Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

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    termed voluntary muscles. Those organs, the move- ments of which are essential to life, are supplied with muscles which act independently of the will, and are hence termed invohmtary muscles. The principal tnvoluntary muscles are the heart and the muscles of respiration and digestion. The involuntary muscles, being independent of the will, act at all times, sleep- ing or waking. Were they dependent on the will, their action would immediately cease on our going to sleep, in which case circulation and respiration would both cease, and death would follow as a necessary consequence. Muscular Contraction.—Muscles possess the property of active contractility, and tonicity, or passive contractility. When the muscles contract they become harder and about one-third shorter, but they do not lessen in real bulk. Portions only of a muscle contract at one time, those fibres wliich are at rest assuming a zig-zag direction. When a muscle is kept long in action its various fibrils alternately rest and contract. (See “ Muscular Tissue.”) The Tendons are the white, glistening, tough, inelastic, flexible cords by which the ends of the muscles are attached to the bones. They consist of white fibrous tissue, and are very sparingly supplied with nerves and bloodvessels. They are well and familiarly shown in the claw of a fowl. Bloodvessels, Nerves, and Lymphatics—The muscles are well supplied with bloodvessels, nerves, and lymphatics. It is said that the blood which leaves a muscle in action is of a dark colour, while that which leaves a muscle in a state of rest is of a bright scarlet colour, like arterial blood. ORGANS OF THE VOICE, AND THEIR FUNCTIONS. Voice and Speech, or the utterance of words, though frequently confounded with each other, are