SECTION 46-3, MUSCULAR SYSTEM
Muscles make up the bulk of the body and account for about one-third of its
weight. Their ability to contract not only enables the body to move, but also
provides the force that pushes substances, such as blood and food, through the
body. Without the muscular system, none of the other organ systems would be
able to function.
OBJECTIVES: Label the major muscles of the body. Distinguish between the
three types of muscle tissue. Describe the function and composition of the
muscular system. Explain how skeletal muscles contract. Explain the
relationship among muscles, bones, and joints. Explain how muscles move
bones.
1. The Skeleton and its
joints support, protect, and
provide flexibility for the
body, but the Skeleton
CANNOT Move Itself.
2. That job is performed by
the Muscle Tissue that
makes up the MUSCULAR
SYSTEM.
3. A MUSCLE TISSUE IS
TISSUE THAT CAN
CONTRACT IN A
COORDINATED
FASHION AND
INCLUDES MUSCLES TISSUE, BLOOD VESSELS, NERVES, AND
CONNECTIVE TISSUE.
4. Approximately 40 to 50 percent of the MASS of the Human Body is composed
of Muscle Tissue. (Figure 46-9)
5. THE MUSCULAR SYSTEM IS COMPOSED OF MUSCLE TISSUE (MUSCLE
FIBER) THAT IS HIGHLY SPECIALIZED TO CONTRACT, OR SHORTEN, TO
PRODUCE MOVEMENT WHEN STIMULATED.
6. The Word Muscle is derived from the Latin word "MUS", meaning mouse.
7. Muscle tissue is found everywhere within the body, not only beneath the skin
but deep within the body, surrounding many internal organs and blood vessels.
8. The size and location of muscle tissue helps determine the shape of our
bodies and the way we move.
TYPES OF MUSCLE TISSUE (THREE TYPES)
1. There are Three Types of
Muscle Tissue, or Muscles:
SKELETAL, SMOOTH, AND
CARDIAC. (Figure 46-10)
2. EACH TYPE HAS A
DIFFERENT STRUCTURE AND PLAYS A DIFFERENT ROLE IN THE BODY.
SKELETAL MUSCLE
1. Skeletal Muscle is Responsible for moving
parts of the body, such as the limbs, trunk, and
face.
2. SKELETAL MUSCLES ARE GENERALLY
ATTACHED TO BONES AND ARE AT WORK
EVERY TIME WE MAKE A MOVE.
3. SKELETAL MUSCLES ARE RESPONSIBLE
FOR VOLUNTARY (CONSCIOUS) MOVEMENT.
4. A Skeletal Muscle is made of Elongated Cells
called MUSCLE FIBERS. Varying movements
require Contraction of variable numbers of Muscles Fibers in a Muscle.
5. Skeletal Muscle fibers are grouped into dense bundles called FASCICLES. A
group of Fascicles are bound together by Connective Tissue to form a MUSCLE.
6. When viewed under a microscope, Skeletal Muscles appear to have
STRIATIONS (BANDS OR STRIPES). This gives Skeleton Muscle the name of
VOLUNTARY OR STRIATED MUSCLE. (Figure 49-10 (a))
7. MOST SKELETAL MUSCLES ARE CONSCIOUSLY CONTROLLED BY THE
CENTRAL NERVOUS SYSTEM (CNS).
8. Skeleton Muscle Cells are LARGE and have MORE than ONE NUCLEUS.
They vary in length from 1mm to 30 to 60 cm.
9. Because they are so long and slender, they are often called MUSCLE FIBERS
rather than Muscle Cells.
10. Muscle Fiber together with the Connective Tissue, Blood Vessels, and
Nerves form a Skeletal Muscle.
SMOOTH MUSCLES
1. SMOOTH MUSCLES ARE USUALLY NOT
UNDER VOLUNTARY CONTROL.
2. SMOOTH MUSCLE CELLS ARE SPINDLESHAPED AND HAVE A SINGLE NUCLEUS,
ARE NOT STRIATED and Interlace to form
Sheets of smooth Muscle Tissue. (Figure 46-10
(b))
3. SMOOTH MUSCLES ARE FOUND IN MANY
INTERNAL ORGANS, STOMACH, INTESTINES,
AND IN THE WALLS OF BLOOD VESSELS.
4. Smooth muscle fibers are surrounded by
connective tissue, but the connective tissue Does Not unite to form TENDONS
as it does in Skeletal Muscles.
5. Most Smooth Muscle Cells can CONTRACT WITHOUT Nervous Stimulation.
Because most of its movements Cannot be consciously controlled, Smooth
Muscle is referred to as Involuntary Muscle.
