Metabolism is the name given to the set of all the reactions that take place in the body.
These numerous reactions are regulated and catalyzed by enzymes.
Among the functions of metabolism, we can highlight the obtaining of energy.
There are two major metabolic processes, catabolism, and anabolism. In the following, we will talk more about metabolism, its importance, and its operations.
What Is Metabolism?
Metabolism is the
collection of all the reactions in the body to control material and energy
resources to meet its structural and energy needs.
These reactions get catalyzed by various enzymes and have the following objectives:
- Obtaining chemical energy.
- Converting nutrient molecules to macronutrient
precursors such as amino acids, nitrogenous bases, sugars, and fatty
acids.
- Producing macromolecules such as proteins, nucleic
acids, polysaccharides, and lipids.
- Synthesizing and degrading specialized biomolecules.
Types of Metabolism
The reactions of
metabolism come together in two metabolic pathways, catabolism, and anabolism.
Catabolism
Also called the
degradative pathway, is a continuous process and comprises the reactions that
promote complex molecules' degradation into more specific products.
The organism uses the
energy released by the catabolic pathway to carry out the most diverse
activities.
The catabolic pathways
can be classified as aerobic metabolism and anaerobic metabolism, as we will
see below:
Aerobic metabolism: Reactions occur
in the presence of oxygen, which, in respiratory chains, functions as the final
electron acceptor and combines with hydrogen to form water.
In aerobic metabolism,
the end products of the reactions are water and carbon dioxide.
Anaerobic metabolism: The reactions
occur in the absence of oxygen. The final electron acceptors in this type of
metabolism can be nitrate ions, sulfate, fumarate, and ammonia.
Among these reactions'
final products are lactate (lactic fermentation) and ethanol (alcoholic
fermentation).
The final balance of
energy produced in aerobic metabolism is more significant than in anaerobic
metabolism.
Anabolism
Also called the
biosynthetic pathway, comprises the reactions in which complex molecules become
produced from simple molecules. For the reactions to occur, energy consumption
is necessary.
Anabolism is
essential, for example, for the body's growth and maintenance process.
The metabolic pathways
are irreversible, distinct, yet interconnected. The energy released in the
degradation of molecules (catabolic or degradative path) is used to synthesize
biomolecules (anabolic or biosynthetic pathway) and other reactions.
The metabolic pathways are irreversible, distinct, yet interconnected. The energy released in the degradation of molecules (catabolic or degradative path) is used to synthesize biomolecules (anabolic or biosynthetic pathway) and other reactions.
Energy Metabolism
Energy metabolism
comprises the set of reactions that involve energy exchange in the body.
For these reactions to
occur, energy substrates are needed, which come from food. The primary sources
of energy used in these reactions are carbohydrates, lipids, and proteins.
In the digestion
process, food is broken down into smaller molecules and absorbed into the
bloodstream.
From the bloodstream,
they are moved to various tissues, and in the cells, they are oxidized, thus
producing energy.
For there to be a
complete degradation of the molecules obtained by eating into CO2 and H2O, with
increased energy production, the presence of oxygen is required.
The excess of these
substrates, when not used, can be stored in the most diverse forms by the
organism.
Carbohydrates, for
example, can be stored in the form of glycogen in the liver and be used when
the body does not consume a sufficient amount of this substance for energy
production.
In addition to
providing energy, food provides the precursors for synthesizing biomolecules
such as essential amino acids.
Energy production is
responsible for the release of heat, which will be used to maintain body
temperature and ATP production (adenosine triphosphate).
ATP is a molecule that participates in numerous metabolic processes, providing energy for their realization. The release of energy occurs by converting ATP into ADP (adenosine diphosphate) and inorganic phosphate.
How Metabolism Works
Metabolism is how
carbohydrates, proteins, fats, and other substances are transformed in the
organism.
This transformation
produces heat, carbon dioxide, water, and residues to have the energy to carry
out chemical changes essential for the organism and develop the muscular
activity.
The metabolic activity comprises the absorption, transformation, and elimination of substances that allow the cells to fulfill their energetic or synthesis functions. Two phases constitute this activity.
Basal Metabolic Rate
(BMR)
Basal Metabolic Rate
is the minimum energy required by a cell to exist and carry out essential
functions, such as respiration.
This energy
expenditure depends on several factors such as age, sex, height, amount of
muscular energy, among others, and is calculated in kilocalories/day.
The Food and
Agriculture Organization of the United Nations proposes to calculate the basal
metabolic rate (BMR) as follows:
For ages 10-18 years:
- Females: 7.4 x weight in kilograms + 428 x height in
meters + 572.
- Males: 16.6 x weight in kilograms + 77 x height in
meters + 572
The basal metabolic rate can also be calculated through the Harris-Benedict equations:
- Male: 66.4730 + ((13.751 x mass (kg)) + (5.0033 x
height (cm)) - ((6.75 x age (years))
- Female: 655.1 + ((9.463 x mass (kg)) + (1.8 x height (cm)) - ((4.6756 x age (years))
The result of these equations will indicate the daily energy expenditure.
Summary About
Metabolism
Metabolism is the set of all the reactions that occur in the body, controlling the material and energy resources to meet its structural and energy needs:
1. The reactions of metabolism are grouped into two metabolic pathways, catabolism, and anabolism.
2. Catabolism degrades complex molecules into more straightforward products, with the release of energy.
3. Catabolism can be divided into aerobic and anaerobic metabolism.
4. Anabolism synthesizes complex molecules from simple molecules.
5. The energy metabolism comprises the set of reactions involving energy exchanges in the body.
6. Energy production is responsible for the release of heat and production of ATP.
7. The basal metabolism is the amount of energy that the body needs to perform its various functions.