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Muscular System
Skeletal, Smooth, & Cardiac
The
term muscle?
“mus”
The
of course is Latin and means______________.
connection???
When
Almost
flexing, muscles look like little mice scurrying beneath the skin…who knew?
_______________________ weight is muscle.
Muscles
allow us to ___________.
Muscles
are made of special tissues that can _____________or ________ when they receive a
signal from the ____________.
Muscles are attached to bones by stretchy tissue called _________________.
When muscles contract, they pull on the tendons which pull on the ____________ and cause
our____________________.
 What are the three types of muscle tissue?
___________________, ____________________., & ________________
Cardiac Muscle
Only in ______________, Involuntary, _________________ (like skeletal)
Makes up ___________________, Pumps ____________of blood per minute
Fibers branch and have ___________________ per cell.
Function: _____________ of the heart.
Smooth Muscle
____________________,Walls all hollow organs (except heart)
_________________blood flow in arteries, Expels _____________ from urinary bladder
Regulates __________________ through lungs.
Skeletal Muscle
 _______________ muscle, Made of ____________ tissue, _____________tissue, blood, &
connective tissues
Under ____________________ All of these muscles ____________________.
Characteristics of Muscles Tissue!
Muscle tissue is endowed with some special functional properties that enable it to perform its
duties
–________________ (responsiveness), ______________________,
–___________________, & _____________________.
Function of Muscles!
Of course muscles perform 4 important functions
–(1) Produce Movement (2) ______________________
–(3) _____________________, (4) ____________________
There are more than __________________and they hardly ever work alone.
Muscles can get shorter and pull, but they __________________.
Most muscles are arranged in _______________________.
1 team pulls the body part 1 way and the other team pulls it back again
(Abduction and adduction)
Abduction- _____________
_______________- pulls toward you
Voluntary___________- automatically controlled by the brain.
Each muscle is served by one________, an__________, and one or more veins
Each skeletal muscle fiber is supplied with a nerve ending that controls ________________.
Contracting fibers require continuous delivery of _______________________ via arteries
__________ must be removed via veins
Each muscle is a discrete organ composed of muscle tissue, blood vessels, nerve fibers, and
connective tissue
Please familiarize yourself with the Table on pg 282…The Organizational level of skeletal
muscles.
The ____________(organ), ______________ (a portion of the muscle), Muscle fiber (cell),
____________ or fibril (complex organelle), ________________ (segment of a myofibril), and
myofilament or filament.
In an intact muscle, the __________________________ are wrapped and held together by several
different_________________________.
Together these connective tissue sheaths _________________ each cell and
__________________the muscle as a whole, preventing the bulging muscles from
_________________ during exceptionally strong ____________________.
The three connective tissue sheaths are:
–Endomysium – fine sheath of connective tissue composed of reticular fibers surrounding each
___________________.
–_________________ – fibrous connective tissue that surrounds groups of muscle fibers called
fascicles
–Epimysium – an overcoat of dense regular connective tissue that surrounds the
_______________________.
An individual skeletal muscle is separated from adjacent muscles and held in position by layers of
dense connective tissue called ____________.
This connective tissue surrounds each muscle and may project beyond the end of its muscle
fibers to form a cordlike tendon.
Most skeletal muscles span ____________ and are attached to bone in at least ______________
When muscles contract the ______________________, the muscle’s _________________ moves
toward the _______________________, the muscle’s _________.
Muscles attach:
–___________________ – epimysium of the muscle is fused to the periosteum of a bone
–Indirectly – connective tissue wrappings extend beyond the muscle as a ____________or
aponeurosis.
–Of the two, _____________________ is much more common because of the durability of tendons.
Microscopic Anatomy of a Skeletal Muscle Fiber
 One ___________________ is an elongated multinucleate cell that has a
____________appearance.
The muscle fiber (or cell) is composed of a ____________(fibril).
These Myofibrils occupy _______________of a cell and are composed of a number of
______________________filaments.
The thick filaments are made of a protein known as ____________and the thin filaments of a
protein called_______________.
This arrangement of bands are called _________________and it is this sacromere that is the
___________________of the muscle cell or fiber.
Sacroplasmic Reticulum

Within the muscle cell are supporting structures to generate energy, the
________________and some __________stores.
 There is also a network of channels within the muscle to transmit signals from the surface
throughout the muscle called the sacroplasmic reticulum.
A little more detail on Myosin Filament
Thick filaments are composed of the protein ____________
Each myosin molecule has a ____________tail and two globular heads
–Tails – two interwoven, heavy polypeptide chains
–Heads – two smaller, light polypeptide chains called cross bridges
A little more detail on the Thin Filaments
Thin filaments are chiefly composed of the protein _________
The subunits contain the _____________to which myosin heads attach during ______________.
Tropomyosin and troponin found in the __________________are the molecular
_______________that control the interaction of actin and myosin during a___________________.
How do Muscle actually contract?
 When you want to move, __________________________ come from the brain, down through
the spinal cord and are transmitted through the ____________________________
 At the ________________between the nerve end and the muscle (the motor end plate),
_____________________are released from the nerve endings. (_______________). This
binds to a key on the surface of the muscle (the receptor)
 The binding of this chemical to the receptor causes ______________to enter the muscle
cell, and this enable the _________________proteins to move the myosin up the actin
molecule.
