The Body’s Fuel Sources
The Body’s Fuel Sources Our ability to run, bicycle, ski, swim, and row hinges on the capacity of the body to extract energy from ingested food. As potential fuel sources, the carbohydrate, fat, and protein in the foods that you eat follow different metabolic paths in the body, but they all ultimately yield water, carbon dioxide, and a chemical energy called adenosine triphosphate (ATP). Think of ATP molecules as high-energy compounds or batteries that store energy. Anytime you need energy—to breathe, to tie your shoes, or to cycle 100 miles (160 km)—your body uses ATP molecules. ATP, in fact, is the only molecule able to provide energy to muscle fibers to power muscle contractions. Creatine phosphate (CP), like ATP, is also stored in small amounts within cells. It’s another high-energy compound that can be rapidly mobilized to help fuel short, explosive efforts. To sustain physical activity, however, cells must constantly replenish both CP and ATP. Our daily food choices resupply the potential energy, or fuel, that the body requires to continue to function normally. This energy takes three forms: carbohydrate, fat, and protein. (See table 2.1, Estimated Energy Stores in Humans.) The body can store some of these fuels in a form that offers muscles an immediate source of energy. Carbohydrates, such as sugar and starch, for example, are readily broken down into glucose, the body’s principal energy source. Glucose can be used immediately as fuel, or can be sent to the liver and muscles and stored as glycogen. During exercise, muscle glycogen is converted back into glucose, which only the muscle fibers can use as fuel. The liver converts its glycogen back into glucose, too; however, it’s released directly into the bloodstream to maintain your blood sugar (blood Continue reading >>
Glucose
Glucose is a carbohydrate, and is the most important simple sugar in human metabolism. Glucose is called a simple sugar or a monosaccharide because it is one of the smallest units which has the characteristics of this class of carbohydrates. Glucose is also sometimes called dextrose. Corn syrup is primarily glucose. Glucose is one of the primary molecules which serve as energy sources for plants and animals. It is found in the sap of plants, and is found in the human bloodstream where it is referred to as "blood sugar". The normal concentration of glucose in the blood is about 0.1%, but it becomes much higher in persons suffering from diabetes. When oxidized in the body in the process called metabolism, glucose produces carbon dioxide, water, and some nitrogen compounds and in the process provides energy which can be used by the cells. The energy yield is about 686 kilocalories (2870 kilojoules) per mole which can be used to do work or help keep the body warm. This energy figure is the change in Gibbs free energy ΔG in the reaction, the measure of the maximum amount of work obtainable from the reaction. As a primary energy source in the body, it requires no digestion and is often provided intravenously to persons in hospitals as a nutrient. Energy from glucose is obtained from the oxidation reaction C6H12O6 + 6O2 --> 6CO2 + 6H2O where a mole of glucose (about 180 grams) reacts with six moles of O2 with an energy yield ΔG = 2870 kJ. The six moles of oxygen at STP would occupy 6 x 22.4L = 134 liters. The energy yield from glucose is often stated as the yield per liter of oxygen, which would be 5.1 kcal per liter or 21.4 kJ per liter. This energy yield could be measured by actually burning the glucose and measuring the energy liberated in a calorimeter. But in living org Continue reading >>
- Exercise and Glucose Metabolism in Persons with Diabetes Mellitus: Perspectives on the Role for Continuous Glucose Monitoring
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
- Exercise and Blood Glucose Levels
How The Body Uses Energy
Those of us who are involved in sports – athletes, coaches and those who work with athletes – understand the importance of fueling the body to maximize energy and performance. It also helps to understand how the body converts energy so that healthy strategies can be used to improve athletic performance. The fundamental law of energy The first law of thermodynamics states that energy cannot be created, but must be transferred or converted from one form to another. Like an automobile only runs on gasoline, the human body runs on only one kind of energy: chemical energy. More specifically, the body can use only one specific form of chemical energy, or fuel, to do biological work – adenosine triphosphate (ATP). ATP – the gas in the tank So, how does the human body make ATP, the only fuel it can convert to energy? Our bodies have three different chemical systems that convert energy. Most everyone knows that we use proteins, carbohydrates and fats for energy. Calories are measurement of a unit of heat or food energy. For example, we can achieve four calories per gram of proteins and carbohydrates, and nine calories per gram from fats. But how do we convert these potential energy substances into ATP? This is where three energy systems come into play. Energy System 1: Ready fuel for immediate energy The Immediate Energy system, or ATP-PC, is the system the body uses to generate immediate energy. The energy source, phosphocreatine (PC), is stored within the tissues of the body. When exercise is done and energy is expended, PC is used to replenish ATP. Basically, the PC functions like a reserve to help rebuild ATP in an almost instantaneous manner. So, in the quadriceps and hamstring muscle groups of an average athlete, a specific quantity of ATP and PC stored within the Continue reading >>
