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Muscular System


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Title: Muscular System

Muscular System
How many muscles do we have?
Over 650!
  • Our over 650 muscles fall into three categories
  • 1. skeletal,
  • 2. cardiac
  • 3. smooth.

Fun Facts
  • There are 50 muscles in your face alone.
  • It takes 17 muscles to smile and 40 muscles to
  • Your heart muscle NEVER gets any rest neither do
    the muscles of your intestines!
  • The most active muscles are those in your eyes.
    They move more than 100,000 times a day!

Biggest, Strongest, and Hardest Working
  • The gluteus maximus is the largest muscle in the
    human body.
  • The strongest muscle in your body is the
    masseter, located on each side of your mouth.
    These muscles help you bite down with 150 pounds
    of force!
  • The hardest working muscle is the heart. Every
    day the heart pumps at least 2,500 gallons of

In one day, your blood travels nearly 12,000
Three Types of Muscle Cells
  • Skeletal
  • Cardiac
  • Smooth

Skeletal Muscle a.k.a. striated muscle
Nuclei are on the periphery of the cells
2. Smooth Muscle
3. Cardiac Muscle
Do Now!
3. What kind of muscle?
1. What kind of muscle?
(C, Sm, Sk?)
(C, Sm, Sk?)
4. Lines hollow organs (C, Sm, Sk?) 5. Makes up
the heart walls (C, Sm, Sk?) 6. Connected to bone
(C, Sm, Sk?) 7. Involuntary (C, Sm, Sk?) 8. Used
to push substances along internal passageways.
(C, Sm, Sk?) 9. Voluntary (C, Sm, Sk?) 10. Moves
bones (C, Sm, Sk?)
2. What kind of muscle?
(C, Sm, Sk?)
Practice Practical Muscle Quiz
  • 1. Identify the type of tissue.
  • A) Dense regular connective tissue
  • B) Smooth muscle
  • C) Cardiac muscle
  • D) Skeletal muscle
  • 2. In question 1, above, what was the most
    distinctive identifying feature?
  • Striations
  • Branched fibers
  • Peripheral nuclei
  • A and C
  • A, B, and C

                      3. Identify this tissue A)
Dense regular connective tissue B) Smooth
muscle C) Cardiac muscle D) Skeletal muscle 4.
In question 3, above, what was the most
distinctive identifying feature? A) Striations B)
Branched fibers C) Central nuclei D) A and C E)
A, B, and C
           5. This specialized junction separates
cells in A) Cardiac muscle B) Skeletal muscle C)
Smooth muscle D) Tendons
  • 6. Identify this tissue.
  • A) Dense regular connective tissue
  • B) Smooth muscle
  • C) Cardiac muscle
  • D) Skeletal muscle
  • E) Dense irregular connective tissue

  • 7. Identify this tissue.
  • A) Dense regular connective tissue
  • B) Smooth muscle
  • C) Cardiac muscle
  • D) Skeletal muscle
  • E) Dense irregular connective tissue

                         8. Identify this
tissue A) Dense regular connective tissue B)
Smooth muscle C) Cardiac muscle D) Skeletal
muscle E) Dense irregular connective tissue 9.
In question 8, above, what was the most
distinctive identifying feature? A) Striations B)
Branched fibers C) Peripheral nuclei D) A and
C E) A, B, and C
                            10. Identify the name
of the connective tissue around each fiber A)
epimysium B) endomysium C) perimysium D)
meromysium E) sarcomysium
                         11. Identify the
structures noted by the arrows A) striations B)
sarcomeres C) Intercalated discs D) Sarcoplasmic
reticulum E) endomysium
Skeletal Muscle Fibers
  • Connect to bones
  • Forms the smoother contours of the body
  • Very long and cylindrical in shape
  • Multinucleated
  • Largest of the 3 muscle types
  • A.K.A. Striated muscles
  • Only muscle type under voluntary control
  • Can also be activated by automatic reflexes

How can they be so strong?
  • Each fiber is wrapped in connective tissue called
  • Several fibers are then wrapped in a courser
    membrane called a perimysium to form a fascicle.
  • The fascicle is bound together by an even tougher
    cover called an epimysium.

