Breathing (or ventilation) is the process of moving
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
into and from the
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s to facilitate
gas exchange
Gas exchange is the physical process by which gases move passively by Diffusion#Diffusion vs. bulk flow, diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liqui ...
with the
internal environment
The internal environment (or ''milieu intérieur'' in French) was a concept developed by Claude Bernard, a French physiologist in the 19th century, to describe the interstitial fluid and its physiological capacity to ensure protective stability f ...
, mostly to flush out
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
and bring in
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
.
All
aerobic
Aerobic means "requiring air," in which "air" usually means oxygen.
Aerobic may also refer to
* Aerobic exercise, prolonged exercise of moderate intensity
* Aerobics, a form of aerobic exercise
* Aerobic respiration, the aerobic process of cel ...
creatures need oxygen for
cellular respiration
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...
, which extracts energy from the reaction of
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
with molecules derived from food and produces carbon dioxide as a waste product. Breathing, or "external respiration", brings air into the lungs where gas exchange takes place in the
alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit.
Uses in anatomy and zoology
* Pulmonary alveolus, an air sac in the lungs
** Alveolar cell or pneumocyte
** Alveolar duct
** Alveolar macrophage
* ...
through
diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
. The body's
circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
transports these gases to and from the cells, where "cellular respiration" takes place.
The breathing of all
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s with lungs consists of repetitive cycles of
inhalation
Inhalation (or Inspiration) happens when air or other gases enter the lungs.
Inhalation of air
Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
and
exhalation
Exhalation (or expiration) is the flow of the breath out of an organism. In animals, it is the movement of air from the lungs out of the airways, to the external environment during breathing.
This happens due to elastic properties of the lungs, ...
through a highly branched system of tubes or
airways which lead from the nose to the alveoli.
The number of respiratory cycles per minute is the breathing or
respiratory rate
The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute.
Measurement
The respiratory rate in humans is me ...
, and is one of the four primary
vital signs
Vital signs (also known as vitals) are a group of the four to six most crucial medical signs that indicate the status of the body's vital (life-sustaining) functions. These measurements are taken to help assess the general physical health of a ...
of life. Under normal conditions the breathing depth and rate is automatically, and unconsciously, controlled by several
homeostatic mechanisms which keep the
partial pressure
In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas ...
s of
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
in the arterial blood constant. Keeping the partial pressure of carbon dioxide in the arterial blood unchanged under a wide variety of
physiological
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
circumstances, contributes significantly to
tight control of the pH of the
extracellular fluids
In cell biology, extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 60% (range 45 to 75%) of total body weight; women and the obese typically have a lower ...
(ECF). Over-breathing (
hyperventilation
Hyperventilation is irregular breathing that occurs when the rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce. This leads to hypocapnia, a reduced concentration of carbon dioxide dissolved in the blood. ...
) and under-breathing (
hypoventilation
Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapni ...
), which decrease and increase the arterial partial pressure of carbon dioxide respectively, cause a rise in the pH of ECF in the first case, and a lowering of the pH in the second. Both cause distressing symptoms.
Breathing has other important functions. It provides a mechanism for
speech
Speech is a human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if ...
,
laughter and similar expressions of the emotions. It is also used for
reflexes such as
yawning
A yawn is a reflex lasting 4-7 seconds, and is characterized by a long inspiratory phase with gradual mouth gaping, followed by a brief climax (or acme) with muscle stretching, and a rapid expiratory phase with muscle relaxation. For fish an ...
,
coughing and
sneezing
A sneeze (also known as sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa. A sneeze expels air forcibly from the mouth and ...
. Animals that cannot
thermoregulate
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
by
perspiration
Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals.
Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distr ...
, because they lack sufficient
sweat glands, may lose heat by evaporation through panting.
Mechanics
The
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s are not capable of inflating themselves, and will expand only when there is an increase in the volume of the thoracic cavity.
In humans, as in the other
mammals
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
, this is achieved primarily through the contraction of the
diaphragm, but also by the contraction of the
intercostal muscles
Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size of ...
which pull the
rib cage
The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels.
The sternum, together known as the thoracic cage, is a semi- ...
upwards and outwards as shown in the diagrams on the right.
