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THE MUSCULAR SYSTEM
Types of Muscle
 Smooth – elongated, spindle-shaped, and flat; one
nucleus; no ________; found in walls of hollow
internal _____, blood ______, eye; in________;
contracts ______; prolonged contractions; doesn’t
easily _______
Smooth muscle video (2:53)
Types of Muscle
 Cardiac – striated, cylindrical, and branched; one nucleus;
interlock at ______ disks (allow synchronized _____;
specialized _____); found only in the _____; involuntary;
extremely resistant to fatigue (enormous # of m________
and myoglobin); pacemaker cells (_____- generate their own
impulse; discovered by Theodor Engelmann)
Red arrow?
Blue arrow?
Yellow arrow?
Types of Muscle
 Skeletal – striated, cylindrical; multi________; voluntary; can
be involuntary (r_____); made of slow- and fast-twitch fibers
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Slow-twitch = ______, endurance, _____ contractions, lots of blood,
energy source is _____, duration is hours; contain lots of myoglobin
(oxygen and iron-binding protein)
Fast-twitch = ______, quick bursts, less blood, energy source is _____ and
___________, duration is up to 30 min; nerves run throughout the muscle
(innervated); not as much ________
Skeletal muscle video (3:33)
General Functions of Muscle
 Stabilizes ________
 Allows us to remain _____
 Produces _____ (body, breathing, digestion,
circulation, birth, excretion)
 Contraction produces ______ through the break
down of _____

Helps maintain body _____
Muscle Anatomy (skeletal)
 muscle  fascicle  muscle fiber (cell)  myofibril
 actin(thin)/myosin(thick); sarcomere
_____
_____
_____
_____
_____
_____
Sliding Filament Theory
 Sliding filament theory – when a myofibril
contracts, the _____ filaments slide past the _____
filaments, causing the myofibril, and therefore the
muscle fiber (cell), to _____ and _____
Basic muscle
physiology
(3:20)
Events at Neuromuscular Junction
 1. Nerve impulse reaches _____ terminal (AT)
 2. Ca2+ protein channels _____ and Ca2+ floods AT
 3. Ca2+ causes synaptic _____ in AT to release ACh
 4. ACh diffuses across _____ _____ and binds with
protein receptors in the _____ of muscle fiber
 5. ACh binds to sodium-potassium pump in the
sarcolemma, causing the pump to allow the
simultaneous passage of Na+ ions _____ and K+ ions
_____ _____ the muscle fiber
 6. When stimulus _____, the enzyme
acetylcholinesterase _____ _____ ACh and the
process ends
Events at Neuromuscular Junction
NMJ Animation
(3:18)
What’s the purpose
of the junctional
folds?
Why are they found
only at the NMJ of
the sarcolemma?
Neuromuscular Junction
Generation of ATP
 Working muscles generate _____ in three
ways:
1. Direct phosphorylation of ADP by creatine
_____ (anaerobic; only in muscle fibers)
o
CP supplies exhausted in ~ 20 seconds
2. Lactic acid _____ (anaerobic)
3. _____ respiration (generates the most ATP)
Muscular System Terms
 Prime mover – muscle that provides the major
_____ for producing a specific movement
 Synergists – assist ____ ____ by providing more
_____ and preventing unnecessary movements
 They enable us to have smooth, fluid movements
 Antagonists – muscles that _____ the movement
of a ____ ____
Muscular System Terms
 Isotonic contraction – muscle contraction that
causes _____
 Isometric contraction – muscle contraction
with ____ _____
Muscular System Terms
 Tone – continuous, partial _____ of a muscle
 Hypertrophy – _____ in tissue size without cell _____
Increase in muscle mass due to forceful _____
 Atrophy – the ____ ____ of tissue due to lack of _____
 DOMS – Delayed onset muscle soreness
 _____ and stiffness felt in muscles several hours to days
(esp. 24-72 hrs) after unaccustomed or strenuous _____
 Appears to be caused by eccentric (lengthening) exercise,
which causes _____ to the _____ _____.
 After exercise, the muscle undergoes _____ to prevent
further _____ if the exercise is _____ (repeated-bout effect)

 Muscle hypertrophy (4:19)
Muscular System Terms
 Origin – point of _____ of a muscle; the end that does
not _____
 Insertion – point of _____ of a muscle; the end that does
_____
Muscular System Terms
 Latent period and contraction & relaxation
phases
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Latent – muscle prepares for _____
Contraction – ____ and ____ bind together; muscle _____
Relaxation – actin and myosin _____; contraction _____
Muscular System Terms
 Summation, tetanus, & fatigue
 Summation – occurs when a skeletal muscle is _____ a
second time before _____ is complete; contractions after
second and subsequent stimuli progressively _____
 Tetanus – occurs if the stimulus is _____ at a sufficiently

high rate; the muscle will not _____ between each stimulus
but will remain _____
Fatigue – occurs if a muscle is not allowed to _____; muscle
_____ even though _____ continues to be administered;
muscle has depleted _____ supply; serves as a protective
mechanism against _____ to sarcolemma and sarcoplasmic
reticulum
Summation, Tetanus and Fatigue
Muscular System Terms
 All-or-none law – muscle fibers either _____
maximally or ____ at ____
 Oxygen debt (EPOC) – occurs during the
recovery period; even though muscles are _____,
_____ rate is still high – Why, you ask? Good
question!
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1. _____ levels (and therefore ____ levels) in cells must be
replenished to pre-exercise levels
2. Assists in the metabolism of _____ in _____ cells
3. Many cells and tissues throughout the body are still
_____ after _____ (e.g. sweat glands, muscles, nerves)
Muscle Nomenclature
 Muscles are named according to a number of
characteristics.
 This system of nomenclature makes learning their
names and functions easier.
 The characteristics are:
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_________ (gluteus maximus)
_________ (deltoid)
___________ ___ _________ (rectus abdominis)
_____________ (frontalis)
Effects of Aging
 Muscle deteriorates and replaced by _______
 Mitochondria break down  decrease of ________
 Water content in tendons decreases = stiffness/pain
 Less blood flow (oxygen) to muscle cells = less
________ respiration = less production of ______