Inhalation
Encyclopedia
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli.
Inhalation begins with the onset of contraction of the diaphragm, which results in expansion of the intrapleural space and an increase in negative pressure according to Boyle's Law
. This negative pressure generates airflow because of the pressure difference between the atmosphere and alveolus. Air enters, inflating the lung through either the nose
or the mouth
into the pharynx
(throat
) and trachea
before entering the alveoli.
Other muscles that can be involved in inhalation include:
on X-ray, a reduction in lung markings and depression of the diaphragm. It may occur in partial obstruction of a large airway, as in e.g. congenital lobar emphysema, bronchial atresia
and mucous plugs in asthma
.
It causes one form of overexpansion of the lung. Overexpansion, however, can also be caused by increase in lung mass itself.
Inhalation begins with the onset of contraction of the diaphragm, which results in expansion of the intrapleural space and an increase in negative pressure according to Boyle's Law
Boyle's law
Boyle's law is one of many gas laws and a special case of the ideal gas law. Boyle's law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system...
. This negative pressure generates airflow because of the pressure difference between the atmosphere and alveolus. Air enters, inflating the lung through either the nose
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
or the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
into the pharynx
Pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
(throat
Throat
In vertebrate anatomy, the throat is the anterior part of the neck, in front of the vertebral column. It consists of the pharynx and larynx...
) and trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
before entering the alveoli.
Other muscles that can be involved in inhalation include:
- External intercostal muscles
- Scalene musclesScalene musclesThe scalene muscles are a group of three pairs of muscles in the lateral neck, namely the scalenus anterior, scalenus medius, and scalenus posterior.They are innervated by the spinal nerves C4-C6....
- Sternocleidomastoid muscleSternocleidomastoid muscleIn human anatomy, the sternocleidomastoid muscle , also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the anterior portion of the neck...
- Trapezius muscleTrapezius muscleIn human anatomy, the trapezius is a large superficial muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula...
Hyperaeration
Hyperaeration or hyperinflation is where the lung volume is abnormally increased, with increased filling of the alveoli. This results in an increased radiolucencyRadiodensity
Radiodensity refers to the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or "transradiancy" to X-ray photons...
on X-ray, a reduction in lung markings and depression of the diaphragm. It may occur in partial obstruction of a large airway, as in e.g. congenital lobar emphysema, bronchial atresia
Atresia
Atresia is a condition in which a body orifice or passage in the body is abnormally closed or absent.Examples of atresia include:* Imperforate anus - malformation of the opening between the rectum and anus....
and mucous plugs in asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
.
It causes one form of overexpansion of the lung. Overexpansion, however, can also be caused by increase in lung mass itself.
See also
- List of terms of lung size and activity
- InhalantInhalantInhalants are a broad range of drugs whose volatile vapors are taken in via the nose and trachea. They are taken by volatilization, and do not include drugs that are inhaled after burning or heating...
– Psychoactive drugs consumed through inhalation - Respiratory systemRespiratory systemThe respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
- Ventilation (physiology)Ventilation (physiology)In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
- ExhalationExhalationExhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....