Transcript MUSCULAR SYSTEM - Simon Land

MUSCULAR
SYSTEM
Chapter 7
Muscular System
½
our body weight comes from muscle
tissue.
 Over 656 different muscles in the human
body.
 Responsible for all body movement.
 Give our body form and shape.
Functions:
1.
2.
3.
Body movement
Body form and shape, to maintain
posture
Body heat, to maintain body
temperature.
TYPES OF MUSCLES
 Skeletal
muscles - striated
 Smooth muscle – spindle-shaped
 Cardiac muscle – non-striated
 Sphincter (dilator) muscles
TYPES OF MUSCLES
 Skeletal



Attached to bone and skeleton
Are called striped or striated b/c have cross
bandings of alternating light and dark band
running perpendicular to the length of the
muscle.
Voluntary muscle
Skeletal Muscle
 Muscle




cells
Multinucleate
Cell – muscle fiber
Cell membrane – sarcolemma
Cytoplasm – sarcoplasm
 Contract
quickly, fatigue easily, lack
ability to remain contracted.
Smooth muscle
 Cells



Small and spindle-shaped
Only one nucleus, located at the center of
the cell
Are unmarked by any distinctive striations
 Unattached
to bones, act slowly, do not
tire easily, can remain contracted for a
long time.
Smooth muscle
 Not


under conscious control
Called involuntary muscles
Controlled by the autonomic nervous
system
 Found

in the walls of the internal organs
Help push food along the alimentary canal,
contract during labor, control the diameter
of blood vessels.
Cardiac muscle
 Found
only in the heart
 Cells




Are striated and branched
Involuntary
Joined in a continuous network w/o a
sheath separation
Membranes are fused at places called
intercalated discs.
Cardiac muscle
 When
one cell receives a signal to
contract, all neighboring cells are
stimulated and they contract together to
produce a heart beat.
 Requires a continuous supply of oxygen to
function.

If cut off for as little as 30 seconds, the
muscle cells start to die.
Sphincter, dilator muscle
 Special,
circular muscles in the openings
b/w the esophagus and stomach, and
the stomach and small intestine.
 Also in walls of anus, urethra, and mouth.
 They open and close to control the
passage of substances.