Part 27 (2/2)

SECRETION.

414. In the human body are found many fluids and solids of dissimilar appearance and character. These are produced by the action of organs, some of which are of simple structure, while others are very complicated in their arrangement. These organs are called _Se-creto-ry_.

ANATOMY OF THE SECRETORY ORGANS.

415. The SECRETORY ORGANS are the _Ex-halants_, _Folli-cles_, and the _Glands_.

416. The EXHALANTS were supposed to be terminations of arteries or capillaries. The external exhalants terminate on the skin and mucous membranes; the internal in the cellular and medullary tissues.

(Appendix I.)

[Ill.u.s.tration: Fig. 86. A secretory follicle. An artery is seen, which supplies the material for its secretion. Follicles are also supplied with veins and organic nerves.]

417. The FOLLICLES are small bags, or sacs, situated in the true skin, and mucous membrane. The pores seen on the skin are the outlets of these bodies.

414. How are the fluids and solids of the body produced? 415-419.

_Give the anatomy of the secretory organs._ 415. Name the secretory organs. 416. Describe the exhalants. What is represented by fig. 86?

417. Define follicles.

418. The GLANDS are soft, fleshy organs, and as various in their structure, as the secretions which it is their function to produce.

Each gland is composed of many small lobules united in a compact ma.s.s, and each lobule communicates by a small duct with the princ.i.p.al outlet, or duct of the organ. Every gland is supplied with arteries, veins, lymphatics, and nerves. These, with the ducts, are arranged in a peculiar manner, and connected by cellular membrane.

419. There are two cla.s.ses of glands, one for the modification of the fluids which pa.s.s through them, as the mesenteric and lymphatic glands; and the other for the secretion of fluids which are either useful in the animal economy, or require to be rejected from the body.

[Ill.u.s.tration: Fig. 87. 1, 1, A secretory gland. 2, 2, Minute ducts that are spread through the glands. These coalesce to form the main duct, 3.]

PHYSIOLOGY OF THE SECRETORY ORGANS.

420. SECRETION is one of the most obscure and mysterious functions of the animal economy. ”It is that process by which various substances are separated from the blood, either with or without experiencing any change during their separation.” Not only is the process by which substances are separated from the blood, called secretion, but the same term is also applied to substances thus separated. Thus physiologists say, that by the process of secretion, bile is formed by the liver; and also, that bile is the secretion of this organ.

418. Give the structure of the glands. 419. How are the glands arranged? 420-431. _Give the physiology of the secretory organs._ 420.

What is secretion?

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