Chapter 8 & 15 muscular

Muscular Tissue &
Muscular System

Dr. Fedeliz Sandil-Tuy Biological Science 1

 To Contrast the structure and
function of skeletal, smooth, and
cardiac muscle tissue
 To Identify morphological differences
in smooth muscle across tissues
 To Explain the structure and function
of the intercalated disc
 To Identify some key pathological
examples related to muscle


Muscle cells are highly specialized for
contraction.
Such contraction may result in the
movement of the whole body or a
portion of it if the muscles are
attached to a movable part of the
skeleton.
If the muscle is located in the wall of a
hollow organ, its contraction may
cause the contents of the organ to
move, e.g. peristaltic movement of
material through the digestive tract.

Dr. Fedeliz Sandil-Tuy

Biological Science 4

 Identifying Features
 Striations caused by
overlapping actin and
myosin filaments.
 Multinucleated
 Functions
 Major body muscle
contractions involved in
locomotion and facial
expressions
 Protection
 Heat production
 Location All major body
muscles
Biological Science Dr. Fedeliz Sandil-Tuy 5

Several specific terms are
used exclusively for muscle
tissue. Muscle cells are
called fibres; their
cytoplasm is termed
sarcoplasm, and their cell
membrane is referred to as
sarcolemma.

 Long thin cells with
tapering ends
 Single nucleus
 No striations
 Function Involuntary
Muscle contraction
 Locations Walls of
digestive tract,
respiratory tract, blood
vessels.


◦ Striated appearance
◦ Branched fibres
◦ Intercalated discs (these
appear as occasional dark
lines)
◦ Single nucleus per cell
 Function
◦ Heart muscle contraction.
Propels blood into
circulation (involuntary
contractions)
 Location
◦ Walls of heart.


Skeletal Visceral Cardiac
Movement voluntary involuntary involuntary

Rate of fast Very slow moderate
action
Striation present absent present

Location periphery center center
of nucleus
Number of several one one
nucleus
Shape filamentous Fusiform/ Net-like
Spindle-like


Voluntary muscle – movement is
controlled by the will.
 Skeletal muscle
Involuntary muscle –movement is not
controlled by the will.
 Cardiac and visceral muscles


 An individual skeletal muscle may be made
up of hundreds, or even thousands, of muscle
fibers bundled together and wrapped in a
connective tissue covering.
 Each muscle is surrounded by a connective
tissue sheath called the epimysium.
 Fascia, connective tissue outside the
epimysium, surrounds and separates the
muscles.
 Portions of the epimysium project inward to
divide the muscle into compartments.

 Each compartment contains a bundle of
muscle fibers.
 Each bundle of muscle fiber is called a
fasciculus and is surrounded by a layer of
connective tissue called the perimysium.
 Within the fasciculus, each individual
muscle cell, called a muscle fiber, is
surrounded by connective tissue called
the endomysium.


 Commonly, the epimysium, perimysium, and
endomysium extend beyond the fleshy part of
the muscle, the belly or gaster, to form a thick
ropelike tendon or a broad, flat sheet-like
aponeurosis.
 The tendon and aponeurosis form indirect
attachments from muscles to the periosteum of
bones or to the connective tissue of other
muscles.
 Typically a muscle spans a joint and is attached
to bones by tendons at both ends.
 One of the bones remains relatively fixed or
stable while the other end moves as a result of
muscle contraction


Actin & Myosin
 Each myofibril is made up of arrays of
parallel filaments.
 The thick filaments have a diameter of
about 15 nm. They are composed of the
protein myosin.
 The thin filaments have a diameter of about
5 nm. They are composed chiefly of the
protein actin along with smaller amounts of
two other proteins:
 troponin and
 ropomyosin


 The thick filaments produce the dark A band.
 The thin filaments extend in each direction from
the Z line. Where they do not overlap the thick
filaments, they create the light I band.
 The H zone is that portion of the A band where
the thick and thin filaments do not overlap.
 These fibrils contain the proteins that do the
actual force production.
 The entire array of thick and thin filaments
between the Z lines is called a sarcomere.


Shivers are reflexes which are things
your body does automatically to keep
you safe and healthy.
Your body needs to stay at 37° Celsius
for you to be safe and comfortable.
The nerves send signals that we are
cold and we need to warm up.
The signals go to your brain and to your
spinal cord, which sends a message to
other nerves all over your body. Your
muscles tighten and loosen really fast.

.
Goosebumps happen because
your skin is covered with hair.
When the muscles that are
attached to each hair get tight,
they pull the hair and your skin
up into the air.


 Skeletons can bend at joints
when muscles pull on skeletal
elements.
 Since muscles act by
contracting and shortening,
they come in opposing pairs.
 One flexes an appendage at a
joint, the other extends it and
each muscle of the pair relaxes
when its partner contracts.


 Size: vastus (huge); maximus (large);
longus (long); minimus (small); brevis
(short).
 Shape: deltoid (triangular); rhomboid
(like a rhombus with equal and parallel
sides); latissimus (wide); teres (round);
trapezius (like a trapezoid, a four-sided
figure with two sides parallel).


 Direction of fibers: rectus (straight);
transverse (across); oblique (diagonally);
orbicularis (circular).
 Location: pectoralis (chest); gluteus
(buttock or rump); brachii (arm); supra-
(above); infra- (below); sub- (under or
beneath); lateralis (lateral).
 Number of origins: biceps (two heads);
triceps (three heads); quadriceps (four
heads).

 Origin and insertion:
sternocleidomastoideus (origin on the
sternum and clavicle, insertion on the
mastoid process); brachioradialis (origin
on the brachium or arm, insertion on the
radius).
 Action: abductor (to abduct a structure);
adductor (to adduct a structure); flexor
(to flex a structure); extensor (to extend
a structure); levator (to lift or elevate a
structure); masseter (a chewer).

 One of the most predominant characteristics of skeletal
muscle tissue is its contractility and nearly all movement
in the body is the result of muscle contraction.
 Four functions of muscle contraction are movement,
posture, joint stability, and heat production.
 Three types of muscle are skeletal, smooth, and cardiac.
 Each muscle fiber is surrounded by endomysium.
 The fibers are collected into bundles covered by
perimysium.
 Many bundles, or fasciculi, are wrapped together by the
epimysium to form a whole muscle.
 Muscles are attached to bones by tendons.


HOW THE SKELETAL SYSTEM WORKS. - Yahoo! Video Search.flv


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