from The American Heritage® Dictionary of the English Language, 4th Edition
- n. One of the segments into which a fibril of striated muscle is divided.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The contractile unit of the myofibril of a striated muscle.
from The Century Dictionary and Cyclopedia
- n. A segment of a muscular fibril inclosed between two Krause's membranes.
- n. One of the segments or pieces of a sarcostyle.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. one of the segments into which a myofibril is divided
The sarcomere is the primary functional unit of cardiac muscle that is responsible for contraction and force generation.
In this way the contraction is brought about: under stimulation the protoplasmic material (the clear substance of the sarcomere) recedes into the sarcous element, causing the sarcomere to widen out and shorten.
A sarcostyle may be said to be made up of successive portions, each of which is termed a sarcomere.
When the muscular fiber is contracted the clear part of the muscular substance is driven into these channels or tubes, and is therefore hidden from sight, but at the same time it swells up the sarcous element and widens and shortens the sarcomere.
When, on the other hand, the fiber is extended, this clear substance is driven out of the tubes and collects between the sarcous element and the membrane of Krause, and gives the appearance of the light part between these two structures; by this means it elongates and narrows the sarcomere.
In muscle there is the same thing, viz., a framework of spongioplasm staining with hematoxylinthe substance of the sarcous elementand this encloses a clear hyaloplasm, the clear substance of the sarcomere, which resists staining with this reagent.
The sarcous element does not lie free in the sarcomere, for when the sarcostyle is stretched, so as to render the clear portion visible, very fine lines, which are probably septa, may be seen running through it from the sarcous element to the membrane of Krause.
The sarcomere is situated between two membranes of Krause and consists of (1) a central dark part, which forms a portion of the dark band of the whole fiber, and is named a sarcous element.
Now, researchers have discovered a protein that is the mainstay of the smallest muscular unit, the sarcomere, which contributes to a healthy heart.
Inhibition of calpain prevents muscle weakness and disruption of sarcomere structure during hindlimb suspension.