Storage And Use Of Glucose
The glucose produced in photosynthesis may be used in various ways by plants and algae. Storage Glucose is needed by cells for respiration. However, it is not produced at night when it is too dark for photosynthesis to happen. Plants and algae store glucose as insoluble products. These include: Use Some glucose is used for respiration to release energy. Some is used to produce: Plants also need nitrates to make proteins. These are absorbed from the soil as nitrate ions. Three factors can limit the speed of photosynthesis: light intensity, carbon dioxide concentration and temperature. Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis. Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide. If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot. If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above. In practice, any one of these factors could limit the rate of photosynthesis. Farmers can use their knowledge of factors limiting the rate of photosynthesis to increase crop yields. This is particularly true in greenhouses, where the conditions are more easily controlled than in the open air outside: The use of artificial light allows photosynthesis to continue beyond daylight hours. Bright lights also provide a higher-than-normal light intensity. The use of artificial heating allows photosynthesis to continue at an increased rate. The use of additional carbon dioxide released i Continue reading >>
- Exercise and Glucose Metabolism in Persons with Diabetes Mellitus: Perspectives on the Role for Continuous Glucose Monitoring
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
- Statin use and risk of diabetes mellitus
Three Ways The Body Uses Energy
The human body uses food as an energy source to carry out various tasks. Our bodies can use a number of foods to produce energy, but the main source of fuel is sugars such as glucose. The process of using oxygen and glucose to produce energy is known as respiration. Respiration Respiration is the process the body uses to convert glucose to energy. It occurs in every living cell within the body, and the simplified formula is: Glucose + Oxygen produces Energy + Carbon dioxide + Water Respiration is the reason we breath in oxygen and breath out carbon dioxide. Muscle Contraction One of the defining features of animals is the ability to move and manipulate the environment. This is due to muscular tissue. Muscle consists of millions of fibres, which when contracted produce movement. The process of muscular contraction uses large amounts of energy and is responsible for the heart beating (the heart is a muscle), breathing, and skeletal movement. Temperature Regulation The body has many chemical processes going on at any one time. These chemical processes are carried out by biological catalysts known as enzymes. Enzymes can only help a chemical reaction take place if they are at a specific temperature. The body regulates temperature to keep enzymes working. This temperature regulation uses energy. An example is sweating. When the body becomes too hot, energy is used to secrete sweat from glands on the skin, cooling the body. Water Regulation The human body largely consists of water, which has to be regulated to ensure cells don`t shrivel up or rupture. The regulation of water is performed by a hormone known as anti-diuretic hormone (ADH). When water levels in the body become too high, the hypothalamus gland detects this and secretes ADH. The ADH stimulates the kidneys to absor Continue reading >>
Everything You Need To Know About Glucose
You may know glucose by another name: blood sugar. Glucose is key to keeping the mechanisms of the body in top working order. When our glucose levels are optimal, it often goes unnoticed. But when they stray from recommended boundaries, you’ll notice the unhealthy effect it has on normal functioning. So what is glucose, exactly? It’s the simplest of the carbohydrates, making it a monosaccharide. This means it has one sugar. It’s not alone. Other monosaccharides include fructose, galactose, and ribose. Along with fat, glucose is one of the body’s preferred sources of fuel in the form of carbohydrates. People get glucose from bread, fruits, vegetables, and dairy products. You need food to create the energy that helps keep you alive. While glucose is important, like with so many things, it’s best in moderation. Glucose levels that are unhealthy or out of control can have permanent and serious effects. Our body processes glucose multiple times a day, ideally. When we eat, our body immediately starts working to process glucose. Enzymes start the breakdown process with help from the pancreas. The pancreas, which produces hormones including insulin, is an integral part of how our body deals with glucose. When we eat, our body tips the pancreas off that it needs to release insulin to deal with the rising blood sugar level. Some people, however, can’t rely on their pancreas to jump in and do the work it’s supposed to do. One way diabetes occurs is when the pancreas doesn’t produce insulin in the way it should. In this case, people need outside help (insulin injections) to process and regulate glucose in the body. Another cause of diabetes is insulin resistance, where the liver doesn’t recognize insulin that’s in the body and continues to make inappropriate am Continue reading >>
What Is The Function Of Glucose In The Human Body?