During forceful inhalation (Figure on the right) the
accessory muscles of inhalation, which connect the ribs and
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
to the
cervical vertebrae
In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
and base of the skull, in many cases through an intermediary attachment to the
clavicles
The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the right ...
, exaggerate the
pump handle and
bucket handle movement
Bucket-handle is a movement of ribs that results in change in transverse diameter of the thorax.
Definition
One of the most important functions of ribs and diaphragm is the change in volume of thorax that helps inspiration
Inspiration, inspire, ...
s (see illustrations on the left), bringing about a greater change in the volume of the chest cavity.
During exhalation (breathing out), at rest, all the muscles of inhalation relax, returning the chest and abdomen to a position called the "resting position", which is determined by their anatomical elasticity.
At this point the lungs contain the
functional residual capacity
Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm ...
of air, which, in the adult human, has a volume of about 2.5–3.0 liters.
During heavy breathing (
hyperpnea
Hyperpnea, or hyperpnoea (forced respiration) is increased volume of air taken during breathing. It can occur with or without an increase in respiration rate. It is characterized by deep breathing. It may be physiologic—as when required by oxyge ...
) as, for instance, during exercise, exhalation is brought about by relaxation of all the muscles of inhalation, (in the same way as at rest), but, in addition, the abdominal muscles, instead of being passive, now contract strongly causing the rib cage to be pulled downwards (front and sides).
This not only decreases the size of the rib cage but also pushes the abdominal organs upwards against the diaphragm which consequently bulges deeply into the thorax. The end-exhalatory lung volume is now less air than the resting "functional residual capacity".
However, in a normal mammal, the lungs cannot be emptied completely. In an adult human, there is always still at least one liter of residual air left in the lungs after maximum exhalation.
Diaphragmatic breathing
Diaphragmatic breathing, abdominal breathing, belly breathing, or deep breathing, is breathing that is done by contracting the diaphragm, a muscle located horizontally between the thoracic cavity and abdominal cavity. Air enters the lungs as the ...
causes the abdomen to rhythmically bulge out and fall back. It is, therefore, often referred to as "abdominal breathing". These terms are often used interchangeably because they describe the same action.
When the accessory muscles of inhalation are activated, especially during
labored breathing Labored respiration or labored breathing is an abnormal respiration characterized by evidence of increased effort to breathe, including the use of accessory muscles of respiration, stridor, grunting, or nasal flaring.
Classification
Labored breat ...
, the clavicles are pulled upwards, as explained above. This external manifestation of the use of the accessory muscles of inhalation is sometimes referred to as
clavicular breathing
Shallow breathing, thoracic breathing, costal breathing or chest breathing is the drawing of minimal Breathing, breath into the lungs, usually by drawing air into the Thoracic cavity, chest area using the intercostal muscles rather than throug ...
, seen especially during
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, cou ...
attacks and in people with
chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...
.
Passage of air
Upper airways
![Nose in cold weather](https://upload.wikimedia.org/wikipedia/commons/5/5d/Nose_in_cold_weather.gif)
Ideally, air is breathed
first out and secondly in through the nose. The
nasal cavities
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal c ...
(between the
nostril
A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...
s and the
pharynx
The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...
) are quite narrow, firstly by being divided in two by the
nasal septum
The nasal septum () separates the left and right airways of the Human nose, nasal cavity, dividing the two nostrils.
It is Depression (kinesiology), depressed by the depressor septi nasi muscle.
Structure
The fleshy external end of the nasal ...
, and secondly by
lateral
Lateral is a geometric term of location which may refer to:
Healthcare
*Lateral (anatomy), an anatomical direction
* Lateral cricoarytenoid muscle
* Lateral release (surgery), a surgical procedure on the side of a kneecap
Phonetics
*Lateral co ...
walls that have several longitudinal folds, or shelves, called
nasal concha
In anatomy, a nasal concha (), plural conchae (), also called a nasal turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals. The conchae are shaped lik ...
e,
thus exposing a large area of
nasal mucous membrane to the air as it is inhaled (and exhaled). This causes the inhaled air to take up moisture from the wet
mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...
, and warmth from the underlying blood vessels, so that the air is very nearly saturated with
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
and is at almost body temperature by the time it reaches the
larynx
The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about ...
.