6. The contractions in Smooth Muscles move food through our digestive tract,
control the way blood flows through the circulatory system, and increases the
size of the pupils of our eyes in bright light.
CARDIAC MUSCLE
1. THE ONLY PLACE IN THE BODY
WHERE CARDIAC MUSCLE IS FOUND IS
IN THE HEART.
2. Cardiac Cells are striated, but they are
NOT under Voluntary Control. (Figure 46-10
(c))
3. Cardiac Muscle Contract Without Direct
stimulation by the Nervous System. A bundle
of specialized muscle cells in the upper part
of the heart sends electrical signals through
cardiac muscle tissue, causing the heart to
rhythmically contract and pump blood through
the body.
4. The Cardiac Muscle Cell contains ONE Nucleus located near the center,
adjacent cells form branching fibers that allow Nerve Impulses to pass from cell
to cell.
MUSCLE STRUCTURE
1. A Muscle Fiber is a single, Multinucleated Muscle Cell.
2. A Muscle made is made up of hundreds or even thousands of Muscle Fibers,
depending on the Muscles Size.
3. Although Muscle Fiber makes up most of the Muscle Tissue, a large amount of
Connective Tissue, Blood Vessels, and Nerves are also present.
4. Connective Tissue Covers and Supports each
Muscle Fiber and reinforces the Muscle as a whole.
5. The health of Muscle depends on a sufficient Nerve
and Blood Supply. Each Skeletal Muscle has a Nerve
Ending that controls its activity.
6. Active Muscles use a lot of Energy and require a
continuous supply of Oxygen and Nutrients, which are
supplied by Arteries. Muscles produce large amounts
of Metabolic Waste that must be removed by Veins.
7. Muscle Fibers consist of Bundles of threadlike
structures called MYOFIBRILS. (Figure 46-11)
8. Each Myofibril is made up of TWO Types of Protein
Filaments- Thick ones and thin ones.
9. The THICK FILAMENTS are made up of a
PROTEIN called MYOSIN.
10. The THIN FILAMENTS are made of a PROTEIN
called ACTIN.
11. Myosin and Actin Filaments are arranged to form overlapping patterns,
which are responsible for the Light and Dark Bands that can be seen in Skeletal
(Striated Appearance) Muscle.
12. Thin Actin Filaments are anchored at their Midpoints to a structure called the
Z-LINE.
13. The Region From one Z-line to the next is called a SARCOMERE the
Functional Unit of Muscle Contractions. (Figure 46-12)
MECHANISM OF MUSCLE CONTRACTIONS
1. The Sarcomere is the functional unit of Muscle contractions.
2. When Muscle Cells Contract, the light and dark bands contained in Muscle
Cells get closer together.
3. This happens because when a Muscle Contracts, Myosin Filaments and Actin
filaments interact to shorten the length of a Sarcoma.
4. When Myosin Filaments and Actin Filaments come near each other, many
knob (heads) like projections in each Myosin Filament form CROSS-BRIDGES
with an Actin Filament.
5. When the
Muscle is
Stimulated to
Contract, the
Cross-bridges
MOVE,
PULLING the
Two Filaments
past each other.
6. After each
Cross-bridge has
moved as far as
it can, it releases the Actin Filament and returns to its original position. The
Cross-bridge then attaches to the Actin Filament at another place and the cycle
is repeated. This action Shortens the Length of the Sarcomere.
7. The synchronized shortening of Sarcomeres along the full length of a Muscle
Fiber causes the Whole Fiber, and hence the Muscle, to Contract. (Figure 46-12)
8. WHEN THOUSANDS OF ACTIN AND MYOSIN FILAMENTS INTERACT IN
THIS WAY, THE ENTIRE MUSCLE CELL SHORTENS.
9. THIS CONCEPT IS THE SLIDING FILAMENT THEORY.
10. Muscle Contractions require Energy, which is supplied by ATP. This Energy
is used to Detach the Myosin Heads from the Actin Filaments.
11. Because Myosin Heads must Attach and Detach a number of times during a
Single Muscle Contraction, Muscle Cells must have a Continuous Supply of ATP.
12. Without ATP the Myosin Heads would stay Attached to the Actin Filaments,
keeping Muscles Permanently Contracted.
13. A Muscle Contraction, like a Nerve Impulse, is an All-or-None Responseeither Fibers Contract or they Remain Relaxed.
14. The force of a Muscle Contraction is determined by the number of Muscle
fibers that are Stimulated. As more fibers are activated, the force of the
contraction Increases.
