Download 5. Muscle Anatomy and Physiology

MUSCLE ANATOMY AND
PHYSIOLOGY
TYPES OF MUSCLE PATTERNS
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PARALLEL
PENNATE
CONVERGENT
CIRCULAR
PARALLEL MUSCLE
The fascicles are parallel.
They are long fibers, which
can contract to 75% of their
length. They contract a long
way, but they are relatively
weak, because there are
relatively few fascicles. E.g.
Sternocleidomastoid.
Arrangement
of Fascicles in
Muscles
Figure 11.3
PENNATE
PENNATE (means “feather shape”) MUSCLES: three types:
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UNIPENNATE; looks like half a feather. The fascicles are
short, but there are more of them. They are stronger, but do
not have the same length contraction ability of the parallel
muscles.
BIPENNATE are fascicles that insert into the tendon from
both sides; they are stronger than unipennate.
MULTIPENNATE are the strongest (biceps femoris). The
fascicles are in multiple bundles inserting on one tendon
PENNATE
CONVERGENT
CONVERGENT MUSCLE has more fibers
than parallel, but contracts a greater distance
than pinnate. E.g. Pectoralis major.
CIRCULAR MUSCLE
CIRCULAR MUSCLE (Sphincter) is arranged
in a circle, with a small area of tendon on the
sides. It allows closure of the eyes, mouth,
etc. They are not very strong, but they don’t
need to be.
TERMS:
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ORIGIN = The region which usually doesn’t move when the
muscle contracts. Look at the biceps brachii; does the
shoulder move when I bend my arm? No; the shoulder =
origin.
INSERTION= The point of attachment that moves; bend
arm, radial tuberosity = attachment.
AGONIST = The main muscle for a particular action; bend
arm, biceps = agonist.
ANTAGONIST = Does the opposite action; bend elbow,
antagonist extends. Every muscle in the body has to have an
antagonist.
SYNERGIST = The muscle that helps the agonist. There are
several muscles that assist when the arm is bent.
Muscle Attachments
Muscle Types
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Skeletal:
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Smooth:
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striated
Voluntary
Moves the skeleton
no striations
Involuntary
Found in organs and lining of blood vessels
Cardiac:
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striated
involuntary
Skeletal Muscle Characteristics
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
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Contractility
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The ability to shorten with force

However, they lengthen passively, by gravity or by the contraction of an
opposing muscle.
Excitability

