Difference between revisions of "Metabolism"

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== External links==
== External links==
* [http://kidshealth.org/parent/general/body_basics/metabolism.html# Metabolism Basics]
* [http://kidshealth.org/parent/general/body_basics/metabolism.html# Metabolism Basics]
* [http://k2.kirtland.cc.mi.us/~balbachl/meta.htm What is Metabolism and Why is it Important?]
* [http://www.mayoclinic.com/health/metabolism/wt00006 Metabolism and weight loss: How you burn calories]
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Revision as of 04:26, 12 May 2010

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Metabolism is the physical and chemical processes that teakes place within the body where molecules are coverted to energy. There are two kinds of reactions: anabolic reactions and catabolic reaction. In anabolic reactions small molecules combined together to form larger molecules like DNA and proteins. In catabolic reactions larger molecules are broken down into smaller molecules to produce energy or building blocks.

Metabolic processes are the means by which the body derives energy and synthesizes the other molecules it needs from the lipid, carbohydrate and protein we eat as food.[1] The substances that are produced or used during metabolic processes are referred to as metabolites.[2] These processes involve a complicated network of enzyme-catalyzed reactions which are helped by mineral and vitamin.[1] Metabolism is essential to digestion, elimination of waste, breathing, circulating blood, proper function of the brain and nerves, and controling body temperature. [3]


Anabolism is also refered to as constructive metabolism. During this process small molecules combined together to form larger molecules which requires the use of ATP. [4] The process of anabolism helps to grow new cells, body tissues, and it also stores energy to be used later. When the smaller molecules form larger molecules they are forming the complex molecules known as carbohydrates, proteins, and fats. [5] Anabolic reactions that take place in our bodies create many different kinds of moleculse. Through anabolism muscle mass is increased and bone is grown. The process builds polymers through monomers. Polymers are large molecules that are made up of small molecules (monomers). For example amino acids are considered monomers while proteins are considered polymers. Anabolic hormones include growth hormones, insulin, testosterone, and estrogen. The growth hormone, which is created in the pituitary gland, helps to stimulate growth through the release of somatomedin. Somatomedin is formed in the liver and causes a person to grow. IGF1 hormones help to stimulate the creation of sulfate and protein. Some of these hormones specifially target an organ to help it grow more rapidly. Insulin is a hormone that is needed to regulate the sugar glucose levels in the blood. The hormone is made in the pancreas by beta cells. The body can't use glucose properly without the use of insulin. [6]


Catabolism is also refered to as destructive metabolism. During catabolism larger organic molecules break down into smaller molecules which occurs through the release of ATP. [4] The energy that is produced through catabolism is needed by all cells in order to function properly. The larger molecules, that are being broken down, are usually carbohydrates and fats. The energy that is created through the break down of these molecules provides the fuel that is necessary for heating the body, anabolism, and the movement of muscels through out the body. As the molecules are being broken down the waste that is produced is expelled from the body through the skin, kidneys, lungs, and intestines. [5] Some catabolic hormones are cortisol, glucagon, adrenalin, and cytokines. Some times refered to as the stress hormone, cortisol, respondes to stress in the body. Cortisol is made by the adrenal cortext, this makes up part of the adrenal gland. Cortisol increases a person's blood sugar and pressure, and also decreases the immune systems responses. Glucagon is a hormone that helps to breakdowm glycogen which causes the blood sugar levels rise. It is a hormone that is made in the pancreas by alpha cells. Glycogen is stored in the liver as a carbohydrate and is used to give a person energy through out their day. Another hormone is adrenalin which is also known as epinephrine. Adrenalin increases a persons heart rate, open the lungs to allow more air, and allows the heart to forcefully contract. Cytokines is a small protein that effects how cells react with each other. Through catabolism the energy that is stored up is used to synthesize enzymes, hormones, and sugars. They also give cells that are involved with cell growth, tissue repair, and reproduction energy. The energy that is in excess is then stored as fat through out the body. Fat cells compared to other cells need barely any energy, contrary to the other cells in the human body that are more active. [6]