What Is the Function of Glucose in the Human Body? Glucose provides a source of energy for the human body. Experts from Georgia State University say glucose is the most important simple sugar used for human metabolism. The human body converts carbohydrates into glucose. Carbohydrates are found in foods such as pasta, fruit, rice, vegetables and baked goods. In healthy people, a hormone called insulin helps glucose enter the cells. People with diabetes do not make insulin or are unable to use insulin to carry glucose into their cells. This allows glucose to build up in the bloodstream, a condition known as high blood sugar. If glucose does not enter the cells, the body is unable to use it for energy, even if there is a large amount of glucose available. In humans, glucose is converted to adenosine triphosphate via the process of cellular respiration. This process is made up of four steps called glycolysis, the transition reaction, the Krebs cycle and the electron transport chain. During glycolysis, glucose is converted to pyruvic acid. Every molecule of glucose used during this stage produces two ATP, according to the IUPUI Department of Biology. The pyruvic acid is converted to a substance called acetyl CoA during the transition reaction. No ATP is produced during this stage of cellular respiration. The hydrogen atoms are stripped away from the acetyl CoA during the Krebs cycle. This stage of cellular respiration produces four ATP. Finally, the electrons from the hydrogen atoms are shuttled into the electron transport chain. The end result is an additional 32 ATP for every glucose. Continue reading >>
What Is Glucose?
Glucose comes from the Greek word for "sweet." It's a type of sugar you get from foods you eat, and your body uses it for energy. As it travels through your bloodstream to your cells, it's called blood glucose or blood sugar. Insulin is a hormone that moves glucose from your blood into the cells for energy and storage. People with diabetes have higher-than-normal levels in their blood. Either they don't have enough insulin to move it through or their cells don't respond to insulin as well as they should. High blood glucose for a long period of time can damage your kidneys, eyes, and other organs. How Your Body Makes Glucose It mainly comes from foods rich in carbohydrates, like bread, potatoes, and fruit. As you eat, food travels down your esophagus to your stomach. There, acids and enzymes break it down into tiny pieces. During that process, glucose is released. It goes into your intestines where it's absorbed. From there, it passes into your bloodstream. Once in the blood, insulin helps glucose get to your cells. Energy and Storage Your body is designed to keep the level of glucose in your blood constant. Beta cells in your pancreas monitor your blood sugar level every few seconds. When your blood glucose rises after you eat, the beta cells release insulin into your bloodstream. Insulin acts like a key, unlocking muscle, fat, and liver cells so glucose can get inside them. Most of the cells in your body use glucose along with amino acids (the building blocks of protein) and fats for energy. But it's the main source of fuel for your brain. Nerve cells and chemical messengers there need it to help them process information. Without it, your brain wouldn't be able to work well. After your body has used the energy it needs, the leftover glucose is stored in little bundles Continue reading >>
- Exercise and Glucose Metabolism in Persons with Diabetes Mellitus: Perspectives on the Role for Continuous Glucose Monitoring
- Postprandial Blood Glucose Is a Stronger Predictor of Cardiovascular Events Than Fasting Blood Glucose in Type 2 Diabetes Mellitus, Particularly in Women: Lessons from the San Luigi Gonzaga Diabetes Study
- Exercise and Blood Glucose Levels
Why Do Body Cells Need Glucose?
