The Muscular System (^201)
Muscular System (^)
(^) has a specific performs specific (^)
(^) Structure enables Functions (^)
(^) involve (^)
(^) Contraction (^)
(^) produces (^)
by^
(^)
epimysium
surrounded
(^) Skeletal muscle Skin Posture Skeletal Heat (^)
(deep fascia) (muscle belly) movements maintenance movements generation (^)
(^)
(^) consists of produce allow (^)
by^
(^)
perimysium
surrounded
Muscle bundles^ Facial^ Reproducing^ Eating,^ Breathing^
(fasciculi)^ expressions^ locomotion,^
other (^)
activities^
consists of (^)
by
(^) controlled for aids in (^)
(^)
endomysium
surrounded
Muscle cell Maintaining Maintaining (^)
(muscle fibers)^ O^2 and CO^2 body^
levels in temperature (^)
extracellular^
fluid (^)
®^
Lear ni ng^
Cen gage^
©^
CONCEPT MAP 9- 1 Muscular system. (^)
rapid transmission of a nerve impulse at the cell mem-brane
to all the thousands of fibrils that make up the muscle cell.
A muscle cell could be thought of as a single thread of
cloth. If you put a single thread under a micro-scope, you
would see that it was made up of hundreds of smaller units
of fiber. Hence, just like the thread, the muscle cell or fiber
is made up of thousands of smaller units called myofibrils.
At the molecular level, each myo-fibril is made up of
microscopic filaments of the proteins myosin (which is
thick and looks dark under the micro-scope) and actin
(which is thin and looks light under the microscope).
The Physiology of the Nerve Impulse
Contraction
To understand how a muscle contracts, it is necessary to
first describe what a motor unit is and what properties
muscle cells possess. Let’s first discuss a motor unit.
All of the muscle cells or fibers innervated by one
motor neuron are called a motor unit because they (the
muscle cells) are always excited simultaneously and
therefore contract together. It is important to remem-ber
that the terminal divisions or axon endings of a mo-tor
neuron are distributed throughout the belly of the