Capacity to respond to a stimulus (nerves)
Extensibility

Can be stretched

After a contraction, they can be stretched to their normal resting length
and beyond to a limited degree.
Elasticity
Can recoil to their original resting length after they have been stretched
Has several nuclei per cell, unlike smooth and cardiac muscle
SKELETAL MUSCLE
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Theses are very long fibers (biceps muscle
can be 8-10 cm).
They have thousands of nuclei because they
start from many stem cells that fuse together
into one skeletal muscle fiber.
Skeletal Muscle
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Myoblasts exist in adults, so muscle heals
well.
A muscle cell torn in half can regenerate.
There are almost no muscle diseases for this
reason (muscular dystrophy is the main
muscle disease).
Skeletal Muscle: Longitudinal section
In skeletal
muscle
fibers, there
are light and
dark stripes
called
striations,
which can be
seen under a
microscope.
Skeletal Muscle
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The plasma membrane of muscles is called a
SARCOLEMMA.
The cytoplasm of muscle cells is called
SARCOPLASM.
Muscle cells contain many mitochondria and
other organelles.
One type of unusual organelle found only in
muscle cells is called a myofibril. They are
packed in bundles and fill up most of the cell.
•
MUSCLE MYOFIBRILS
• Cylindrical organelles found within muscle cells
• Contain actin and myosin myofilaments
• Extend from one end of the muscle fiber (muscle cell) to the other
• Contain sarcomeres joined end to end.
Skeletal Muscle: Longitudinal
section
These striations
(stripes) are caused
by dark and light
bands.
SARCOMERES
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The striations result from the internal
structure of SARCOMERES within the
sarcoplasm.
The sarcomere is the basic structural and
functional unit of skeletal muscle. The
sarcomere is what contracts.
Actin and Myosin
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Sarcomere model video
Sarcomeres consist of two types of myofilaments
made out of protein:
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thin (ACTIN) myofilaments
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Look like two strands of beads twisted together.
thick (MYOSIN) myofilaments.
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Both ends of a thick filament are studded with knobs
called myosin heads (look like little golf clubs).
Actin
Myosin
Actin
Myosin
Don’t confuse these terms!
MUSCLE FASCICLE: a group of muscle fibers,
surrounded by perimysium.
MUSCLE FIBER: a single muscle cell
MYOFIBRIL: a long organelle inside a muscle fiber,
contains actin and myosin myofilaments.
MYOFILAMENTS: these are proteins, and there are two
types: actin (with troponin and tropomyosin) and myosin.
The myofilament is the lowest level of organization that is
composed of actin, troponin, and tropomyosin proteins.
Therefore, a myofilament is part of a myofibril, which is
inside a muscle fiber, which is inside a muscle fascicle.
MECHANISM OF CONTRACTION
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The Sliding Filament Theory
Contraction results as the myosin heads of the thick filaments
attach like hooks to the thin actin filaments at both ends of the
sarcomere and pull the thin filaments toward the center of the
sarcomere.
The myosin head is like a hook with a hinge. After a myosin
head pivots at its hinge, it draws the actin closer, then lets go,
springs up again to grab the actin filament again, pulls it closer,
and it keeps repeating this until the entire actin filament has
been drawn in as far as it can go.
Sarcomere Contraction
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The complete process of contraction of the sarcomere takes
only a fraction of a second.
The actin and myosin filaments do not shorten; they
merely slide past each other.
The energy required is ATP.
This sliding filament mechanism begins whenever calcium
ions bind to the thin filament.
Where does the calcium come from?
SARCOPLASMIC RETICULUM AND
T TUBULES
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Within the cytoplasm of all body cells is an
endoplasmic reticulum.
The endoplasmic reticulum in muscle cells is
called the SACROPLASMIC RETICULUM.
It surrounds each sarcomere like the sleeve of a
loosely crocheted sweater.
Most of the “yarn fibers” of this “knit sweater”
run longitudinally, but some run perpendicular to
them and surround structures called T tubules.
Sarcoplasmic
reticulum is in
blue
T tubules are in
yellow
Calcium is needed
for muscle contraction
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The sarcoplasmic reticulum stores a lot of calcium
ions, which are released when the muscle is stimulated
to contract.
The calcium diffuses through the sarcoplasmic
reticulum to the actin filaments, where they trigger the
sliding filament mechanism of contraction.
After the contraction, the calcium ions are pumped
back into the sarcoplasmic reticulum for storage.
Calcium is needed for muscle
contraction
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ACTIVE TRANSPORT is required to return the
calcium ions to the sarcoplasmic reticulum.
It also requires energy to make the myosin head cock
back again, ready to spring onto the next binding site.
