Catabolysis
Encyclopedia
Catabolysis is a biological process
in which the body breaks down fat
and muscle
tissue in order to stay alive. Catabolysis occurs only when there is no longer any source of protein
, carbohydrate
, or vitamin
nourishment feeding all body systems; it is the most severe type of malnutrition
.
and malnourished people. Around 100 000 people die from starvation each day. Also, officials estimate that over 800,000,000 people are "chronically undernourished" and that a child dies from starvation every five seconds.
of human
s catabolysis becomes life-threatening only after 1–2 months from the cessation of nutrition going into the body. After this time, the damage to muscles and organs can be permanent and can also eventually cause death
, if left untreated. Catabolysis is a last resort effort of the body to keep itself — particularly the nervous system
— alive.
Protein stores, especially in muscle tissue, provide the amino acids needed for the process. Amino acids are released into the blood and converted in the liver to alpha keto acids. Alpha keto acids can than be converted to glucose to maintain proper blood sugar levels.
The situation can become dire when one begins to lose muscle
mass; this is a sign that the fat has been expended and the body is now metabolizing
the muscle tissue. This results in muscle atrophy
, a loss of strength and, ultimately, a depletion of muscular tissue completely. Muscle weakness is not necessarily a symptom of catabolysis: the muscles will normally feel fatigued when they are not receiving enough energy or oxygen
. Ultimately, catabolysis can progress to the point of no return when the body's machinery for protein synthesis, itself made of protein, has been degraded to the point that it cannot handle any protein. At this point, attempts to correct the disorder by giving food or protein are futile.
The body has a natural store of fat
(also called adipose
) that stores reserve energy. One can still stay alive while the body breaks down the fatty tissue (hence people wasting
away from starvation).
The person may, during catabolysis, have large amounts of lipid
s, protein
s, and amino acid
s in the bloodstream, due to the muscle fibers and adipose tissues being broken down and sent to the nervous system and brain
. One may also exhibit a fever
, since the body is working hard to transfer the nutrients in the muscles and fat to the blood.
nutrition
, a blood transfusion
, and/or oxygen replenishment. After that, it may be a few weeks to a few months before the person's muscle mass and fat deposits can build themselves up again; there is a possibility that they may never build back up, depending on the severity of the condition.
Biological process
A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....
in which the body breaks down fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
and muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
tissue in order to stay alive. Catabolysis occurs only when there is no longer any source of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
, or vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
nourishment feeding all body systems; it is the most severe type of malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
.
Disease settings
Catabolysis is seen in starvedStarvation
Starvation is a severe deficiency in caloric energy, nutrient and vitamin intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death...
and malnourished people. Around 100 000 people die from starvation each day. Also, officials estimate that over 800,000,000 people are "chronically undernourished" and that a child dies from starvation every five seconds.
Mechanism
Due to the normal metabolic rateBasal metabolic rate
Basal Metabolic Rate , and the closely related resting metabolic rate , is the amount of daily energy expended by humans and other animals at rest. Rest is defined as existing in a neutrally temperate environment while in the post-absorptive state...
of human
Human
Humans are the only living species in the Homo genus...
s catabolysis becomes life-threatening only after 1–2 months from the cessation of nutrition going into the body. After this time, the damage to muscles and organs can be permanent and can also eventually cause death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
, if left untreated. Catabolysis is a last resort effort of the body to keep itself — particularly the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
— alive.
Protein stores, especially in muscle tissue, provide the amino acids needed for the process. Amino acids are released into the blood and converted in the liver to alpha keto acids. Alpha keto acids can than be converted to glucose to maintain proper blood sugar levels.
The situation can become dire when one begins to lose muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
mass; this is a sign that the fat has been expended and the body is now metabolizing
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
the muscle tissue. This results in muscle atrophy
Muscle atrophy
Muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass...
, a loss of strength and, ultimately, a depletion of muscular tissue completely. Muscle weakness is not necessarily a symptom of catabolysis: the muscles will normally feel fatigued when they are not receiving enough energy or oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. Ultimately, catabolysis can progress to the point of no return when the body's machinery for protein synthesis, itself made of protein, has been degraded to the point that it cannot handle any protein. At this point, attempts to correct the disorder by giving food or protein are futile.
The body has a natural store of fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
(also called adipose
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
) that stores reserve energy. One can still stay alive while the body breaks down the fatty tissue (hence people wasting
Wasting
In medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...
away from starvation).
The person may, during catabolysis, have large amounts of lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s, protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, and amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s in the bloodstream, due to the muscle fibers and adipose tissues being broken down and sent to the nervous system and brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
. One may also exhibit a fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, since the body is working hard to transfer the nutrients in the muscles and fat to the blood.
Treatment
While catabolysis can be deadly over time, if the person is given medical treatment early enough, the effects of catabolysis can be reversed. However, the person may require intravenousIntravenous therapy
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...
nutrition
Essential nutrient
An essential nutrient is a nutrient required for normal body functioning that either cannot be synthesized by the body at all, or cannot be synthesized in amounts adequate for good health , and thus must be obtained from a dietary source...
, a blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
, and/or oxygen replenishment. After that, it may be a few weeks to a few months before the person's muscle mass and fat deposits can build themselves up again; there is a possibility that they may never build back up, depending on the severity of the condition.
See also
- WastingWastingIn medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...
- MetabolismMetabolismMetabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
- StarvationStarvationStarvation is a severe deficiency in caloric energy, nutrient and vitamin intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death...
- Superior mesenteric artery syndromeSuperior mesenteric artery syndromeSuperior mesenteric artery syndrome is a very rare, life-threatening gastro-vascular disorder characterized by a compression of the third portion of the duodenum by the abdominal aorta and the overlying superior mesenteric artery...
- ConatusConatusConatus is a term used in early philosophies of psychology and metaphysics to refer to an innate inclination of a thing to continue to exist and enhance itself. This "thing" may be mind, matter or a combination of both...
| Wiktionary - Anorexia NervosaAnorexia nervosaAnorexia nervosa is an eating disorder characterized by refusal to maintain a healthy body weight and an obsessive fear of gaining weight. Although commonly called "anorexia", that term on its own denotes any symptomatic loss of appetite and is not strictly accurate...