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the study of muscles

nervous and endocrine

muscles are controlled by these two systems

skeletal, cardiac, smooth

muscles classified under three types

voluntary, striated

skeletal muscle....
-voluntary or involuntary
-striated or not

involuntary, striated

cardiac muscle...
-voluntary or involuntary
-striated or not

involuntary, not striated

smooth muscle...
-voluntary or involuntary
-striated or not

smooth muscle

lines organs and sphincters

producing body movements, stabilizing body positions, storing and moving substances within the body, generating heat

four functions of muscle tissue

producing body movements

integrated functioning of bones, joins, and skeletal muscles causes all movement
(function of muscle tissue)

stabilizing body positions

skeletal muscle contractions stabilize joints and help maintain body positions, such as standing or sitting
(function of muscle tissue)

storing and moving substances within the body

cardiac muscle, smooth muscle, skeletal muscles all move substances and store them
(function of muscle tissue)

generating heat

as muscle tissue contracts, it produces heat, a process known as thermogenesis
(function of muscle tissue)



measure or length




electrical excitability, contractility, extensibility, elasticity

four properties of muscle tissue

electrical excitability

property of both muscle and nerve cells, the ability to respond to certain stimuli by producing electrical signals such as action potentials
(property of muscle tissue)


the ability of a muscle tissue to contract forcefully when stimulated by an action potential
(property of muscle tissue)


the ability of muscle to stretch without being damaged
(property of muscle tissue)


the ability of muscle tissue to return to its original length and shape after contraction or extension
(property of muscle tissue)


principle action of the muscle


relative shape of the muscle

origin and insertion

site where muscle inserts and originates

number of origins

number of tendons of origin


structure near which a muscle is found

direction of fibers

orientation of muscle fascicles relative to the body's midline


relative size of the muscle


a sheet or broad band of fibrous connective tissue that supports and surrounds muscles and other organs in the body

superficial fascia

separates muscle from skin

deep fascia

dense, irregular connective tissue that lines body wall


the connective tissue wrapping that surrounds individual muscle cells (fibers)


the plasma membrane of the muscle cell


the connective tissue wrapping that surrounds each fascicle


the connective tissue wrapping that surrounds the entire muscle


bundle of muscle cells (fibers) bound together by connective tissue to form a functional unit


sheet-like tendon joining one muscle with another or with bone or with skin, muscle to bone


cord of dense fibrous connective tissue that attaches muscle to bone


cylindrical bundle of contractile filaments within the skeletal muscle cell


protein filaments that make up the myofibrils of skeletal muscle cells. 2 types

thick filaments

made up chiefly of the protein myosin

thin filaments

composed mainly of the protein actin, also has troponin and tropomyosin


protein, composes the two major portions of the thick filament. each molecule includes two heads (cross bridges) and a tail region


protein, makes up the thin filament


protein molecule that entwines around actin and blocks the myosin binding sites. In this way, tropomyosin prevents cross bridge cycling until it is moved aside by troponin. one component of the thin filament.


the region of the myofibril's striation that has the darker appearance; also called the dark band. alternates with the light region, corresponds to the length of the thick filaments

Z-band (disc)

zigzag line bisecting the I band. The Z line is actually a protein disc that anchors the thin filaments and connects adjacent myofibrils

H-band (zone)

a lighter stripe in the center of the dark (A) band, corresponding to the region between thin filaments. width varies depending on the degree of muscle contraction. widest when muscle is related and stretched.


the light region of the myofibril's striation that alternates with dark (A) bands; contains only thin filaments. the I band's width is the distance between adjacent thick filaments. gets narrower during muscle contraction

M line

a line in the center of the H zone consisting of protein fibers that connect neighboring myosin filaments


-compartment that contains the filaments in each myofibril
-the contractile unit of that extends from one Z line to the next; includes the entire A band and half of the I band (to the Z line) on each side of the A band


a three-unit group consisting of one T tubule lying between 2 adjacent terminal cisternae

sarcoplasmic reticulum (SR)

the endoplasmic reticulum of the muscle cell. Its interconnecting tubules surround each myofibril like the sleeve of a loosely knit sweater

terminal cisterns

the sac-like regions of the sarcoplasmic reticulum lying adjacent to the T tubules; serve as specialized reservoirs of calcium ions

T-(transverse) tubules

an invagination of the sarcolemma that projects deep into the muscle cell's interior


to make a synaptic connection with an effector organ

neuromuscular junction

synapse between a motor neuron and skeletal muscle fiber. the muscle cell and motor neruron do not actually touch, but are separated by the synaptic cleft

synaptic cleft

the space between the axon terminal and the membrane of the target cell

acetylcholine (ACh)

neurotransmitter released by neurons that simulate skeletal muscles, some neurons of autonomic nervous system, and some neurons in the brain


red pigment protein similar to hemoglobin that stores oxygen in skeletal muscle


The cytoplasm of striated muscle cells.


giant protein that functions as a molecular spring which is responsible for the passive elasticity of muscle

actin, tropomyosin, troponin

thin filament composed of... (3)

Z line

where is actin connected to?