Therefore, ATP is used.
 ATP is used to return calcium to the sarcoplasmic
reticulum
 ATP is used to cock back the myosin heads
ATP is required for contraction
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ATP attaches to the myosin myofilaments
 Provides energy for the movement of the cross
bridges
ATP is required for muscle relaxation
ATP releases part of its energy as heat.
 That is why we get hot when we exercise
 When we are cold, we shiver (muscle contraction)
to warm up.
In order for the mitochondria to produce enough ATP,
it needs oxygen and the sugars that are in storage.
For contraction to take place, you need two
things: nerve signal and calcium
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For skeletal muscle to contract, the synaptic knob of
a neuron must first release a chemical called
ACETYLCHOLINE onto the region where it sits
on the muscle cell, known as the ENDPLATE.
Calcium is also needed for muscle contraction.
The nerve signal is called an ACTION
POTENTIAL.
It causes a release of calcium from the sarcoplasmic
reticulum, which causes contraction.
Muscle Contraction
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In a muscle fiber, an action potential results in
muscle contraction. How does this happen?
The action potential continues to travel along the
sarcolemma (cell membrane of the muscle).
Part of this electrical impulse breaks away from
the sarcolemma and travels down the T-tubules,
while the rest of the electrical impulse continues
longitudinally down the muscle cell to the next
sarcomere and T-tubule.
T tubules are in
yellow
T TUBULES
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T TUBULES (“T” stands for “transverse”)
are continuations of the sarcolemma (cell
membrane) which invaginate to the deepest
regions of the muscle cell.
Since the T tubules conduct the nerve impulse
throughout the muscle cell, all the sarcomeres
of that cell contract at the same time.
Muscle Contraction
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The action potential of the nerve goes down the Ttubules and causes calcium to leak out of the
sarcoplasmic reticulum.
The calcium causes the muscle fibers to contract.
After a while, the calcium gets pumped back
where it came from, the muscle fibers relax,
although it requires gravity or another muscle to
pull the sarcomere back to its original length.
How does the calcium cause the muscle fibers to
contract?
TROPOMYOSIN is a single long protein strand like a piece
of yarn that winds around the actin filament.
• Tropomyosin blocks actin’s attachment site for the
myosin head, so the myosin “hook” has nothing to grab
onto, thus preventing contraction.
TROPONIN is a globular complex of three proteins, and is
found in clumps around the tropomyosin protein.
• Troponin is the specific molecule that provides the
calcium binding site on actin.
• Calcium binds to troponin and causes troponin to move
a little, taking the tropomyosin thread with it, so the
attachment sites on the actin molecule are now
exposed. The myosin heads can now hook into the
exposed sites on the actin myofilament.
Both troponin and tropomyosin cover the actin filament
when the muscle is relaxed.
This is an
illustration of
an actin
molecule.
You can see
the thready
tropomyosin
and the
globular
troponin
proteins
wrapping
around the
doublestranded
actin.
When
calcium binds
to the
globular
troponin, it
moves,
taking the
tropomyosin
thread with it.
This exposes
the myosin
binding site
on the actin.
Calcium in muscle contraction
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When the muscle cell is stimulated to contract by an
action potential, calcium channels open in the
sarcoplasmic reticulum and release calcium into the
sarcoplasm.
Some of this calcium attaches to troponin, causing a
conformational change that moves tropomyosin out of the
way so that the myosin heads can attach to actin and
produce muscle contraction.
When the calcium gets pumped back where it came from,
the tropomyosin protein blocks the myosin head again so
it can no longer get its hook into the actin filament, and
the muscle will relax.
Rigor Mortis
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A new ATP molecule must bind to the myosin
before the cross-bridge can be release. When ATP
is not available after a person dies, the crossbridges that have formed are not released, causing
muscle to become rigid (rigor mortis)
NOTE: Sarcomeres lengthen during muscle
relaxation, but only if gravity or an opposing
muscle pulls the sarcomere back to its original
length.
Muscle Contraction
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http://www.youtube.com/watch?v=CepeYFvq
mk4
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http://www.youtube.com/watch?v=WRxsOM
enNQM&feature=related
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http://www.youtube.com/watch?v=InIha7bCT
jM&NR=1
Sequence of events
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The action potential reaches the cell membrane
The action potential reaches the T-tubules
The ion channels in the sarcoplasmic reticulum open
Calcium ions move along their concentration gradient
Actin forms cross-bridges to myosin
The actin myofilaments move closer to each other,
causing contraction of the sarcomere.
