Post on 13-Dec-2015
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Chapter 8:The Muscular
System
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Key Terms
acetylcholine insertion spasm
actin synapse
myalgia
myoglobin tendon
bursitis myosin tonus
neuromuscular junction tropomyosin
neurotransmitter troponin
origin
glycogen
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Cohen: Memmler’s The Human Body in Health and Disease
Types of Muscle
Learning Outcome
1. Compare the three types of muscle tissue.
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Cohen: Memmler’s The Human Body in Health and Disease
Types of Muscle
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Cohen: Memmler’s The Human Body in Health and Disease
Types of Muscle
✓Checkpoint
8-1 What are the three types of muscle?
Exam Question: Which ones are voluntary?
Which one is visceral?
Which one is in heart?
Which ones are striated?
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Cohen: Memmler’s The Human Body in Health and Disease
Types of Muscle
?Pop Quiz
8.1 Which type of muscle tissue is striated and involuntary?
A)Cardiac
B)Intercalated
C)Smooth
D)Skeletal
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Cohen: Memmler’s The Human Body in Health and Disease
Types of Muscle
?Pop Quiz Answer
8.1 Which type of muscle tissue is striated and involuntary?
A)Cardiac
B)Intercalated
C)Smooth
D)Skeletal
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Skeletal Muscle Has Three Primary Functions:
•Skeletal movement
•Posture maintenance
•Heat generation
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Muscle Cells in Action
•Neuromuscular junction (NMJ): The point at which a nerve fiber contacts a muscle fiber
– A type of synapse
– NMJ anatomy
• Motor neuron
• Neurotransmitter (acetylcholine; ACh)
• Motor end plate (on muscle fiber)
Contains acetylcholine receptors
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Muscle Cells in Action
•NMJ allows motor neuron to stimulate muscle fiber to become electrically excited (action potential)
•Action potential stimulates muscle contraction
•Events at the NMJ
– Ach is released from motor neuron into synaptic cleft
– Ach diffuses across synaptic cleft towards motor end plate
– Ach binds to receptors on motor end plate and stimulates action potential
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-2 Nerve supply to a skeletal muscle and the NMJ.
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
✓Checkpoints
8-2 What are the three main functions of skeletal muscle?
8-3 What is the name of the special synapse in which a nerve cell makes contact with a muscle cell?
8-4 What neurotransmitter is involved in the stimulation of skeletal muscle cells?
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Muscle Cells in Action
•The sarcomere is the functional unit of contraction in the skeletal muscle fiber
•Sarcomere anatomy:
– Thick filaments (myosin)
– Thin filaments (actin)
– Regulatory proteins
• Troponin
• Tropomyosin
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-3 Detailed structure of a skeletal muscle cell.
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Muscle Cells in Action
•Sarcomeres contract via the sliding filament mechanism:
– Myosin heads bind to actin, forming cross-bridges
– Using stored energy, myosin heads pull actin filaments together within the sarcomeres and the cell shortens
– New ATP is used to detach myosin heads and move them back into position for another “power stroke”
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-4 Sliding filament mechanism of skeletal muscle contraction.
Sliding filament mechanism of skeletal muscle contraction.
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Muscle Cells in Action
•Calcium regulates sarcomeric contraction within the muscle cell:
– Action potential from NMJ travels to sarcoplasmic reticulum (SR)
– SR releases calcium into cytoplasm
– Calcium shifts troponin and tropomyosin off of thin filament so that binding sites on actin are exposed
– Sliding filament mechanism now able to proceed
– Muscle relaxes when stimulation ends and calcium is pumped back into SR
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-5 Role of calcium in muscle contraction.
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Summary of Events in a Muscle Contraction
1.ACh is released from neuron ending into synaptic cleft at NMJ
2.ACh binds to motor end plate and produces action potential
3.Action potential travels to sarcoplasmic reticulum (SR)
4.SR releases calcium into cytoplasm
5.Calcium shifts troponin and tropomyosin so that binding sites on actin are exposed
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Summary of Events in a Muscle Contraction (continued)
6.Myosin heads bind to actin, forming cross-bridges
7.Using stored energy, myosin heads pull actin filaments together within sarcomeres and cell shortens
8.New ATP is used to detach myosin heads and move them back to position for another “power stroke”
9.Muscle relaxes when stimulation ends and calcium is pumped back into SR
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
✓Checkpoints
8-6 What filaments interact to produce muscle contraction?
