stoma

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Related to stomas: esophagomalacia, cheilorrhaphy

stoma

1. Botany an epidermal pore, present in large numbers in plant leaves, that controls the passage of gases into and out of a plant
2. Zoology anatomy a mouth or mouthlike part
3. Surgery an artificial opening made in a tubular organ, esp the colon or ileum

Stoma

 

a slitlike opening in the epidermis of aboveground organs of plants. The stoma is bordered by two guard cells, which are usually bean-shaped. The walls of the guard cells that face the stoma are thick, while the opposite walls are thin. The stoma leads to a large intercellular space, the substomatal cavity. The stoma is often surrounded by two or more cells that differ in shape from ordinary epidermal cells.

Stomata are found in the epidermis of all aboveground parts of the plant containing chlorophyll but are especially numerous in leaf epidermis (100–300 per sq mm). They regulate the exchange of gas and water vapor between the atmosphere and the cells of the plant by increasing and decreasing in width. Stomatal movement is effected by changes in the turgor of the guard cells. When turgor is increased, the thin parts of their walls stretch and are drawn away from the stoma. The walls that face the stoma are distended in the same direction, and the stoma opens. When the turgor of the guard cells decreases, the stoma closes. Change in the turgor of the guard cells occurs as a result of reversible conversion of starch, which is osmotically inactive, into osmotically active sugars. However, according to some data, potassium ions play an important, possibly leading, role in regulating the turgor of the guard cells. Scientists are currently investigating these data with the intention of formulating a new hypothesis of the mechanism of stomatal movement.

At night, the stomata of most plants are closed, and gas exchange and transpiration are minimal. During the day, when the weather is fair, the stomata are open. Carbon dioxide gas readily enters the internal tissues of the plant, and oxygen formed as a result of photosynthesis is released with water vapor into the atmosphere.

E. A. MIROSLAVOV

stoma

[′stō·mə]
(biology)
A small opening or pore in a surface.
(botany)
One of the minute openings in the epidermis of higher plants which are regulated by guard cells and through which gases and water vapor are exchanged between internal spaces and the external atmosphere.
References in periodicals archive ?
Sponsorship will take the form of a contribution to the departments overall running costs, and the department shall be free to use any such contribution for the benefit of stoma care service requirements on any of the Trusts sites as it deems fit, provided that it shall only be used to fund the operating of the stoma care department and not for any other purpose or department.
But she says the stoma - a bag that sits outside her tummy and collects bodily waste - has dramatically improved her quality of life.
They were divided into group A and B (intervention groups) and C (control group), in which the stomas were closed at 2, 4 and 8 weeks of its formation respectively.
There is one study in the French literature (Jeanroy-Beretta 2011) that offers a remarkable reading of the stoma from the point of view of a concern regarding shame and sexual modesty.
Noncontinent diversions are accomplished by ureteral anastomosis to the ileum or colon, with the stoma being formed by the bowel segment sutured to the outer skin (ileal conduit) (Costa, 2013; McDonald, 2011; Piras & Hurley, 2011).
The most common cause of stoma formation is colorectal cancer (67.
Prophylactic colostomies prevent burn-wound infection in severe, deep partial- or full-thickness burns of the peri-anal area, and therapeutic stomas aid with local control of systemic sepsis.
Background: Morbidity after stoma closure, however, is not negligible and the most common complication is postoperative surgical site infection.
Stoma care clinic and enterostomal therapist can be helpful in educating families for stoma care and to decrease the incidence of complications.
Another Tauranga nurse, Lyn Hudson, spoke about her experience working in Abu Dhabi; Waikato nurse Kay Berryman discussed a Maori perspective on bowel cancer; and Palmerston North nurse Dorothy Chimwayange talked about her experiences with stomas and bowel cancer in Africa.
After commencement of monitoring, the Hudson mask was disconnected and the elbow catheter mount connector from the circuit was placed over the stoma to pre-oxygenate the patient.