NOTE: A muscle fiber will not respond to a stimulus
until that stimulus reaches the threshold level.
Muscle Contraction
A muscle TWITCH is one single muscle fiber
contraction.
 It takes 1/20th of a second.
 How is it that I can pick up and hold a chair if the
fiber only contracts for 1/20th second?
 There are ten thousand fibers per muscle; each
one contracts at different intervals, so contraction
is maintained, just like tug-of-war. One person in
ten can drop the rope and get a better grip
because the others are maintaining the tension.
Motor Units
A MOTOR UNIT is a single neuron and all of
the muscle fibers on which it synapses.
If one neuron sends a signal, only its muscle
fibers contract (the motor unit). This allows
for strength variations in lifting a chair vs. an
eraser. For full strength, all the motor units
contract. For half strength, half of the motor
units contract.
Motor
Units
There are 3 motor units in this diagram; that allows for 3
different levels of contraction. The more motor units there
are, the more precisely the muscle can respond.
Motor Units
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The action potential continues from one motor neuron
to the next motor neuron until the last neuron lands on
its target cells; in this case, skeletal muscle fibers.
A single motor neuron and all the skeletal muscle
fibers it iterates constitute a motor unit.
A muscle in your tongue may be innervated by many
neurons to allow for precise movement. However,
large thigh muscles may have only one neuron
innervating thousands of muscle fibers, since precision
is not necessary.
Motor Units
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A large motor unit is when one neuron
supplies many muscle fibers. An example is
the muscles of the back. These areas will
have fewer motor units present. Therefore,
you get more strength, but less precision.
A small motor unit is when one neuron
supplies few muscle fibers. Therefore, many
motor units will be present in that muscle. An
example is the tongue. That causes less
strength but more precision.
Muscle Twitch Phases
A muscle twitch has three phases
 The lag phase is the time between the application of a
stimulus and the beginning of contraction.
 The contraction phase is the time of contraction.
 The relaxation phase is the time during which the
muscle relaxes.
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The refractory period is the time between muscle
twitches.
Refractory
period
Force of Contraction
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The strength of muscle contraction can vary from weak to
strong. For example, the force generated by muscles to lift a
feather is much less than the force required to lift a 25 pound
weight.
The force of contraction produced by a muscle is increased in
two ways:
Summation, which involves increasing the force of contraction
of the muscle fibers within the muscle
Recruitment, which involves increasing the number of muscle
fibers contracting
Summation
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The force of contraction of individual muscle fibers is increased by rapidly
stimulating them.
Stimulus frequency is the number of times a motor neuron is stimulated per
second.
When the stimulus frequency is low, there is time for complete relaxation of
muscle fibers between twitches.
As stimulation frequency increases, there is not enough time between
contractions for muscles to completely relax.
Thus, one contraction summates, or is added onto, a previous contraction. As
a result, the overall force of contraction increases.
Tetanus is the condition in which a muscle remains contracted between
stimuli without relaxing.
TETANUS TOXIN
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A toxin caused by a certain bacteria can cause muscle to remain
contracted (in tetanus).
It quickly results in death because the diaphragm and other
respiratory muscles cannot function properly, and the person
suffocates.
The bacteria that make this toxin
live deep in the soil and cannot
survive in air.
If you step on something that
imbeds soil deeply into your
tissues (like a rusty nail), you
might contract the bacteria.
You will need a tetanus vaccine
before the toxins accumulate.
Recruitment
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In recruitment, the strength of contraction of the muscle is
increased by increasing the number of motor units
stimulated.
When only a few motor units are stimulated, a small force of
contraction is produced, because only a small number of muscle
fibers are contracting.
As the number of motor units stimulated increases, more muscle
fibers are stimulated to contract, and the force of contraction
increases.
Maximum force of contraction is produced in a given muscle
when all the motor units of that muscle are stimulated, or
recruited.
Types of Muscle Contractions
Muscle contractions are classified as either isometric or isotonic. Most muscle
contractions are a combination.
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Isometric (equal distance)
tension increases during contraction
length of the muscle does not change
Example is when you push against a wall or try to pick up an object
that is too heavy to lift
Isotonic (equal tension)
tension is generally constant during contraction

