Mrs. Ashley The Muscular System. Functions of the Muscular System Movement-responsible for all types...
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Mrs. Ashley The Muscular System. Functions of the Muscular System Movement-responsible for all types of body movement both voluntary and involuntary Add
Functions of the Muscular System Movement-responsible for all
types of body movement both voluntary and involuntary Add in
digestion Pump blood Supporting soft tissues in body cavities
Maintaining body temperature Guarding entrances and exits to
body
Slide 3
Three Types of Muscles Skeletal Muscles Cardiac Muscles Smooth
Muscles
Slide 4
Comparison of Skeletal, Cardiac, and Smooth Muscles
Slide 5
Slide 6
Characteristics of Muscles Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber) Contraction of muscles is
due to the movement of microfilaments All muscles share some
terminology Prefixes myo and mys refer to muscle Prefix sarco
refers to flesh
Slide 7
Skeletal Muscles Produce movement Maintain posture Stabilize
joints Generate heat Skeletal muscle tissue Associated with &
attached to the skeleton Under our conscious (voluntary) control
Microscopically the tissue appears striated Cells are long,
cylindrical & multinucleate
Slide 8
Sites of Muscle Attachments Sites of muscle attachment Bones
Cartilages Connective tissue coverings
Slide 9
Microanatomy of a Muscle Fiber (cell)
Slide 10
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Cardiac Muscle Cardiac muscle tissue Makes up myocardium of
heart Unconsciously (involuntarily) controlled Microscopically
appears striated Cells are short, branching & have a single
nucleus Cells connect to each other at intercalated discs
Slide 12
Slide 13
Smooth Muscle Smooth (visceral) muscle tissue Makes up walls of
organs & blood vessels Tissue is non-striated & involuntary
Cells are short, spindle-shaped & have a single nucleus Tissue
is extremely extensible, while still retaining ability to
contract
Slide 14
Physiology of skeletal muscle contraction Skeletal muscles
require stimulation from the nervous system in order to contract
Motor neurons are the cells that cause muscle fibers to
contract
Slide 15
Stimulation and Contraction of Single Skeletal Muscle Cells
Excitability (also called responsiveness or irritability) ability
to receive and respond to a stimulus Contractilityability to
shorten when an adequate stimulus is received Extensibilityability
of muscle cells to be stretched Elasticityability to recoil and
resume resting length after stretching
Slide 16
The Nerve Stimulus and Action Potential Skeletal muscles must
be stimulated by a motor neuron (nerve cell) to contract Motor
unitone motor neuron and all the skeletal muscle cells stimulated
by that neuron
Slide 17
Control of Muscles Skeletal muscles are made up of thousands of
muscle fibers A single motor neuron may directly control a few
fibers within a muscle, or hundreds to thousands of muscle fibers
All of the muscle fibers controlled by a single motor neuron
constitute a motor unit
Slide 18
The Nerve Stimulus and Action Potential
Slide 19
The size of the motor unit determines how fine the control of
movement can be small motor units precise control (e.g. eye muscles
large motor units gross control (e.g. leg muscles)
Slide 20
Recruitment is the ability to activate more motor units as more
force (tension) needs to be generated Hypertrophy stressing a
muscle (i.e. exercise) causes more myofilaments/myofibrils to be
produced within muscle fibers; allows for more cross bridges
resulting in more force (strength) as well as larger size There are
always some motor units active, even when at rest. This creates a
resting tension known as muscle tone, which helps stabilize bones
& joints, & prevents atrophy
Slide 21
How Muscles Work For muscles to create a movement, they can
only pull, not push Muscles in the body rarely work alone, &
are usually arranged in groups surrounding a joint A muscle that
contracts to create the desired action is known as an agonist or
prime mover A muscle that helps the agonist is a synergist A muscle
that opposes the action of the agonist, therefore undoing the
desired action is an antagonist
Slide 22
Anatomy of the Muscular System Origin Muscle attachment that
remains fixed Insertion Muscle attachment that moves Action What
joint movement a muscle produces i.e. flexion, extension,
abduction, etc.
