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Section 11.2 Your Muscular System
Objectives
Describe the functions of the three types of muscles.
Explain how you can keep your muscular system healthy.
Section 11.2 Your Muscular System
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Section 11.2 Your Muscular System
Myth No pain, no gain.
Fact Pain is not a sign of a good workout. Rather, pain is a signal from your body that you are working too hard or you have an injury. Continuing to exercise through the pain could lead to a more serious injury.
Where do you think most teens get their information about muscles? How factual do you think their information is?
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Section 11.2 Your Muscular System
• Muscles move your eyes as you read.The Muscles in Your Body
• Muscles in your chest allow you to breathe.• Muscles in your heart pump your blood. • Every time your body moves, muscles are at work.
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Section 11.2 Your Muscular System
Your body has three types of muscle tissue that perform different functions.
Types of Muscle
• Smooth muscle is involuntary muscle that causes movements within your body.
• Cardiac muscle is involuntary muscle that is found only in the heart.
• Skeletal muscles are the muscles that you control to do activities, such as walk or play a musical instrument. A thick strand of tissue called a tendon attaches a muscle to a bone.
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Section 11.2 Your Muscular System
• All muscles do work by contracting, or becoming shorter and thicker.
How Muscles Work
• Many skeletal muscles work in pairs.• One muscle in the pair contracts to move the
bone in one direction.• Then, the other muscle in the pair contracts to
move the bone back.
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Section 11.2 Your Muscular System
Muscle Pairs
Biceps contracted
Biceps relaxedTriceps relaxed
Triceps contracted
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Section 11.2 Your Muscular System
• Even when a skeletal muscle is not contracting to cause movement, a few of its individual muscle fibers are still contracting.
Muscle Tone
• Contractions tense and firm the muscle.
• This slight tension is called muscle tone.• Muscles that cannot contract due to injury, or are not
used often, will weaken and shrink, a condition known as atrophy.
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Section 11.2 Your Muscular System
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The Muscular System
1) Frontalis
2) Temporalis
3) Trapezius
4) Deltoid
5) Pectoralis major
6) Sartorius
7) Tibialis anterior
8) Biceps
9) Triceps
10) External oblique
11) Rectus abdominus
12) Quadriceps muscles
13) Gastrocnemius
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Section 11.2 Your Muscular System
• You can maintain a healthy muscular system by regularly participating in different types of exercise.
Keeping Healthy
• To help prevent injuries, exercise sessions should include a warm-up and cool-down period.
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Section 11.2 Your Muscular System
• Some types of exercise increase a muscle’s endurance—how long it can contract without tiring.
Working Your Muscles
• Other exercises make individual fibers grow, which causes the muscles to thicken and increase in strength.
• Anabolic steroids are artificial forms of the male hormone testosterone.
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Section 11.2 Your Muscular System
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Section 11.2 Your Muscular System
• Strains A muscle strain, or a pulled muscle, is a painful injury that may happen when muscles are overworked or stretched too much or too quickly.
Avoiding Muscle Injuries
• Tendonitis Overuse of tendons may lead to painful swelling and irritation called tendonitis (ten duh NY tis).
• Prevent injuries• regular strengthening and stretching exercises • vary your exercise routine • warm up and cool down • stop exercising if you feel a sharp or sudden pain
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Section 11.2 Your Muscular System
• A muscle cramp is a strong, uncontrolled muscle contraction.
Preventing Muscle Cramps
• To relieve a cramp, try massaging the affected area and exercising the limb gently.
• Stretching and drinking plenty of water before and during exercise can help you avoid muscle cramps.
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Section 11.2 Your Muscular System
Vocabulary
smooth muscle Involuntary muscle that causes movements inside your body, such as those involved in breathing and digestion.
cardiac muscle Involuntary muscle that is found only in the heart.
skeletal muscle Voluntary muscle that is attached to and moves your bones.
tendon A think strand of tissue that attaches a muscle to a bone.
muscle tone Contractions of limited muscle fibers that keep a muscle tense, but do not produce movement.
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Section 11.2 Your Muscular System
Vocabulary
atrophy A condition in which muscles that cannot contract or are not used often weaken and shrink.
anabolic steroid An artificial form of the male hormone testosterone that is used to increase muscle size and strength.
strain A pulled muscle.
tendonitis Painful swelling and irritation of a tendon, often caused by overuse.
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Section 11.2 Your Muscular System
QuickTake Quiz
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Section 11.2 Your Muscular System
End of Section 11.2
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