Muscle Tissue

What are the functions of the muscular system?

•The tissues and organs of the muscular
system are unique in that they are able to contract, producing movement.

•The muscular system…

•Produces movement- locomotion of
whole body, facial expressions,
circulation of blood, passage of food, etc.

•Maintains posture- working against gravity to keep us upright

•Stabilizes joints- reinforcing the
connections of bones

•Generates heat- cellular respiration
causes heat energy, allowing constant body temperature

What are characteristics of muscle tissue?

•All muscle tissues have these 4
characteristics:

1.

Excitability- the ability to respond to a stimulus (from a motor neuron or hormone)

2.

Contractability- the ability to shorten when stimulated

3.

Extensibility- the ability to lengthen or stretch, even past their original shape

4.

Elasticity- the ability to recoil or
bounce back to the original shape and length after being stretched

How do the 3 types of muscle

tissues differ?

Skeletal Muscle

Cardiac Muscle

Smooth Muscle

• Cylindrical
• Striated (muscle fibers have stripes)

• Multinucleated
• Voluntarily

controlled

• Contracts slowly or

very quickly

• Branched
• Striated
• Uninucleated
• Involuntarily controlled

• Mostly slow and steady contractions
except during short periods of activity

• Arranged in

uniform layers

• Nonstriated
• Uninucleated
• Involuntarily controlled

• Slow contractions, sustained for long
periods of time

Connected to bones

Found in heart

Found in walls of internal organs (ex: stomach)

Muscle

Fascicle

Muscle fiber

Myofibril

Myofilaments

-Skeletal
muscle is
attached to
bone by
tendons
-Made of
many bundles
of fibers

-Bundles
within
muscles

-Long, thin
muscle cells
-Each is covered
by sarcoplasmic
reticulum, which
transmit an
impulse to the
muscle fiber

-Thread-like
organelles of
the muscle
fibers
-Structured in
long, striated
units called
sarcomeres

-2 types of
filaments: actin
(thin) & myosin
(thick) make up
the sliding
filament model of
the muscle
-Responsible for
contracting activity
of muscle fibers

What is the microscopic structure of a skeletal muscle?

How are muscle fibers protected?

Epimysium-
Covers the whole muscle

Perimysium-
Covers a fascicle

Endomysium-
Covers an individual muscle fiber

Greek roots:
“Epi”= over/tip
“Peri”= surrounding
“Endo” = within

Membranes
allow the
muscle fibers
to SLIDE and
keeps them
contained to
prevent
bursting
during
contractions.

Summary

•Muscle cells are able to contract when
stimulated by an impulse. Skeletal muscle
is consciously controlled and is made of
many bundles of muscle fibers protected
by membranes. Cardiac and smooth
muscle movements are involuntary and
provide slower, longer motion.