Download The Muscular System - Harrison High School

The Muscular
System
Angie Guggino, MS, ATC, LAT
Essential Questions
• What is the structure and function of the muscular
system?
• What care the common disorders and injuries of the
muscular system?
Course Standard 6
Evaluate the anatomy, physiology, and basic pathophysiology of the
muscular and skeletal systems, and perform technical skills related to the
systems.
• 6.1 Analyze the basic structures and functions of the muscular system.
• 6.3 Explain the relationship between the muscular and skeletal systems,
and identify their interdependence as they relate to body structure,
movement and posture.
• 6.4 Identify and explain medical terms related to the muscular and
skeletal systems, and utilize when documenting in the electronic medical
record.
• 6.5 Research common diseases, disorders, and emerging disorders of the
muscular and skeletal systems including pathophysiology, prevention,
diagnosis and treatment that might be utilized.
• 6.9 Locate and identify the types of muscles in the muscular system.
• 6.10 Perform range of motion (ROM) for joints such as the shoulder, wrist
and ankle.
• 6.11 Differentiate between active and passive range of motion.
• 6.12 Demonstrate proper techniques for ambulation with assistive devices
(crutches, cane, walker); and identify limitations and abnormalities.
Muscle Tissue Types
• Skeletal
• Smooth
• Cardiac
Smooth Muscle
• Non-striated (smooth)
• Involuntary
• Found mainly in the
walls of hollow organs
Cardiac Muscle
• Involuntary
• Found only in the heart
Skeletal Muscle
• Responsible for body movement
• Striated muscle: cross-strips or striation seen under
microscope
• Voluntary
• Muscle fiber: individual skeletal muscle cell
o Number genetically determined
o Increase diameter with activity
Skeletal Muscle
• Fascicle: groups of
muscle fibers
• Epimysium: encloses all
the fascicles in the
muscle
• Connects to bone via
tendon or aponeuroses
epimysium
tendon
perimysium
Muscle Fascicle
Surrounded by
perimysium
Skeletal
muscle
Surrounded by
epimysium
endomysium
Skeletal
muscle
fiber (cell)
Surrounded by
endomysium
Microanatomy of a Muscle Fiber (Cell)
transverse
(T) tubules
sarcoplasmic
reticulum
sarcolemma
terminal
cisternae
mitochondria
myoglobin
thick myofilament
thin
myofilament
myofibril
nuclei
triad
Muscle fiber
sarcomere
Z-line
myofibril
Thin filaments
Thick filaments
Thin myofilament
Myosin molecule of
thick myofilament
Characteristics of Muscle
Tissue
• Excitability
o tissue can receive & respond to stimulation
• Contractibility
o tissue can shorten & thicken
• Extensibility
o
tissue can lengthen
• Elasticity
o after contracting or lengthening, tissue always wants to return to its resting
state
Muscle Contraction
• Electrical impulse
travels down a motor
neuron and
acetylcholine is
released into the
synapse.
• Acetylcholine binds to
special receptors on
the muscle cell and
causes an electrical
impulse (Action
Potential) to spread
over the cell
Generating Action
Potentials
• Acetylcholine makes the sarcolemma more
permeable
• Channels open and Na+ rapidly invade the fiber
• At the same time K+ rush out of the fiber
• More Na+ enters than K+ exits and a positive charge
is created
• Flood of positive ions into the fiber generates and
electrical charge called an Action Potential
Muscle Contraction
• Ca2+ released by the
sarcoplasmic reticulum
• Enables the
attachment of actin
and myosin
• Contraction of the
sarcomere
Summary
• Skeletal muscle fibers shorten as thin filaments
interact with thick filaments and sliding occurs.
