Respiration (physiology)

With Respiration ( Latin: Respiratio ) is called

• In common parlance, the lung activity (ventilation),
• In the broader sense all operations involved. Because it is necessary that the oxygen in the air is diffused by the inner surface of the lung, is passed through the blood to the tissues and cells and the carbon dioxide is passed from cells and tissues by the blood to the lungs and then exhaled.
• In the broadest sense, a more comprehensive term is denoted by Breathing: All processes of the recording of a reducible substance (for aerobes is the oxygen, O2), its transport into the target cells, its reduction with the aid of the respiratory chain (final product in the case of aerobic respiration: water), storing the largest possible part of the energy released in the form of chemical energy-rich biomolecules (usually ATP) and release ( exhalation ) of carbon dioxide ( degradation product of organic matter ) should be included breathing. In this sense, can be formulated in general terms: Respiration is the oxidation of an energy-rich substance ( reductant ), for example glucose, with reduction of an external electron -accepting substance ( oxidant, such as oxygen ), where a (large ) part of the released energy of this redox reaction synthesis of high-energy molecules is chemically stored.

The respiratory system is species-specific organized: mammal about to breathe no water, lots of fish, no air. The reason for the latter is that the gill filaments, which receive their propagation through the water, dry it in the air and stick to one another, whereby the gas exchange on the very delicate exchange area comes to a standstill. In the alveoli water penetration, on the other hand it is difficult to exhale against gravity effect and finally the oxygen content of the water is considerably less than the normal air we breathe, it comes to suffocation due to its comparatively high to air specific weight.

• 2.1 Aerobic respiration
• 2.2 Anaerobic respiration

• 3.1 Respiratory
• 3.2 Respiratory mechanics of the mammalian
• 3.3 Respiratory control of mammalian
• 3.4 measurements in humans 3.4.1 Respiratory rate
• 3.4.2 tidal volume
• 3.4.3 minute ventilation
• 3.4.4 dead space
• 3.4.5 breath pressure

Internal and external respiration

In biology, a distinction is made according to anatomical / physiological and biochemical aspects of the interior of the external respiration:

Internal respiration

As internal respiration those metabolic processes are referred to, which serve the energy gain of the cells. In particular is understood to mean at the biochemical processes of the respiratory chain ( descending in eukaryotes in the inner membrane of the mitochondria ), is synthesized at the end of ATP.

External respiration

An external respiration is only available for aerobes, anaerobes because not act as multi-cellular organisms. The following components can be distinguished, they can also occur in combination.

• Skin respiration, in which the gas exchange takes place with water or with the atmosphere over the whole body surface.
• The gill respiration, in which the gas exchange with water on a thin, vascularized Hautausstülpungen, the gills takes place. It occurs in many invertebrates, including land animals, and fish.
• The Tracheenatmung on tubular invaginations of the body skin. It occurs in insects, centipedes and some spiders.
• Lungs: oxygen is discharged from the alveoli to capillaries and carbon dioxide is delivered from the capillaries of the lung alveoli. It occurs in lung -breathing snails and in amphibians, reptiles, birds and mammals (including humans) for example.
• Various hollow organs occur in air-breathing teleosts.
• Gas exchange of plants during photosynthesis through the stomata.
• The plastron respiration or " physical gill".
• The distribution of gases to the target cells in the respiratory fluid (blood or lymph ), usually with oxygen transport vectors ( hemoglobin or hemocyanin ), some cellular (erythrocytes).

Gas exchange

From gas exchange is only mentioned in gaseous substrates, ie not for iron, nitrate, fumarate or sulfur respiration.

Gas exchange occurs primarily via diffusion always. This is a process of physics, in which substances spatially distributed: from areas of high concentration to areas they spread out at lower concentration, ideally, everywhere there is to the same concentration. The exchange of a boundary layer ( in biology: membrane) caused an unobstructed for these substances as possible permeability (permeability). It is also essential to promote the exchange to have a largest possible diaphragm surface.

At differentiated multicellular organisms special organs are often responsible for part of the external respiratory gas exchange.

Factors influencing the gas exchange:

• Permeability of the membrane for the substance to be exchanged
• Surface of the membrane
• Membrane thickness ( = diffusion distance )
• Temperature affects the velocity of the molecules in the substance to be exchanged
• Difference in concentration in the two spaces separated by the membrane, the higher the difference, the faster the passive exchange of gas takes place.

Aerobic and anaerobic respiration

Aerobic respiration there is only since elemental oxygen is in the atmosphere and in water. Its formation dates back to the first photosynthetic prokaryotes, probably forerunners of today's cyanobacteria. Can predict and in a low-oxygen environment / could only take place an anaerobic respiration.

Many organisms are capable of several types of breathing. Thus, for example, live Escherichia coli under anaerobic and aerobic conditions. Other organisms dominate only a breathing type. Mammals, including the human one, are obligate aerobes, and are therefore dependent on oxygen to live.

By the oxidation of high-energy compounds ( inorganic substances or organic substances such as glucose ), electrons are liberated in bound form. This will eventually transmitted through a usually long chain of redox reactions that make energy for the formation of ATP is diverted to a terminal electron acceptor ( respiratory chain ). The latter is in the aerobic respiration always oxygen, during anaerobic respiration, various organic and inorganic substances are present as an electron acceptor.