neuromuscular junction

functional site of communication between the motor neuron and muscle fiber

blood capillaries

bring in oxygen and nutrients and remove heat and waste products of muscle metabolism

lactic acid

buildup causes muscle soreness


sum of all chemical reactions that take place, both building up and breaking down
-requires a ton of ATP at a rapid pace

creatine phosphate, anaerobic cellular respiration, cellular respiration

ways to produce ATP (3)

muscle fatigue

inability of a muscle to contract forcefully after prolonged activity
-results from changes within muscle fibers but don't know actual cause


growth of skeletal muscles after birth is mainly due to...
-enlargement of existing cells


increase in number of fibers


replacement of muscle fibers by fibrous scar tissue




breaking down

anabolism and catabolism

together, they make up metabolism (2)

oxygen debt

added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise

muscular atrophy

a wasting away of muscles, individual muscle fibers decrease in size bc of progressive loss of myofibrils





disuse atrophy

atrophy that occurs when muscles are not used
-ex: bedridden individuals and people with casts

denervation atrophy

nerve supply to a muscle is disrupted or cut

above or excessive


muscular hypertrophy

the enlargement of existing muscle cells, increase in the diameter of muscle fibers owing to the production of more myofibrils, mitochondria, etc. results from very forceful repetitive muscle activity


increase in the number of fibers


increased muscle tone, either rigidity (muscle stiffness) or spasticity (muscle stiffness associated with an increase in tendon reflexes)


decreased or lost muscle tone, usually due to damage to somatic motor neurons

below or deficient


painful condition



painful, nonarticular rheumatic disorder that usually appears between the ages of 25 and 50


known as muscle strain; tearing of a muscle bc of forceful impact and causes bleeding and severe pain

muscular dystrophy

group of inherited muscle-destroying diseases that cause progressive degeneration of skeletal muscle fibers

duchenne muscular dystrophy (DMD)

most common form of muscular dystrophy and strikes boys almost exclusively


inflammation of muscle fibers (cells)

inflammation of



pain in or associated with muscles

myastenia gravis

autoimmune disease that causes chronic, progressive damage of the neuromuscular junction


a tumor consisting of muscle tissue




a sudden involuntary contraction of a single muscle in a large group of muscles


a painful spasmodic contraction


rhythmic, involuntary, purposeless contraction that produces a quivering or shaking movement


an involuntary, brief twitch of an entire motor unit that is visible under the skin


spontaneous contraction of a single muscle fiber that is not visible under the skin but can be recorded by electromyography. May signal destruction of motor neurons.


spasmodic twitching made involuntarily by muscles that are ordinarily under voluntary control


shortening of a muscle

rigor mortis

muscles are in a state of rigidity

exercise induced muscle damage

torn sarcolemmas in muscle fibers, damaged myofibrils, disrupted z discs, increases in blood levels or proteins, such as myoglobin and the enzyme creatine kinsae (normally confined within muscle fibers)

creatine supplementation

small, amino acid-like molecule that is both synthesized in the body's own synthesis of creatine and it's not known whether natural synthesis recovers after long term creatine supplementation


pain relief


the site of a muscle's attachment to the more stationary bone


the site of a muscle's attachment to the more moveable bone
-usually moves toward origin as muscle contracts


a rigid structure that can move around a fixed point


a fixed point


causes movement


opposes movement

effort and load

two forces

mechanical advantage

when a smaller effort can move a heavier load, effort must move a greater distance and faster than the load

mechanical disadvantage

when a larger effort moves a lighter load, effort must move a shorter distance and slower than the load

first class lever

-the fulcrum is between the effort and the load
-can produce either a mechanical advantage or disadvantage
-ex: scissors and seesaws and head on vertebral column
E---F-L : mechanical advantage
E-F---L : mechanical disadvantage

second class lever

-the load is between the fulcrum and the effort
-always produces a mechanical advantage
-no second class levers in the body
-ex: wheelbarrows
F-L---E : makes mechanical advantage

third class lever

-the effort is between the fulcrum and the load
-always produces a mechanical disadvantage
-most common levers in the body
-ex: forceps, elbow joint, bones of the arm and forearms, the biceps brachii muscle
F-E---L : makes mechanical disadvantage

first class lever


second class lever


third class lever



the fleshy part of the muscle between the tendons of the origin and insertion


originate on outside and insert


originate and insert on inside


increase angle


decrease angle


moves away from midline


moves towards midline


palm backwards/down


palm foreward/up


turn soles outward


move soles inward


revolve around axis


distal part moves in a circle





prime movers/agonist

muscle that contracts to cause an action


stretches and yields to the effects of the prime mover


-muscles that contract and stabilize the intermediate joints
-aids movement of prime mover and helps prevent unwanted movements

improved physical performance, decreased risk of injury, reduced muscle stress, improved posture

benefits of stretching (4)

sternocleidomastoid muscle (sternomastoid)

side of neck, large, from clavicle/sternum to mastoid

trapezius muscle

largest muscle on outside of back, goes down and outward and then down and inward

levator scapulae muscle

back side of neck, medial to scalenus muscle

scalenus muscle

three muscles on side of neck, lateral to levator scapulae muscle

subclavius muscle

muscle right below clavicle

deltoid muscle

shoulder muscle, largest on shoulder

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