THE MUSCULAR SYSTEM

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THE MUSCULAR SYSTEM

• C14L2

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How do bones, muscles, and skin help maintain the
bodys homeostasis?
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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?

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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).

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Functions of muscles

• movement
• stability
• protection
• maintain body temperature
• helps digestion and respiration

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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.

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Stability

• Your muscles pull in different directions to help
  you keep your balance.

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Protection

• Muscles protect your body by covering most of
  your skeleton and most of the organs inside
  your body like a layer of padding.

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Maintain Body Temperature

• Shivering occurs when muscles contract rapidly
  and change chemical energy to thermal energy,
  thereby raising your bodys temperature.
• Muscles also change chemical energy to
  thermalenergy during exercise.

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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.

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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
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Types of muscle tissue
(distinguished by their location, microscopic
appearance, and type of nervous control)

• Skeletal Muscle
• Visceral Muscle
• Cardiac Muscle

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Skeletal Muscle

• named for its location (usually attached to
  skeleton)
• striated (dark and light stripes in its
  cells)-appearance
• voluntary (controlled by conscious thought)

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Skeletal Muscle

• Skeletal muscles move bones by pulling them and
  working in pairs.

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Skeletal Muscle

• Skeletal muscles move bones by pulling them and
  working in pairs.

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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.

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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)

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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
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Visceral Muscle
Contraction of smooth muscles helps move
material through the body, such as food in the
stomach and blood through the vessels
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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

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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.

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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.

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Muscles Disorders Diseases
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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
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convulsions
violent, involuntary contractions of an entire
group of muscles characteristic of epileptic
seizures and drug withdrawals
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cramps
painful, involuntary contractions in those
muscles that have been used heavily and have
suffered from fatigue
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muscular dystrophy
a progressively crippling disease of unknown
cause in which the muscles gradually weaken and
atrophy
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paralysis
inability to move a muscle or muscles usually
because of some nervous system failure
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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
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spasm
an involuntary contraction of shorter duration
than a cramp and usually not as painful