File:A text-book of physiology for medical students and physicians (1911) (14592070908).jpg

Identifier: textbookofphysio1911howe (find matches)
Title: A text-book of physiology for medical students and physicians
Year: 1911 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology
Publisher: Philadelphia, London, W.B. Saunders company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ty so great as to defymeasurement. But in this same period a simple but completeexperiment by Helmholtz demonstrated that its velocity is, ascompared with light or with electrical conduction through the airor through metals, exceedingly slow.—27 meters per second.Modern views have taken divergent directions; the movementor excitation that is conducted along the fiber has been named 111 112 THE PHYSIOLOGY OF MUSCLE AND NERVE. the nerve principle, the nerve energy, the nerve force, the nerveimpulse. As the latter term is less specific regarding the natureof the movement, and emphasizes the fact of the conduction of anisolated disturbance or pulse, it seems preferable to employ ituntil a more satisfactory solution of its nature has been reached.The Velocity of the Nerve Impulse.—The determination ofthe velocity of the nerve impulse was first made by Helmholtz*upon the motor nerves of frogs. His experiment consisted instimulating the sciatic nerve, first, near its ending in the muscle
Text Appearing After Image:
Fig. 51. -Record to show the method of estimating the veloc tyof the nerve impulsein a motor nerve. The experiment was made upon a ner^muscle pref™XlumVy£frog, the contractions bring recorded upon the rapidly moving plate, of a Pe™ulum «££graph. Two contractions were obtained, the first a) when the.nerve™*f f™^ thenear the muscle, the second (b) when the nerve was stimulated as far as)possible inm™muscle The latent period of the second contraction was longer, as shown by the dbtancebetween the curves measured on the line x The value of this chstaace in tlme is^obta nedhv reference to the record of a tuning fork vibrating 100 times per secon,anv;^V* ^J^,on the lower line. In the experiment the length of a tuning fork wave (0.01 ■)•*mm^, the distance between the two muscular contractions was3.35 mms anjcityof ttetance between the points stimulated upon the ^^ef^^^ ^^J^f^l 16 m)nerve impulse in this experiment was 49 dividedby (oWff X T?o) or 30716 mms. (6V., lom.j per

Note About Images