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103 terms

Anatomy and Physiology Chapter 8

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muscular tissue enables the body and its parts to...
move
muscle cells shorten by converting chemical energy into...
mechanical energy
how many types of muscle tissue exist in the body
3
skeletal muscle is also called
striated or voluntary
what % of body weight is skeletal muscle?
40-50%
skeletal muscle contractions are
voluntarily controlled
what does skeletal muscle look like?
crosswise stripes or striations
what kind of muscle tissue composes the bulk of the heart?
cardiac muscle
which kind of muscle cells branch frequently?
cardiac
which muscle tissue is characterized by dark bands called intercalated disks?
cardiac
cardiac muscle cells allow the heart to contract as a ....
unit
smooth muscle is also referred to as....
nonstriated, involuntary, or visceral muscle
how does smooth muscle appear under a microscope?
smooth
where can one fine smooth muscle?
in walls of hollow visceral structures (such as digestive tract, blood vessels, and ureters)
contractions of smooth muscle are?
involuntary
what is the function of all muscles?
contraction (shortening)
attachment to the bone that remains relatively stationary or fixed when movement at the joint occurs
(parts of a skeletal muscle:) origin
the point of attachment to the bone that moves when a muscle contracts
(parts of the skeletal muscle:) insertion
the main part of the muscle
(parts of the skeletal muscle:) body
skeletal muscles are organs composed of...
skeletal muscle cells and connective tissue
how are muscles attached to bones?
by tendons (cords of fibrous connective tissue; sometimes closed in tendon sheaths)
what is the name of the sac that is located between some tendons and underlying bones?
bursae (synovial lined sac)
contractile cells are also referred to as...
muscle fibers (they are grouped into bundles)
fibers contain...
(thick myofilaments) myosin and (thin myofilaments) actin
basic functional (contractile) units; separated by dark bands (z lines)
sacromere
it explains the mechanism of contraction; thick and thin myofilaments slide past each other as a muscle contracts
the sliding filament model
contraction requires?
calcium and ATP
What are the functions of skeletal muscle?
movement, posture, heat production, and fatigue
how do muscles produce movement?
by pulling on bones as a muscle contracts; (insertion bone is pulled closer to origin bone and movement occurs at the joint between the origin and the insertion)
muscle whose contraction is mainly responsible for producing a given movement
a prime mover
muscle whose contractions help the prime mover produce a given movement
a synergist
muscle whose actions oppose the action of a prime mover in any given movement
an antagonist
what type of muscle contraction allows us to maintain a position?
tonic contraction
tonic contractions maintain muscle tone called?
posture
no movement of body parts and use of only few muscle fibers at one time are ?
tonic contraction
to enable best body functioning....
good posture (optimum body positioning) is favored
skeletal muscle tone maintains posture by?
counteracting the pull of gravity
survival depends on the body's ability to maintain?
a constant body temperature
an elevated body temperature and also a common sign of illness is?
fever
when your body temp is too low
hypothermia
what produces the most amount of heat required to maintain normal body temp?
contraction of muscle fibers
reduced strength or muscle
contraction; not enough rest after repeated muscle stimulation; muscle burning due to inadequate oxygen producing lactic acid; oxygen debt; depleted cellular ATP
fatigue
term used to describe the metabolic effort required to burn excess lactic acid that may accumulate during prolonged periods of exercise
oxygen debt
how to pay the debt?
labored breathing after strenuous exercise
what other body systems are important to muscle functioning?
respiratory, circulatory, nervous, muscular, and skeletal systems
name some exs of pathological conditions in other body organ systems that can dramatically affect movement?
multiple sclerosis, brain hemorrhage, and spinal cord injury
before a muscle can shorten and produce movement it must be stimulated by?
nerve impulse
what is a nerve cell that transmits an impulse to a muscle, causing contraction?
a motor neuron
what is the point of contact between a nerve ending and the muscle fiber it innervates?
a neuromuscular junction
what is the combination of a motor neuron and the muscle cell or cells it innervates?
a motor unit
a muscle will contract only if an applied stimulus reaches a minimal level of intensity...this is called?
threshold stimulus
after the threshold stimulus, a muscle fiber will contract completely...this is referred to as?
