capillary


capillary
/kap"euh ler'ee/, adj., n., pl. capillaries.
adj.
1. pertaining to or occurring in or as if in a tube of fine bore.
2. resembling a strand of hair; hairlike.
3. Physics.
a. pertaining to capillarity.
b. of or pertaining to the apparent attraction or repulsion between a liquid and a solid, observed in capillarity.
4. Anat. pertaining to a capillary or capillaries.
n.
5. Anat. one of the minute blood vessels between the terminations of the arteries and the beginnings of the veins.
6. Also called capillary tube. a tube with a small bore.
[1570-80; capill(ar) (obs., < L capillaris pertaining to hair, equiv. to capill(us) hair + -aris -AR1) + -ARY]

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Any of the minute blood vessels that form networks where the arterial and venous circulation (see artery, vein) meet for exchange of oxygen, nutrients, and wastes with body tissues.

Capillaries are just large enough for red blood cells to pass through in single file. Their thin walls are semipermeable, allowing small molecules to pass through in both directions. The smallest lymphatic vessels and minute bile channels in the liver are also called capillaries.

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      in human physiology, any of the minute blood vessels that form networks throughout the bodily tissues; it is through the capillaries that oxygen, nutrients, and wastes are exchanged between the blood and the tissues. The capillary networks are the ultimate destination of arterial blood from the heart and are the starting point for flow of venous blood back to the heart. Between the smallest arteries, or arterioles, and the capillaries are intermediate vessels called precapillaries, or metarterioles, that, unlike the capillaries, have muscle fibres that permit them to contract; thus the precapillaries are able to control the emptying and filling of the capillaries.

      The capillaries are about 8 to 10 microns (a micron is 0.001 millimetre) in diameter, just large enough for red blood cells to pass through them in single file. The single layer of cells that form their walls are endothelial cells, like those that form the smooth channel surface of the larger vessels.

      The networks of capillaries have meshes of varying size. In the lungs and in the choroid—the middle coat of the eyeball—the spaces between capillaries are smaller than the vessels themselves, while in the outer coat of arteries—the tunica adventitia—the intercapillary spaces are about 10 times greater than the diameter of the capillaries. In general, the intercapillary spaces are smaller in growing parts, in the glands, and in mucous membranes; larger in bones and ligaments; and almost absent in tendons.

      The smallest vessels in the lymphatic system are also called capillaries, as are the minute channels for bile in the liver. See also artery; vein.

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Universalium. 2010.

Synonyms:
(like a hair), , , ,


Look at other dictionaries:

  • Capillary — Cap il*la*ry (k[a^]p [i^]l*l[asl]*r[y^] or k[.a]*p[i^]l l[.a]*r[y^]; 277), a. [L. capillaris, fr. capillus hair. Cf. {Capillaire}.] 1. Resembling a hair; fine; minute; very slender; having minute tubes or interspaces; having very small bore; as,… …   The Collaborative International Dictionary of English

  • capillary — 1650s (adj.), 1660s (n.), from L. capillaris of hair, from capillus hair (of the head); probably related to caput head. Borrowed earlier as capillar (14c.). Capillary attraction attested from 1813. Capillarity is recorded from 1830, from Fr.… …   Etymology dictionary

  • capillary — ► NOUN 1) Anatomy any of the fine branching blood vessels that form a network between the arterioles and venules. 2) (also capillary tube) a tube with an internal diameter of hair like thinness. ► ADJECTIVE ▪ relating to capillaries or… …   English terms dictionary

  • capillary — [kap′ə ler΄ē; ] Brit [ kə pil′ə ri] adj. [L capillaris < capillus, hair] 1. of or like a hair, esp. in being very slender 2. having a very small bore 3. in or of capillaries n. pl. capillaries 1. a tube with a very small bo …   English World dictionary

  • Capillary — Cap il*la*ry, n.; pl. {Capillaries}. 1. A tube or vessel, extremely fine or minute. [1913 Webster] 2. (Anat.) A minute, thin walled vessel; particularly one of the smallest blood vessels connecting arteries and veins, but used also for the… …   The Collaborative International Dictionary of English

  • Capillary — Capillaries are the smallest of a body s blood vessels, measuring 5 10 μm in diameter, which connect arterioles and venules, and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances… …   Wikipedia

  • Capillary — One of the tiny blood vessels that connect the arterioles (the smallest divisions of the arteries) and the venules (the smallest divisions of the veins). The capillaries form a fine network in many parts of the body. Although minute, the… …   Medical dictionary

  • capillary — I. adjective Etymology: French or Latin; French capillaire, from Latin capillaris, from capillus hair Date: 14th century 1. a. resembling a hair especially in slender elongated form < capillary leaves > b. having a very small bore < a capillary… …   New Collegiate Dictionary

  • capillary — /kəˈpɪləri / (say kuh piluhree) noun (plural capillaries) 1. Anatomy one of the minute blood vessels between the terminations of the arteries and the beginnings of the veins. 2. Also, capillary tube. a tube with a small bore. –adjective 3.… …   Australian English dictionary

  • capillary — adj. & n. adj. 1 of or like a hair. 2 (of a tube) of hairlike internal diameter. 3 of one of the delicate ramified blood vessels intervening between arteries and veins. n. (pl. ies) 1 a capillary tube. 2 a capillary blood vessel. Phrases and… …   Useful english dictionary


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