Muscular System
Muscular Tissue
- makes up 40–50% of total adult body weight
- produce body movements
- stabilize body positions
- store and move substances within the body
- generate heat
Myology
- myo = muscle, -logy = study of
- is the scientific study of muscles
TYPES OF MUSCULAR TISSUE
1. Skeletal Muscle Tissue
- moves most of the bones of the skeletons
- striated: alternating light and dark protein bands; work
mainly in a voluntary manner
- Most skeletal muscles are controlled subconsciously to
some extent. For example, your diaphragm continues to
alternately contract and relax without conscious control
so that you don’t stop breathing. Also, you do not need to
consciously think about contracting the skeletal muscles
that maintain your posture or stabilize body positions.
2. Cardiac Muscle Tissue
- forms most of the heart wall
- striated; involuntary action
- built-in rhythm is termed autorhythmicity
3. Smooth Muscle Tissue
- located in the walls of hollow internal structures, such as
blood vessels, airways, and most organs in the
abdominopelvic cavity; also found in the skin, attached to
hair follicles.
- non-striated; involuntary action
- Some smooth muscle tissue, such as the muscles that
propel food through your gastrointestinal tract, has
autorhythmicity.
L.G. ROM
,PROPERTIES OF MUSCULAR TISSUE
1. Electrical excitability
- the ability to respond to certain stimuli by producing
electrical signals called action potentials (impulses)
- Action potentials in muscles : muscle action
potentials;
- Autorhythmic electrical signals arising in
the muscular tissue itself, as in the heart’s
pacemaker
- Action potentials in nerve cells : nerve action
potentials
- Chemical stimuli, such as
neurotransmitters released by neurons,
hormones distributed by the blood, or
even local changes in pH
2. Contractility
- the ability of muscular tissue to contract forcefully when
stimulated by an action potential
3. Extensibility
- the ability of muscular tissue to stretch, within limits,
without being damaged
4. Elasticity
- the ability of muscular tissue to return to its original
length and shape after contraction or extension
NERVES AND BLOOD SUPPLY
Somatic Motor Neuron
- stimulates skeletal muscle to contract
MICROSCOPIC ANATOMY OF A SKELETAL MUSCLE FIBER
Muscle Fiber
- structural and functional unit of a skeletal muscle.
- Diameter: 10 to 100 m.*
- Length: average -10 cm (4 in.) although some are as long
as 30 cm (12 in.)
L.G. ROM
, PARTS OF A SKELETAL MUSCLE
● Fascia
- a dense sheet or broad band of irregular connective tissue
that lines the body wall and limbs and supports and
surrounds muscles and other organs of the body
- allows free movement of muscles; carries nerves, blood
vessels, and lymphatic vessels; and fills spaces between
muscles
- white part between subcutaneous tissue and muscle
tissue
- surrounds individual muscles and groups of muscles
● Epimysium
- thick dense irregular connective tissue
- surrounds the entire skeletal muscle
● Perimysium
- thin but dense connective tissue
- surrounds groups of 10 to 100 or more muscle fibers,
separating them into bundles called fascicles
● Fascicle
- bundle of skeletal muscle that is surrounded by
perimysium
● Endomysium
- delicate connective tissue
- penetrates the interior of each fascicle and separates
individual muscle fibers from one another
- surrounds muscle fiber
● Muscle fiber
- elongated, multinuclear cells composed of several
myofibrils
● Myofibril
- long, cylindrical filament bundles in the sarcoplasm of
myocytes
L.G. ROM
Muscular Tissue
- makes up 40–50% of total adult body weight
- produce body movements
- stabilize body positions
- store and move substances within the body
- generate heat
Myology
- myo = muscle, -logy = study of
- is the scientific study of muscles
TYPES OF MUSCULAR TISSUE
1. Skeletal Muscle Tissue
- moves most of the bones of the skeletons
- striated: alternating light and dark protein bands; work
mainly in a voluntary manner
- Most skeletal muscles are controlled subconsciously to
some extent. For example, your diaphragm continues to
alternately contract and relax without conscious control
so that you don’t stop breathing. Also, you do not need to
consciously think about contracting the skeletal muscles
that maintain your posture or stabilize body positions.
2. Cardiac Muscle Tissue
- forms most of the heart wall
- striated; involuntary action
- built-in rhythm is termed autorhythmicity
3. Smooth Muscle Tissue
- located in the walls of hollow internal structures, such as
blood vessels, airways, and most organs in the
abdominopelvic cavity; also found in the skin, attached to
hair follicles.
- non-striated; involuntary action
- Some smooth muscle tissue, such as the muscles that
propel food through your gastrointestinal tract, has
autorhythmicity.
L.G. ROM
,PROPERTIES OF MUSCULAR TISSUE
1. Electrical excitability
- the ability to respond to certain stimuli by producing
electrical signals called action potentials (impulses)
- Action potentials in muscles : muscle action
potentials;
- Autorhythmic electrical signals arising in
the muscular tissue itself, as in the heart’s
pacemaker
- Action potentials in nerve cells : nerve action
potentials
- Chemical stimuli, such as
neurotransmitters released by neurons,
hormones distributed by the blood, or
even local changes in pH
2. Contractility
- the ability of muscular tissue to contract forcefully when
stimulated by an action potential
3. Extensibility
- the ability of muscular tissue to stretch, within limits,
without being damaged
4. Elasticity
- the ability of muscular tissue to return to its original
length and shape after contraction or extension
NERVES AND BLOOD SUPPLY
Somatic Motor Neuron
- stimulates skeletal muscle to contract
MICROSCOPIC ANATOMY OF A SKELETAL MUSCLE FIBER
Muscle Fiber
- structural and functional unit of a skeletal muscle.
- Diameter: 10 to 100 m.*
- Length: average -10 cm (4 in.) although some are as long
as 30 cm (12 in.)
L.G. ROM
, PARTS OF A SKELETAL MUSCLE
● Fascia
- a dense sheet or broad band of irregular connective tissue
that lines the body wall and limbs and supports and
surrounds muscles and other organs of the body
- allows free movement of muscles; carries nerves, blood
vessels, and lymphatic vessels; and fills spaces between
muscles
- white part between subcutaneous tissue and muscle
tissue
- surrounds individual muscles and groups of muscles
● Epimysium
- thick dense irregular connective tissue
- surrounds the entire skeletal muscle
● Perimysium
- thin but dense connective tissue
- surrounds groups of 10 to 100 or more muscle fibers,
separating them into bundles called fascicles
● Fascicle
- bundle of skeletal muscle that is surrounded by
perimysium
● Endomysium
- delicate connective tissue
- penetrates the interior of each fascicle and separates
individual muscle fibers from one another
- surrounds muscle fiber
● Muscle fiber
- elongated, multinuclear cells composed of several
myofibrils
● Myofibril
- long, cylindrical filament bundles in the sarcoplasm of
myocytes
L.G. ROM