• The trigger for contraction is the calcium ions
released by the sarcoplasmic reticulum when the
muscle fiber is stimulated by its motor neuron
(action potential)
• Contraction is an active process; relaxation and the
return to resting length is passive
Slow vs. Fast
• Fast-Twitch Muscle Fibers
o
o
o
o
Contract faster
Speed and strength
White fibers
Some contract slower
• Slow-Twitch Muscle Fibers
o Contract slower
o Endurance
o Red fibers
• FT fibers can be converted to ST fibers with years of
endurance training, but the reverse is not true
• Progressive loss of FT fibers occurs with age
Muscle Fiber Architecture
(Handout)
• Unipennate: fibers alligned in one direction to a
central tendon
• Bipennate: fibers that attach to a central tendon
(rectus femoris)
• Multipennate: fibers that attach to a central tendon
in more than two directions (deltoid)
• Triangular: parallel along the length of the muscle
(pectoralis major)
• Bundled: parallel (rectus abdominis)
• Fusiform: parallel wide in the middle (biceps brachii)
Muscle Contractions
• These physiological processes describe what
happen at the cellular level – how skeletal muscle
fibers contract
• But what about at the organ level? How do skeletal
muscles (like your biceps brachii) contract to create
useful movement?
Energy for Contraction
• Muscles require energy in the form of ATP to
contract.
o ATP is produced by aerobic respiration.
• Secondary sources
o Creatine phosphate stored in the muscle is broken down to produce
more ATP.
o Glycogen stored in the muscle and liver is broken down into glucose
which is broken down to produce ATP. This process requires Oxygen.
Skeletal Muscles
• Origin
o Point of attachment that remains fixed
• Insertion
o Point of attachment that moves
• Action
o What joint movement is produced
o Flexion, extension, abduction, etc. . .
o (Review muscle movements)
Muscle Contractions
• Isotonic contraction: length of muscle changes
usually resulting in movement of a joint
o Concentric phase = shortening
o Eccentric phase = lengthening
• Isometric contraction: no change in length of
muscle even as tension increases.
Agonist, Antagonist, and
Synergist
• Muscles can only pull, not push
• Muscles in the body rarely work alone, and 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
Disorders and Injuries
The Muscular System
Strain
• An overstretching or tearing of the muscle and/or
adjacent tissues such as a tendon
• Strain Classifications:
1st degree
2nd degree
3rd degree
Tendinitis
• Inflammation of a
tendon
• Pain and inflammation
Contusion
• Bruise
• Ecchymosis – discoloration commonly called
bruising
Myositis Ossificans
• A calcification that
forms within the muscle
tissue
• Can be a side-effect
from a contusion
Delayed-Onset Muscle
Soreness (DOMS)
• Presence of soreness in the muscles a day or two
after overuse of the muscle
• Begins usually 24-72 hours later
• Microscopic tearing in the muscle fibers causing
inflammation, pain, swelling, and stiffness
Muscle Cramp or Spasm
• Sudden and involuntary contraction of one or more
muscles
• Common Causes:
o
o
o
o
Inadequate blood supply
Nerve compression
Mineral depletion
Certain medications
• Risk factors:
o
o
o
o
Age
Pregnancy
Dehydration
Certain medical conditions such as diabetes, nerve, or thyroid disorders
Fibromyalgia
• Connective, soft tissue disease involving chronic,
spontaneous, and widespread musculoskeletal pain, as
well as recurrent fatigue and sleep disturbances
• Often mistaken as “chronic fatigue syndrome”
• Cause is unknown but may involve the relationship
among the nervous and endocrine systems and sleep
o Cannot reach the deepest stage of sleep
• 40-70 % of patients have Irritable Bowel Syndrome
• Cold weather, hormonal fluctuations, stress, anxiety,
depression, and physical exertion can produce flare-ups
• Traditional treatments focus on improving quality of
sleep and reducing pain
• Psychological treatment can be effective in some
Amyotrophic Lateral
Sclerosis
• Progressive, degenerative neurological disorder
that affects the cells in the bran and spinal cord
• Appears to occur at random between the ages of
40-60; more common in men than women
• Characterized by degeneration of spinal motor
neurons, leading to:
o
o
o
o
Denervation
Muscle wasting
Paralysis
Eventually death, most often secondary to respiratory failure
Muscular Dystrophy
Salem Health Article
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What occurs to the muscle tissue with Muscular
Dystrophy?
Describe the most common form of Muscular
Dystrophy.
How does Becker’s Muscular Dystrophy differ from
Duchenne’s?
What is Myotonia?
How is Muscular Dystrophy diagnosed?
Why is Muscular Dystrophy said to be “X-linked”?
What laboratory procedures can be done to confirm
diagnosis?
What things can be done to treat Muscular Dystrophy?
Is there a cure for Muscular Dystrophy?
The End