Muscles Flashcards
what is sarcolemma
outer cell membrane on striated muscle fibers
what are the functions of the sarcolemma
excitable membrane, can pass an electrical current, and acts as a barrier
do skeletal muscle cells have multiple nuclei
yes, one is not enough, they are too long
what is muscle tone
(readiness to fire) the continuous and passive partial contraction of the muscles, or the muscle’s resistance to passive stretch during resting state
where do you want your muscles to be at on the muscle tone scale
just below firing threshold (fibers will be slightly firing)
when does a spasm or twitch occur
when the muscle tone is too high or there is too much stimulation
what happens to muscle tone during REM sleep
the tone shuts down or decreases
why do our muscles act as a smooth movement
because the muscles are continuously and steadily contracting/firing as it is being used
what is a myofilament
actin and myosin stacked end to end, a protein filament that makes up a myofibril
what makes up a myofibril
myofilaments: actin and myosin, longitudinal fibril
what makes up a muscle cell
myofibrils; cells that make up muscle tissue
how does a muscle grow
most of the time the muscle cells get larger (myofilaments get bigger) through exercise
what does new research suggest for how muscle cells grow
through satellite stem cells
if you cut through a muscle, will it regenerate
yes, to a certain extent
what is a sarcomere
a minimal contractile or functional unit (basic unit), actin -thin filament and myosin- thick filament as “parts”, stack these on end to make a myofilament
what is sarcoplasmic reticulum
surrounds the myofibrils; an exchange or turnover system of oxygen and fuel, stores and releases calcium ions during muscle contraction and absorb them during relaxation
what is the true measure of physical fitness
speed of recovery and the VO2 max
what is endomysium
a thin layer of connective tissue around each muscle cell/fiber, separates the muscle fibers in a fascicle
what is a fascicle
bundle of muscle fibers wrapped by perimysium
what is a “muscle”
a bundle of fascicles surrounded by epimysium
what is epimysium
dense irregular connective tissue that surrounds the whole muscle
what do you have left if you take away all the muscle fibers (cells)
a connective harness (3 layers of “mysiums”: endo, epi, peri)
what happens when you “pull” a muscle
you are either tearing the connective harness or tendon
what are the 4 types of muscle
circular, convergent, parallel, and pennate (bipennate or unipennate)
what is a circular muscle
a sphincteral muscle, surrounds a body opening
what is a convergent muscle
(pectoralis major) “fan shaped” arises from a broad area and converges to a single tendon
what is a parallel muscle
(biceps brachii) “tubular or cigar shaped” forces are parallel
what is an example of a bipennate muscle
rectus femoris
what is an example of a unipennate muscle
extensor digitorium longus
what is a pennate muscle
feather like, distribute the load, high efficiency, tend to be type I
what are the 2 muscle roles
stabilizing and mobilizing
what muscle role is a type I muscle
stabilizing
what muscle role is a type II muscle
mobilizing
what type of muscle is the red-slow fiber
Type I
what type of muscle is the white-fast fiber
Type II
what are the characteristics of a Type I fiber
deep, postural or anti-gravity, high endurance, crosses one joint, oxidative
what are the characteristics of a Type II fiber
low endurance, inefficient, superficial muscle, crosses 2 joints, glycolytic (anaerobic)
what is smooth muscle
unstriated, spindle-shaped, randomly arranged, involuntary, autonomic, visceral muscle, slow contraction
what is cardiac muscle
striated, involuntary visceral muscle (walls of heart and adjacent parts of the vessels) autonomic, held together by discs
what is atrial fibrillation
loses the “beat” or rhythm of the cardiac muscle, the heart can stop suddenly
what is the origin of a muscle
a fixed point where the muscle attaches to bone
what is the insertion of a muscle
the more distal point, end that tends to move
what are the 4 types of muscle action
agonist, antagonist, synergist, and stabilizer
what is an agonist muscle
the prime mover, causes specific movement through its own contraction
what is an antagonist muscle
it opposes the agonist, returns the limb to its initial position
what is a synergist muscle
assists, supports, or helps perform the same set of joint motion as the agonist “neutralizer”
what is a stabilizer muscle
supports joints at rest or during other movements (postural muscles)
what is a neuromuscular junction
connects the nervous system to the muscular system via synapses
what is the neurotransmitter that activates the neuromuscular junction
acetylcholine
what happens with myasthenia gravis
you first get neuromuscluar weakness first in the eyelid (ptosis) then speaking, then swallowing
what is the standard way to describe muscles and their function
OINA
what is muscle action
named for the joint where the action is of the affected muscles
what does smooth muscle (not jerky) action rely on
all 4 actions to happen at once (agonist, antagonist, synergist, and stabilizer)
what are you testing when you check reflexes
the connections to the spinal cord and that the muscles are all working together like they should
where in the brain are muscle movements controlled/coordinated
the cerebellum
what is an ataxia
a neurological sign consisting of lack of voluntary coordination of muscle movements
what happens when two cardiac muscle touch each other
they start beating together
If someone is paralyzed from the neck down, do they still have reflexes
yes they still work, they are hyper-reflexive (even stronger than before) muscle tone is set too high
what happens if you cut a nerve i.e. the femoral nerve
you wouldn’t have reflexes anymore
what are the 3 layers of connective tissue in a skeletal muscle
epimysium, perimysium, and endomysium
