy expended.
d correct Right! Good job! The thermic effect of food is proportional to the food energy taken in and is usually estimated at 10 percent of energy intake. The proportions vary for different foods, however, and are also influenced by factors such as meal size and frequency. In general, the thermic effect of food is greater for high-protein foods than for high-fat foods; presence or absence of a regular eating schedule; & spiciness of foods.
A pound of fat in our bodies roughly equals 3,500 calories of stored energy. If Sarah were to add an additional can of soda (150 calories) to her daily intake without compensation, about how long would it take her to gain a pound of fat? a. less than a week b. around three weeks c. about a month and a half d. the answer isn't that simple, the amount of weight gain depends on multiple factors despite caloric intake
d correct Right! Good job! 3,500 Calories divided by 150 Calories yields 23 days for an additional pound which is around three weeks to gain another pound; however, studies show that, even when people are given the same amount of Calories over their needs and all gain weight, the amount of weight gained doesn't follow the prescribed formula of 3,500 kcals/pound.
Where does the body store glycogen? a. liver and pancreas b. gallbladder and hypothalamus c. brain and stomach d. liver and muscles
d correct Right! Good job! The glycogen stored in the liver is utilized by the whole body when blood glucose levels drop. The glycogen stored in muscles is reserved for physical activity alone.
Which of the following factors has the MOST influence on the body's metabolic rate? a. Age b. Gender c. Amount of fat tissue d. Amount of lean body mass
d correct Right! Good job! The major component of basal metabolism is the amount of lean body mass a person has—that is the amount of tissue in the body that isn't fat. Lean body mass accounts for 80% of the variance between individuals in their basal metabolism.
Which of the following is the definition of metabolism? a. the body's way of breaking down foods into nutrients to prepare them for absorption. b. the process by which digested nutrients are moved into the body through the walls of the digestive tract & carried to body tissues. c. a physical & immunological barrier for a variety of microorganisms, foreign materials, & potential antigens consumed with food or formed from food during its passage. d. the sum total of all the chemical reactions that go on in living cells including all reactions from which the body obtains and expends energy from foods.
d correct Right! Good job! Metabolism = the sum total of all the chemical reactions that go on in living cells including all reactions from which the body obtains and expends energy from foods.
In term of exercise and energy, you cannot maintain high-power, high-intensity moves over a long period. To maintain physical activity over a long period, you must
decrease the intensity of the exercise because the anaerobic system cannot go on for long and the aerobic system simply cannot provide energy fast enough for high intensity moves. As the duration of exercise increases, the greater the reliance on fat, as intensity increases the greater the reliance on carbohydrate.
Not all individuals who take a weight-loss drug lose weight and not all people who smoke are thin. An explanation for these discrepancies is that each individual's genes respond
differently to a specific environment. Alternatively, environmental factors can influence a person's gene profile, which is exemplified by the effects of the prenatal environment on body weight and fatness and disease incidence later in life.
Our body turns food into energy for physical activity through the processes of
digestion, absorption, and metabolism.
energy is the capacity to
do work
Anabolic pathways are regulated by their
end-products, but even more so by the energy state of the cell. When there is ample energy, bigger molecules, such as protein, RNA and DNA, will be built as needed. Alternatively when energy is insufficient, proteins and other molecules will be destroyed and catabolized to release energy.
Activity thermogenesis is the term for the
energy expended during sports for fitness exercises and can vary between 100 kcal/day up to 3,000 kcal/day.
The sum of caloric expenditure is referred to as total
energy expenditure (TEE).
Energy balance is the relationship between If energy in equals energy out, a person has a weight that is considered If a person consumes more than they expend, they become When a person expends more energy than they consume, they
energy intake, energy expenditure, and body weight. "normal". overweight or obese. will lose weight.
Glucose is the preferred
energy source by most tissues, but fatty acids and amino acids can also be catabolized to the cellular energy molecule, ATP.
To ensure cellular efficiency, the metabolic pathways involved in catabolism and anabolism are regulated in concert by
energy status, hormones, and substrate and end-product levels. The concerted regulation of metabolic pathways prevents cells from inefficiently building a molecule when it is already available. Just as it would be inefficient to build a wall at the same time as it is being broken down, it is not metabolically efficient for a cell to synthesize fatty acids and break them down at the same time.
Nonexercise activity thermogenesis (NEAT) is the energy
expended during activities of daily living. For example, a person who has a job that requires them to stand and move around quite a bit (like a restaurant server) has a higher NEAT expenditure of calories than a person who sits at a desk all day.