Although in one type of isotonic contraction, the tension increases
Length of the muscle changes (either increases or decreases).
Example is when you lift a weight.
Concentric and Eccentric
Contractions
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Two types of isotonic contractions:
CONCENTRIC CONTRACTIONS are isotonic contractions
in which the muscle tension increases as the muscle shortens.
Most movements performed by muscle contractions are of this
type.
ECCENTRIC CONTRACTIONS are isotonic contractions in
which tension is maintained as the muscle lengthens. An
example is when a person lets down a heavy weight slowly.
Substantial force is produced in the muscles and injuries can
occur from repetitive eccentric contractions, such as in the
hamstring muscles when a person runs downhill.
Muscle Tone
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Even when muscles are relaxed, some of their fibers
are still contracting, giving the muscle some tone.
Therefore, the normal state of a muscle, with some
contraction, is called muscle tone. This is important
in posture so you can stand upright but mostly relaxed.
Muscle tone refers to the constant tension produced by
muscles of the body over long periods of time. It is
responsible for keeping the back and legs straight, the
head held in an upright position, and the abdomen
from bulging. it declines during REM sleep.
Muscle Tone
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Hypertonia
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Can present clinically as either spasticity or
rigidity
Hypotonia
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Seen in lower motor neuron diseases
Can present clinically as muscle flaccidity, where
the limbs appear floppy, stretch reflex responses
are decreased, and the limb’s resistance to passive
movement is also decreased.
Muscle Spasticity
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Spasticity is a feature of altered skeletal muscle performance
in muscle tone involving hypertonia, which is also referred to
as an unusual "tightness" of muscles. Clinically spasticity is
defined as velocity dependent resistance to stretch, where a
lack of inhibition from the CNS results in excessive
contraction of the muscles.
Passively moving an elbow quickly will elicit increased
muscle tone, but passively moving elbow slowly may not
elicit increased muscle tone
It mostly occurs in disorders of the central nervous system
(CNS) impacting the upper motor neuron in the form of a
lesion, but it can also present in various types of multiple
sclerosis, which are autoimmune conditions.
Muscle Spasticity
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Precise cause aside, whenever there is a loss of muscle tone
inhibition from the brain to the spinal cord such that muscles
become overactive, this loss of inhibitory control can cause
an ongoing level of contraction, with decreased ability for the
affected individual to volitionally control the muscle
contraction, and increased resistance felt on passive stretch.
There is a difference in cause of two of the most common
spasticity conditions, spastic diplegia and multiple sclerosis.
In spastic diplegia, the upper motor neuron lesion arises often
as a result of neonatal asphyxia (lack of oxygen in a
newborn), while in conditions like multiple sclerosis,
spasticity is from autoimmune destruction of the myelin
sheaths around nerve endings.
Muscle Spasticity
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A defining feature of spasticity is that the
increased resistance to passive stretch is
velocity-dependent.
There is a velocity-dependent increase in
tonic stretch reflexes (muscle tone) with
exaggerated tendon jerks, resulting from
hyper-excitability of the stretch reflex.
Muscle Spasticity
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Causes include
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Cerebral palsy
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Spastic diplegia (a form of Cerebral palsy)
Multiple sclerosis
Spinal cord injury
Stroke
Muscle Rigidity
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Unlike spasticity, rigidity is velocityindependent resistance to passive stretch.
There is uniform increased tone whether the
elbow is passively moved quickly or slowly.
Muscle Clonus
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Clonus (from the Greek for "violent, confused motion") is a series
of involuntary muscular contractions and relaxations.
Clonus is a sign of certain neurological conditions, and is
particularly associated with upper motor neuron lesions such as in
stroke, multiple sclerosis, spinal cord damage.
Clonus causes large motions that are usually initiated by a reflex.
Clonus is most common in the ankles, where it is tested by
rapidly flexing the foot upward (dorsiflexion).
It can also be tested in the knees by rapidly pushing the patella
(knee cap), towards the toes.
Only sustained clonus (5 beats or more) is considered abnormal.
Muscle Fasciculations
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These are small, local, involuntary muscle
contraction and relaxation visible under the
skin arising from the spontaneous discharge
of a bundle of skeletal muscle fibers (muscle
fascicle).
