accommodation


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Acronyms, Wikipedia.

accommodation

Physiol the automatic or voluntary adjustment of the shape of the lens of the eye for far or near vision

accommodation

  1. (in race relations) a process in which ethnic groups adjust to each other's existence and coexist without necessarily resolving underlying differences and conflicts (compare ASSIMILATION).
  2. (more generally, e.g. in politics or in domestic life) any individual or group behaviour of the above kind.
  3. (as used by the CHICAGO SCHOOL, e.g. PARK and Burgess, 1921) a fundamental social process, analogous to biological adaptation, by which societies achieve adjustment to 4 (in PIEGET's theory of CHILD DEVELOPMENT) one of the mechanisms by which development from one stage to the next is achieved. See ASSIMILATION AND ACCOMMODATION.

Accommodation

 

a term used in biology and medicine, similar to “adaptation.” The term is traditionally used in the three phrases “accommodation of the eye,” “physiological accommodation,” and “histological accommodation.”

Accommodation of the eye is adaptation of the eye in order to obtain clear vision of objects at various distances. It is achieved by a change in the refractive power of the optical system, which leads to the focusing of the image on the retina. In fish the eye is constructed for close vision, and accommodation is achieved by the rearward displacement of the spherical crystalline lens. In amphibians and reptiles the eye at rest is constructed for distant vision, and accommodation is achieved by the forward movement of the crystalline lens. In birds, mammals, and humans accommodation is achieved by a change in the curvature of the crystalline lens. Accommodation is performed by the accommodation muscles and is possible within certain limits—that is, when the object is at a particular distance from the eye within the field between the points of close and distant vision.

When the intraocular, so-called accommodation muscles contract, the ligaments are relaxed and the crystalline lens suspended on them becomes more protuberant. An increase in the curvature of the crystalline lens leads to a stronger refraction, in consequence of which it becomes possible for the eye to focus the light rays emanating from closely placed objects on the retina and to see them clearly.

The physical factor of crystalline lens elasticity also enters into eye accommodation. In humans the ability of the accommodation muscles to contract and the elasticity of the crystalline lens may change because of a number of conditions. Accommodation is most highly developed in children. With age, elasticity of the crystalline lens diminishes, the ability to see close objects decreases, and so-called senile vision, or presbyopia, develops. Signs of diminution of eye accommodation in persons with normal refraction (emmetropia) appear most commonly between the ages of 40 and 45. When such diminution of eye accommodation occurs, glasses with convex lenses are prescribed for close work (reading and writing) to compensate for the defect. Subsequently, the strength of the eyeglass lenses is gradually increased; by the age of 60 or 70 eye accommodation is usually entirely lost and it is no longer necessary to increase the strength of the eyeglass lenses. Spasm of the accommodation muscles may occur as a result of prolonged eyestrain, bright light, eye trauma, or other factors. Paralysis of these muscles may occur with certain infections and intoxications—for example, syphilis, influenza, diabetes, diphtheria, and botulism. The treatment of spasm or paralysis depends on the cause.

Physiological accommodation, or accommodation of excited muscular or neural tissue, is adaptation to the action of a slowly intensifying stimulus. For example, rapid chilling or a blow may excite an isolated nerve fiber, whereas slow cooling or gradual pressure may not. The same thing is observed with electrical stimulation; with the slow intensification of current, the action potential of a nerve or muscle does not emerge. Such accommodation is associated with active changes in the tissue that raise the threshold of irritability and obstruct the development of excitation.

Histological accommodation, or tissue accommodation, is a change in the forms and relationships of tissue elements (cells) in the process of adaptation to changed conditions. An example of histological accommodation is the transformation of the cubical epithelium of the glomerular capsule into long cylindrical cells when the volume of the glomerulus decreases. However, histological accommodation is often difficult to differentiate from other processes, such as metaplasia and atrophy. The term is therefore merely a formal one.

REFERENCES

Dashevskii, A. I. “Refraktsiia i akkomodatsiia glaza.” In Mnogotomnoe rukovodstvo po glaznym bolezniam, vol. 1, book 1. Edited by V. N. Arkhangel’skii. Moscow, 1962.
Fiziologiia cheloveka. Edited by E. B. Babskii. Moscow, 1966.

M. L. KRASNOV and S. P. LANDAU

accommodation

[ə‚käm·ə′dā·shən]
(control systems)
Any alteration in a robot's motion in response to the robot's environment; it may be active or passive.
(ecology)
A population's location within a habitat.
(mapping)
The limits or range within which a stereo-plotting instrument is capable of operating.
(physiology)
A process in most vertebrates whereby the focal length of the eye is changed by automatic adjustment of the lens to bring images of objects from various distances into focus on the retina.

accommodation

accommodationclick for a larger image
Accommodation: adjustment of eye focus on distant object (left) and close object (right).
i. The ability of the human eye to adjust itself to give sharp images for different object distances. It is the process by which the lens of the eye can be flattened to focus distant points on the retina or made more convex to focus nearby points on the retina.
ii. The limits or range within which a stereo-plotting instrument is capable of operating. For example, a multiplex stereograph can adjust or accommodate for small tilts in the projector, ranging from approximately 10° about the X-axis to 20° about the Y-axis.
References in periodicals archive ?
Asia Pacific was the largest region in the global non-residential accommodation services market, accounting for 34% of the market in 2018.
One of the Accommodation Association's core activities is to build and maintain strong, positive relationships with key federal and state/territory political decision-makers.
The former police chief had taken notice of the critical shortage of official accommodation facing low and high-ranking officials and officers, and directed divisional police chiefs across the province for details of the available and occupied accommodation as well as the shortage facing police in every district.
Ending the accommodation dialogue with the employee because no reasonable accommodation would allow the employee to perform the job's essential functions.
He informed the House hat Rule 7 (1) tells that the allotment of Government owned accommodation shall be made to the most senior FGS on GWL of a particular class or category of accommodation.
Low share in EU comparisonThe neighbouring countries report one of the smallest shares in the use of shared economy services in the European Union.In the Czech Republic, only less than 5 percent of people booked alternative private accommodation via the internet, while only 2 percent used a shared drive.
Research from our lab and elsewhere is showing that accommodation is definitely not a one-size-fits-all situation.
New Delhi [India], June 20 ( ANI ): India's leading travel distribution solutions provider for hotels and accommodations AxisRooms is working with Airbnb to provide a level-playing field to travel accommodations other than commercial Hotels and Resorts.
The concerned authority is actively pursuing eviction of illegal occupants from government accommodations in coordination with the local administration, an official in the ministry told APP.
Over at Conifer Court in Bedworth , the council wants to turn the empty warden flats into two flats for sheltered living accommodation. There is also a proposal to convert the vacant warden flats at John Haynes Court in Bedworth into two flats for those who need sheltered living accommodation.
(36) Trinity argued that "Kowitz was not a qualified individual under the ADA, because performing BLS was an essential function of both of her positions." (37) Furthermore, Trinity contended that Kowitz never requested an accommodation. (38)

Full browser ?