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PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
10
HUMAN
ANATOMY
PART 1
Muscle Tissue
fifth edition
MARIEB | MALLATT | WILHELM
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Muscle


Muscle – a Latin word for “little mouse”
Muscle is the primary tissue in the
 Heart (cardiac MT)
 Walls of hollow organs (Smooth MT)

Skeletal muscle
 Makes up nearly half the body’s mass
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Overview of Muscle Tissue

Functions of muscle tissue
 Movement
 Skeletal muscle - attached to skeleton
 Moves body by moving the bones
 Smooth muscle – squeezes fluids and other
substances through hollow organs
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Overview of Muscle Tissue

Functions of muscle tissue (continued)
 Maintenance of posture – enables the body to
remain sitting or standing
 Joint stabilization
 Heat generation
 Muscle contractions produce heat
 Helps maintain normal body temperature
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Functional Features of Muscles

Functional features
 Contractility
 Long cells shorten and generate pulling force
 Excitability
 Electrical nerve impulse stimulates the muscle cell
to contract
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Functional Feature of Muscles

Functional features
 Extensibility
 Can be stretched back to its original length by
contraction of an opposing muscle
 Elasticity
 Can recoil after being stretched
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Types of Muscle Tissue

Three types of MT
 Skeletal muscle tissue
 Packaged into skeletal muscles
 Makes up 40% of body weight
 Cells are striated
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Types of Muscle Tissue

Three types of MT (continued)
 Cardiac muscle tissue – occurs only in the walls
of the heart
 Smooth muscle tissue – occupies the walls of
hollow organs
 Cells lack striations
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Similarities of Muscle Tissue

Cells of muscles
 Are known as fibers

Muscle contraction
 Depends on two types of myofilaments (contractile
proteins)
 One type contains actin
 Another type contains myosin
 These two proteins generate contractile force
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Similarities of Muscle Tissues


Plasma membrane is called a sarcolemma
Cytoplasm is called sarcoplasm
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Skeletal Muscle

Each muscle is an organ
 Consists mostly of muscle tissue
 Skeletal muscle also contains
 Connective tissue
 Blood vessels
 Nerves
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Basic Features of a Skeletal Muscle

Connective tissue and fascicles
 Connective tissue sheaths bind a skeletal muscle
and its fibers together
 Epimysium – dense regular connective tissue
surrounding entire muscle
 Perimysium – surrounds each fascicle
(group of muscle fibers)
 Endomysium – a fine sheath of connective tissue
wrapping each muscle cell
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Basic Features of a Skeletal Muscle


Connective tissue sheaths are continuous with
tendons
See Figure 10.1a
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Connective Tissue Sheaths in Skeletal Muscle
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Figure 10.1a
Basic Features of a Skeletal Muscle

Nerves and blood vessels
 Each skeletal muscle supplied by branches of
 One nerve
 One artery
 One or more veins
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Basic Features of a Skeletal Muscle

Nerves and blood vessels
 Nerves and vessels branch repeatedly
 Smallest nerve branches serve
 Individual muscle fibers
 Neuromuscular junction – signals the muscle to
contract
 Draw a picture of neuromuscular junction
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Basic Features of a Skeletal Muscle

Muscle attachments
 Most skeletal muscles run from one bone to
another
 One bone will move – other bone remains fixed
 Origin – less movable attachment
 Insertion – more movable attachment
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Muscle Attachments
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Figure 10.3
Basic Features of a Skeletal Muscle

Muscle attachments (continued)
 Muscles attach to origins and insertions by CT
 Fleshy attachments – CT fibers are short
 Indirect attachments – CT forms a tendon or
aponeurosis
 Bone markings present where tendons meet bones
 Tubercles, trochanters, and crests
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Microscopic and Functional Anatomy
of Skeletal Muscle Tissue

The skeletal muscle fiber
 Fibers are long and cylindrical
 Are huge cells – diameter is 10–100µm
 Length – several centimeters to dozens of
centimeters
 Each cell formed by fusion of embryonic cells
 Cells are multinucleate
 Nuclei are peripherally located
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Diagram of Part of a Muscle Fiber
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Figure 10.4b
Myofibrils and Sarcomeres


Striations result from internal structure of
myofibrils
Myofibrils
 Long rods within cytoplasm
 Make up 80% of the cytoplasm
 Are a specialized contractile organelle found in
muscle tissue
 A long row of repeating segments called
sarcomeres (functional unit of Skeletal MT)
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Sarcomere

Basic unit of contraction of skeletal muscle
 Z disc (Z line) – boundaries of each sarcomere
 Thin (actin) filaments – extend from Z disc
toward the center of the sarcomere
 Thick (myosin) filaments – located in the center
of the sarcomere
 Overlap inner ends of the thin filaments
 Contain ATPase enzymes
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Sarcomere Structure

A bands – full length of the thick filament
 Includes inner end of thin filaments

H zone – center part of A band where no thin
filaments occur
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Sarcomere Structure (continued)

M line – in center of H zone
 Contains tiny rods that hold thick filaments
together

I band – region with only thin filaments
 Lies within two adjacent sarcomeres
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Sarcoplasmic Reticulum and T Tubules