Fasciculations have a variety of causes, the
majority of which are benign, but can also be
due to disease of the lower motor neurons.
Muscle Fasciculations
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Benign causes of fasciculations include:
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Magnesium deficiency
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Diarrhea
Overexertion
Inadequate intake from diet (almonds are a good
source of magnesium)
Dehydration
Fatigue
Muscle Fasciculations
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They can also be caused by long-term use of:
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Benadryl (antihistamine)
Dramamine (for nausea and motion sickness).
Caffeine
Sudafed
Asthma medicines
ADD medicines
Muscle Fasciculations
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More serious conditions causing
fasciculations include
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Fibromyalgia
Myasthenia Gravis
Lyme Disease
Rabies
Hyperreflexia
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The most common cause of exaggerated
reflexes is spinal cord injuries (upper motor
neuron diseases).
Other causes include
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Medication
Stimulants
Hyperthyroidism
Electrolyte imbalance
Severe brain trauma.
Hyporeflexia
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This means diminished or absent reflexes.
The most common cause is lower motor
neuron diseases.
Muscle Contractures
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Muscle contractures can occur from paralysis,
muscular atrophy, muscular dystrophy,
immobilization from a cast, and chronic spastic
conditions like cerebral palsy.
Fundamentally, the muscle and its tendons shorten,
resulting in reduced flexibility.
Muscle contractures in tendons are caused from the
fibrinogen leaking out of the fibroblasts, which turn
the elastic fibers into inelastic fibers.
Most treatments involve surgery, so physical therapy
efforts focus on prevention of contractures.
Energy Requirements of Muscle
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What fuel does a car use?
 Gasoline
What fuel does a candle use?
 Wax
What fuel do humans use?
 Oxygen?
 NO
 Sugars?
 NO
 ATP
 YES
ATP
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Where do we get ATP?
We can make a little ATP in the cytoplasm of our cells, but not
enough to live on.
Most of our ATP is made by the mitochondria inside our cells.
Mitochondria are like little protozoa (animals) that live in our
cells. Each cell has hundreds of them. Muscle cells have
thousands of them.
What is their fuel?
 Oxygen and glucose
THAT is why we need to inhale oxygen and consume sugars….to
feed our mitochondria so they can make ATP for us!
Energy Requirements
For Muscle Contraction
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In order for the muscle mitochondria to produce
enough ATP, they need oxygen (for their own aerobic
respiration) and sugars that are in storage.
Mitochondria can only perform aerobic respiration.
What can we do to make ATP if our muscle cells run
out of oxygen?
Start performing anaerobic respiration.
We can do this ourselves in the cytoplasm of our cells.
Making ATP by Aerobic
Respiration
Aerobic respiration
 Takes place in the mitochondria
 Requires oxygen
 Breaks down glucose to produce ATP
 Waste products are CO2 and H2O (we exhale them)
 The good thing about making ATP from our
mitochondria is that we can make a LOT of it.
 The bad things are that it takes longer to make it,
and it requires oxygen, and a muscle cell may have
used up all the oxygen during a sprinting run.
Making ATP by Anaerobic
Respiration
Anaerobic respiration
 Takes place in the cytoplasm
 Does not require oxygen
 Breaks down glucose to produce ATP
 Waste product is lactic acid
 The good thing about making ATP this way is
that we can make it FAST.
 The bad thing is that it does not make much
ATP, and we deplete the reserves quickly.
Lactic Acid
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The waste product of aerobic respiration is carbon
dioxide and water. These are not a problem…we
eliminate them by exhaling.
The waste product of anaerobic respiration is lactic
acid, which can irritate muscle fibers, causing muscle
pain (stitch in your side) and muscle cramps.
We deactivate lactic acid by adding oxygen to it.
Therefore, breathing heavily adds the oxygen to our
system to deactivate lactic acid, and the muscle pains
go away.
ATP and Creatine Phosphate
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What do we do when we run out of ATP?
Muscle fibers cannot stockpile ATP in preparation for future
periods of activity.
However, they can store another high energy molecule called
creatinine phosphate.
Creatine phosphate is made from the excess ATP that we
accumulate when we are resting.
During short periods of intense exercise, the small reserves
of ATP existing in a cell are used first.
Then creatinine phosphate is broken down to produce ATP.
Aerobic vs. Anaerobic Respiration
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When do we use aerobic respiration?
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Resting (can breathe easily)
Running marathons (can breathe easily on long
runs)


