diaphragm

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diaphragm

(dī`əfrăm'), term used to describe any of several large muscles, found in humans and other mammals, which separate two adjacent regions of the body. The most commonly known muscle of this class is the thoraco-abdominal diaphragm. In humans, the thoraco-abdominal diaphragm acts as a partition between the cavity of the chest and that of the abdomen. The chief muscle used in respiration, it is relaxed and dome-shaped during exhalation. During inhalation it contracts, pulling downward, and with the combined contraction of the chest muscles allows the chest cavity to expand. Any interference with its free movement, as in the paralysis of poliomyelitis, seriously impedes the function of the lungs and therefore endangers life. In its downward movement the thoraco-abdominal diaphragm also stimulates the stomach and liver and thus aids in the digestive processes. Spasmodic contraction results in hiccupshiccup
or hiccough,
involuntary spasmodic contraction of the diaphragm followed by a sharp intake of air, which is abruptly stopped by a sudden, involuntary closing of the glottis (opening between the vocal cords); the consequent blocking of air produces a repeated
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. The thoraco-abdominal diaphragm is also subject to developmental defects, hernia, injury, displacement, and infection. Other diaphragms in the human body include the pelvic diaphragm and the urogenital diaphragm, which use similar muscular contractions and expansions in their respective functions.

diaphragm

(dÿ -ă-fram) See stop.

Diaphragm

A relatively thin element in a structural member, which is capable of withstanding shear in its plane; it stiffens the structural member.

Diaphragm

 

the musculotendinous partition that (in mammals and man) divides the thoracic cavity from the abdominal cavity.

The diaphragm provides for diaphragmatic respiration and equalization of pressure in the thoracic and abdominal cavities; it also regulates the outflow of blood from the inferior and superior venae cavae into the right atrium of the heart and the distribution of gases in the cardiac part of the stomach and intestine (cardiac opening). During exhalation the diaphragm protrudes cupola-like into the thoracic cavity: with inhalation it flattens by contracting and thereby increases the volume of the thoracic cavity. The diaphragm has a peripheral muscular part and a central tendinous part. In many insectivorous and predatory mammals the tendinous part of the diaphragm is not well developed. In all mammals the diaphragm has openings through which pass the inferior vena cava; the azygos and hemiazygos veins: the vagus (two branches), phrenic, splanchnic, and sympathetic nerves: and the periaortic plexus. The muscular part of the diaphragm consists of lumbar, costal, and sternal sections. The aorta and esophagus usually pass through openings (in sloths through a single opening) between the internal muscle bundles in the lumbar section of the diaphragm. The muscle bundles, in contracting, prevent the backing up of food from the stomach. In the anthropoid apes and man the pericardium fuses with the upper surface of the diaphragm.


Diaphragm

 

(in Russian, diafragma, also stiffener—see [4] below). In engineering, a part of instruments, machines, mechanisms, and structures; it is usually a plate or partition (with or without an aperture).

(1) A measuring diaphragm most often is a disk with an aperture. Along with the venturi and the common nozzle, it serves as one of the standard constricting devices used in industry for measuring the rate of flow of liquids, gases, and vapors passing through a pipe, on the basis of the principle of variable pressure drop. The axis of the diaphragm aperture should coincide with the axis of the pipe. As the substance to be measured passes through the diaphragm, the average rate of flow in the constricted section increases as a result of the conversion of part of the potential energy of pressure into kinetic energy. The static pressure of the flow is lower behind a diaphragm than in front of it. The pressure difference (drop), which is measured by a differential manometer, is proportional to the square of the rate of flow of the flowing substance and serves as a measure of the flow rate.

Measuring diaphragms are divided into standard (normal) and nonstandard types. The use of standard diaphragms is governed by special rules. When the flow rate is to be measured under conditions that differ from the conditions established by these rules, nonstandard diaphragms (such as eccentric, segmented, and paired types), which require individual calibration under conditions similar to operating conditions, are used. Depending on the methods of pressure selection, normal diaphragms are divided into the disk type (in the form of a flat disk), with reading of pressure by means of separate pipes, and the chamber type (with ring chambers), for reading pressures in the planes of the diaphragm disk. Normal diaphragms are used in pipes larger than 50 mm in diameter; chamber diaphragms, for pipes up to 500 mm in diameter and for a working pressure of up to 10 meganewtons per sq M (MN/m2), or 100 kilograms-force per sq cm (kgf/cm2); and disk diaphragms, for pipes 450–1,600 mm in diameter and pressures of up to 1.6 MN/m2 (16 kgf/cm2). The relative error of measurement of the flow rate when diaphragms are under favorable conditions (in the absence of additional corrections for viscosity and the roughness of the pipe) ranges from ±0.5 percent to 1.5 percent, and under more severe conditions from ±3 percent to 3.5 percent.

