THE MUSCULAR SYSTEM
C14L2
How do bones,
muscles, and skin help
maintain the body’s
homeostasis?
The Muscular System
• What does the muscular system do?
• How do types of muscle differ?
• How does the muscular system
interact with other body systems?
Muscular System Stats
There are approximately 600 muscles.
Of all the many different kinds of cells in
the human body, only muscle cells have
the ability to shorten (contract) and
return to their original length (relax).
Functions of muscles
movement
stability
protection
maintain body temperature
helps digestion and respiration
Movement
Bones move when muscles contract.
Tendons attach muscles to bones and help
keep joints in place when your body moves.
The two key words that describe the muscular
system are contraction and movement.
Contraction refers to the ability of a muscle
tissue to shorten and thereby cause movement.
Your muscles can move your body only by
pulling, never by pushing.
Stability
Your muscles
pull in different
directions to help
you keep your
balance.
Protection
Muscles protect your body by
covering most of your
skeleton and most of the
organs inside your body
like a layer of padding.
Maintain Body Temperature
• Shivering occurs when muscles
contract rapidly and change
chemical energy to thermal energy,
thereby raising your body’s
temperature.
• Muscles also change
chemical energy to thermal
energy during exercise.
Helps Digestion & Respiration
There are many muscles in
your body that are not attached
to bones.
The contraction of these
muscles cause blood and food
to move throughout your body.
Muscle Nervous Control
Some muscles you consciously control, and
others you can't.
 voluntary - a muscle that can be
controlled at will (you consciously control)
 involuntary - muscles controlled
automatically by the brain; controlled
without conscious effort
Types of muscle tissue
(distinguished by their location,
microscopic appearance, and type of
nervous control)
Skeletal Muscle
Visceral Muscle
Cardiac Muscle
Skeletal Muscle
named for its location
(usually attached to
skeleton)
striated (dark and light
stripes in its cells)appearance
voluntary (controlled
by conscious thought)
Skeletal Muscle
Skeletal muscles move bones by pulling
them and working in pairs.
Skeletal Muscle
Skeletal muscles move bones by pulling
them and working in pairs.
Skeletal Muscle
• Your skeletal muscles can change
throughout your lifetime.
• Exercise allows muscle cells to
increase in size, making the entire
muscle larger and
stronger.
Visceral Muscle
location: walls of
internal organs, iris of the
eye, sphincters
appearance: nonstriated
or smooth (shorter, one
nucleus, arranged
loosely)
nervous control:
involuntary (not directly
controlled by conscious
thought)
Visceral Muscle
the term visceral refers to internal organs
the name fits well because visceral muscles is
located in the walls of internal organs such as the
stomach, intestines, blood vessels, and urinary
bladder
visceral muscle is also located in the iris of the eye
most of the sphincters (circular bundles of
muscles that regulate the diameter of various
tubular organs and openings) are visceral
muscles; the muscular valves at both ends of the
stomach are examples of sphincters
Visceral Muscle
Contraction of smooth
muscles helps move
material through the
body, such as food
in the stomach
and blood through
the vessels
Cardiac Muscle
location: only in heart
appearance: striated
(striations are not as
regular and distinct as
skeletal; muscle fibers
are branched and joined
together)
nervous control:
involuntary
Cardiac Muscle
• When cardiac muscles contract and
relax, they pump blood through your
heart and through vessels throughout
your body.
• Cardiac cells send signals to other
cardiac cells so that they all contract
at the same time.
The Muscular System and
Homeostasis
Muscle contractions convert chemical
energy to thermal energy and keep
your body warm.
When you exercise, the cardiac
muscles of your heart help maintain
homeostasis by contracting more often.
When it contracts faster, the heart
pumps more blood and more oxygen is
carried to the cells.
Muscles Disorders
& Diseases
atrophy
a great reduction in muscle fibers
and possible replacement by
fibrous tissue; commonly occurs
when limbs are in casts or when
nerve cells that supply muscles
are destroyed by injury or
disease
convulsions
violent, involuntary
contractions of an entire
group of muscles;
characteristic of epileptic
seizures and drug
withdrawals
cramps
painful, involuntary
contractions in those muscles
that have been used heavily
and have suffered from
fatigue
muscular dystrophy
a progressively crippling
disease of unknown cause in
which the muscles gradually
weaken and atrophy
paralysis
inability to move a muscle or
muscles; usually because of
some nervous system failure
shin splints
a soreness on the front of the
lower leg due to straining a
muscle; often as a result of
walking up and down hills
spasm
an involuntary contraction of
shorter duration than a
cramp and usually not as
painful