Glucose is the most abundant sugar in humam body and simplest monosacchride with molecular formula C6H12O6. Glucose is the ubiquitous fuel in biology. It is used as an energy source through aerobic respiration,anaerobic respiration and fermentation. Glucose is the key source of energy providing 3.75kilocalories of foodenergy per gram. Through glycolysis, citric acid cycle and oxidative phosphorylation glucose is oxidized to yield CO2 and H2O which yields energy in the form of ATP. It is the only source of fuel for brain. It’s level in the body is maintained by insulin when the concentration of glucose is high in blood due to carbohydrate rich diet insulin acts by reducing it’s level by storing it as glycogen in liver and function as secondary long term energy storage and when it’s concentration is low in blood glucagon acts by breaking the reservoir of glycogen back into glucose to be utilised by body as a source of energy. In anaerobic respiration(in the absence of oxygen) one glucose molecule produces a net gain of 2ATP molecules[4ATPs are produced during glycolysis by substrate level phosphorylation(formation of ATP/GTP by direct transfer pf phosphoryl group to ADP/GDP)] In aerobic respiration is much more profitable as it produces maximum of 30–32ATP through oxidative phosphorylation. Continue reading >>
Dynamic Adaptation Of Nutrient Utilization In Humans
Most cells use glucose for ATP synthesis, but there are other fuel molecules equally important for maintaining the body's equilibrium or homeostasis. Indeed, although the oxidation pathways of fatty acids, amino acids, and glucose begin differently, these mechanisms ultimately converge onto a common pathway, the TCA cycle, occurring within the mitochondria (Figure 1). As mentioned earlier, the ATP yield obtained from lipid oxidation is over twice the amount obtained from carbohydrates and amino acids. So why don't all cells simply use lipids as fuel? In fact, many different cells do oxidize fatty acids for ATP production (Figure 2). Between meals, cardiac muscle cells meet 90% of their ATP demands by oxidizing fatty acids. Although these proportions may fall to about 60% depending on the nutritional status and the intensity of contractions, fatty acids may be considered the major fuel consumed by cardiac muscle. Skeletal muscle cells also oxidize lipids. Indeed, fatty acids are the main source of energy in skeletal muscle during rest and mild-intensity exercise. As exercise intensity increases, glucose oxidation surpasses fatty acid oxidation. Other secondary factors that influence the substrate of choice for muscle include exercise duration, gender, and training status. Another tissue that utilizes fatty acids in high amount is adipose tissue. Since adipose tissue is the storehouse of body fat, one might conclude that, during fasting, the source of fatty acids for adipose tissue cells is their own stock. Skeletal muscle and adipose tissue cells also utilize glucose in significant proportions, but only at the absorptive stage - that is, right after a regular meal. Other organs that use primarily fatty acid oxidation are the kidney and the liver. The cortex cells of the Continue reading >>
How Do Our Bodies Use Carbohydrates?
What are the carbohydrates used for in our body? originally appeared on Quora : the place to gain and share knowledge, empowering people to learn from others and better understand the world. Answer by Ray Schilling , M.D., author of Healing Gone Wrong, Healing Done Right , on Quora : Carbs are varied. There are complex carbohydrates that are absorbed slowly and you hardly get an insulin reaction. On the other end of the spectrum there are refined carbs like sugar, which are rapidly absorbed in the gut and to which the body reacts swiftly with an insulin reaction to lower high blood sugars. Generally speaking, all carbs are broken down into glucose and absorbed in the gut. Glucose is the fuel that is metabolized inside the cells in the mitochondria to give us energy. This is particularly important in the brain, which lives solely by glucose as the energy supply, but our muscles, our heart, our liver and kidneys are all very rich in mitochondria for the metabolism of glucose. There is a dark side to refined carbs that we need to know about: when all our glucose storage spaces in the liver and the muscles are full (glycogen is the storage form of glucose), then the liver starts processing glucose. With our sugar consumption having spiraled upwards in the last 183 years, this surplus sugar metabolism is causing more and more problems. The liver produces triglycerides from the extra sugar and LDL cholesterol, the bad cholesterol. This causes the hardening of arteries and causes heart attacks, strokes and high blood pressure. We need to come to our senses and cut out processed foods (which has extra sugar in it), switch to a Mediterranean diet and only consume complex carbs, contained in legumes, vegetables and fruit. It is also recommendable to cut out starchy foods with a Continue reading >>
What Is Insulin?
