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Stoma

Definition

noun, plural: stomata

(botany) A tiny pore in a plant leaf surrounded by a pair of guard cells that regulate its opening and closure, and serves as the site for gas exchange.

(zoology) Mouth-like opening, such as the stoma (or the oral cavities) of nematodes.

(anatomy) A natural opening in the body, such as the mouth.

(medicine) Artificial opening in the body created by surgery, connecting a portion of the body cavity to the outside environment.


Supplement

Stomata may refer to the natural openings to the outside environment, such as those on plant leaves or oral cavities of certain animals. Stomata may also refer to the artificial body openings created by surgery.

In plants, the stomata are actually the pores created by the swelling of guard cells to allow CO2 to enter into the leaf, which is a necessary reactant of photosynthesis. The water vapor and O2 are also allowed to escape via the pore. In order to form a pore or stoma, osmotic pressure draws water to increase the cells volume; this in turn causes the guard cells to bow apart from each other because the inner wall of the pore is more rigid than the wall on the oppostie side of the cell.

Stomata are present in all terrestrial plants (in sporophyte phase), except for the liverworts. Dicots usually have more stomata on the lower epidermis than the upper epidermis whereas monocots usually have the same number of stomata on both sides. Plants whose leaves float in water have stomata only on the upper epidermis whereas plants whose leaves are completely submerged may lack stomata entirely.

In medicine, any hollow organ can be manipulated into an artificial stoma as necessary. This includes the esophagus, stomach, duodenum, ileum, colon, pleural cavity, ureters, etc. A widely known example is colostomy, which is a stoma created in the abdominal wall to permit the passage of waste.


Word origin: From Ancient Greek stoma, “‘mouth’”.

Related forms: stomal, stomatal (adjective).

Synonym: stomate (botany).


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Re: Co2

You asked about Water Lilies, and these plants function much like other terrestrial plants do, with the adaptation of stoma on the upper epidermis. However, other aquatic plants have adapated in other ways. In other words, I don't think you can generalize plants, each species has ...

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by MichaelXY
Tue Nov 11, 2008 7:29 am
 
Forum: Ecology
Topic: Co2
Replies: 14
Views: 10181

Re: Co2

The stomata is used for transpiration and exchange of gases. Water Lilies are adapted with stoma on the upper dermis and not the lower. I guess we all learn new things everyday, I did not know about the concentration ratio among ...

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by MichaelXY
Mon Nov 10, 2008 7:47 pm
 
Forum: Ecology
Topic: Co2
Replies: 14
Views: 10181

Photosynthesis Trivia

... cuticle in a plant? (A.) To direct chromosomes during meiosis. (B.) To form a barrier to water loss on the leaf surface. (C.) To provide a cue for stoma opening and closing. (D.) To store the energy of photosynthesis in the form of chemical bonds. (E.) Transporting minerals from the roots. 17. ...

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by vstexas09
Mon Oct 13, 2008 12:46 am
 
Forum: Cell Biology
Topic: Photosynthesis Trivia
Replies: 5
Views: 28855

Respiration

... are three important adaptations in the mammalian respiratory system? What advantages do these adaptations provide? 4/Among lenticel, spiracle and stoma. a/ Which of these structures open and close? b/ Does opening and closing serve the same purpose for the different structures? Thanks for helping. ...

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by vhpk
Tue May 06, 2008 9:47 am
 
Forum: Cell Biology
Topic: Respiration
Replies: 2
Views: 2256

Stomata Question.

How long does the stoma stay open when it is closed? Does it open and close instantly or not?

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by negativefx14
Sun Jan 13, 2008 8:18 pm
 
Forum: Botany Discussion
Topic: Stomata Question.
Replies: 5
Views: 3179
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