  • The epimysium (outer layer) can blend into strong
    cordlike tendons or
  • Into sheet-like aponeuroses (fascia) which attach
    muscle indirectly to bone, cartilages, or other
    connective tissue coverings.

Label this skeletal muscle using the diagram on
the next slide
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What do you remember?
Origin vs. Insertion
  • The muscles origin is attached to the immovable
  • At its other end, the insertion is attached to
    the movable bone.

Youll need this for lab!
The endomysium can be further divided.
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The myofilaments of a myofibril are arranged in a
regular fashion so that their ends are all lined
up. This is what gives the muscle its striated
appearance. The contractile units of the cells
are called sarcomeres.
The myofibrils have distinct, repeating
microanatomical units, termed sarcomeres.
The sarcomere is composed of thick and thin
filaments myosin and actin, respectively. Chemic
al and physical interactions between the actin
and myosin cause the sarcomere length to shorten
(contract). The interactions between actin and
myosin serve as the basis for the sliding
filament theory of muscle contraction.
Sliding Filament Theory
  • The sliding filament theory is the basic summary
    of the process of skeletal muscle contraction.
  • Myosin moves along the filament by repeating a
    binding and releasing sequence that causes the
    thick filament to move over the thinner filament.
  • This progresses in sequential stages. By
    progressing through this sequence the filaments
    slide and the skeletal muscles contract and

Naming Skeletal Muscles
  • Named based on structural or functional
  • 1. Direction of fibers Rectus (straight or
    parallel to an imaginary line) or oblique (at a

Naming Skeletal Muscles
  • 2. Size of muscle
  • Maximus (largest),
  • Minimus (smallest) and
  • Longus (long)

Naming Skeletal Muscles
  • 3. Location of the Muscle
  • Some are named for the bone they attach are
    associated with.

Ex. The temporalis muscle lays over the temporal
bones of the skull.
Naming Skeletal Muscles
  • 4. Number of Origins
  • Ex. Bicep muscle has two heads, triceps have
    three and quadriceps have four.

Naming Skeletal Muscles
  • 5. Location of Muscles origin and insertion.
  • Ex. Sternocleidomastoid has its origin on the
    sternum (sterno), and clavicle (cleido) and
    inserts on the mastoid process of the temporal

Naming Skeletal Muscles
  • 6. Shape of the Muscle
  • If a muscle has a definitive shape, it is used to
    help identify them.
  • Ex. Deltoid (triangular)

Naming Skeletal Muscles
Adductor A motion that pulls a structure or
part towards the midline of the body, or towards
the midline of a limb
7. Action of the Muscle
  • Flexor Closes a joint
  • Bending movement that decreases the angle
    between two parts. For ex. bending the elbow, or
    clenching a hand into a fist

Extensor opens a joint a straightening movement
that increases the angle between body parts
Abductor moves away from midline
Four functions of skeletal muscles.
  • Maintain posture
  • Stabilize joints
  • Generate heat
  • Produce movement

Aging and Muscles
  • After 30, your muscle mass dwindles some 3-8
    percent each decade. Once you hit 60, these
    losses accelerate even more quickly.
  • Decreased muscle mass means you'll burn far fewer
  • Muscles require a lot of calories to maintain.
    (Think of them as a bunch of high-strung, active
    family members visiting your home. They're always
    up, moving around. As a result, they're hungry
    and require a lot of food.)
  • The strength of your muscles is related to the
    strength of your bones. When your muscles are
    weak, your bones are more likely to be weak.
    (This is esp. important for women who have higher
    risk of osteoporosis.)