An elite athlete can train their muscles to burn fat for fuel during high-intensity, short-duration exercise rather than carbohydrate. True False
f correct Right! Good job! In order to produce energy from fat, the body has to use oxygen. This is a slower process than anaerobic glycolysis so is only useful for lower-intensity activity. That is the nature of the universe we live in and no amount of training can change that.
Adenosine Diphosphate is the 'energy currency' in our cells. True False
f correct Right! Good job! Adenosine Diphosphate (ADP) is the result of breaking Adenosine Triphosphate (ATP) to release energy. ADP is the equivalent of a dead battery while ATP is the equivalent of a charged battery.
Protein is the primary fuel used during activities of short duration and high intensity, such as weight lifting. True False
f correct Right! Good job! Protein is not used during physical activity if the body can help it (and only then when physical activity has been going on for quite some time, like during an endurance race). The body uses carbohydrate for activities of short duration and high intensity because it is the only macronutrient that can be burned without oxygen—which is not used during high-intensity, short-duration activities.
It is easier to override the sensation of hunger than it is to override the sensation of satiation and/or satiety. True False
f correct Right! Good job! There's probably a reason that "hungry" and "angry" have been combined together into "hangry". Hunger is an important signal for survival so it is very difficult to ignore while eating a little more—perhaps that what we really need—would actually be protective in a pre-industrialized society.
Amino acids cannot be broken down to provide energy. True False
f correct Right! Good job! Amino acids can be broken down for energy. Most amino acids can be converted into glucose and enter glycolysis or be converted to Acetyl CoA and be used in the Kreb's cycle or converted to fat. A few amino acids enter the Kreb's cycle directly.
While the electron transport chain is the last step of the generation of ATP in metabolism, it also produces the least amount of ATP. True False
f correct Right! Good job! The ETC is able to produce the most ATP out of all the metabolic processes. This is why fat metabolism produces more energy than glucose metabolism--the end result generates much more ATP.
Match the energy-yielding substances to the actual amount of energy metabolized by the human body. a. 9 calories per gram b. 4 calories per gram c. 4 calories per gram d. 7 calories per gram 1. Carbohydrate 2. Protein 3. Fat 4. Alcohol
fat 9 cals protein/carbs 4 cals alcohol 7 cals
The newly made triglycerides are transported to
fat-storing cells called adipocytes. Fat is a better alternative to glycogen for energy storage as it is more compact (per unit of energy) When the body is in positive-energy balance, excess carbohydrates, lipids, and protein are all metabolized to fat.
deamination
first the amine group is taken off of the amino acid. the amino group will be converted to ammonia and then urea. the carbon Skelton that is left of the amino acid will then determine where it enters into the energy producing pathway
The amount of calories you expend on the TEF is directly related to how much
food you eat and is roughly 10% of our daily energy expenditure. For example, if your energy expended is around 2,500 calories per day, you will probably burn around 250 kcals per day in TEF. The amount of calories expended in the TEF depends on the type of food you consumed, whether or not the food was spicy, how often you generally eat, and whether the meal was higher protein vs. fat.
It is a circular pathway because a
four-carbon compound called oxaloacetate begins the first step and is re-synthesized in the last step. Oxaloacetate is critical to the TCA cycle, if there isn't enough, the cycle slows down and cells cannot make enough energy. Oxaloacetate is made from pyruvate or certain amino acids—it cannot be made from fat, therefore, carbohydrate is required for metabolic processes to start.
Energy balance is a careful balancing act between
genetics, environment, energy in, & energy out
During glycolysis, a phosphate molecule is attached to the
glucose molecule and this requires the use of one ATP molecule. Then, the glucose-6-phosphate is rearranged by an enzyme, another phosphate is added, one more ATP molecule is used and makes the compound fructose-1,6-diphosphate (this is where fructose can enter the metabolic pathway). Fructose-1,6-diphosphate breaks in half making two different 3-carbon compounds which go through a series of reactions to turn them into two pyruvate molecules.
Excess glucose that is consumed can be converted to
glycogen, a huge carbohydrate molecule formed from millions of glucose molecules stored in the liver and muscles which provides glucose to the bloodstream, brain, and for physical activity. However, we only have the ability to store so much glycogen (only about 18 hours worth) so anything that is not needed right away for energy gets converted into fat.