Marathon runners want to make sure there will be
enough readily available energy for the muscles, so they
eat a lot of carbohydrates over a two-day period before
the marathon. That’s why they load up on pasta before a
marathon.
When do we use anaerobic respiration?

Sprint running (can’t talk while sprinting!)
Aerobic vs. Anaerobic
Respiration




Why does sprinting require anaerobic respiration?
 We use up all of the ATP faster than we can make it.
When we run out of ATP, we break down creatine phosphate to
make more ATP.
When we run out of glucose, or too much lactic acid is built up,
we have to stop and rest.
Anaerobic metabolism is ultimately limited by depletion of
glucose and buildup of lactic acid within the muscle fiber.
Sprint Runners



Why do sprint runners tire out during the last part of a
fast run?
Sprinting is an anaerobic activity…the oxygen
requirement is quickly exceeded, so the muscle has to
use anaerobic respiration to continue to contract. This
requires a lot of glucose and also results in a buildup
of lactic acid.
Once the sprint-runner has used up the available
glucose, or has produced too much lactic acid, the
muscles fatigue.
Oxygen Debt





Anaerobic respiration produces lactic acid, which
causes the painful cramps because it creates an oxygen
debt.
The amount of oxygen needed to replenish the
supply following aerobic demand is called the
oxygen debt.
When you continue to breathe heavily after exercising,
it means you have an oxygen debt.
Muscles can do without oxygen for a while pretty well,
unlike the brain.
To pay back a minor oxygen debt, you just have to
breathe heavily for a while.
Oxygen Debt



This heavy breathing brings in oxygen, which is used
to convert lactic acid to glucose, replenish the depleted
ATP and creatinine phosphate stores in the muscle
fibers, and to replenish oxygen stores in the lung,
blood, and muscles.
After the oxygen debt has been paid back, breathing
returns to normal.
People who are in good physical condition can carry
out both aerobic and anaerobic activities efficiently,
and do not suffer from an oxygen debt for very long.
EXERCISE

1.
2.
3.
4.
5.
There are many physiological benefits of
exercise:
Improved muscular strength, endurance,
flexibility
Improved cardio-respiratory endurance
Increased bone density and strength
Relief from depression
Increased HDLs
Hypertrophy



Weight training and other exercises can cause muscles to
hypertrophy ( enlarge). This occurs as more myofilaments and
myofibrils are produced inside a myofiber, causing them to
enlarge. The number of mitochondria also increases, causing
additional enlargement.
However, you don’t grow new muscle cells. The number of
cells in a skeletal muscle remains relatively constant following
birth.
Hypertrophy can happen in two ways:



Increase in number of fibers inside a muscle cell
Increase in size of individual fibers
Muscle hypertrophy is greater in males due to the hormone
testosterone.
Hypertrophy




A professional athlete may have many muscles that exhibit
hypertrophy.
Eating protein does not automatically increase muscle. The
average person only needs one ounce of protein a day, two if
you work out.
Two ounces is like one mini hamburger.
Most people eat too much meat.
Fun Fact: -You use 200 muscles to take one step.
Atrophy





Lack of use causes muscle ATROPHY. This happens quickly.
Astronauts can lose 40% of their muscle in two weeks! It is
regained quickly, too.
Atrophy is a decrease in muscle size because of the decrease in
myofilaments within muscle fiber.
Severe atrophy involves the permanent loss of skeletal muscle
fiber and the replacement of those fibers by connective tissue.
Damage to the nervous system, or a severed motor nerve can
cause atrophy. The muscle becomes flaccid (having no tone) .
Casting a broken limb also leads to temporary atrophy.
Muscular Dystrophy


This refers to a group of inherited muscle
disorders in which skeletal, cardiac, and smooth
muscle tissue degenerates and the person
experiences progressive weakness and other
symptoms, including heart problems.
The disorders are characterized by the
progressive degeneration of muscle fibers
leading to atrophy and their eventual
replacement by fat and other connective tissue.
Muscular Dystrophy


MUSCULAR
DYSTROPHY
This is a genetic lack of a
protein called
DISTROPHIN. It causes
the muscle tissue to harden,
inhibiting contraction,
causing progressive
paralysis.
 Duchenne muscular
dystrophy is more
common in males.
Muscle Problems