Key Biochemicals

Animals, microbes, and plants come from three different kinds of molecules: carbohydrates, fats (or lipids), and amino acids. These three molecules are esential to sustain life. These molecules are the main focus in metabolic reactions when the body is building new cells and tissues. As well as beng a source of energy. Combinding these biochemicals creates polymers like that of proteins and DNA [7]
Proteins are made up of amino acids that are joined together with peptide bonds. They are arranged in a linear chain. Most of the proteins created are catalysts used in different chemical reactions. Some of the other proteins are used to help construct the cytoskeleton. [7]
Lipids are part of the cell membrane as well as a source for energy. Fats covers a lot of compounds that have different fatty acids as well as glycerol. Steroids are also considered to be a major group of lipids, cholesterol being one of them.
Carbohydrates store and transport energy. They are made up of straight chain aldenhydes with a lot of hydrolxyl groups that make up rings or straight chains. [7]
Nucleotides are long chained polymers like DNA and RNA. These specific molecules are essential in the use of gentic information. Nucleosides are created when a nucleobase attaches to a ribose sugar.
Coenzymes have many chemical reactions that can take place, but still many only react with the basic types. The most well known coenzyme is ATP. There isnt a lot of ATP n the cells but because it is always creating more than it never runs out. [7]

Enzymes and Hormones

Moleculse in the digestive system that break down proteins, fats, and carbohydrates are refered to as enzymes. The enzymes break protein down into different amino acids, carbohydrates are broken down into simple sugars like glucose, and fats are broken down into fatty acids. After the molecules are broken down they are absorbed into the blood stream. The blood then transports them into the cells throughout the rest of the body. Once the molecules enter the cells then new enzymes help to regulate how many chemical reactions take place. The energy from these cells is then either released into the body or stored in the liver, muscles, or in fat. [5] A few of the hormones that are secreted by the endocrine system help control a persons metabolism. One of the main hormones is thyroxine which helps to determine how quickly or slowly the chemical reactions should take place within a person. The pancreas produces a hormone that can tell whether a person needs to begin anabolic or catabolic reaction. this usuallly takes place after a meal when the increase in glucose tells the body that it needs insulin. [5] [8]

Metabolism Disorders

Metabolic disorders are usually chracterized by chemical reactions that are irregular within the cells of the body. These disorders are usually caused by the levels of enzymes or hormones that are not normal. If the metabolism is not finctioning properly than the chemicals that are toxis begin to build up in the body and can lead to serious complications. Although not all are gentetic some have found to be inherited from parents or grandparents. One of the enzymes that is needed for the metabolism to function correctly is G6PD (or Glucose-6-phosphate dehydrogenase). G6PD is one of the main enzymes that is used in the break down of carbohydrates and is produced by red blood cells. If there is not enough G6PD in the blood than specific substances that are harmful to the body will destroy the red blood cells. This disorder is known as hemolytic anemia. When red blood cells are destroyed at an early age than a person's bone marrow is unable to keep up with a persons growth and therefore puts them at risk for injury. This condition is refered to as hemolysis. People who have a G6PD deficiency have the following symptoms: [5]

  • pale skin
  • fatigued and tired
  • rapid and shallow breathing
  • abnormal/rapid heartbeat
  • enlarged spleen
  • yellowish tint to eyes

Another metabolism disorder is galactosemia which is found in babies. Babies born with galactosemia don't have the enzymes that are needed to break down the sugar molecules in milk. The sugar is refered to as galactose. The enzyme is secreted from the liver and if there is not enough produced then galactose will start to build up in the babies blood. This build up can lead to major health problems such as liver, brain, kidney, and eye damage. It can be diagnosed within the first couple days after birth. The symptoms include vomiting, swollen liver, and jaundice. Another serious metabolism condition is hyperthyroidism. Hyperthyroidiam is the result of an overative thyroid. If the thyroid secretes too much thyroxine then that person's BMR (or basal metabolic rate) will increase. The major symptoms of hyperthyroidism are:

  • rapid weight loss
  • increased blood pressure
  • increased heart rate
  • swollen neck due to an enlarged thyroid gland
  • enlarged eyes

Hyperthroidism can be controlled as simply as medications, or through surgery. It can also be treated through radiation treatments. [5]


  1. 1.0 1.1 Nutritional and Metabolic Diseases By the National Library of Medicine
  2. Metabolite Medical Encyclopedia. By Medline Plus
  3. Metabolism By Elsas LJ. Approach, Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 216
  4. 4.0 4.1 Catabolism and Anabolism By John W. Kimball, Kimball's Biology Pages
  5. 5.0 5.1 5.2 5.3 5.4 5.5 Metabolism Basics By Steven Dowshen, MD. KidsHealth, The Nemours Foundation
  6. 6.0 6.1 Anabolism (constructive metabolism) and Catabolism (destructive metabolism) By Christian Nordqvist. Endocrinology, 10 Aug 2009
  7. 7.0 7.1 7.2 7.3 Metabolism Key Biochemicals By The Medical News
  8. Metabolism Network of Hormones and Enzymes By Colette Bouchez, WebMD Weight Loss Clinic-Feature

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