Ch. 1 Muscular, Neuromuscular, Cardiovascular, and Respiratory Systems Flashcards
epimysium
continous with the tendons at the ends of the muscle
tendon
attaches the muscle to the bone periosteum
bone periosteum
a special connective tissue covering all bones
attachments of limb muscles to bone
proximal (closer to the trunk) & distal (farther from the trunk)
attachments of trunk muscles
superior (closer to the head) & inferior (closer to the feet)
origin of muscle
the proximal attachment
insertion of muscle
its distal attachment
muscle cells (aka muscle fibers)
long, have lots of nuclei on the edges of the cell, striated appearance
fasciculi
bundled groups of muscle fibers
perimysium
the connective tissue holding the fasciculi together
endomysium
connective tissue that surrounds each muscle fiber
sarcolemma
the muscle fiber membrane, encircles the endomysium
motor neuron
nerve cell
neuromuscular junction
the junction between the nerve cell and the muscle fibers it innervates (aka the moror end plate)
motor unit
a motor nueron and the muscle fibers it innervates
sarcoplasm
the cytoplasm of a muscle fiber, contains many cell componets
myofibrils
hundreds of them dominate the sarcoplasm, contains the apparatus that contracts the muscle cell
types of myofilament
myosin and actin
cross-bridges
globular heads that protrude away from the myosin filaments
sarcomere
the smallest contractile unit of skeletal muscle, repeat the entire length of the muscle fiber, within them the myosin and actin filaments are organized longitudinally
M-bridge
where adjacent myosin filaments connect
A-band
where myosin filaments align
I-band
area where two sarcomeres are adjacent and there are only actin filaments
Z-line
middle of the I-band, looks dark running through it
H-zone
where only myosin is present, shrinks during contraction as actin slides over the myosin
sarcoplasmic reticulum
parallels and surrounds each myofibril, terminates around the z-lines, stores calcium ions
T-tubules
run perpendicular to the sarcoplasmic reticulum
triad
the pattern of one t-tubule between two sarcplasmic reticulum vesicles
action potential
electrical nerve impulse, causes the release of calcium ions from the sarcoplasmic reticulum into the myofibril, which causes tension development in the muscle
sliding-filament theory
states that the actin filaments at each end of the sarcomere slife inward on myosin filaments, pulling the Z-lines toward the centre of the sarcomere and this shortening the muscle fiber
What dictates the force production of a muscle?
the number of cross-bridges that are attached to actin filaments at any instant in time
what is necessary for mysoin cross-bridge cycling with actin filaments?
calcium and ATP
When does relaxation occur?
when actin and myosin return to their unbound state
acetylocholine
a neurotransmitter, diffuses across the neuromuscular junction, causing excitation of the sarcolemma, when enough of it is released and action potential is generated
all-or-none principle
a motor neuron stimulus always stimulates all fibers equally
troponin
a protein that is situated at regular intercals along the actin filament and has a high affinity for calcium ions
tropomyosin
a protein that runs along the length of the actin filament in the groove of the double helix
what does the extent muscle control depend on?
the number of muscle fibers within each motor unit
twitch
the brief contraction that results from an action potential
tetanus
when the stimuli are delivered as so high a frequency that the twitches merge and eventually completely fuse
types of muscle fibers
slow twitch (Type I), fast twitch (Type IIa and Type IIb/Type IIx)
recruitment
a means of varying skeletal muscle force involving an increase in force through varying the number of motor units activated
preloading
the loading of the muscle prior to the motion, helps to fully activate the muscle fibers that are needed for the early range of motion
proprioceptors
specialized sensory receptors located within joins, muscles, and tendons
muscle spindles
proprioceptors that consist of several modified muscle fibers enclosed in a sheath of connective tissue, they provide information concerngin muscle length and the rate of change in length
intrafusal fibers
the modified muscle fibers that make up muscle fibers
Golgi tendon organs
proprioceptors located in tendons near the myotendinous junction and are in a series with extrafusal muscle fibers
sarcopenia
the reduction of skeletal muscle in size and strength due as a result of aging or inactivity
the heart
a muscular organ comprised of two interconnected but separate pumps
atrium
delivers blood into the ventricles
ventricle
supply the main force for moving blood through the pulminary and peripheral circulations
tricuspid and mitral valves (AV valves)
prevent blood flow from the ventricles back into the atria
semilunar valves- aortic and pulmonary
prevent backflow from the aorta and pulmonary artieries into the ventricles during ventricular relaxation
sinoastrial (SA) node
the intrinsic pacemaker (where rhythmic electril impluses are normally initiated
atrioventricular (AV) node
wher the impulse is delayed slightly before passing into the ventricles
atrioventricular (AV) bundle
conducts the impulse to the ventricles
myocardium
the heart muscle
sympathetic and parasympathetic nervous systems
components of the autonomic nervous system (sympathetic nerves accelerates heart beat, parasympathetic slows it)
bradycardia
a heart beat less that 60 beats/min
tachycardia
a heart beat higher than 100 beats/min
electrocardiogram (ECG)
a graphic representation of this activity
P-Wave
the first wave, genereated by the changes in the electrical potential of cardiac muscle cells that depolarize the atria and result in atrial contraction
QRS complex
three separate waves, genereated by the electrical potential that depolarizes the ventricles and results in ventircular contraction
T-wave
cause by the electrical potential genereated as the ventricles recover from the state of depolarization
repolarization
the recovery of the ventricles or atria from their depolarized state