Tendonitis is an inflammation of the tendon or
its attachment point. It usually occurs in
athletes who overuse the muscle to which the
tendon is attached.
A strain is a tear in a muscle. Remember, a
sprain is a tear in a ligament.
A muscle strain will heal faster than a torn
ligament because muscles have good blood
supply and ligaments do not.
Treatment for Injuries: RICE


Rest
Ice



Compression



20 minutes on, 20 minutes off
Ice pack or frozen bag of peas!
Ace wrap from distal to proximal
Don’t leave any openings while wrapping
Elevation

Above the heart
Treatment for Injuries


Ice for the first 72 hours (NO heat!)
Anti-inflammatory medicines




Ibuprofin, 600 mg TID (3x a day)
Over the counter (OTC) pills are 200 mg
Heat and massage as needed after third day.
Can try a muscle stimulator too…works pretty
well!
Muscle Spasms



Muscle spasms/cramps are sudden and involuntary muscle
contractions. They are painful, spastic contractions that are
usually caused from overexertion. Lactic acid builds up and
irritates the overused muscles, causing inflammation. If the
muscle remains in spasm for longer than a few minutes, might
need heat and massage to increase circulation.
Avoid spasms by stretching before and after activities.
For people with frequent low back spasms throughout the day, a
portable muscle stimulator that clips to the belt will help a
great deal.
Muscle
stimulator to
relieve
muscle
spasms or to
prevent
muscle
atrophy in
casts
$59
http://www.m
edicalproduct
sonline.org/m
eprondi75mu.
html
$3.50
http://www.m
edicalproduc
tsonline.org/r
ecaclel10pa.
html
Fibromyalgia (muscle and tissue pain)





Common disorder in adults, especially women
Painful muscles, debilitating fatigue, sleep
disturbance, and joint stiffness
Many trigger points: painful lumps in muscles
Treatment includes anti-inflammatory
medicines, physical therapy, acupuncture, and
exercise.
Muscle stimulators help
Ganglion Cysts




Ganglion cysts arise as outpouchings from fluid
filled areas such as the fluid around tendon
sheaths.
When the fluid, called synovial fluid, leaks out
from these spaces, it can become a cystic
structure.
Treatment is to drain the fluid with a needle, but
they frequently grow back.
Then you do a surgery to scoop out the whole
cyst, find the stalk and tie it off.
• Ganglion cyst
Baker’s Cyst




A Baker's Cyst, or popliteal cyst, is a collection of
fluid in the back of the knee joint.
A Baker's cyst is usually a symptom of another
problem, or it may be an incidental finding with no
significant meaning.
Most often in adults the Baker's cyst is found in
conditions where there is chronic swelling or fluid
accumulation in the knee joint.
These conditions include knee arthritis, meniscus
injuries, and ligamentous injuries.
Baker’s Cyst



Treatment of a Baker's cyst that is the result of a
problem within the knee consists of treating the
underlying problem. These treatments may include
anti-inflammatory medications and cortisone
injections.
The cyst can be drained with a needle, but the fluid can
be jelly-like and difficult to remove.
If conservative treatments fail to correct the cyst, an
operation can be done to excise the cyst.
• Baker’s Cyst

Rotator Cuff Injury

http://www.youtube.com/watch?v=-tx2SqWz3BY

How do rotator cuff injuries occur?

https://www.youtube.com/watch?v=t6FCBBijROo

What is an MRI?

https://www.youtube.com/watch?v=H0adTNhzGxU

How does a CT scan work?

http://www.youtube.com/watch?v=81PeTqmtzjk
110
AGING


With aging, fibrous connective tissue
replaces some muscle fibers, causing
decreased strength.
As people age, the number of muscle
fibers decreases, and new ones cannot be
added.
FUN FACTS ABOUT STRENGTH




The strongest humans can lift about 3 times their own body
weight, but the average gorilla can lift 10 times its own body
weight! Gorillas can lift 4,600 pounds.
But the strongest creature is the ant. If you had the strength of
an ant, you could lift over your head and carry 6,600 pounds.
The flea, however, can jump up to 200 times its own height.
This is equivalent to a man jumping the Empire State Building
in New York.
Elephants are the only animals that cannot jump!