Sarcoplasmic reticulum
 A specialized smooth ER
 Interconnecting tubules surround each myofibril
 Some tubules form cross-channels called terminal
cisternae
 Cisternae occur in pairs on either side of a
t-tubule
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Sarcoplasmic Reticulum and T Tubules

Sarcoplasmic reticulum
 Contains calcium ions – released when muscle is
stimulated to contract
 Calcium ions diffuse through cytoplasm
 Trigger the sliding filament mechanism
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Sarcoplasmic Reticulum and T Tubules
in the Skeletal Muscle Fiber
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Figure 10.6
Sarcomere and Myofibrils
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Figure 10.4c
Mechanism of Contraction

Sliding filament theory
 Myosin heads attach to actin in the thin filaments
 Then pivot to pull thin filaments inward toward the
center of the sarcomere
PLAY
Sliding Filament Theory
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Sliding Filament Mechanism
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Figure 10.7a
Changes in Striation During Contraction
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Figure 10.8a–c
Microscopic and Functional Anatomy
of Skeletal Muscle Tissue

Muscle extension
 Muscle is stretched by a movement opposite that
which contracts it

Muscle fiber length and force of contraction
 Greatest force produced when a fiber starts out
slightly stretched
 Myosin heads can pull along the entire length of
the thin filaments
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
The Role of Titin

Titin – a spring-like molecule in sarcomeres
 Resists overstretching
 Holds thick filaments in place
 Unfolds when muscle is stretched
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 10.4d
Sarcoplasmic Reticulum and T Tubules

Muscle contraction
 Ultimately controlled by nerve-generated impulse
 Impulse travels along the sarcolemma of the
muscle cell
 Impulses further conducted by T tubules
 T tubule – a deep invagination of the
sarcolemma
PLAY
Anatomy Review: Skeletal Muscle Tissue
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Innervation of Skeletal Muscle

Motor neurons innervate skeletal muscle tissue
 Neuromuscular junction is the point where nerve
ending and muscle fiber meet
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Innervation of Skeletal Muscle
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Figure 10.9
Innervation of Skeletal Muscle
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Figure 10.10
Types of Skeletal Muscle Fibers

Skeletal muscle fibers are categorized according
to
 How they manufacture energy (ATP)
 How quickly they contract
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Types of Skeletal Muscle Fibers

Skeletal muscle fibers
 Are divided into 3 classes
 Slow oxidative fibers (Type I)
 Red Slow twitch
 Fast glycolytic fibers (Type IIx)
 White fast-twitch
 Fast oxidative fibers (Type IIa)
 Intermediate fibers
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Types of Skeletal Muscle Fibers

Slow oxidative fibers (Type I)
 Red color due to abundant myoglobin
 Obtain energy from aerobic metabolic reactions
 Contain a large number of mitochondria
 Richly supplied with capillaries
 Contract slowly and resistant to fatigue
 Fibers are small in diameter
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Types of Skeletal Muscle Fibers

Fast glycolytic fibers (Type IIx)
 Contain little myoglobin and few mitochondria
 About twice the diameter of slow-oxidative fibers
 Contain more myofilaments and generate more
power
 Depend on anaerobic pathways
 Contract rapidly and tire quickly
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Types of Skeletal Muscle Fibers

Fast oxidative fibers (Type IIa)
 Have an intermediate diameter
 Contract quickly like fast glycolytic fibers
 Are oxygen-dependent
 Have high myoglobin content and rich supply of
capillaries
 Somewhat fatigue-resistant
 More powerful than slow oxidative fibers
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Table 10.2 (1 of 3)
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Table 10.2 (2 of 3)
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Table 10.2 (3 of 3)
Disorders of Muscle Tissue

Muscle tissues experience few disorders
 Heart muscle is the exception
 Skeletal muscle
 Remarkably resistant to infection
 Smooth muscle
 Problems stem from external irritants
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Disorders of Muscle Tissue

Muscular dystrophy
 A group of inherited muscle destroying disease
 Affected muscles enlarge with fat and connective
tissue
 Muscles degenerate
 Types of muscular dystrophy
 Duchenne muscular dystrophy
 Myotonic dystrophy
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Disorders of Muscle Tissue

Myofascial pain syndrome
 Pain is caused by tightened bands of muscle fibers

Fibromyalgia
 A mysterious chronic-pain syndrome
 Affects mostly women
 Symptoms – fatigue, sleep abnormalities, severe
musculoskeletal pain, and headache
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Muscle Tissue Throughout Life

Muscle tissue develops from myoblasts
 Myoblasts fuse to form skeletal muscle fibers
 Skeletal muscles contract by the seventh week of
development
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Muscle Tissue Throughout Life

Cardiac muscle
 Pumps blood three weeks after fertilization

Satellite cells
 Surround skeletal muscle fibers
 Resemble undifferentiated myoblasts
 Fuse into existing muscle fibers to help them grow
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Muscle Tissue Throughout Life

With increased age
 Amount of connective tissue increases in muscles
 Number of muscle fibers decreases

Loss of muscle mass with aging
 Decrease in muscular strength by 50% by age 80
 Sarcopenia – muscle wasting
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