Part of this moisture and heat is recaptured as the exhaled air moves out over the partially dried-out, cooled mucus in the nasal passages, during exhalation. The sticky mucus also traps much of the particulate matter that is breathed in, preventing it from reaching the lungs.
Lower airways
The anatomy of a typical mammalian respiratory system, below the structures normally listed among the "upper airways" (the nasal cavities, the pharynx, and larynx), is often described as a respiratory tree or tracheobronchial tree (figure on the left). Larger airways give rise to branches that are slightly narrower, but more numerous than the "trunk" airway that gives rise to the branches. The human respiratory tree may consist of, on average, 23 such branchings into progressively smaller airways, while the respiratory tree of the
mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
has up to 13 such branchings. Proximal divisions (those closest to the top of the tree, such as the trachea and bronchi) function mainly to transmit air to the lower airways. Later divisions such as the respiratory bronchioles, alveolar ducts and alveoli are specialized for
gas exchange
Gas exchange is the physical process by which gases move passively by Diffusion#Diffusion vs. bulk flow, diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liqui ...
.
The trachea and the first portions of the main bronchi are outside the lungs. The rest of the "tree" branches within the lungs, and ultimately extends to every part of the
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s.
The alveoli are the blind-ended terminals of the "tree", meaning that any air that enters them has to exit the same way it came. A system such as this creates
dead space
''Dead Space'' is a science fiction/ horror media franchise created by Glen Schofield and Michael Condrey, developed by Visceral Games, and published and owned by Electronic Arts. The franchise's chronology is not presented in a linear format; ...
, a term for the volume of air that fills the airways at the end of inhalation, and is breathed out, unchanged, during the next exhalation, never having reached the alveoli. Similarly, the dead space is filled with alveolar air at the end of exhalation, which is the first air to breathed back into the alveoli during inhalation, before any fresh air which follows after it. The dead space volume of a typical adult human is about 150 ml.
Gas exchange
The primary purpose of breathing is to refresh air in the alveoli so that
gas exchange
Gas exchange is the physical process by which gases move passively by Diffusion#Diffusion vs. bulk flow, diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liqui ...
can take place in the blood. The equilibration of the partial pressures of the gases in the alveolar blood and the alveolar air occurs by
diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
. After exhaling, adult human lungs still contain 2.5–3 L of air, their
functional residual capacity
Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm ...
or FRC. On inhalation, only about 350 mL of new, warm, moistened atmospheric air is brought in and is well mixed with the FRC. Consequently, the gas composition of the FRC changes very little during the breathing cycle. This means that the pulmonary, capillary blood always equilibrates with a relatively constant air composition in the lungs and the diffusion rate with arterial blood gases remains equally constant with each breath. Body tissues are therefore not exposed to large swings in oxygen and carbon dioxide tensions in the blood caused by the breathing cycle, and the
peripheral
A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
and
central chemoreceptors
Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface in the vicinity of the exit of the 9th and 10th cranial nerves, are sensitive to the pH of their environment.
These act to detect the changes in ...
measure only gradual changes in dissolved gases. Thus the homeostatic control of the breathing rate depends only on the partial pressures of oxygen and carbon dioxide in the arterial blood, which then also maintains
a constant pH of the blood.
Control
The rate and depth of breathing is automatically controlled by the
respiratory center
The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal ...
s that receive information from the
peripheral
A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...
and
central chemoreceptors
Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface in the vicinity of the exit of the 9th and 10th cranial nerves, are sensitive to the pH of their environment.
These act to detect the changes in ...
. These
chemoreceptor
A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...
s continuously monitor the partial pressures of carbon dioxide and oxygen in the arterial blood. The first of these sensors are the central chemoreceptors on the surface of the
medulla oblongata of the
brain stem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is co ...
which are particularly sensitive to
pH as well as the partial pressure of carbon dioxide in the blood and
cerebrospinal fluid
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
.
The second group of sensors measure the partial pressure of oxygen in the arterial blood. Together the latter are known as the peripheral chemoreceptors, and are situated in the
aortic and
carotid bodies
The carotid body is a small cluster of chemoreceptor cells, and supporting sustentacular cells. The carotid body is located in the adventitia, in the bifurcation (fork) of the common carotid artery, which runs along both sides of the neck.
The ca ...
.
Information from all of these chemoreceptors is conveyed to the
respiratory center
The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal ...
s in the
pons
The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum.