Muscle Pairs
  • Muscles are usually in (Antagonistic) pairs. When
    one muscle contracts, the other extends.
  • Adrenaline allows your muscles to use 4 to 6
    times more oxygen than usual thus creating a huge
    amount of energy.
  • Extreme strength http//
  • Two man strength performance http//

(No Transcript)
Disorders of the Muscular System
  • Muscular Dystrophy Occurs when a particular gene
    on the X chromosome a. fails to make the
    protein dystrophin.
  • b. makes low amounts of dystrophin.
  • the membranes around muscle cells become weak
    and tear easily, eventually leading to the death
    of muscle fibers.
  • More common in males.

  • Types of MD
  • A. When one of these proteins, dystrophin, is
    absent, the result is Duchenes muscular
  • B. Poor or inadequate dystrophin results in
    Beckers muscular dystrophy.

Animation http//
akY A familys story http//
Disorders of the Muscular System
  • 2. ALS Amyotrophic lateral sclerosis disease of
    the nerve cells in the brain and spinal cord that
    control voluntary muscle movement.
  • AKA Lou Gehrig's disease.
  • The symptoms usually do not develop until after
    age fifty.
  • Persons with this disease have a loss of muscle
    strength and coordination that eventually gets
  • Breathing or swallowing muscles may be the first
    muscles affected. As the disease gets worse, more
    muscle groups develop problems.
  • Life expectancy of an ALS patient averages about
    two to five years from the time of diagnosis.

  • Amyotrophic lateral sclerosis (ALS) is caused by
    the degeneration and death of motor neurons in
    the spinal cord and brain. These neurons convey
    electrical messages from the brain to the muscles
    to stimulate movement in the arms, legs, trunk,
    neck, and head. As motor neurons degenerate, the
    muscles are weakened and cannot move as
    effectively, leading to muscle wasting.

Fans, for the past two weeks you have been
reading about the bad break. Today I consider
myself the luckiest man on the face of this
earth. That I might have been given a bad break,
but I have an awful lot to live for. Thank you.
His record for most career grand slam home runs
(23) still stands today (Alex Rodriguez has 22,
Manny Ramirez has 21)
Disorders of the Muscular System
  • 3. Myasthenia gravis is caused by a defect in
    the transmission of nerve impulses to muscles.
  • Its a disease in which the immune system attacks
    the body's own tissues ("autoimmune" disease)
  • Causes a weakness of voluntary muscles without
    pain that gets worse with repeated or sustained
    use of the muscle (fatigued muscle weakness).
  • In two thirds of patients with MG, the first
    muscles to be affected are those controlling eye
    movements (causing double vision) and those
    holding the eyelids up (causing drooping of the
  • There are medications to treat the disorder. It
    is not fatal.

  • 4. Chronic Fatigue Syndrome Symptoms of chronic
    fatigue syndrome include loss of memory,
    difficulty concentrating, fatigue, random muscle
    pain, headaches, unrefreshing sleep and sore
  • 5. Fibromyalgia results in widespread pain
    throughout every muscle in a person's body.
    Approximately 2 of the entire US population is
    affected by fibromyalgia. Symptoms of
    fibromyalgia include joint tenderness, fatigue
    problems, and sleep disturbances. No cure.

  • 6. Cerebral Palsy
  • Cerebral palsy is condition that can involve
    brain and nervous system functions such as
    movement, learning, hearing, seeing, and
  • There are several different types of cerebral
  • Cerebral palsy is caused by injuries or
    abnormalities of the brain.
  • Most of these problems occur as the baby grows in
    the womb, but they can happen at any time during
    the first 2 years of life, while the baby's brain
    is still developing.