Excess glucose that is consumed can be converted to
glycogen, a huge carbohydrate molecule formed from millions of glucose molecules stored in the liver and muscles which provides glucose to the bloodstream, brain, and for physical activity. However, we only have the ability to store so much glycogen (only about 18 hours worth) so anything that is not needed right away for energy gets converted into fat.
how to calculate calories when there is no food box label
go to MyFood-a-pedia, a website maintained by the USDA. Also listed on the Nutrition Facts panel are the amounts of total fat, total carbohydrate, and protein in grams. To calculate the contribution of each macronutrient to the total kilocalories in a serving, multiply the number of grams by the number of kilocalories yielded per gram of nutrient.
Physiological influences on hunger include=
having an empty stomach, gastric contractions (sometimes stimulated by the thought, sight, or smell of food--sensory influences), absence of nutrients in small intestine, hormones detecting absence of nutrients in the bloodstream. Endorphins (the brain's pleasure chemicals) can also influence hunger.
A cell in positive energy balance detects a
high concentration of ATP as well as acetyl-CoA produced by catabolic pathways. In response, catabolism is shut off and the synthesis of triglycerides, which occurs by an anabolic pathway called lipogenesis, is turned on.
food environment can also override signals of
hunger and satiety. Things like large portion sizes, presence of our favorite foods, even just an abundance and/or variety of foods in front of us will keep us eating. Since the previous sentence just described our current food supply, it makes sense that these influences also influence our weight and current obesity crisis.
The breakdown of acetyl CoA releases
hydrogens with their electrons, which are carried by coenzymes made from B vitamins to the electron transport chain.
Acetyl CoA, like pyruvate, has two metabolic options:
if there is enough ATP, acetyl CoA becomes fat to be stored for later energy use (any molecule that can make acetyl CoA [glucose, glycerol, fatty acids, and amino acids] can be used to make fat—however, the pathway is only reversible for fat!) or if there isn't enough ATP, then acetyl CoA enters the TCA cycle. This is the end of glucose metabolism.
video notes on satiety and hunger
in hypothalamus of the brain is where hunger or satiety is experienced. stomach/small intestines empty sends signal nerves that it is empty and that brain will express hunger when high blood glucose levels= increase insulin which will tell brain satiety when low blood glucose level= glucagon incase which will tell the brain huger
This is also how amino acids can be used to make glucose, they are converted
into pyruvate (minus the nitrogen and the "R" side chain) and then another pyruvate is added to make glucose (this process is called gluconeogenesis).
Once pyruvate is formed from glucose, it has two options:
it can enter an anaerobic pathway that provides energy for short, intense bursts of activity or an aerobic indicator pathway that provides energy for longer but less intense activity.
Once pyruvate is formed from glucose, it has two options:
it can enter an anaerobictext annotation indicatortext annotation indicator pathway that provides energy for short, intense bursts of activity or an aerobictext annotation indicatortext annotation indicator pathway that provides energy for longer but less intense activity. If pyruvate enters the anaerobic pathway—that means that no oxygen is involved in the chemical reactions—pyruvate can accept the hydrogens produces during glycolysis (instead of them being carried off to the electron transport chain).
The consequence is a buildup of However, with training athletes can actually increase the number of
lactic acid in the system which is associated with fatigue, pain, and a drop of blood pH. mitochondria in muscle cells which reduces the amount of lactic acid buildup during high-intensity exercise.
the major influence of BMR is the amount of
lean body mass (LBM) a person has—that is the amount of tissue in the body that isn't fat: LBM accounts for 80% of the variance in BMR and all other influences on BMR (like age, gender, body weight), all relate back to the amount of LBM a person has.]
During physical activity, the muscles need extra energy to move, and the heart and lungs need extra energy to deliver nutrients and oxygen and dispose of wastes. The amount of energy you burn during physical activity is due, at least in part, to your
level of metabolic fitness (discussed in Unit 15) which is the ability of the respiratory system to provide oxygen for metabolism.
Of all the organs, the _____ requires the most energy
liver
With the loss of a phosphate group, high-energy ATP (charged battery) becomes
low-energy adenosine diphophate or ADP (used battery). Energy is required when a phosphate group is attached to ADP, making ATP. Just as a used battery needs energy from an electrical outlet to get recharged, ADP (used battery) needs energy from the breakdown of carbohydrate, fat, and protein to make ATP (recharged battery).
Energy is provided by the Energy is locked in Ideally, their energy intakes cover their
macronutrients. chemical bonds in our food, it is released when food is metabolized, & must be supplied regularly to meet the needs of the body. energy expenditures without too much excess.