Slide 23
Muscles and Body Movements Movement is attained due to a muscle
moving an attached bone Muscles are attached to at least two points
Origin Attachment to a moveable bone Insertion Attachment to an
immovable bone
Types of Body Movements Flexion Decreases the angle of the
joint Brings two bones closer together Typical of bending hinge
joints like knee and elbow or ball-and- socket joints like the hip
Extension Opposite of flexion Increases angle between two bones
Typical of straightening the elbow or knee Extension beyond 180 is
hypertension
Slide 27
Slide 28
Types of Body Movements Rotation Movement of a bone around its
longitudinal axis Common in ball-and-socket joints Example is when
you move atlas around the dens of axis (shake your head no)
Slide 29
Slide 30
Types of Body Movements Abduction Movement of a limb away from
the midline Adduction Opposite of abduction Movement of a limb
toward the midline
Slide 31
Slide 32
Types of Body Movements Circumduction Combination of flexion,
extension, abduction, and adduction Common in ball-and-socket
joints
Slide 33
Slide 34
Types of Body Movements Dorsiflexion Lifting the foot so that
the superior surface approaches the shin (toward the dorsum)
Plantar flexion Depressing the foot (pointing the toes) Planting
the foot toward the sole
Slide 35
Slide 36
Special Movements Inversion Turn sole of foot medially Eversion
Turn sole of foot laterally
Slide 37
Slide 38
Special Movements Supination Forearm rotates laterally so palm
faces anteriorly Radius and ulna are parallel Pronation Forearm
rotates medially so palm faces posteriorly Radius and ulna cross
each other like an X
Slide 39
Slide 40
Special Movements Opposition Move thumb to touch the tips of
other fingers on the same hand
Slide 41
Slide 42
Naming of Skeletal Muscles By direction of muscle fibers
Example: Rectus (straight) By relative size of the muscle Example:
Maximus (largest) By location of the muscle Example: Temporalis
(temporal bone) By number of origins Example: Triceps (three heads)
By location of the muscles origin and insertion Example: Sterno (on
the sternum) By shape of the muscle Example: Deltoid (triangular)
By action of the muscle Example: Flexor and extensor (flexes or
extends a bone)
Slide 43
a) Convergent (d) Circular
Slide 44
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Slide 49
Muscles of the shoulder
Slide 50
Slide 51
Muscles that move the arm
Slide 52
Slide 53
Muscles that move the forearm and wrist
Slide 54
Muscles that move the thigh
Slide 55
Slide 56
Muscles that move the leg
Slide 57
Muscles that move the foot and toes
Slide 58
Slide 59
Slide 60
Slide 61
List of Muscles to Know Trapezius Latissimus dorsi Gluteus
medius Gluteus maximus Calcaneus Frontalis Orbicularis oculi
Zygomaticus Orbicularis oris Temporalis Occipitalis Buccinator
Masseter External oblique Linea alba External intercostal Internal
oblique Levator scapulae Deltoid Pectoralis major Pectoralis minor
Tricheps brachii
Slide 62
More List of Muscles to Know Flexor Carpi ulnaris Flexor carpi
raialis Extensor carpi ulnaris Flexor digitorum longus Fibularis
muscles Gastrocnemius Tibialis anterior
Slide 63
The Nerve Stimulus and Action Potential
Slide 64
Slide 65
Synaptic cleft Gap between nerve and muscle Nerve and muscle do
not make contact Area between nerve and muscle is filled with
interstitial fluid Action potential reaches the axon terminal of
the motor neuron Calcium channels open and calcium ions enter the
axon terminal
Slide 66
The Nerve Stimulus and Action Potential
Slide 67
Transmission of Nerve Impulse to Muscle Sodium rushes into the
cell generating an action potential Once started, muscle
contraction cannot be stopped Muscle fiber contraction is all or
none Within a skeletal muscle, not all fibers may be stimulated
during the same interval Different combinations of muscle fiber
contractions may give differing responses Graded responsesdifferent
degrees of skeletal muscle shortening
Slide 68
Contraction of Skeletal Muscles Graded responses can be
produced by changing: The frequency of muscle stimulation The
number of muscle cells being stimulated at one time
Slide 69
Types of Graded Responses Twitch Single, brief contraction Not
a normal muscle function Summing of contractions One contraction is
immediately followed by another The muscle does not completely
return to a resting state due to more frequent stimulations The
effects are added Unfused (incomplete) tetanus Some relaxation
occurs between contractions but nerve stimuli arrive at an even
faster rate than during summing of contractions Unless the muscle
contraction is smooth and sustained, it is said to be in unfused
tetanus
Slide 70
Types of Graded Responses Fused (complete) tetanus No evidence
of relaxation before the following contractions Frequency of
stimulations does not allow for relaxation between contractions The
result is a smooth and sustained muscle contraction
Slide 71
Muscle Response to Strong Stimuli Muscle force depends upon the
number of fibers stimulated More fibers contracting results in
greater muscle tension Muscles can continue to contract unless they
run out of energy
Slide 72
Energy for Muscle Contraction Aerobic respiration Glucose is
broken down to carbon dioxide and water, releasing energy (about 32
ATP) A series of metabolic pathways occur in the mitochondria This
is a slower reaction that requires continuous oxygen Carbon dioxide
and water are produced
Slide 73
Energy for Muscle Contraction Anaerobic glycolysis and lactic
acid formation This reaction is not as efficient, but is fast Huge
amounts of glucose are needed Lactic acid produces muscle
fatigue
Slide 74
Muscle Fatigue and Oxygen Deficit When a muscle is fatigued, it
is unable to contract even with a stimulus Common cause for muscle
fatigue is oxygen debt Oxygen must be repaid to tissue to remove
oxygen deficit Oxygen is required to get rid of accumulated lactic
acid Increasing acidity (from lactic acid) and lack of ATP causes
the muscle to contract less
Slide 75
Types of Muscle Contractions Isotonic contractions Myofilaments
are able to slide past each other during contractions The muscle
shortens and movement occurs Example: bending the knee; rotating
the arm Isometric contractions Tension in the muscles increases The
muscle is unable to shorten or produce movement Example: push
against a wall with bent elbows
Slide 76
Muscle Tone Some fibers are contracted even in a relaxed muscle
Different fibers contract at different times to provide muscle tone
and to be constantly ready
Slide 77
Effect of Exercise on Muscles Exercise increases muscle size,
strength, and endurance Aerobic (endurance) exercise (biking,
jogging) results in stronger, more flexible muscles with greater
resistance to fatigue Makes body metabolism more efficient Improves
digestion, coordination Resistance (isometric) exercise (weight
lifting) increases muscle size and strength
