Transcript Nerve activates contraction

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 6
The Muscular System
Slides 6.1 – 6.17
Lecture Slides in PowerPoint by Jerry L. Cook
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
The Muscular System
 Named for Latin word “mus” meaning
little mouse
 Dominant tissue in heart and the walls
of other hollow organs
 Essential function is to shorten or
contract
 Responsible for all body movement
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.1
The Muscular System
 Three basic muscle types are found in
the body
 Skeletal muscle
 Cardiac muscle
 Smooth muscle
 Differ in cell structure, location in body
and how they’re stimulated to contract
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.1
Characteristics of All Muscle Types
 Muscle cells are elongated & called fibers
 Contraction of muscles is due to the
movement of myofilaments
 All muscles share some terminology
 Prefixes myo & mys refers to muscle
 Prefix sarco refers to flesh
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.2
Skeletal Muscle Characteristics
 Most are attached by tendons to bones
 Cells are cigar shaped & multinucleate
 Striated – have visible banding
 Largest of the muscles (up to 1 foot)
 Voluntary – subject to conscious control
 Often react involuntarily or by reflex
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.3
Skeletal Muscle Characteristics
 Can contract rapidly & with great force
but tires easily
 Fibers (cells) are surrounded and
bundled by connective tissue
 This allows skeletal muscle to exert
great force without damaging the
muscle fibers
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.3
Connective Tissue Wrappings of
Skeletal Muscle
 Endomysium –
around single
muscle fiber
 Perimysium –
around a
fascicle
(bundle) of
fibers
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.1
Slide 6.4a
Connective Tissue Wrappings of
Skeletal Muscle
 3 layers of
connective tissue:
endomysium,
perimysium &
epimysium
 Each layer gets
thicker & tougher
Figure 6.1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.4b
Skeletal Muscle Attachments
 Epimysium blends into a connective
tissue attachment, usually a tendon
which attaches to a bone
 Sites of muscle attachment
 Bones (attached by tendon)
 Cartilages
 Connective tissue coverings of muscles
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.5
Smooth Muscle Characteristics
 Has no striations
 Spindle-shaped
cells
 Single nucleus
 Involuntary – no
conscious control
 Found mainly in
the walls of hollow
organs
Figure 6.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.6
Smooth Muscle Characteristics
 Arranged in sheets or layers – one runs
circular or around & the other runs up and
down
 2 layers take turns contracting & relaxing to
change shape of organ and move food or
waste through the digestive system, etc
 A slow steady contraction that goes on
almost continuously
Figure 6.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.6
Cardiac Muscle Characteristics
 Has striations
 Usually has a
single nucleus
 Involuntary
 Found only in the
heart
 Joined to another
muscle cell at an
intercalated disc
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.2b
Slide 6.7
Cardiac Muscle Characteristics
 Muscle is arranged in
spirals or figure 8s
 This causes the
chambers to get
smaller & squeeze
the blood out when it
contracts
 Contracts at a steady
rate controlled by the
heart’s pacemaker –
nervous system can
speed it up
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 6.2b
Slide 6.7