Respiratory physiology - AbsoluteAstronomy.com

Respiratory physiology is the branch of human physiology

Human physiology

Human physiology is the science of the mechanical, physical, bioelectrical, and biochemical functions of humans in good health, their organs, and the cells of which they are composed. Physiology focuses principally at the level of organs and systems...

focusing upon respiration

Respiration (physiology)

'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...

.

Topics include:

Volumes

lung volumes
Lung volumes
Lung volumes and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. Lung volumes are directly measured...
vital capacity
Vital capacity
Vital capacity is the maximum amount of air a person can expel from the lungs after a maximum inspiration. It is equal to the inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume....
functional residual capacity
Functional residual capacity
Functional Residual Capacity is the volume of air present in the lungs, specifically the parenchyma tissues, at the end of passive expiration...
dead space
spirometry
Spirometry
Spirometry is the most common of the pulmonary function tests , measuring lung function, specifically the measurement of the amount and/or speed of air that can be inhaled and exhaled...
body plethysmography
Body plethysmography
Body plethysmography or "Body Box" for short, is a very sensitive lung measurement used to detect lung pathology that might be missed with conventional pulmonary function tests. This method of obtaining the absolute volume of air within one's lungs may also be used in situations where several...
peak flow meter
Peak flow meter
The peak expiratory flow , also called peak expiratory flow rate is a person's maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ability to breathe out air...

Mechanics

Inhalation (breathing in) is usually an active movement. The contraction of the diaphragm muscles cause a pressure variation, which is equal to the pressures caused by elastic, resistive and inertial components of the respiratory system. In contrast, expiration (breathing out) is usually a passive process.

Where P_el equals the product of elastance

Elastance

Compliance is a measure of the tendency of a hollow organ to resist recoil toward its original dimensions upon removal of a distending or compressing force. It is the reciprocal of "elastance".-Blood vessels:...

E (inverse of compliance

Pulmonary compliance

Pulmonary compliance can refer to either dynamic or static lung compliance. Static lung compliance is the change in volume for any given applied pressure...

) and volume of the system V, P_re equals the product of flow resistance

Airway resistance

Airway resistance is a concept used in respiratory physiology to describe mechanical factors which limit the access of inspired air to the pulmonary alveoli, and thus determine airflow....

R and time derivate of volume V (which is equivalent to the flow), P_in equals the product of inertance I and second time derivate of V. R and I are sometimes referred to as Rohrer's constants.

Anatomy: pleural cavity
Pleural cavity
In human anatomy, the pleural cavity is the potential space between the two pleura of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally...

, thoracic diaphragm
Thoracic diaphragm
In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

, Intercostales externi muscles
Intercostales externi muscles
The Intercostales externi are eleven in number on either side.They extend from the tubercles of the ribs behind, to the cartilages of the ribs in front, where they end in thin membranes, the anterior intercostal membranes , which are continued forward to the sternum.Each arises from the lower...

, Intercostales interni muscles
Intercostales interni muscles
The Intercostales interni are eleven in number on either side. They commence anteriorly at the sternum, in the interspaces between the cartilages of the true ribs, and at the anterior extremities of the cartilages of the false ribs, and extend backward as far as the angles of the ribs, whence they...
inhalation
Inhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....

and exhalation
Exhalation
Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....
lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

, pulmonary alveolus
Pulmonary alveolus
An alveolus is an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the dead ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well...
With insufficient pulmonary surfactant
Pulmonary surfactant
Pulmonary surfactant is a surface-active lipoprotein complex formed by type II alveolar cells. The proteins and lipids that surfactant comprises have both a hydrophilic region and a hydrophobic region...

, the pulmonary alveoli
Pulmonary alveolus
An alveolus is an anatomical structure that has the form of a hollow cavity. Found in the lung parenchyma, the pulmonary alveoli are the dead ends of the respiratory tree, which outcrop from either alveolar sacs or alveolar ducts, which are both sites of gas exchange with the blood as well...

collapse, causing atelectasis
Atelectasis
Atelectasis is defined as the collapse or closure of alveoli resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.It is a very common finding in chest x-rays and other...

(in infants, infant respiratory distress syndrome
Infant respiratory distress syndrome
Infant respiratory distress syndrome , also called neonatal respiratory distress syndrome or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural...

)
the law of Laplace,
compliance (physiology) - decreased with fibrosis
Fibrosis
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. This is as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue...

, increased with emphysema
Emphysema
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
Poiseuille's law
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...

and COPD
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
hysteresivity
Hysteresivity
Hysteresivity derives from “hysteresis”, meaning “lag”. It is the tendency to react slowly to an outside force, or to not return completely to its original state...

Circulation, ventilation, and perfusion

pulmonary circulation
Pulmonary circulation
Pulmonary circulation is the half portion of the cardiovascular system which carries Oxygen-depleted Blood away from the heart, to the Lungs, and returns oxygenated blood back to the heart. Encyclopedic description and discovery of the pulmonary circulation is widely attributed to Doctor Ibn...
positive pressure ventilation
hypoxic vasoconstriction
Hypoxic Pulmonary Vasoconstriction
Hypoxic pulmonary vasoconstriction is a paradoxical, physiological phenomenon in which pulmonary arteries constrict in the presence of hypoxia without hypercapnia , redirecting blood flow to alveoli with a higher oxygen content.The process might at first seem illogical, as low oxygen levels should...
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:...