The amount of energy needed for any activity, whether playing tennis or studying for an exam, depends on three factors:
muscle mass, body weight, and activity (e.g. LBM!). The larger the muscle mass and the heavier the weight of the body part being moved, the more energy is expended. Just like with your basal metabolic rate, the amount of energy you burn during physical activity is related to the amount of lean body mass you have. Therefore, women burn less calories during physical activity than men, older people burn less calories during physical activity than younger people, and so forth. Heavier people burn more calories than lighter people (even if the heavier person weights more because of fat mass).
The first step in amino acid metabolism for energy is to remove the
nitrogen-containing amino group through deamination or transamination. The amino acids can then be converted to pyruvate or acetyl CoA. Carbon skeletons from amino acids can also enter the TCA cycle at varying points depending on their structure. Amino acids used to make pyruvate can be used to make glucose instead, but any made into acetyl CoA cannot be used to make anything other than fat or ATP.
This pathway occurs to a limited extent when we are
not very active, but short-term, high-intensity activity relies heavily on this pathway for energy.
Another theory is referred to as the "settling" point system, which takes into account (more so than the "set-point" theory) the contribution of the
obesogenic environment to weight gain. In this model, the reservoir of body fatness responds to energy intake or energy expenditure, such that if a person is exposed to a greater amount of food, body fatness increases, or if a person watches more television body fatness increases. A major problem with these theories is that they overgeneralize and do not take into account that not all individuals respond in the same way to changes in food intake or energy expenditure. This brings up the importance of the interactions of genes and the environment.
A metabolic pathway is a series
of enzymatic reactions that transforms the starting material (known as a substrate) into intermediates, which are the substrates for the next enzymatic reactions in the pathway, until, finally, an end product is synthesized by the last enzymatic reaction in the pathway. Some metabolic pathways are complex and involve many enzymatic reactions, and others involve only a few chemical reactions.
For each molecule of glucose stored,
one molecule of ATP is used. Therefore, it costs energy to store energy.
A more efficient energy pathway requires the use of
oxygen and as exercise continues further, the aerobic pathway provides the majority of fuel. Oxygen is required for the electron transport chain, without oxygen no more ATP can be made after 60-120 seconds of physical activity. Thereofre, oxygen received through respiration is of vital importance for energy metabolism.
Sedentary behavior is defined as the
participation in the pursuits in which energy expenditure is no more than one-and-one-half times the amount of energy expended while at rest and include sitting, reclining, or lying down while awake. Of course, the sedentary lifestyle of many North Americans contributes to their average energy expenditure in daily life. Simply put, the more you sit, the less energy you expend. A study published in a 2008 issue of the American Journal of Epidemiology reports that 55 percent of Americans spend 7.7 hours in sedentary behavior daily (1).
Glycogen levels do not take long to reach their
physiological limit and when this happens excess glucose will be converted to fat.
Energy is classified as either
potential or kinetic. Potential energy is stored energy, or energy waiting to happen. Kinetic energy is energy in motion
Cognitive influences include the
presence of others (social stimulation), perception of hunger, awareness of fullness (satiety), presence of favorite foods, presence of foods with special meanings, time of day, and the abundance of available food.
Appetite hunger Satiation satiety
prompts a person to eat (or not to eat) as an irritating feeling that prompts thoughts of food and motivates them to start eating is the sensation that occurs during a meal that tells us to "stop eating" sensation that occurs between meals and tells us "do not start eating again"
Aerobic metabolism is limited by the amount of substrate:
protein, glucose, fat; a continuous and adequate supply of O2: (basically, the capacity of the cardiovascular system to supply adequate oxygen) and the availability of coenzymes (why your B vitamin intake is so important!).
anaerobic the pyruvate is converted
to lactic acid which frees the co-enzymes that picked up the hydrogens to return to the glycolysis pathway to pick up more hydrogens. This pathway occurs to a limited extent when we are not very active, but short-term, high-intensity activity relies heavily on this pathway for energy. The consequence is a buildup of lactic acid in the system which is associated with fatigue, pain, and a drop of blood pH. However, with training athletes can actually increase the number of mitochondria in muscle cells which reduces the amount of lactic acid buildup during high-intensity exercise.
unlike glycogen, the body does not store _____along with fat.
water Water weighs a significant amount and increased glycogen stores, which are accompanied by water, would dramatically increase body weight.
The hormone ghrelin is produced by the stomach and serves to signal when the hormone leptin is produced by our fat cells and tells our brain to
we're hungry. reduce food intake and can interfere with storage of fat in our cells.