The pons is also called the pons Varolii ("bridge of Va ...
and
medulla oblongata, which responds to fluctuations in the partial pressures of carbon dioxide and oxygen in the arterial blood by adjusting the rate and depth of breathing, in such a way as to restore the partial pressure of carbon dioxide to 5.3 kPa (40 mm Hg), the pH to 7.4 and, to a lesser extent, the partial pressure of oxygen to 13 kPa (100 mm Hg).
For example,
exercise
Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness.
It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic ...
increases the production of carbon dioxide by the active muscles. This carbon dioxide diffuses into the venous blood and ultimately raises the partial pressure of carbon dioxide in the arterial blood. This is immediately sensed by the carbon dioxide chemoreceptors on the brain stem. The respiratory centers respond to this information by causing the rate and depth of breathing to increase to such an extent that the partial pressures of carbon dioxide and oxygen in the arterial blood return almost immediately to the same levels as at rest. The respiratory centers communicate with the muscles of breathing via motor nerves, of which the
phrenic nerves, which innervate the diaphragm, are probably the most important.
Automatic breathing can be overridden to a limited extent by simple choice, or to facilitate
swimming
Swimming is the self-propulsion of a person through water, or other liquid, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs and the body to achieve hydrodynamic thrust that r ...
,
speech
Speech is a human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if ...
,
singing
Singing is the act of creating musical sounds with the voice. A person who sings is called a singer, artist or vocalist (in jazz and/or popular music). Singers perform music (arias, recitatives, songs, etc.) that can be sung with or without ...
or other
vocal
The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production i ...
training. It is impossible to suppress the urge to breathe to the point of hypoxia but training can increase the ability to hold one's breath.
Conscious breathing practices have been shown to promote relaxation and stress relief but have not been proven to have any other health benefits.
Other automatic breathing control reflexes also exist. Submersion, particularly of the face, in cold water, triggers a response called the
diving reflex
The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It o ...
.
This has the initial result of shutting down the airways against the influx of water. The
metabolic rate
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run ce ...
slows right down. This is coupled with intense vasoconstriction of the arteries to the limbs and abdominal viscera, reserving the oxygen that is in blood and lungs at the beginning of the dive almost exclusively for the heart and the brain.
The diving reflex is an often-used response in animals that routinely need to dive, such as penguins, seals and whales.
It is also more effective in very young infants and children than in adults.
Composition
Inhaled air is by volume 78%
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, 20.95% oxygen and small amounts of other gases including
argon
Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...
, carbon dioxide,
neon
Neon is a chemical element with the symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypton ...
,
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
, and
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
.
The gas exhaled is 4% to 5% by volume of carbon dioxide, about a 100 fold increase over the inhaled amount. The volume of oxygen is reduced by a small amount, 4% to 5%, compared to the oxygen inhaled. The typical composition is:
*5.0–6.3% water vapor
*79% nitrogen
*13.6–16.0% oxygen
*4.0–5.3% carbon dioxide
*1% argon
*
parts per million
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...
(ppm) of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
, from the metabolic activity of microorganisms in the large intestine.
*ppm of
carbon monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
from degradation of
heme
Heme, or haem (pronounced / hi:m/ ), is a precursor to hemoglobin, which is necessary to bind oxygen in the bloodstream. Heme is biosynthesized in both the bone marrow and the liver.
In biochemical terms, heme is a coordination complex "consis ...
proteins.
*1 ppm of
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...
.
* Trace many hundreds of
volatile organic compounds
Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a ...
especially
isoprene
Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals ...
and
acetone
Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour.
Acetone is miscib ...
. The presence of certain organic compounds indicate disease.
In addition to air,
underwater divers
This is a list of underwater divers whose exploits have made them notable.
Underwater divers are people who take part in underwater diving activities – Underwater diving is practiced as part of an occupation, or for recreation, where t ...
practicing
technical diving
Technical diving (also referred to as tec diving or tech diving) is scuba diving that exceeds the agency-specified limits of recreational diving for non-professional purposes. Technical diving may expose the diver to hazards beyond those normally ...
may breathe oxygen-rich, oxygen-depleted or helium-rich
breathing gas
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed h ...
mixtures. Oxygen and
analgesic
An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...
gases are sometimes given to patients under medical care. The atmosphere in
space suit
A space suit or spacesuit is a garment worn to keep a human alive in the harsh environment of outer space, vacuum and temperature extremes. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, ...
s is pure oxygen. However, this is kept at around 20% of Earthbound atmospheric pressure to regulate the rate of inspiration.