15. Some Muscles, such as the muscles that hold the body in an upright position
and maintain posture, are nearly always at least Partially Contracted.
CONTROL OF MUSCLE
CONTRACTION
1. Muscles are useful only if they
Contract in a Controlled fashion.
2. Motor Neurons connect the
CNS to Skeleton Muscle Cells
(EFFECTORS); Impulses
(ACTION POTENTIALS) from
Motor Neurons Control the
Contraction of Skeleton Muscle
Cells.
3. The point of contact between a Motor Neuron and a Muscle Cell is called the
NEUROMUSCULAR JUNCTION.
4. Vesicles, or pockets, in the AXON TERMINALS of the Motor Neuron release
molecules of the NEUROTRANSMITTER ACETYLCHOLINE.
5. These molecules Diffuse across the SYNAPSE, producing and IMPULSE in
the Cell Membrane of the Muscle Cell.
6. The impulse causes the release of Calcium ions within the cell. The Calcium
Ions affect regulatory proteins that allow Actin and Myosin Filaments to interact
and form cross-bridges.
7. A Muscle Cell WILL remain in a state of CONTRACTION until the production
of Acetylcholine STOPS.
8. An ENZYME called ACETYLCHOLINESTERASE, also produced at the
Neuromuscular Junction, DESTROYS ACETYLCHOLINE, permits the
reabsorption of Calcium Ions into the Muscle Cell, and Terminates the
Contraction.
9. You can have a Weak or Strong Contraction depending on what you are trying
to accomplish. The BRAIN (frontal lobes of the cerebrum) decides what and how
many Muscles Cells need to Contract. Blinking your eye would be a Weak
Contraction, but lifting heavy weights, the brain would signal most Muscle Cells
to Contract.
10. MUSCLE SENSE IS THE BRAINS ABILITY TO KNOW WHERE OUR
MUSCLES ARE AND WHAT THEY ARE DOING. Permits us to perform
everyday activities without having to concentrate on muscle position.
HOW MUSCLES AND BONES INTERACT
1. Skeleton Muscles generate Force and produce Movement only by
CONTRACTING or PULLING on Body Parts.
2. Individual Muscles can only PULL; they CANNOT
PUSH.
3. Skeleton Muscles are joined to bone by TOUGH
CONNECTIVE TISSUE CALLED TENDONS.
4. TENDONS ATTACH MUSCLE TO BONE; THE ORIGIN IS THE MORE
STATIONARY BONE, THE INSERTION IS THE MORE MOVABLE BONE.
5. Tendons are attached in such a way that they PULL on the Bones and make
them work like LEVERS. The movements of the Muscles and Joints enable the
Bones to act as LEVERS.
6. The Joint functions as a FULCRUM (The fixed point around which the lever
moves) and the Muscles provide the FORCE to move the Lever.
7. Usually there several Muscles surrounding each Joint that PULL in
DIFFERENT DIRECTIONS.
8. MOST SKELETAL MUSCLES WORK IN PAIRS.
9. When one
Muscle or set of
Muscles
CONTRACTS,
the other
RELAXES.
10. The Muscles
of the upper arm
are a good
example of this
dual action:
ANTAGONISTI
C MUSCLES.
(Figure 46-13) FLEXOR, A MUSCLE THAT BENDS A JOINT. EXTENSOR, A
MUSCLE THAT STRAIGHTENS A JOINT.
A. When the BICEPS Muscle (on the front of the upper arm, FLEXOR)
CONTRACTS, it BENDS OR FLEXES THE ELBOW JOINT.
B. When the TRICEPS Muscle (on the back of the upper arm, EXTENSOR)
CONTRACTS, it opens, or extends, the elbow joint.
C. A controlled movement requires contraction by both muscles.
11. ANTAGONISTIC MUSCLES ARE OPPONENTS,
MUSCLES WHICH HAVE OPPOSING OR OPPOSITE
FUNCTIONS. A muscle pulls when it contracts, but exerts
no force when it relaxes and CANNOT PUSH. When one
muscle Pulls a bone in one direction, another muscle is
needed to PULL the bone in the other direction.
12. SYNERGISTIC MUSCLES ARE THOSE WITH THE
SAME FUNCTION, OR THOSE THAT WORK TOGETHER
TO PERFORM A PARTICULAR FUNCTION. They also
stabilize a joint to make a more precise movement
possible.
13. A normal characteristic of all Skeleton Muscles is that
they remain in a state of PARTIAL CONTRACTION.
14. At any given time, some Muscles are being Stimulated
while other are not. This causes a TIGHTENED, or
FIRMED, Muscle and is known as MUSCLE TONE.
