Download Muscular system 15

Chapter 11-12:
Muscular System
Types and Functions of Muscles
• Skeletal
muscle
• Smooth
muscle
• Cardiac
muscle
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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Characteristics of Muscles
•Skeletal and smooth muscle cells are
elongated (muscle cell = muscle fiber)
•Contraction and shortening 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”
© 2012 Pearson Education, Inc.
Whole Muscle Structure
• Fascia
– Epimysium
– Perimysium
– Endomysium
• Fascicles (bundles)
• Tendon
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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Muscle Fiber: Cell
• Group of myofibrils
– Series of sarcomeres
– Sarcomere is inside a
myofibril
• Sarcoplasmic reticulum
– Covering of each
sarcomere
• T-tubule system
– Transmit electrical
signal
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Sarcomeres: Inside the Myofibril
• From Z line to Z line
• Thin filaments
– Protein called Actin
– Troponin-tropomyosin
• Binding part of Actin
• Thick filaments
– Protein called Myosin
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Two Aspects of Muscle Contraction
Electrical
• Involves motor
neuron and NMJ
• Results in calcium
release from SR
• Happens first
Contractile
• Involves actin and
myosin
• Sliding filaments
• Happens second
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Contractile Function: Sliding
Filament Mechanism
•
•
•
•
•
Myosin heads make contact with actin.
Myosin heads rotate.
Actin is pulled to the center of the sarcomere.
Sarcomere shortensmuscle contraction
Animation
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Contracting Muscles Need Calcium
• Calcium is stored away from thin and thick
filaments in the sarcoplasmic reticulum (SR).
• When stimulated, the SR releases calcium.
• Calcium allows actin, myosin, and ATP to
interact, causing muscle contraction.
• Why does muscle relax?
– Calcium returns to the SR. Then Muscle relaxes
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Whole Muscle Contraction
• A single muscle fiber has an “all or nothing”
response, but a whole muscle can vary its
force of contraction.
• Two characteristics of a whole muscle allow
this
– Motor unit
– Recruitment
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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Motor Unit and Recruitment
• Motor unit: The
nerve and
innervated muscle
fibers
• Recruitment: The
more motor units
activated, the
greater the force of
contraction.
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Two Aspects of Muscle Contraction
Electrical
• Involves motor
neuron and NMJ
• Results in calcium
release from SR
• Happens first
Contractile
• Involves actin and
myosin
• Sliding filaments
• Happens second
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Neuromuscular Junction (NMJ)
• Space between
motor neuron and
muscle
• Site of ACh action
and activation of
muscle membrane
– Ach= Acetylcholine
• Neurotransmitter
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Electrical Events
• Electrical signal travels to axon terminal,
releasing ACh.
• ACh diffuses across NMJ and activates muscle
receptors.
• Activated receptors send electrical signal along
muscle membranes and T tubules.
• Electrical signal stimulates the SR to release
calcium, initiating the sliding filament.
Impairment at the NMJ
• Myasthenia gravis:
– Autoimmune disease:
atrophy and weakness
• Curare
– Alkaline substance that
can paralyze (poison
darts)
• Neurotoxins
– Clostridium tetani
(tetanus)
– Clostridium botulinum
(botulism and Botox)
Muscles Part II
• Define twitch and tetanus.
• Identify the sources of energy for muscle
contraction.
• State the basis for naming muscles.
• List the actions of the major muscles.
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Responses of a Whole Muscle
• Twitch: Single muscle response in which
muscle contracts and then fully relaxes
• Tetanus: Sustained muscle contraction caused
by repeated stimulation
• Tonus: Normal, continuous state of partial
muscle contraction
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Sources of Energy (ATP)
• Aerobic metabolism: need oxygen
– Breakdown of fat, and sugars into energy
• Anaerobic metabolism: no oxygen present
– Causes lactic acid to build up (soreness)
– D.O.M.S.: Delayed onset muscle
• Metabolism of creatine phosphate
– Quick boost of ATP
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Muscle Terms
• Origin: Nonmoving part
• Insertion: Movable part
• Prime mover
– “Chief” muscle, most
responsible for movement
• Synergist
– Helps prime mover
• Antagonist
– Opposes prime move
– Returns to “normal” position
Muscle Overuse and Underuse
• Hypertrophy: Growth in response to overuse
• Atrophy: Wasting
– Disuse atrophy: cast for broken bone
– Denervation atrophy: damage to nervous system
– Senile atrophy: wearing down of muscle (age
related)
• Contracture: Abnormal fibrous formation in
muscle that “freezes” in flexed position
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How Skeletal Muscles Are Named
• Size: vastus(huge); maximus(large); longus(long);
minimus(small); brevis(short)
– Ex.:Gluteus maximus
• Shape: deltoid(triangular); latissimus(wide); trapezius
(trapezoid); rhomboideus (rhomboid); teres(round)
– Ex. Trapezius, Latissimus dorsi
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• Direction of fibers: Fibers are lined up;
rectus(straight); oblique(diagonal);
transverse(across); circularis(circular)
– Ex. Rectus abdominis
• Location: reflect location on body; pectoralis
(chest); gluteus (buttock); brachii (arm);
supra(above); infra(below); Sub(underneath);
lateralis(lateral)
– Ex.: Pectoralis major, biceps brachii
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• Number of origins: where it’s anchored;
Biceps(2), Triceps(3); Quadriceps(4)
• Origin and insertion: Both sites of attachment;
Sterno-cleido-mastoid (sternum-claviclemastoid)
• Muscle action: type of action; aways from
midline(abductor), toward midline(Adductor);
levator(elevates); masseter(chews)
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Muscles from Head to Toe
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Facial Muscles
• Frontalis: raises eyebrows and wrinkles
forehead
• Orbicularis oculi: closes eye,
winking, blinking
• Levator palpebrae superioris:
lifts eyelid
• Orbicularis oris: closes mouth,
forms words
• Buccinator: flattens cheek, positions
food
• Zygomaticus: smiling muscles
• Platysma: open your mouth wide,
pout
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Facial Muscles: Chewing
• Masseter: chewing muscles
• Temporalis: temple
• Sternoclediomastoid: flexion
and rotation of the head and rotation
of the head.
• Trapezius: helps with the
extension and hyperextension of
the head at the neck
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Muscles of the Trunk: Breathing
• Intercostal
muscles
– Internal
– External
• Diaphragm
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More Muscles of the Trunk
• Abdominal wall
–
–
–
–
Transversus abdominis
Internal oblique
Rectus abdominis
External oblique
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Muscles of the Shoulder and Arm
•
•
•
•
•
Trapezius
Serratus anterior
Pectoralis major
Latissimus dorsi
Deltoid
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Muscles of the Forearm
•
•
•
•
•
Biceps brachii
Triceps brachii
Brachialis
Brachioradialis
Supinators and
pronators
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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Muscles of the Thigh
• Extend thigh, climb stairs, and sitting:
– Gluteus maximus, medius, and minimus
• Iliopsoas: Flexes thigh, opposes gluteual group
• Adductor group: inner thigh, horseback riders
muscle
• Quadriceps femoris: Extend Leg(kicking), anterior
• Sartorius: crosses over leg, allows you to sit in
crossed leg position
• Hamstrings: posterior side of leg, flex leg opposes
quadriceps
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Muscles: Leg and Foot, Posterior
View
• Gastrocnemius: calf
• Soleus: calf
• Tibialis posterior:
flexes foot, shin splits
• Calcaneal or Achilles
tendon: where muscles
connect to work foot
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Muscles with Colorful Names
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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Carpal Tunnel Syndrome
Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights
reserved.
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