Effects of ambient air pressure
Breathing at altitude
Atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
decreases with the height above sea level (altitude) and since the alveoli are open to the outside air through the open airways, the pressure in the lungs also decreases at the same rate with altitude. At altitude, a pressure differential is still required to drive air into and out of the lungs as it is at sea level. The mechanism for breathing at altitude is essentially identical to breathing at sea level but with the following differences:
The atmospheric pressure decreases exponentially with altitude, roughly halving with every rise in altitude.
The composition of atmospheric air is, however, almost constant below 80 km, as a result of the continuous mixing effect of the weather.
The concentration of oxygen in the air (mmols O
2 per liter of air) therefore decreases at the same rate as the atmospheric pressure.
At sea level, where the
ambient pressure
Ambient or Ambiance or Ambience may refer to:
Music and sound
* Ambience (sound recording), also known as atmospheres or backgrounds
* Ambient music, a genre of music that puts an emphasis on tone and atmosphere
* ''Ambient'' (album), by Moby
* ...
is about 100
kPa
KPA may refer to:
* Keele Postgraduate Association, Keele University, UK, formerly Keele Research Association (KRA)
* Kensington (Olympia) station, London, England, National Rail station code
* Kenya Ports Authority
* ''Kiln phosphoric acid'', a ...
, oxygen constitutes 21% of the atmosphere and the partial pressure of oxygen () is 21 kPa (i.e. 21% of 100 kPa). At the summit of
Mount Everest
Mount Everest (; Tibetan: ''Chomolungma'' ; ) is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point. Its elevation (snow heig ...
, , where the total atmospheric pressure is 33.7 kPa, oxygen still constitutes 21% of the atmosphere but its partial pressure is only 7.1 kPa (i.e. 21% of 33.7 kPa = 7.1 kPa).
Therefore, a greater volume of air must be inhaled at altitude than at sea level in order to breathe in the same amount of oxygen in a given period.
During inhalation, air is warmed and saturated with
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
as it passes through the nose and
pharynx
The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struc ...
before it enters the alveoli. The ''saturated'' vapor pressure of water is dependent only on temperature; at a body core temperature of 37 °C it is 6.3 kPa (47.0 mmHg), regardless of any other influences, including altitude. Consequently, at sea level, the ''tracheal'' air (immediately before the inhaled air enters the alveoli) consists of: water vapor ( = 6.3 kPa), nitrogen ( = 74.0 kPa), oxygen ( = 19.7 kPa) and trace amounts of carbon dioxide and other gases, a total of 100 kPa. In dry air, the at sea level is 21.0 kPa, compared to a of 19.7 kPa in the tracheal air (21% of
00 – 6.3= 19.7 kPa). At the summit of Mount Everest tracheal air has a total pressure of 33.7 kPa, of which 6.3 kPa is water vapor, reducing the in the tracheal air to 5.8 kPa (21% of
3.7 – 6.3= 5.8 kPa), beyond what is accounted for by a reduction of atmospheric pressure alone (7.1 kPa).
The
pressure gradient
In atmospheric science, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular location. The p ...
forcing air into the lungs during inhalation is also reduced by altitude. Doubling the volume of the lungs halves the pressure in the lungs at any altitude. Having the sea level air pressure (100 kPa) results in a pressure gradient of 50 kPa but doing the same at 5500 m, where the atmospheric pressure is 50 kPa, a doubling of the volume of the lungs results in a pressure gradient of the only 25 kPa. In practice, because we breathe in a gentle, cyclical manner that generates pressure gradients of only 2–3 kPa, this has little effect on the actual rate of inflow into the lungs and is easily compensated for by breathing slightly deeper. The lower
viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
of air at altitude allows air to flow more easily and this also helps compensate for any loss of pressure gradient.