Botulism Botox
  • Difficulty swallowing or speaking
  • Facial weakness on both sides of the face
  • Blurred vision
  • Drooping eyelids
  • Trouble breathing
  • Nausea, vomiting and abdominal cramps (only in
    food-borne botulism)
  • Paralysis
  • Botulism is a rare but serious condition caused
    by toxins from bacteria called Clostridium
  • can be fatal
  • A weakened botulinum toxin (BOTOX) has been used
    to reduce facial wrinkles by paralyzing muscles
    beneath the skin, and for medical conditions,
    such as eyelid spasms and severe underarm

  • Botulism What is this toxin? http//
  • Botulism Cerebral Palsy treatment and Botox
  • http//

Poisons vs. Venom
  • Terms are often used interchangeably, but they
    actually have very different meanings.
  • It is the delivery method that distinguishes one
    from the other.
  • Poison is absorbed or ingested Ex. Toxin in skin
    or organs. (frogs, puffer fish, poison ivy)
  • Venom is always injected. Ex. Stab with tails.
    Slash with spines. Pierce with fangs. Spike with
    spurs. Shoot with harpoons. Chew with teeth.
    (snakes, spiders, bees)

Poisons (venom)
Stiletto Snake bite Part 1 Envenomation Part
2 http//
iletto-snakebite-symptoms.html Part 3 surgery
Part 3 automatically plays first so select Part 1
  • Effects of snake venom
  • Part 3 Rattlesnake Compartment Syndrome
  • Part 2Symptoms of the Bite
  • http//
  • Part 1 Bitten By a Rattler
  • http//

Two Types of Venom and What They Do To The Body
  • 1. Neurotoxin acts on the victim's nervous
    system, causing excitation (cramps, vomiting,
    convulsions) or depression (paralysis,
    respiratory or cardiac depression or arrest).
  • Black Widow Spider
  • Cobra
  • Coral Snakes
  • Gila monster
  • Puffer fish
  • Short-tailed shrew
  • Kraits

Two Types of Venom and What They Do To The Body
  • 2. Hemotoxin ("blood poison") breaks down the
    victim's tissues, usually by an acid or a toxin
    that prevents or causes blood clotting, or
    destroys red or white blood cells. Venom usually
    contains both types, but one dominates.
  • scorpion
  • Copperhead
  • Rattlesnakes
  • Water Moccasin/Cottonmouth

You are 9X more likely to die by lightening
strike than getting bit by a venomous snake.
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Hey You! Label my muscles!
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Steroids anyone?
  • http//

Steroid use 15minutes (some bad lang.) Part 3
related Part 4 http//
dmXRAKieQNR1 Tyra Greg Today
Muscle System Test
  • 3 types of muscles chara. of each one, and ID a
    picture.(matching description with muscle type)
  • Four functions of skeletal muscles.
  • Produce movement
  • Maintain posture
  • Stabilize joints
  • Generate heat
  • Basic Microscopic Anatomy/sliding filament
    theory. Label muscle cell.
  • 7 ways to name muscles ex of each.
  • Name the main anterior and posterior muscles.
  • Disorders/diseases (M.D., cerebral palsy, ALS,
    myasthenia gravis, botulism, snake venom)
    treatment Botox

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The anatomy of a sarcomere
  • The entire array of thick and thin filaments
    between the Z disks is called a sarcomere.
  • The thick filaments produce the dark A band.
  • The thin filaments extend in each direction from
    the Z disk. 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.
  • The M line runs through the exact center of the
    sarcomere. Molecules of the giant protein, titin,
    extend from the M line to the Z disk. One of its
    functions is to provide a scaffold for the
    assembly of a precise number of myosin molecules
    in the thick filament (294 in one case). It may
    also dictate the number of actin molecules in the
    thin filaments.
  • Shortening of the sarcomeres in a myofibril
    produces the shortening of the myofibril and, in
    turn, of the muscle fiber of which it is a part.
  • This electron micrograph of a single sarcomere
    was kindly provided by Dr. H. E. Huxley.

