Introduction - from the book
Muscle tissues can contract; that is, their elongated cells, or muscle fibers, can shorten. As they contract, muscle fibers pull at their attached ends, which moves body parts.
There are three specific types of muscle tissue.
1. Skeletal Muscle - also called volutnary or striated muscle.
The striations (stripes) are due to a very orginized pattern of proteins found within the cells. The black arrow is pointing to a nucleus.
This is the type of muscle that you eat if you eat meat.
2. Smooth Muscle - also called involuntary or visceral muscle.
Smooth muscle is stronger than skeletal muscle. If you ever had stomach cramps you know how strong smooth muscle can be - a better example is labor (for those of you who have experienced or seen child birth) - the uterus has a large quantity of smooth muscle that works to "birth" a baby.
3. Cardiac muscle - or heart muscle
Found only in the heart! Like skeletal muscle, cartiac muscle is striated, but cardiac muscle also contains structures called intercalated disks (blue arrow) that work to produce the rhythmic contractions of the heart. Intercalated disks are found only in cardiac muscle.
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