All of the above effects of low atmospheric pressure on breathing are normally accommodated by increasing the respiratory minute volume (the volume of air breathed in — ''or'' out — per minute), and the mechanism for doing this is automatic. The exact increase required is determined by the
respiratory gases homeostatic mechanism, which regulates the arterial and . This
homeostatic mechanism prioritizes the regulation of the arterial over that of oxygen at sea level. That is to say, at sea level the arterial is maintained at very close to 5.3 kPa (or 40 mmHg) under a wide range of circumstances, at the expense of the arterial , which is allowed to vary within a very wide range of values, before eliciting a corrective ventilatory response. However, when the atmospheric pressure (and therefore the atmospheric ) falls to below 75% of its value at sea level, oxygen
homeostasis
In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
is given priority over carbon dioxide homeostasis. This switch-over occurs at an elevation of about . If this switch occurs relatively abruptly, the hyperventilation at high altitude will cause a severe fall in the arterial with a consequent rise in the
pH of the arterial plasma leading to
respiratory alkalosis
Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide. This condition is one of the four primary dis ...
. This is one contributor to
high altitude sickness. On the other hand, if the switch to oxygen homeostasis is incomplete, then
hypoxia may complicate the clinical picture with potentially fatal results.
Breathing at depth
![Breathing Resistance](https://upload.wikimedia.org/wikipedia/commons/0/0c/Breathing_Resistance.svg)
Pressure increases with the depth of water at the rate of about one
atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
— slightly more than 100 kPa, or one
bar
Bar or BAR may refer to:
Food and drink
* Bar (establishment), selling alcoholic beverages
* Candy bar
* Chocolate bar
Science and technology
* Bar (river morphology), a deposit of sediment
* Bar (tropical cyclone), a layer of cloud
* Bar (u ...
, for every 10 meters. Air breathed underwater by
divers
Diver or divers may refer to:
*Diving (sport), the sport of performing acrobatics while jumping or falling into water
*Practitioner of underwater diving, including:
**scuba diving,
**freediving,
**surface-supplied diving,
**saturation diving, a ...
is at the ambient pressure of the surrounding water and this has a complex range of physiological and biochemical implications. If not properly managed, breathing compressed gasses underwater may lead to several
diving disorders which include
pulmonary barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretching the tissues in tensi ...
,
decompression sickness
Decompression sickness (abbreviated DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompressio ...
,
nitrogen narcosis
Narcosis while diving (also known as nitrogen narcosis, inert gas narcosis, raptures of the deep, Martini effect) is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain g ...
, and
oxygen toxicity
Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen () at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lu ...
. The effects of breathing gasses under pressure are further complicated by the use of one or more
special gas mixtures.
Air is provided by a
diving regulator
A diving regulator is a pressure regulator that controls the pressure of breathing gas for diving. The most commonly recognised application is to reduce pressurized breathing gas to ambient pressure and deliver it to the diver, but there are als ...
, which reduces the high pressure in a
diving cylinder
A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a sc ...
to the ambient pressure. The
breathing performance of regulators is a factor when choosing a suitable regulator for the
type of diving to be undertaken. It is desirable that breathing from a regulator requires low effort even when supplying large amounts of air. It is also recommended that it supplies air smoothly without any sudden changes in resistance while inhaling or exhaling. In the graph, right, note the initial spike in pressure on exhaling to open the exhaust valve and that the initial drop in pressure on inhaling is soon overcome as the
Venturi effect
The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe. The Venturi effect is named after its discoverer, the 18th century Italian physicist, Giovanni Battista V ...
designed into the regulator to allow an easy draw of air. Many regulators have an adjustment to change the ease of inhaling so that breathing is effortless.
Respiratory disorders
Abnormal breathing patterns include
Kussmaul breathing
Kussmaul breathing is a deep and labored breathing pattern often associated with severe metabolic acidosis, particularly diabetic ketoacidosis (DKA) but also kidney failure. It is a form of hyperventilation, which is any breathing pattern that red ...
,
Biot's respiration and
Cheyne–Stokes respiration
Cheyne–Stokes respiration is an abnormal pattern of breathing characterized by progressively deeper, and sometimes faster, breathing followed by a gradual decrease that results in a temporary stop in breathing called an apnea. The pattern repe ...
.
Other breathing disorders include
shortness of breath
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...