8-7 What mineral is needed for interaction of the contractile filaments?
Exam Question: What are the regulatory proteins in muscle fibers?
What is the source of Energy for contraction?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
?Pop Quiz
8.3 The two filaments that form cross-bridges are
A)Actin and troponin
B)Tropomyosin and myosin
C)Actin and myosin
D)Troponin and tropomyosin
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
?Pop Quiz Answer
8.3 The two filaments that form cross-bridges are
A)Actin and troponin
B)Tropomyosin and myosin
C)Actin and myosin
D)Troponin and tropomyosin
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Energy Sources
•Muscle contraction requires ATP
•Skeletal muscle prefers to produces ATP via aerobic metabolism, which requires
– Oxygen
– Glucose
•Storage compounds ensure an adequate supply of oxygen and glucose for aerobic ATP metabolism
– Myoglobin
– Glycogen
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Energy Sources
•During strenuous activity, muscle cells use anaerobic ATP metabolism, which does not require ATP
– Breakdown of creatine phosphate
– Anaerobic glycolysis
• Lactic acid accumulation and oxygen debt
• Excess postexercise oxygen consumption
– After strenuous exercise, person takes in extra oxygen (via rapid breathing) to remove lactic acid and replenish energy stores
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
Effects of Exercise
•Improved balance, joint flexibility
•Increased muscle size (hypertrophy)
•Improved muscle tissue
•Vasodilation
•Strengthened heart muscle
•Improved breathing and respiratory efficiency
•Weight control
•Stronger bones
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Cohen: Memmler’s The Human Body in Health and Disease
The Muscular System
✓Checkpoints
8-8 What compound is formed in oxidation of nutrients that supplies the energy for contraction?
8-9 What acid accumulates during anaerobic metabolism?
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Cohen: Memmler’s The Human Body in Health and Disease
The Mechanics of Muscle Movement
• Tendons attach muscles to bones.
– Origin: Attached to more fixed part of skeleton
– Insertion: Attached to more movable part of skeleton
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-6 Muscle attachments to bones.
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-8 Superficial muscles, anterior view.
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-9 Superficial muscles, posterior view.
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
Muscles That Move the Shoulder and Arm
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
Muscles That Move the Forearm and Hand
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-11 Muscles that move the forearm and hand.
What does carpi refer to in the names of muscles? Digitorum?
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
Muscles of the Trunk
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-12 Muscles of respiration.
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Cohen: Memmler’s The Human Body in Health and Disease
What does rectus mean? Oblique?
Figure 8-13 Muscles of the abdominal wall.
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
Muscles That Move the Leg and Thigh
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
Muscles That Move the Leg and Thigh (continued)
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-15 Muscles of the thigh.
How many muscles make up the quadriceps femoris?
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Cohen: Memmler’s The Human Body in Health and Disease
Skeletal Muscle Groups
✓Checkpoints
8-14 What muscle is most important in breathing?
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Cohen: Memmler’s The Human Body in Health and Disease
Muscular Disorders
Common Terms Used When Describing Muscular Disorders
•Spasms
– Colic
– Seizure
– Convulsion
•Cramps
•Atrophy
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Cohen: Memmler’s The Human Body in Health and Disease
Muscular Disorders
Muscle Injuries
•Strains
•Sprains
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Cohen: Memmler’s The Human Body in Health and Disease
Muscular Disorders
Diseases of Muscle
•Muscular dystrophy
•Myalgia
– Myositis
•Fibromyalgia syndrome (FMS)
•Bursitis
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Cohen: Memmler’s The Human Body in Health and Disease
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Cohen: Memmler’s The Human Body in Health and Disease
Muscular Disorders
Disorders of Associated Structures
•Bursitis
•Tendinitis
•Carpal tunnel syndrome
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Cohen: Memmler’s The Human Body in Health and Disease
Figure 8-17 Carpal tunnel syndrome.