 This causes the functional unit, __________________, to shorten and when several of these
shorten along the length of the fibre, the muscles as a whole
___________________________.
 To release the bond between actin and myosin_____________________, to shorten the
muscle further or________________.
 When the signal for contraction ends, the calcium is pumped back into the
_______________________ and the muscle___________.
Contraction of Skeletal Muscle Fibers
The operation of most skeletal muscles involves the use of _________________systems
The force exerted by a contracting muscle on an object is called muscle tension
The opposing force exerted on the muscle by the weight of the object to be moved is called the
__________.
 Contraction of muscle fibers (cells) and muscles (organs) is similar
The two types of muscle contractions are:
–______________contraction – increasing muscle tension (muscle does not
____________during contraction)
–Isotonic contraction – ___________________________(muscle shortens during contraction)
Isometric Contractions
Tension increases to the muscle’s capacity, but the muscle neither
________________________________
Occurs if the load is greater than the tension the muscle is able to develop
Isotonic Contractions
 In isotonic contractions, the muscle changes in length (_________the angle of the joint) and
moves the ______.
Muscle Twitch
A muscle twitch is the response of a muscle to a___________, brief threshold _______________
There are three phases to a muscle twitch
–Latent period, _____________________, Period of relaxation
Phases of a Muscle Twitch
Latent
period – first ____________after stimulus; EC coupling taking place
Period
of contraction –_____________form; _____________________
Period
of relaxation –_____________________; muscle tension goes to zero
Treppe: The Staircase Effect
Staircase – increased contraction in response to ________________of the same strength
Contractions increase because:
–There is _______________________of Ca2+ in the sarcoplasm
–Muscle enzyme systems become _________________ because ___________ is increased as
_______________________.
Muscle Tone
–Is the _______________, slightly contracted state of all muscles, which does not produce
_____________________.
–Keeps the muscles firm, healthy, and ______________________to stimulus
Spinal reflexes account for muscle tone by:
–Activating one motor unit and then another
–Responding to activation of ____________________ in muscles and tendons
Muscle Metabolism: How do Muscles Get the Energy Needed for Contraction?
______is the only source used directly for contractile activity.
Remember ATP’s produced in the___________________. They are energy storing molecules…the
energy is released when __________________is broken then forming ADP.
Muscles can work in one of two environments…______________ and_______________________.
ATP supplies energy for _____________________
Active muscles depend on cellular respiration for energy
ATP is necessary for __________ muscle contraction and relaxation
Aerobic Exercise
As long as it has_______________________, a muscle cell will form ATP by aerobic reactions.
This is internal stores of ATP and can be supplemented by high energy phosphate compounds
called __________________________(cp).
This can be for _________________in well conditioned adults.
Anaerobic Exercise
If
the rate at which energy is demanded is high…generally when muscle contractile activity
reaches_____________________; then this is supplemented by contributions
from__________________________.
The
immediate consequences include:
–The production of _______________in the muscles which immediately breaks down to lactate and
hydrogen ions.
–Bulging
muscles_______________________.
–Oxygen delivery is _________________.
Muscle Metabolism: Anaerobic Glycolysis
The lactic acid:
–Diffuses into the _______________
–Is picked up and used as fuel by the________, kidneys, and heart
–Is converted back into ______________by the liver
Muscle Fatigue
Muscle fatigue – the muscle is in a state of _____________________________
Muscle fatigue occurs when:
–ATP production ______________________with ATP use
–There is a relative deficit of ATP, causing contractures
–Lactic acid _________________in the muscle
–Ionic imbalances are present
Intense exercise produces rapid muscle fatigue (with rapid recovery)
______________pumps cannot restore ionic balances quickly enough
Low-intensity exercise produces slow-developing fatigue
SR is damaged and Ca2+ regulation is disrupted
Oxygen Debt
Oxygen debt – the __________________________needed for restorative processes
This is why your muscles ache
Vigorous exercise causes dramatic changes in _________________
For a muscle to return to a resting state:
–Oxygen reserves must be ______________
–________________ must be converted to _________________
–___________________stores must be replaced
–ATP and CP reserves must be resynthesized
Heat Production During Muscle Activity
Only ________of the energy released in muscle activity is useful as work
The remaining 60% is given off as _______
Dangerous heat levels are prevented by __________________from the skin and _____________.
Product of _____________________
Muscles act as heat source because muscle tissue represents such a large portion of the body
Effects of Aerobic Exercise
Aerobic exercise results in an increase of:
–____________________
–Number of mitochondria
–Myoglobin synthesis
Effects of Resistance Exercise
Resistance exercise (typically anaerobic) results in:
–Muscle hypertrophy
–Increased mitochondria, ____________, and glycogen stores
Muscle Fatigue
Muscle loses its ______________________.
Causes:_____________________, ion imbalances, ____________________of desire to exercise.
Fatigue and ____________ may occur together
Cramps occur when intracellular fluid triggers uncontrolled stimulation of the muscle
Usually due to ___________________________.
_______________ usually produce less lactic acid than nonathletes b/c of their ability to supply
oxygen and nutrients to muscles.
Heat Production
Product of cellular respiration
Muscles act as _______________because muscle tissue represents such a _______________of the
body.
Energy Sources for Contraction
________supplies energy for contractions
Active muscles depend on ______________for energy
Relaxation
Nerve impulses ________and 2 events relax the fiber in muscles
1-when _________________are transported back into sacroplasmic reticulum
2-when _____________________decomposes and prevents stimulation