REFERENCES

Kremlevskii, P. P. Raskhodomery, 2nd ed. Moscow-Leningrad, 1963.
Pravila 28–64 izmereniia raskhoda zhidkostei, gazov i parov standartnymi diafragmami i soplami. Moscow, 1964.
Avtomatizatsiia, pribory kontrolia i regulirovaniia proizvodstvennykh protsessov v neftianoi i neftekhimicheskoi promyshlennoist, Spravochnik, book 2. Moscow, 1964.

G. G. MIRZABEKOV

(2) For optical instruments seeIRIS.

(3) In turbines, a diaphragm is a ring partition to which the vanes of the guiding unit are secured. The diaphragms are removable along the horizontal. Diaphragms that operate at temperatures up to 250° C are made from SCh 18–36, SCh 21–40, and SCh 24–44 cast iron; diaphragms operating at high temperatures are made of 15KhM, 20KhM, and 35KhM chromium-molybdenum steel.

(4) In hydraulic-engineering structures, a stiffener is a device within the body of earth dams and rock-filled dams; it is made in the form of a vertical wall of concrete, reinforced concrete, metal, or less frequently, wood. It ensures the rigidity of the movable part of the stop gate.

V. N. POSPELOV

diaphragm

[′dī·ə‚fram]
(anatomy)
The dome-shaped partition composed of muscle and connective tissue that separates the abdominal and thoracic cavities in mammals.
(electromagnetism)
(engineering)
A thin sheet placed between parallel parts of a member of structural steel to increase its rigidity.
(engineering acoustics)
A thin, flexible sheet that can be moved by sound waves, as in a microphone, or can produce sound waves when moved, as in a loudspeaker.
(optics)
Any opening in an optical system which controls the cross section of a beam of light passing through it, to control light intensity, reduce aberration, or increase depth of focus. Also known as lens stop.
(physics)
A separating wall or membrane, especially one which transmits some substances and forces but not others.
In general, any opening, sometimes adjustable in size, which is used to control the flow of a substance or radiation.

diaphragm

2. A floor slab, metal wall panel, roof panel, or the like, having a sufficiently large in-plane shear stiffness and sufficient strength to transmit horizontal forces to resisting systems.

diaphragm

diaphragm
i. As applicable to air photogrammetry, a device for varying the amount of light passing through the lens. It is fitted behind, in front of, or between the lenses of cameras. It provides apertures of varying sizes. Any particular size is called a stop, and the act of reducing the aperture is called stepping down.
ii. In accumulators, the portion that divides its two portions—one filled with gas and the other fluid.

diaphragm

1. Anatomy any separating membrane, esp the dome-shaped muscular partition that separates the abdominal and thoracic cavities in mammals
2. Optics a disc with a fixed or adjustable aperture to control the amount of light or other radiation entering an optical instrument, such as a camera
3. Chem
a. a porous plate or cylinder dividing an electrolytic cell, used to permit the passage of ions and prevent the mixing of products formed at the electrodes
b. a semipermeable membrane used to separate two solutions in osmosis
4. Botany a transverse plate of cells that occurs in the stems of certain aquatic plants
References in periodicals archive ?
Surgeons usually use a mesh to close diaphragmatic gap (64%) without hernial sac reduction (69%) (6,8-11).
Delayed discovery of diaphragmatic injury after blunt trauma: Report of three cases.
Diaphragmatic hernia of uterus with two fetuses in thorax and one fetus in abdomen was diagnosed in cat.
Reversibility of paraneoplastic bilateral diaphragmatic paralysis after nephrectomy for renal cell carcinoma.
Rattner, "Paraesophageal and other complex diaphragmatic hernias," in Shackelford's Surgery of the Alimentary Tract, C.
Affected patients typically have severe multisystem injures that may overshadow the diagnosis of TDR, and there may be lack of awareness of the various imaging signs of diaphragmatic injury [1,8].
In conclusion, although it is a rare condition, diaphragmatic rupture and kidney herniation should remain a part of the differential diagnosis when a mass is seen in posterior mediastinum on the CT scan after blunt trauma.
The present communication describes successful surgical management of diaphragmatic hernia by transabdominal approach.
The hernia porta were localized between the right diaphragmatic crus and the esophagus.
7) Consequently a good knowledge of the structural variations of the diaphragmatic crura becomes crucial to our understanding of gastrointestinal physiology.
London, Sept 5 ( ANI ): In a bizarre incident, a man from Ireland has been suffering from a chronic condition called 'synchronous diaphragmatic flutter', due to which he has been hiccupping every seven seconds since last July.
Sarper and her colleagues in their letter to the editor, entitled "Severe iron deficiency anemia due to late presentation of congenital diaphragmatic hernia in a toddler", was not a late but rather a delayed diagnosis case since iron deficiency anemia was diagnosed in this patient at least a year earlier with intermittent vomiting (1).