Insulin is a hormone made by the pancreas that allows your body to use sugar (glucose) from carbohydrates in the food that you eat for energy or to store glucose for future use. Insulin helps keeps your blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia). The cells in your body need sugar for energy. However, sugar cannot go into most of your cells directly. After you eat food and your blood sugar level rises, cells in your pancreas (known as beta cells) are signaled to release insulin into your bloodstream. Insulin then attaches to and signals cells to absorb sugar from the bloodstream. Insulin is often described as a “key,” which unlocks the cell to allow sugar to enter the cell and be used for energy. If you have more sugar in your body than it needs, insulin helps store the sugar in your liver and releases it when your blood sugar level is low or if you need more sugar, such as in between meals or during physical activity. Therefore, insulin helps balance out blood sugar levels and keeps them in a normal range. As blood sugar levels rise, the pancreas secretes more insulin. If your body does not produce enough insulin or your cells are resistant to the effects of insulin, you may develop hyperglycemia (high blood sugar), which can cause long-term complications if the blood sugar levels stay elevated for long periods of time. Insulin Treatment for Diabetes People with type 1 diabetes cannot make insulin because the beta cells in their pancreas are damaged or destroyed. Therefore, these people will need insulin injections to allow their body to process glucose and avoid complications from hyperglycemia. People with type 2 diabetes do not respond well or are resistant to insulin. They may need insulin shots to help them better process Continue reading >>
How Our Bodies Turn Food Into Energy
All parts of the body (muscles, brain, heart, and liver) need energy to work. This energy comes from the food we eat. Our bodies digest the food we eat by mixing it with fluids (acids and enzymes) in the stomach. When the stomach digests food, the carbohydrate (sugars and starches) in the food breaks down into another type of sugar, called glucose. The stomach and small intestines absorb the glucose and then release it into the bloodstream. Once in the bloodstream, glucose can be used immediately for energy or stored in our bodies, to be used later. However, our bodies need insulin in order to use or store glucose for energy. Without insulin, glucose stays in the bloodstream, keeping blood sugar levels high. Insulin is a hormone made by beta cells in the pancreas. Beta cells are very sensitive to the amount of glucose in the bloodstream. Normally beta cells check the blood's glucose level every few seconds and sense when they need to speed up or slow down the amount of insulin they're making and releasing. When someone eats something high in carbohydrates, like a piece of bread, the glucose level in the blood rises and the beta cells trigger the pancreas to release more insulin into the bloodstream. When insulin is released from the pancreas, it travels through the bloodstream to the body's cells and tells the cell doors to open up to let the glucose in. Once inside, the cells convert glucose into energy to use right then or store it to use later. As glucose moves from the bloodstream into the cells, blood sugar levels start to drop. The beta cells in the pancreas can tell this is happening, so they slow down the amount of insulin they're making. At the same time, the pancreas slows down the amount of insulin that it's releasing into the bloodstream. When this happens, Continue reading >>
Insulin's Role In The Human Body
Insulin is a hormone produced by the pancreas that has a number of important functions in the human body, particularly in the control of blood glucose levels and preventing hyperglycemia. It also has an effect on several other areas of the body, including the synthesis of lipids and regulation of enzymatic activity. Insulin and Metabolic Processes The most important role of insulin in the human body is its interaction with glucose to allow the cells of the body to use glucose as energy. The pancreas usually produces more insulin in response to a spike in blood sugar level, for example after eating a meal high in energy. This is because the insulin acts as a “key” to open up the cells in the body and allows the glucose to be used as an energy source. Additionally, when there is excess glucose in the bloodstream, known as hyperglycemia, insulin encourages the storage of glucose as glycogen in the liver, muscle and fat cells. These stores can then be used at a later date when energy requirements are higher. As a result of this, there is less insulin in the bloodstream, and normal blood glucose levels are restored. Insulin stimulates the synthesis of glycogen in the liver, but when the liver is saturated with glycogen, an alternative pathway takes over. This involves the uptake of additional glucose into adipose tissue, leading to the synthesis of lipoproteins. Results Without Insulin In the absence of insulin, the body is not able to utilize the glucose as energy in the cells. As a result, the glucose remains in the bloodstream and can lead to high blood sugar, known as hyperglycemia. Chronic hyperglycemia is characteristic of diabetes mellitus and, if untreated, is associated with severe complications, such as damage to the nervous system, eyes, kidneys and extremitie Continue reading >>
How The Body Uses Carbohydrates, Proteins, And Fats
How the Body Uses Carbohydrates, Proteins, and Fats The human body is remarkably adept at making do with whatever type of food is available. Our ability to survive on a variety of diets has been a vital adaptation for a species that evolved under conditions where food sources were scarce and unpredictable. Imagine if you had to depend on successfully hunting a woolly mammoth or stumbling upon a berry bush for sustenance! Today, calories are mostly cheap and plentifulperhaps too much so. Understanding what the basic macronutrients have to offer can help us make better choices when it comes to our own diets. From the moment a bite of food enters the mouth, each morsel of nutrition within starts to be broken down for use by the body. So begins the process of metabolism, the series of chemical reactions that transform food into components that can be used for the body's basic processes. Proteins, carbohydrates , and fats move along intersecting sets of metabolic pathways that are unique to each major nutrient. Fundamentallyif all three nutrients are abundant in the dietcarbohydrates and fats will be used primarily for energy while proteins provide the raw materials for making hormones, muscle, and other essential biological equipment. Proteins in food are broken down into pieces (called amino acids) that are then used to build new proteins with specific functions, such as catalyzing chemical reactions, facilitating communication between different cells, or transporting biological molecules from here to there. When there is a shortage of fats or carbohydrates, proteins can also yield energy. Fats typically provide more than half of the body's energy needs. Fat from food is broken down into fatty acids, which can travel in the blood and be captured by hungry cells. Fatty aci Continue reading >>