, perfusion
Perfusion
In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."...

, ventilation/perfusion ratio
Ventilation/perfusion ratio
In respiratory physiology, the ventilation/perfusion ratio is a measurement used to assess the efficiency and adequacy of the matching of two variables: It is defined as: the ratio of the amount of air reaching the alveoli to the amount of blood reaching the alveoli.* "V" – ventilation – the air...

(V/Q), and ventilation/perfusion scan
Ventilation/perfusion scan
A ventilation/perfusion lung scan, also called a V/Q lung scan, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patient's lungs, in order to determine the ventilation/perfusion ratio...
shunts: right-to-left (tetralogy of fallot
Tetralogy of Fallot
Tetralogy of Fallot is a congenital heart defect which is classically understood to involve four anatomical abnormalities...

), left-to-right (patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...

)
respiratory rate
Respiratory rate
Respiratory rate is also known by respiration rate, pulmonary ventilation rate, ventilation rate, or breathing frequency is the number of breaths taken within a set amount of time, typically 60 seconds....

and respirometer
Respirometer
A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide. They allow investigation into how factors such as age, chemicals or the effect of light affect the rate of respiration...

Gas exchange/transport (primarily oxygen and carbon dioxide)

gas exchange
Gas exchange
Gas exchange is a process in biology where gases contained in an organism and atmosphere transfer or exchange. In human gas-exchange, gases contained in the blood of human bodies exchange with gases contained in the atmosphere. Human gas-exchange occurs in the lungs...
Dalton's law
Dalton's law
In chemistry and physics, Dalton's law states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture...
hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
oxygen-hemoglobin dissociation curve, Bohr effect
Bohr effect
Bohr effect is a property of hemoglobin first described in 1904 by the Danish physiologist Christian Bohr , which states that an increasing concentration of protons and/or carbon dioxide will reduce the oxygen affinity of hemoglobin...

, Haldane effect
Haldane effect
The Haldane effect is a property of hemoglobin first described by the Scottish physician John Scott Haldane. Deoxygenation of the blood increases its ability to carry carbon dioxide; this property is the Haldane effect. Conversely, oxygenated blood has a reduced capacity for carbon...
carbonic anhydrase
Carbonic anhydrase
The carbonic anhydrases form a family of enzymes that catalyze the rapid interconversion of carbon dioxide and water to bicarbonate and protons , a reversible reaction that occurs rather slowly in the absence of a catalyst...
oxyhemoglobin
respiratory quotient
Respiratory quotient
The respiratory quotient , is a unitless number used in calculations of basal metabolic rate when estimated from carbon dioxide production. Such measurements, like measurements of oxygen uptake, are forms of indirect calorimetry...
arterial blood gas
Arterial blood gas
An arterial blood gas is a blood test that is performed using blood from an artery. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery at the wrist, but sometimes the femoral artery in the groin or...

Control and response

control of respiration
Control of respiration
Control of ventilation refers to the physiological mechanisms involved in the control of physiologic ventilation. Gas exchange primarily controls the rate of respiration.The most important function of breathing is gas exchange...
reticular formation
Reticular formation
The reticular formation is a part of the brain that is involved in actions such as awaking/sleeping cycle, and filtering incoming stimuli to discriminate irrelevant background stimuli...
pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...

(apneuistic and pneumotaxic)
chemoreceptors (medulla
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...

, carotid body
Carotid body
The carotid body is a small cluster of chemoreceptors and supporting cells located near the fork of the carotid artery ....

, aortic body
Aortic body
In the human heart, the aortic body is one of several small clusters of chemoreceptors, baroreceptors, and supporting cells located along the aortic arch.-Function:...

)
Hering-Breuer reflex
Hering-Breuer reflex
The Hering–Breuer inflation reflex, named for Josef Breuer and Ewald Hering, is a reflex triggered to prevent over-inflation of the lungs. Pulmonary stretch receptors present in the smooth muscle of the airways respond to excessive stretching of the lung during large inspirations.Once activated,...
involuntary control of respiration
exercise
hyperoxia
Hyperoxia
Hyperoxia is excess oxygen or higher than normal partial pressure of oxygen.In medicine, it refers to excess oxygen in the lungs or other body tissues, which can be caused by breathing air or oxygen at pressures greater than normal atmospheric pressure...
hypoxemia
Hypoxemia
Hypoxemia is generally defined as decreased partial pressure of oxygen in blood, sometimes specifically as less than or causing hemoglobin oxygen saturation of less than 90%.-Distinction from anemia and hypoxia:...

(hypoxic hypoxia
Hypoxic hypoxia
Hypoxic hypoxia is a result of insufficient oxygen available to the lungs. A blocked airway, a drowning or a reduction in partial pressure are obvious examples of how lungs can be deprived of oxygen. Some medical examples are abnormal pulmonary function or respiratory obstruction, or a...

)

Disorders

altitude sickness
Altitude sickness
Altitude sickness—also known as acute mountain sickness , altitude illness, hypobaropathy, or soroche—is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude...
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...
carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
emphysema
Emphysema
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
infant respiratory distress syndrome
Infant respiratory distress syndrome
Infant respiratory distress syndrome , also called neonatal respiratory distress syndrome or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural...
pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...

External links

Overview at Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...

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