October 29-30, 2014
What are the functions of muscles?

Producing movement
Muscle contraction allows movement
• Of the body
• For facial expression
• To move fluids, digesting food, and other
substances through the body
• Maintain blood pressure


Maintaining posture
Muscles are constantly varying their
contraction to maintain posture while we
are seated or standing.
Stabilizing joints
Muscle contraction helps
keep joints in
position

Generating heat
• Muscle contraction requires an enormous amount of
energy.
• When food is converted to ATP to power the
muscles, nearly 75% of the energy is lost to heat.
• Remember: shivering functions to raise body
temperatures by contracting muscles
Notice the prefixes! -mys, -myo, and -sarco
 A single muscle cell is called a muscle fiber.
Muscle fibers are LONG (up to 1 ft).

Each muscle
fiber is
wrapped in a
delicate
connective
tissue called
endomysium
Remember:
Endo = inside
 Multiple fibers (cells!) are grouped together to form a

fascicle.
Each fascicle is wrapped up with a connective tissue
called
perimyscium.
Remember:
peri = around


Blood vessels branch out between the fascicles.
The whole muscle is covered by a thick, tough layer of
connective tissue called epimysium.
Epi = outer

The epimysia fuse to
• The periosteum (outer connective
tissue) of bone
- or • The perichondrium (outer connective
tissue)of cartilage
- or • Tendons (rope like connective tissue
that connects muscle to bone)
- or • Aponeuroses (sheetlike connective
tissue that attaches muscle to bones,
cartilage, or other muscles)
This is a micrograph of muscle tissue, magnified ~70 X
Identify:
Nuclei,
Muscle fibers,
Endomysium
Perimysium
Blood vessels
This is a micrograph of muscle tissue, magnified ~70 X
Identify:
Nuclei,
Muscle fibers,
Endomysium
Perimysium
Blood vessels
What do you already know about the three
types of muscles?
Attached to bones
(or, in the face, to
skin)
Walls of heart
Walls of hollow
organs, airways,
and arteries
Skeletal
Smooth
Cardiac
Nervous
Muscle system
excites
contraction is
contraction.
stimulated by
nervous
No
effect of
system.
hormones
Hormones
have no effect
Nervous
system
Contraction
can be
excites
or inhibits
stimulated
(excited)
contraction.
OR reduced
(inhibited) by
Hormones
other
EITHER theand
nervous
chemicals
system OR(e.g. CO2,
pH,
low O2, OR
) may
hormones
body
stimulate
inhibit
chemicalsor(e.g.
pH)
contraction.
Intrinsic regulation
from a pacemaker
within the heart.
Speed of
contraction
Slow to fast
Very slow
slow
Rhythmic
contraction
No
Yes, can be triggered
by stretch receptors
Yes, has internal
pacemaker
Regulation of
contraction
Natural rhythm can be
excited or inhibited by
the nervous system OR
by body hormones
Relate at least 3 differences between
skeletal, cardiac, and smooth muscle to
differences in their function.
Make a Venn Diagram comparing and
contrasting skeletal, smooth, and cardiac
muscle
1)
The connective tissue covering that
encloses the sarcolemma of an
individual muscle fiber is called the
a) Epimysium
b) Perimysium
c) Endomysium
d) periosteum
2) A fascicle is
a) A muscle
b) A bundle of muscle fibers
c) A bundle of myofibrils
d) A group of myofilaments
3) Muscle tissue that is involuntary
a) cardiac muscle only
b) Smooth muscle only
c) Skeletal muscle only
d) Cardiac and smooth muscle
e) Cardiac and skeletal muscle
4) The muscle tissue that consists of single,
very long, cylindrical, multinucleate cells
with very obvious striations is:
a) cardiac muscle only
b) Smooth muscle only
c) Skeletal muscle only
d) Cardiac and smooth muscle
e) Cardiac and skeletal muscle
5) Which of the following is NOT a function
of the muscular system
a) Producing movement
b) Maintaining posture
c) Stabilizing joints
d) Generating heat
e) hematopoiesis