Actin Myosin
Actin Myosin
Sliding Filament Theory
  • 1. http//
  • 2. http//

7 stages of the Sliding Filament Theory
  • First Stage The first stage is when the
    impulse gets to the unit. The impulse travels
    along the axon and enters the muscle through the
    neuromuscular junction. This causes full two to
    regulate and calcium channels in the axon
    membrane to then open. Calcium ions come from
    extra cellular fluid and move into the axon
    terminal causing synaptic vessels to fuse with
    pre synaptic membranes. This causes the release
    of acetylcholine (a substance that works as a
    transmitter) within the synaptic cleft. As
    acetylcholine is released it defuses across the
    gap and attaches itself to the receptors along
    the sarcolemma and spreads along the muscle
    fiber. Second Stage The second stage is for
    the impulse spreads along the sarcolemma. The
    action potential spreads quickly along the
    sarcolemma once it has been generated. This
    action continues to move deep inside the muscle
    fiber down to the T tubules and the action
    potential triggers the release of calcium ions
    from the sarcoplasmic reticulum. Third Stage
    During the third stage calcium is released from
    the sarcoplasmic reticulum and actin sites are
    activated. Calcium ions once released begin
    binding to Troponin. Tropomyosin blocking the
    binding of actin is what causes the chain of
    events that lead to muscle contraction. As
    calcium ions bind to the Troponin it changes
    shape which removes the blocking action of
    Tropomyosin (thin strands of protein that are
    wrapped around the actin filaments). Actin active
    sites are then exposed and allow myosin heads to
    attach to the site. Fourth Stage The fourth
    stage then begins in which myosin heads attach to
    actin and form cross bridges, ATP is also broken
    down during this stage. Myosin binds at this
    point to the exposed binding sites and through
    the sliding filament mechanism the muscles
    contract. Fifth Stage During the fifth stage
    the myosin head pulls the Actin filament and ADP
    and inorganic Phosphate are released. ATP binding
    allows the myosin to detach and ATP hydrolysis
    occurs during this time. This recharges the
    myosin head and then the series starts over
    again. Stage Six Cross bridges detach while
    new ATP molecules are attaching to the myosin
    head while the myosin head is in the low-energy
    configuration. Cross bridge detachment occurs
    while new ATP attaches itself to the myosin head.
    New ATP attaches itself to the myosin head during
    this process. Stage Seven During stage seven
    the ATP is broken down and used as energy for the
    other areas including new cross bridge formation.
    Then the final stage (stage 8) begins and a drop
    in stimulus causes the calcium concentrate and
    this decreases the muscle relaxation.
  • Read more http//

Resting and Action Potential
  • Neurons send messages electrochemically. This
    means that chemicals cause an electrical signal.
  • The important ions in the nervous system are
    sodium and potassium (both have 1 positive
    charge, ), calcium (has 2 positive charges, )
    and chloride (has a negative charge, -).
  • Resting Membrane Potential
  • When a neuron is not sending a signal, it is "at
  • Action Potential
  • An action potential occurs when a neuron sends
    information down an axon, away from the cell
    body. Neuroscientists use other words, such as a
    "spike" or an "impulse" for the action potential.
  • The action potential is an explosion of
    electrical activity that is created by some event
    (a stimulus).
  • There are no big or small action potentials in
    one nerve cell - all action potentials are the
    same size. Therefore, the neuron either does not
    reach the threshold or a full action potential is
    fired - this is the "ALL OR NONE" principle.
  • This is in reference to an individual muscle cell
    not the whole muscle therefore there can be a
    graded response in the muscle contraction.

(No Transcript)
Neuromuscular Junction
  • A skeletal muscle cannot contact unless
    stimulated by a motor nerve.
  • This junction between a nerve fiber (axon) and
    muscle cell is called a neuromuscular junction.
  • http//
  • Watch it using flash player
  • http//

  • When acetylcholine is released from an axon
    terminal, it moves across the synaptic cleft to
    bind to a receptor on the other side of the
    synapse (on the post-synaptic membrane).
  • In the peripheral nervous system, acetylcholine
    is located at the "neuromuscular junction" where
    it acts to control muscular contraction.

Extra Credit
  • 1. How does adrenaline make you stronger?
  • 2. Muscles are usually in antagonistic pairs.
    What does that mean and give an example of a