(dyspnea),
stridor,
apnea,
sleep apnea
Sleep apnea, also spelled sleep apnoea, is a sleep disorder in which pauses in breathing or periods of shallow breathing during sleep occur more often than normal. Each pause can last for a few seconds to a few minutes and they happen many times ...
(most commonly
obstructive sleep apnea),
mouth breathing
Mouth breathing, medically known as chronic oral ventilation, is long-term breathing through the mouth. It often is caused by an obstruction to breathing through the nose, the innate breathing organ in the human body. Chronic mouth breathing ma ...
, and
snoring
Snoring is the vibration of respiratory structures and the resulting sound due to obstructed air movement during breathing while sleeping. The sound may be soft or loud and unpleasant. Snoring during sleep may be a sign, or first alarm, of ob ...
. Many conditions are associated with obstructed airways. Chronic mouth breathing may be associated with illness.
Hypopnea
Hypopnea is overly shallow breathing or an abnormally low respiratory rate. Hypopnea is defined by some to be less severe than apnea (the complete cessation of breathing), while other researchers have discovered hypopnea to have a "similar if not ...
refers to overly
shallow breathing
Shallow breathing, thoracic breathing, costal breathing or chest breathing is the drawing of minimal Breathing, breath into the lungs, usually by drawing air into the Thoracic cavity, chest area using the intercostal muscles rather than throug ...
;
hyperpnea
Hyperpnea, or hyperpnoea (forced respiration) is increased volume of air taken during breathing. It can occur with or without an increase in respiration rate. It is characterized by deep breathing. It may be physiologic—as when required by oxyge ...
refers to fast and deep breathing brought on by a demand for more oxygen, as for example by exercise. The terms
hypoventilation
Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapni ...
and
hyperventilation
Hyperventilation is irregular breathing that occurs when the rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce. This leads to hypocapnia, a reduced concentration of carbon dioxide dissolved in the blood. ...
also refer to shallow breathing and fast and deep breathing respectively, but under inappropriate circumstances or disease. However, this distinction (between, for instance, hyperpnea and hyperventilation) is not always adhered to, so that these terms are frequently used interchangeably.
A range of
breath test
A breath test is a type of test performed on air generated from the act of exhalation.
Types include:
*Breathalyzer – by far the most common usage of this term relates to the legal breath test to determine if a person is driving under the inf ...
s can be used to diagnose diseases such as dietary intolerances.
A
rhinomanometer uses acoustic technology to examine the air flow through the nasal passages.
Society and culture
The word "spirit" comes from the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''spiritus'', meaning breath. Historically, breath has often been considered in terms of the concept of life force. The
Hebrew Bible
The Hebrew Bible or Tanakh (;["Tanach"](_blank)
''Random House Webster's Unabridged Dictionary''. Hebrew: ''Tān ...
refers to God breathing the breath of life into clay to make Adam a living soul (
nephesh
Nephesh ( ''nép̄eš'') is a Biblical Hebrew word which occurs in the Hebrew Bible. The word refers to the aspects of sentience, and human beings and other animals are both described as being nephesh. Plants, as an example of live organisms, a ...
). It also refers to the breath as returning to God when a mortal dies. The terms spirit,
prana, the Polynesian
mana
According to Melanesian and Polynesian mythology, ''mana'' is a supernatural force that permeates the universe. Anyone or anything can have ''mana''. They believed it to be a cultivation or possession of energy and power, rather than being a ...
, the Hebrew
ruach
In Judaism, the Holy Spirit ( he, רוח הקודש, ''ruach ha-kodesh'') refers to the divine force, quality, and influence of God over the universe or over God's creatures, in given contexts.Maimonides, Moses. Part II, Ch. 45: "The various c ...
and the
psyche
Psyche (''Psyché'' in French) is the Greek term for "soul" (ψυχή).
Psyche may also refer to:
Psychology
* Psyche (psychology), the totality of the human mind, conscious and unconscious
* ''Psyche'', an 1846 book about the unconscious by Car ...
in psychology are related to the concept of breath.
In
T'ai chi
Tai chi (), short for Tai chi ch'üan ( zh, s=太极拳, t=太極拳, first=t, p=Tàijíquán, labels=no), sometimes called " shadowboxing", is an internal Chinese martial art practiced for defense training, health benefits and meditation. ...
