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BIO304: Human Physiology

Unit 7: The Muscular System   The muscular system allows the body to move, inside and out. Often we think of the muscular system as big biceps like Popeye or strong leg muscles like you might see on Olympic runners. While these skeletal muscles are important, the muscular system is much more than just skeletal muscle. The cardiac muscles that make up the myocardium of the heart keep the heart contracting 24 hours a day 7 days a week. Unlike skeletal muscle that gets tired and we control (voluntary), cardiac muscle never fatigues and we have no control over it (involuntary). A third type of muscle is smooth muscle. It is also involuntary and can be found lining the gastrointestinal track, around the alveoli in the lungs, and even in the female uterus, among other places. Smooth muscle has long rhythmic contractions that are involuntary. Unless they are super strong – like in childbirth – or they are erratic and cause stomach cramping, we do not even realize that they are contracting. All three muscle types work hard to move things – for example blood (cardiac), food (smooth), and our pencil to take notes (skeletal). In this unit, we will explore how muscles contract to cause this movement and learn a bit more how these three muscle types are alike and differ. Finally, we will make the important connection between the muscular system and other systems in the body, such as the nervous system.

Unit 7 Time Advisory
This unit should take approximately 8 hours to complete.

☐    Subunit 7.1: 2.5 hours

☐    Subunit 7.2: 4 hours
 

☐    Web Media: 2 hours

☐    Assessment: 2 hours

☐    Subunit 7.3: 1.25 hours

☐    Subunit 7.4: 0.25 hours

Unit7 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - identify the different types of muscle tissues; - describe the structure of skeletal muscle; - explain the mechanisms of the contraction of skeletal muscles, including neuromuscular junction and sliding theory; and - describe the mechanism of smooth muscle contraction.

7.1 Types of Muscle Tissue   - Reading: Wikibooks’ Human Physiology: “The Muscular System” Link: Wikibooks’ Human Physiology: “The Muscular System” (HTML)

 Instructions: Click on the link above and read this chapter on the
muscular system. As you read note the key differences between
skeletal, cardiac, and smooth muscles and consider how each muscle
type has a particular structure that helps it to carry out its own
function. This chapter contains a lot of information. It may be
helpful to make a chart with the three muscle types and their
characteristics and location.  

 Reading this chapter and taking notes should take 2 hours and 30
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

7.2 Skeletal Muscles   - Web Media: YouTube: Great Pacific Media’s “Skeletal Muscle Structure” Link: YouTube: Great Pacific Media’s “Skeletal Muscle Structure” (YouTube)

 Instructions: Click on the link above and watch this video for a
brief visual illustration of the structure of skeletal muscles. The
structure function relationship is very important in skeletal
muscle. Notice how the cross bridges allow for contraction and when
relaxed, myosin binding sites are covered to prevent cross bridges
from forming.  

 Watching this video and pausing to take notes should take
approximately 30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Garland Science’s “Skeletal Muscle Contraction” Link: YouTube: Garland Science’s “Skeletal Muscle Contraction” (YouTube)

    Instructions: Click on the link above and watch this video to visualize the process of contraction in skeletal muscle tissue. Notice the complexity of this process! Can you believe that this process is happening in milliseconds?

    Watching this video and pausing to take notes should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: Khan Academy’s “Myosin and Actin”, “Tropomyosin and Troponin”, “Role of the Sarcoplasmic Reticulum”, and “Anatomy of a Muscle Cell” Link: YouTube: Khan Academy’s “Myosin and Actin” , “Tropomyosin and Troponin” , “Role of the Sarcoplasmic Reticulum” , and “Anatomy of a Muscle Cell” 

    Instructions: Watch these videos to review the specifics of muscle contraction.

    Watching these videos and pausing to take notes should take approximately 1 hour and 15 minutes.

    Terms of Use: These videos are licensed under a Creative Commons Attribution-NonCommercial-NoDerives United States License 3.0. They are attributed to the Khan Academy. 

7.3 Smooth Muscle   - Web Media: YouTube: Khan Academy’s “Three Types of Muscle” Link: YouTube: Khan Academy’s “Three Types of Muscle” (YouTube)
 
Instructions: Watch this video which describes in simple and clear detail the structure and function of smooth muscle, skeletal muscle, and cardiac muscle.
 
Watching this video and taking notes should take approximately 30 minutes.
 
Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License. It is attributed to Khan Academy, and the original version can be found here.

7.4 Cardiac Muscle   - Web Media: YouTube: “Anatomy and Physiology in Focus: Cardiac Tissue” Link: YouTube: “Anatomy and Physiology in Focus: Cardiac Tissue” (YouTube)

 Instructions: This is a brief video, but it includes a lot of
detailed information. Cardiac muscle cells are shown and the key
features of these cells are illustrated. Keep in mind as you view
this video that similar cells are working in your body so that your
heart continues to contract.  

 Watching this video and pausing to take notes should take you
approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.