Muscle Tissue:  Focus on Skeletal Muscle

You are reading chapter 9, pages 234 - 243 (and part of page 251) for this material in your Marieb book (stop before "Contraction of a Skeletal Muscle Fiber").  That's only 10 pages!  You will be reading similar amounts for the next few units.  However, this material is tough, and you will need to spend a lot of time on it in order to understand it thoroughly... you will also be using the Interactive Physiology CD that you bought with your book to learn the concepts in this muscle unit.

This unit's material can be divided into the following major concepts:

A few additional notes that will help you to work through this material...

1. You might want to run through the CD web page and the CD program before going through the web page.  The material on the CD program you will be using this week will include material from the composition of a muscle, composition of a muscle fiber, and composition of a myofibril web pages.
2. Muscle cells use electrical signals to tell them when to contract.  The signal originates in the nervous system and comes to the muscle cells as a nervous system command.  The cells in the nervous system also work electrically.  We will spend a lot of time going over how this electrical signalling works when we get to the nervous system... so for now, we will only discuss it briefly.
3. Muscle cells, called muscle fibers, are odd-looking cells.  In order to understand these cells you have to be able to lose your mental image of the "typical cell" and try to re-create a new type of cellular image using the same organelles, but in different arrangements.  You will see that muscle fibers are huge cells, filled with cytoskeleton; they have many nuclei (not just one) and have lots and lots of sER.
4. The cytoskeleton of cells can be quite complex.  In muscle fibers it is very organized and orderly.  If you work to understand this order, you will find it easier to understand how muscle fibers can contract.
5. Just because something is arranged in a long tube does not mean that it is a cell or that it is a part of a cell.  You will see that muscles are made up of tubes inside of tubes inside of tubes inside of tubes.  The largest tube is the muscle itself, and the smallest tube is the contractile machinery within individual muscle fibers.   Therefore, when you see an image of these tubes in tubes, take your time to figure out what level the image is from... is it of muscle fibers?  ...of something larger?   ...of something smaller?

© 2011 STCC Foundation Press
written by Dawn A. Tamarkin, Ph.D.