Muscle Contraction

Kaylee Hennessey            November 22, 2013       Period A

The Mechanism of Muscle Contraction

Texas A&M University

1 Page

Summary of the Article

The following steps are involved in muscle contraction:

1. Reflexes from the spinal cord or instructions from the brain cause nerve cells to initiate a reaction

2. A motor neuron is activated, and action potential passes out of the spinal cord

3. Action potential is conveyed to a numerous amount of places on the motor unit

4. ACh is released into synaptic clefts on the surface of the muscle fiber

5. ACh causes an action potential on the muscle fiber surface, dragging in separate directions

The Sliding Filament Theory

6. Action potential spreads into the muscle fiber through each transverse tubule

7. Sarcoplasmic reticulum releases calcium ions

8. Calcium ions result in movement of tropomin and tropomyosin on thin filaments. Myosin molecules swivel the filaments, which is the driving force of muscle contraction.

In conclusion, the nervous system plays a large part in the contraction and relaxation of muscles.

Smooth and Skeletal Muscle

Kaylee Hennessey                  November 6, 2013           Period A

Smooth and Skeletal Muscle

Dr. Thomas Caceci

1 page (continuous)

Summary of the Article:

           There are two major classifications of muscle: smooth and striated. Skeletal as well as cardiac muscle fall under the category of striated. Muscles are metabolically dynamic tissues and receive plentiful blood flow.All muscles can be excited, in that they respond to stimuli outside or inside the body. Both neuron stimulation and chemical stimulation affects the response of the cells.  

Skeletal Muscle:

Skeletal muscle is voluntary because it is subject to control by the nervous system. Most movement requires skeletal muscle. 

Skeletal muscle fibers

 Skeletal muscle is made of numerous fibers grouped together. Fibers can be grouped into larger groups, which are then grouped into even larger groups and attached to bones by tendons.

Smooth Muscle:

Smooth muscle is non-striated and found in all organ systems. They are involuntary muscles and help with processes like digestion and sometimes are present in large blood vessels.

Smooth muscle fibers are largest in the center.