all or none
different motor units responding to different threshold stimuli permit a muscle as a whole to execute contractions of....
graded force
individual muscle fibers always respond in an All or None mode....T or F?
true: (fibers do, the muscle as a whole does not)
quick, jerky responses to a stimulus; they are laboratory phenomena and do not play a significant role in normal muscular activity?
twitch contractions
sustained and steady muscular contractions caused by a series of stimuli bombarding a muscle in rapid succession
tetanic contractions
contraction of a muscle that produces movement of a joint; the muscle changes length, causing the insertion end of the muscle to move relative to the point of origin
isotonic contractions
what type of contractions shorten muscles?
concentric
which type of contractions allow a muscle to increase in length?
eccentric
most types of body movements are caused by what type of contraction?
isotonic contractions
muscle contractions that do not produce movement; the muscle as a whole does not shorten; tension in the muscle increases
isometric contractions
what improves muscle tone and posture, results in more efficient heart and lung functioning and reduces fatigue?
exercise
what causes disuse atrophy?
prolonged inactivity
regular exercise increases muscle size...this is called?
hypertrophy
contraction of muscles against heavy resistance is; increase in number of myofilaments in each muscle fiber; total mass of muscle increases; does not increase the # of fibers
strength training
what increases a muscle's ability to sustain moderate exercise over a long period; allows more efficient delivery of oxygen and nutrients to a muscle via increased blood flow; does not result in hypertrophy?
endurance training (aerobic training)
facial muscles
orbicularis oculi, orbicularis oris, and zygomaticus
muscles of mastication
masseter and temporal
what muscle flexes the head?
sternocleidomastoid
what muscle elevates the shoulders and extends the head?
trapezious
what muscle flexes the upper arm?
pectoralis major
what muscle extends the upper arm?
latissimus dorsi
what muscle abducts the upper arm?
deltoid
what muscle flexes the forearm?
biceps brachii
what muscle extends the forearm?
triceps brachii
what are the abdominal muscles?
rectus abdominus, external oblique, internal oblique, and transverse abdominis
what are the respiratory muscles?
intercostal muscles and diaphragm
what muscle flexes the thigh?
iliopsoas
what muscle extends the the thigh?
gluteus maximus
what muscle adducts the thighs?
adductor muscles
what muscle flexes the lower leg?
hamstring muscles (semimembranosus, semitendinosus, and biceps femoris)
what muscle extends the lower leg?>
the quadriceps femoris group (rectus femoris and vastus muscles)
what muscle dorsiflexes the foot?
tibialis anterior
what muscle plantar flexes foot?
gastrocnemius
what muscle flexes the foot?
peroneus group
movement that decreases the angle between two bones at their joint: bending?
flexion
movement that increases the angle between two bones at their joint: straightening?
extension
movement of a part away from the midline of the body?
abduction
movement of a part toward the midline of the body?
adduction
movement around a longitudinal axis?
rotation and circumduction
hand positions that result from rotation of the forearm; hand position with the palm turned to the anterior position
supination
hand positions that result from rotation of the forearm; when the palm faces posteriorly
pronation
foot movements; results in elevation of the dorsum or top of the foot
dorsiflexion
foot movements; the bottom of the foot is directed downward
plantar flexion
muscle disorders; can range from mild to life threatening
myopathies
injury from overexertion or trauma; involves stretching or tearing of muscle fibers; accompanied by myalgia, myositis and fibromyositis
strain ( called a sprain when injury is near a joint and involves ligament damage)
painful muscle spasms (involuntary twitching)
cramps
what injuries result from severe muscle trauma and may release cell contents that ultimately cause kidney failure?
crush injuries
stress induced muscle tension can cause
headaches and back pain
viral infection of motor nerves that ranges from mild to life threatening
poliomyelitis
group of genetic disorders characterized by muscle atrophy?
muscular dystrophy
most common muscular dystrophy characterized by rapid progression of weakness and atrophy; it is x linked affecting mostly boys?
duchenne (pseudohypertrophic) muscular dystrophy
autoimmune muscle disease characterized by weakness and chronic fatigue?
myasthenia gravis