15. Muscle Tone is responsible for keeping the back and legs straight and the
head upright even when you are relaxed.
16. EXERCISE IS THE KEY TO MAINTAINING GOOD MUSCLE TONE WITHIN
YOUR BODY.
17. MUSCLES THAT ARE EXERCISED REGULARLY STAY FIRM AND
INCREASE IN SIZE BY ADDING MORE MATERIALS TO THE INSIDE OF
MUSCLE FIBERS.
18. MUSCLE FATIGUE is a Physiological Inability of a muscle to contract.
Muscle fatigue is a result of a relative depletion of ATP. When ATP is absent, a
state of continuous contraction occurs. This causes severe muscle cramps.
BACK TO BIOLOGY II HOME PAGE
CHAPTER 46, SECTIONS 3 AND 4
REVIEW THE MUSCULAR AND
INTEGUMENTARY SYSTEMS
THE MUSCULAR SYSTEM NOTES
THE INTEGUMENTARY SYSTEM NOTES
CAN YOU LABEL THESE MUSCLES
1. The skeleton Cannot move itself, that job is preformed by the
_______________________ ________________________.
2. Muscle tissue consists of cells that are specialized for
______________________________.
3. What are the three types of muscle tissue and the functions of each?
4. Thick filaments of skeleton muscle are composed of a protein called
___________________.
5. Which muscle tissue is described by the following words; Involuntary; single
large nucleus, and are not striated. ______________________________________
6. Thin filaments of skeleton muscle are composed of a protein called
___________________________.
7. Which muscle tissue is described by the following words; Voluntary, Striated,
large cells with more than one nucleus
___________________________________________.
8. These type of muscles have opposing or opposite functions
__________________________.
9. These types of muscles have the same function, or work together to perform a
particular function _________________________________.
10. Skeleton muscles are joined to bone by tough connective tissue called
________________.
11. What type of muscle tissue is found only in the heart?
__________________________
12. Most skeleton muscles work in ______________________________.
13. The skin consists of two main layers, the outermost is known as the
_____________________________ and the innermost is the
________________________.
14. Hair is produced by cells at the base of structures called _________
__________________.
15. The __________________ contains two major types of glands:
______________________ glands and ____________________________ glands.
16. The primary purpose of the integumentary system is
______________________________.
17. The cells that give us our skin color are called
_______________________________ and they produce
_________________________, a dark pigment.
18. Individual hairs are actually large columns of cells that have filled with
_________________________ and then died.
19. Epidermmal ridges form what part of our anatomy
__________________________________.
20. ________________ provides the energy necessary to make and break
connections between actin and myosin filaments.
21. Because skeleton muscle cells are long and slender, they are often called
________________________ ________________________.
22. The neurotransmitter that causes muscle contractions is called
_______________________________________.
23. When the muscle is stimulated to contract, __________________
_________________ on the myosin filaments move and pull the actin filaments
past each other.
24. In humans __________________ forms the basic structure of hair, nails, and
calluses.
25. What is the largest organ in the body ?
_____________________________________
26. Sebaceous glands produce a fluid known as ____________________________.
1. Which of the following types of muscle tissues is found in the walls of the stomach, intestines, and blood
vessels?
a. cardiac muscle
b. smooth muscle c. skeletal muscle d. voluntary muscle
2. Which of the following types of muscle tissues is responsible for moving most parts of the
body?