Aerobic respiration

For aerobic respiration, oxygen is required. In general, organic compounds such as carbohydrates or fatty acids are oxidized and finally transferred to a respiratory chain to O2 as the terminal electron acceptor. When glucose is used as the substrate, then in the aerobic respiration of carbon dioxide and water is produced. The redox potential E0 ' is 0.82 V. The total equation is:

Microorganisms can oxidize for energy not only organic but also inorganic substances. Thus, for example, uses the archaeon Acidianus ambivalens sulfur in a sulfur oxidation in:

The oxidation of ammonia ( NH3) occurs in bacteria and archaea. This ammonia is oxidized to nitrite (NO2 - ):

Anaerobic respiration

In anaerobic respiration, which is operated by prokaryotes, which obtained from the oxidation of a source of energy electrons instead of oxygen to other external reducible substrates transferred. This should not be confused with forms of fermentation, in which the electrons are transferred to metabolic end products, and thus there is no possibility of Elektronentransportphosphorylierung.

The various anaerobic respirations are classified by " respired " substrate or metabolic end products.

In the table only a selection of anaerobic respiration types was recorded (others see main article):

Pulmonary respiration of vertebrates

Respiratory

When breathing, air passes through the mouth or through the nose into the body. If inhaled through the nose, the air is first cleaned, moistened and warmed by the nasal hairs and mucus membranes. Then the breath passes through the throat past the larynx and vocal cords into the trachea. The trachea branches into the two branches of the bronchi, which continues to branch out as bronchioles. In the trachea, the air is cleaned again by small cilia. At the end there are the alveoli in the lungs, through the thin membrane oxygen passes into the blood vessels and reverse route and carbon dioxide is released from the blood to the lungs.

Respiratory mechanics of the mammalian

The two lungs fill up a small gap from the paired pleural cavity in the chest. This increases by raising the ribs ( chest breathing ) and pulling down the muscular diaphragm (belly breathing). Since the fluid-filled pleural space does not change its volume, the lungs of such extension must follow and is filled via the airways with air. Here, the alveoli expand against the surface tension. A soap-like liquid ( surfactant) is that surface tension reducing, on the one hand to relieve the respiratory muscles and on the other hand to avoid the collapse of especially the smaller bubbles. Elastic fibers while preventing overextension already stretched bubble ( in connection with the instability of surface tension, see Young-Laplace equation). For a uniform ventilation of different parts of the lungs also contributes to the regulation of the bronchioles diameter.

During exhalation relaxes the respiratory muscles and leaves the lungs to contract. The pressure in the pleural space usually remains slightly negative. The expiratory respiratory muscles is only forced exhalation during physical exertion in speaking, singing, coughing, or shortness of breath.

Breath control of mammalian

Respiration is controlled by the brain or the respiratory center in the medulla oblongata. The crucial factor is the reaction of chemoreceptors on the carbon dioxide content of the blood. If this exceeds a certain threshold, is a respiratory irritant. Receptors that respond to the pH of arterial blood as well as a lack of oxygen, have only a secondary importance as a respiratory irritant.

About the sensory fibers of the vagus nerve and the expansion of the lung is detected. If this exceeds a certain level, the respiration is limited by reflex.

Measurements in humans

Respiratory rate

The average number of in-and exhalations per unit of time ( the breathing frequency f) is at rest

Tidal volume

The tidal volume in an adult at rest is about 0.5 liters.

Minute Ventilation

The respiratory minute volume is the sum of tidal volumes within one minute, the number of which is equal to the product of respiratory rate f per minute, so:

Or as understood rate:

Example: 4200ml/Min = 12/min x 350ml

Dead space volume

The dead space is the amount of air that is not actively involved in gas exchange, ie in breathing in the gas-conducting system ( space between the mouth and alveoli ) " stops ". The rest breath of an adult of about 500 ml, the dead space is about 30% of the tidal volume. In an adult, the dead space is about 150-200 ml

Respiratory pressure

The breath pressure of adult humans usually hovers around 50 mbar, a maximum of about 160 mbar can be achieved.

Pathological breathing forms

The disorders of the respiratory ( breathing Pathological forms ) are summarized in the ICD -10 from the symptoms that affect the circulatory system and the respiratory system as R06. (The following examples serve initially as a basis for work! )

• Biot- breathing

( Sign of central respiratory disorder; breathing typical of brain injury ( traumatic brain injury, affected: the brain stem ), increased intracranial pressure or meningitis)

• Cheyne -Stokes respiration

( Sign of central respiratory disorder; breathing typical of brain injury (eg, traumatic brain injury, affected: cerebrum ) )

• Hyperventilation; exclusive psychogenic hyperventilation!
• Kussmaul breathing (Typical for diabetic ketoacidosis: consequently hyperventilation )
• Mouth breathing, snoring
• Obstructive Sleep Apnea Syndrome
• Gasping
• Sigh breathing
• Hiccups; exclusive psychogenic hiccough
• Stridor

Respiratory therapy

The clinical respiratory therapy deals with the diseases and disorders of the lungs and vocal apparatus.

Composition of the inhaled and exhaled air