The Muscular System

The allows the body to move voluntarily, but it also controls involuntary movements of other such as heartbeat in the circulatory system and peristaltic waves in the . It consists of over six hundred skeletal muscles, as well as the heart muscle, the smooth muscles that surround your entire alimentary canal, and all your arterial blood vessels (see Figure 2.24 “The Muscular System in the Human Body”). Muscle contraction relies on energy delivery to the muscle. Each movement uses up cellular energy, and without an adequate energy supply, muscle function suffers. Muscle, like the liver, can store the energy from in the large polymeric molecule . But unlike the liver, muscles use up all of their own stored energy and do not export it to other in the body. Muscle is not as susceptible to low levels of blood glucose as the brain because it will readily use alternate fuels such as fatty acids and protein to produce cellular energy.


Illustration of a human figure highlighting the 6 muscle types with close up illustrations of each type: A: Circular (orbicularis oris muscle) B: Convergent (Pectoralis muscle), C: Multipennate (Deltoid muscle), D: Parallel (Biceps brachii muscle), E: Unipennate (Extensor digitorum muscle), F: Bipennate (Rectus femoris muscle).
Figure 2.24 The Muscular System in the Human Body
“Muscle Types” by BruceBlaus / CC BY-SA 4.0

Learning Activities

Technology Note: The second edition of the Human Nutrition Open Educational Resource (OER) textbook features interactive learning activities.  These activities are available in the web-based textbook and not available in the downloadable versions (EPUB, Digital PDF, Print_PDF, or Open Document).

Learning activities may be used across various mobile devices, however, for the best user experience it is strongly recommended that users complete these activities using a desktop or laptop computer.




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