a. cardiac muscle
b. smooth muscle
c. skeletal muscle
d. involuntary muscle
3. Your hair and nails are part of your
a. skeleton system
b. integumentary system
c. nervous system
d. muscular system
4. Muscle tone of skeleton muscle results from their
a. total relaxation
b. partial relaxation
c. total contraction d. partial contraction
5. The dermis contains all of the following Except
a. striated muscle
b. nerves
c. glands
d. blood vessels
6. The term that is least closely related to others is
a. skeletal muscle
b. smooth muscle
c. voluntary muscle d. striated muscle
7. A layer of fat and loose connective tissue is found in the
a. dermis
b. epidermis
c. subcutaneous layer
d. endodermis
8. The contraction of a muscle is terminated by the action of
a. calcium ions b. axon terminals
c. acetylcholine
d. acetylcholinesterase
9. The sliding filament theory is used to explain the
a. production of melanin pigment
c. ossification of bone
b. growth of hair cells
d. contraction of muscle
10. Oily secretions on the surface of the skin are produced by
a. sweat glands
b. sebaceous glands
c. hair follicles
d. red marrow
11. Muscles cells that contract without nervous stimulation are found in
a. skeletal and smooth muscles
c. smooth and cardiac muscles
b. skeletal and cardiac muscles
d. skeletal muscles only
12. The cells of the nail matrix produce strong, platelike nails when they become filled with
a. synovial fluid
b. sebum
c. karatin
d. melanin
13. The top layer of the epidermis is made of?
a. healthy, living cells
b. melanin
c. tough, dead cells
d. collagen
14. Whish is the function of sweat?
a. increase melanin count
b. increase keratin
c. regulate body temperature
d. excrete cholesterol
15. The muscles of the digestion system consists of
a. cardiac muscle
b. smooth muscle
c. skeletal muscle
d. connective tissue
16. Muscles that cause a joint to bend are called
a. flexors
b. origins
c. extensors
d. insertions
17. A sarcomere
a. is the functional unit of muscle contraction
c. uses ATP
b. consists of myofibrils
d. all of the above
18. Muscles move bones by
a. puling them
b. pushing them
c. stretching back and forth
d. relaxing
19. An example of a semimoveable joint is a
a. pivot joint
b. saddle joint
c. hinge joint
d. None of the above.
20. Which of the following occurs when skeleton muscles contracts?
a. the myosin heads remain attached to actin filaments
b. the myosin filaments overlap
c. the myosin heads bend outward
d. the sarcomeres shorten
21. The epidermis contains
a. glands
b. kertin
c. sensory neurons
d. muscle tissue
22. Which type of joint allows the shoulder to make circular motions?
a. pivot joint
b. angular joint
c. hinge joint
d. ball-and-socket joint
MATCHING:
______ cardiac muscle
a. tough membrane covering bone
______ ligament
b. bends a joint
______ extensor
c. cell layers covering body surfaces
______ appendicular skeleton
d. attaches muscles to bones
______ periosteum
e. straightens a joint
______ epithelial tissue
f. pumps blood through the body
______ tendon
______ flexor
g. includes bones in the arms and legs
h. holds bones of a joint in place
TRUE OR FALSE IF FALSE EXPLAIN WHY
1. TRUE OR FALSE Muscle tissue is highly specialized to push or contract to
produce movement.
2. TRUE OR FALSE The thick filaments in a muscle cell are made of actin.
3. TRUE OR FALSE Two types of striated muscle are cardiac and skeleton.
4. TRUE OR FALSE Ligaments attach the muscles to the bones.
5. TRUE OR FALSE Cardiac muscles contract without direct stimulation by the
nervous system.
6. TRUE OR FALSE Exercise is the key to maintaining good muscle tone.
7. TRUE OR FALSE The process of a muscle shortening is called the sliding
filament theory.
8. TRUE OR FALSE Muscel contractions is an all-or-nothing response.
9. TRUE OR FALSE Hair color and skin color are determined by karatin.
Identify each trait as a characteristic of one of the three types of muscle tissue.
___________________ 1. Controlled by the nervous and endocrine system.
____________________ 2. Striated and involuntary muscle.
____________________ 3. Found in many internal organs, but not the heart.
____________________ 4. Causes the pupils to contract in bright sunlight.
____________________ 5. Enables the bones of the body to move.
____________________ 6. Regulates the width of blood vessels.
____________________ 7. Works slowly, but constantly.
____________________ 8. Not under conscious control.
____________________ 9. Straited and voluntary muscle.
____________________ 10. Regulates the contractions of the digestive system.
____________________ 11. Muscle that makes up the heart.
____________________ 12. Nucleus divides during mitosis, but cells do not.
____________________ 13. Contracts and relaxes throughout your life.
____________________ 14. Contracts in response to nerve impulses.
____________________ 15. Unstriated and involuntary muscle.
DIRECTIONS: Answer the questions below as completely and as thoroughly as
possible.
Answer the question in essay form using complete sentences. You may use
diagrams to supplement your answers, but a diagram alone without appropriate
discussion is inadequate.
1. Explain why smooth muscle is referred to as involuntary muscle?
2. What is a muscle fiber? Explain, why does it appear striated?
3. Compare the functions of tendons and ligaments.
4. What are the three main types of muscle tissues found in the body, and what
are their functions?
5. Explain, what are actin and myosin, and how are they organized in a muscle?
How do
they interact during a muscle contraction?
6. Explain why smooth muscle is referred to as involuntary muscle?
7. Explain how skeletal muscles contract.
8. What are the Primary functions of skin?
9. Define the term insertion. Define the term origin.
10. Explain how muscles pairs work together to move a limb?
11. What are actin and myosin, and explain how they are organized in a
muscle? Explain how they interact during a muscle contraction?