front 1 What You'll Learn After you finish this lesson, you will be able to: | back 1
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front 2 Muscular System The muscular system contains over 600 muscles. About 40% of a person's body weight comes from muscles. The muscular system performs these functions: | back 2
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front 3 Muscle Traits Muscles usually act in groups to create movement, although each muscle is a distinct part. All muscles have four common traits. | back 3 Excitability or Irritability: The ability to respond to a stimulus, such as anerve orhormone. Muscles can be stimulated electrically, mechanically, or chemically.
Muscle tone refers to the ability of muscles to be slightly contracted at all times, even when not in use. It allows a person to be in a state of readiness to act. |
front 4 The ability of muscles to be slightly contracted at all times to be ready to act is known as muscle _______. | back 4 tone |
front 5 Ability to be stretched and lengthened | back 5 extensibility |
front 6 Ability to shorten and produce movement when stimulated | back 6 contractibility |
front 7 Ability to respond to a stimulus, such as a nerve or hormone | back 7 excitability (irratibility) |
front 8 Ability to return to its original shape after contracting or stretching | back 8 elasticity |
front 9 Types of Muscles The three types of muscle tissue are cardiac, visceral, and skeletal. | back 9 Cardiac muscle forms the walls of the heart. When it contracts, this type of muscle causes the heart to beat to circulate blood.
Cardiac and visceral muscles are involuntary, which means that they are not controlled by a person's conscious thought, or will. Most skeletal muscles are voluntary, which means that a person can control their actions. |
front 10 A person can control the actions of involuntary muscles.
| back 10 False |
front 11 Which types of muscle are generally voluntary?
| back 11 Skeletal |
front 12 Attached to the bones to help produce body movement | back 12 skeletal |
front 13 Forms the walls of the heart and causes the heart to beat | back 13 cardiac |
front 14 Found in hollow organs, in the walls of blood vessels, and in the eyes | back 14 visceral |
front 15 Attachment of Skeletal Muscles | back 15 While ligaments attach bone to bone, muscles are attached to bones by bands of fibrous tissue called tendons. The end of the muscle that is connected to the bone that does not move is called the origin. The end connected to the bone that moves when the muscle contracts is called the insertion. Fascia is a sheet of tough fibrous tissue that wraps around an individual muscle. |
front 16 Attaches muscle to bone | back 16 tendon |
front 17 End of the muscle connected to the bone that moves | back 17 insertion |
front 18 Sheet of tough fibrous tissue that wraps around an individual muscle | back 18 fascia |
front 19 End of the muscle connected to the bone that does NOT move | back 19 origin |
front 20 Types of Body Movements Types of body movements made by skeletal muscles include: | back 20 Flexion: Bending a body part, which decreases the angle of thejoint.
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front 21 What type of body movement occurs in the leg when a person kicks a soccer ball forward?
| back 21 Extension |
front 22 What type of body movement occurs in the neck when a person turns the head from side-to-side to signal "No?"
| back 22 Rotation |
front 23 Lesson Summary In this lesson, you learned that: | back 23
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