,
aerobic exercise
Aerobic exercise (also known as endurance activities, cardio or cardio-respiratory exercise) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process. "Aerobic" is defined as "relating to, inv ...
is combined with breathing exercises to strengthen the
diaphragm muscles, improve posture and make better use of the body's
qi. Different forms of
meditation
Meditation is a practice in which an individual uses a technique – such as mindfulness, or focusing the mind on a particular object, thought, or activity – to train attention and awareness, and achieve a mentally clear and emotionally cal ...
, and
yoga
Yoga (; sa, योग, lit=yoke' or 'union ) is a group of physical, mental, and spiritual practices or disciplines which originated in ancient India and aim to control (yoke) and still the mind, recognizing a detached witness-consciou ...
advocate various breathing methods. A form of
Buddhist meditation
Buddhist meditation is the practice of meditation in Buddhism. The closest words for meditation in the classical languages of Buddhism are '' bhāvanā'' ("mental development") and '' jhāna/dhyāna'' (mental training resulting in a calm and ...
called
anapanasati meaning mindfulness of breath was first introduced by
Buddha
Siddhartha Gautama, most commonly referred to as the Buddha, was a śramaṇa, wandering ascetic and religious teacher who lived in South Asia during the 6th or 5th century BCE and founded Buddhism.
According to Buddhist tradition, he was ...
. Breathing disciplines are incorporated into
meditation
Meditation is a practice in which an individual uses a technique – such as mindfulness, or focusing the mind on a particular object, thought, or activity – to train attention and awareness, and achieve a mentally clear and emotionally cal ...
, certain forms of
yoga
Yoga (; sa, योग, lit=yoke' or 'union ) is a group of physical, mental, and spiritual practices or disciplines which originated in ancient India and aim to control (yoke) and still the mind, recognizing a detached witness-consciou ...
such as
pranayama
Pranayama is the yogic practice of focusing on breath. In Sanskrit, '' prana'' means "vital life force", and ''yama'' means to gain control. In yoga, breath is associated with ''prana'', thus, pranayama is a means to elevate the '' prana'' ''sha ...
, and the
Buteyko method
The Buteyko method or Buteyko Breathing Technique is a form of complementary or alternative physical therapy that proposes the use of breathing exercises primarily as a treatment for asthma and other respiratory conditions.
Buteyko asserts tha ...
as a treatment for asthma and other conditions.
In music, some
wind instrument
A wind instrument is a musical instrument that contains some type of resonator (usually a tube) in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator. The pitc ...
players use a technique called
circular breathing
Circular breathing is a technique used by players of some wind instruments to produce a continuous tone without interruption. It is accomplished by breathing through the nose while simultaneously pushing air through the mouth using air stored ...
.
Singers
Singing is the act of creating musical sounds with the voice. A person who sings is called a singer, artist or vocalist (in jazz and/or popular music). Singers perform music (arias, recitatives, songs, etc.) that can be sung with or without ...
also rely on
breath control.
Common cultural expressions related to breathing include: "to catch my breath", "took my breath away", "inspiration", "to expire", "get my breath back".
Breathing and mood
Certain breathing patterns have a tendency to occur with certain moods. Due to this relationship, practitioners of various disciplines consider that they can encourage the occurrence of a particular mood by adopting the breathing pattern that it most commonly occurs in conjunction with. For instance, and perhaps the most common recommendation is that deeper breathing which utilizes the diaphragm and abdomen more can encourage relaxation.
Practitioners of different disciplines often interpret the importance of breathing regulation and its perceived influence on mood in different ways. Buddhists may consider that it helps precipitate a sense of inner-peace, holistic healers that it encourages an overall state of health and business advisers that it provides relief from work-based stress.
Breathing and physical exercise
During physical exercise, a deeper breathing pattern is adapted to facilitate greater oxygen absorption. An additional reason for the adoption of a deeper breathing pattern is to strengthen the body's core. During the process of deep breathing, the thoracic diaphragm adopts a lower position in the core and this helps to generate intra-abdominal pressure which strengthens the lumbar spine.
Typically, this allows for more powerful physical movements to be performed. As such, it is frequently recommended when lifting heavy weights to take a deep breath or adopt a deeper breathing pattern.
See also
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Further reading
*
*
References
External links
*
*
{{Authority control
Respiration
Reflexes
Human body
Gases
Articles containing video clips