Chapter 9: The Muscular System Flashcards
Contractility
the ability of muscle to shorten forcefully
What are the functions of the Muscular System? (7)
- movement of the body
- maintenance of posture
- respiration
- production of body heat
- communication
- constriction of organs and vessels
- contraction of the heart
Excitability
the capacity of muscle to respond to a stimulus
Extensibility
muscle can be stretched beyond its normal resting length and still be able to contract
Elasticity
is the ability of muscle to recoil to its original resting length after being stretched
Fasciculi
numerous visible bundles that a muscle is composed of
perimyseum
heavy connective tissue surrounding the fasciculi of muscle
epimysium
connective tissue that surround the entire muscle composed of dense collagenous connective tissue
Muscular Fascia
connective tissue sheets within the body located superficial to the epimysium, separates and compartmentalizes individual muscles of group of muscles
Motor neurons
specialized nerve cells that stimulate muscles to contract
myoblasts
less mature, multi-nucleated cells that develop muscle fibers
hypertrophy
enlargement of muscles after body grows, number of muscle fibers stays relatively the same
Sarcolemma
the plasma membrane of a muscle fiber
endomysium
loose connective tissue with reticular fibers that surrounds muscle fibers
T tubules
along the surface of the sarcolemma, extending to the extracellular environment with the interior of the muscle fiber
myofibril
consists of actin and myosin, extend to the end of the muscle fiber
Sarcomeres
basic ordered units of skeletal muscle that contain myofibrils
neuromuscular junction
point where neurons are sent in the muscle
titin
coil spring on end of myosin allows sarcomere to stretch
What is globular actin?
one actin molecle
What is F actin?
twisted pair of globular actin
What is the job of tropomyoisin
to reveal or conceal the active binding sites
what does myosin do?
binds to active sites
what does troponin do?
binds to calcium, tropomyosin, and G actin in order to expose actin
What is a cross-bridge?
when myosin head binds to active site
I bands
light bands
A bands
Dark bands
H zone
region inside A band that appears to be lighter because actin and myosin do not overlap
M line
middle of H zone holding myosin in place
What does the sarcoplasmic reticulum do?
supplies calcium
how does the sarcoplasmic reticulum supply calcium
through ion channels and voltage-gated channels
antiport, synport
sends two things in two different direction, sends two things in the same direction
charges of cell at resting potential
- inside (K+ and proteins-), + outside (Na+)
How does the sodium/potassium pump work?
pumps 3 Na+ out and 2 K+ in
Ligand-gated ion channel
molecules bind to receptor
Voltage gated ion channel
open and close in response to short voltage changes across plasma membrane
Bi-gated channel
lids on both ends
visceral or unitary smooth muscle
occurs in sheets, has numerous gap junctions found in digestive, reproductive, and urinary tracts
multiunit smooth muscle
occurs as sheets, walls of blood vessels, fewer gap junctions, cells or groups of cells act as independent units, only contracts when stimulated by nerves of hormones. ex: arrector pili, iris of the eye
origin
fixed end of muscle attached to bones
insertion
muscle end attached to bone with greatest movement
belly
largest portion of the muscle between origin and insertion
aponeuroisis
a very large tendon
agnonist
muscle that when it contracts causes an action
antagonist
a muscle working in opposition to agonist (when you move a bowling ball back to prepare to bowl, biceps)
synergists
muscles that work together to cause movement
prime mover
plays the major role in synergistics
fixator
stabilizing joints in synergistics
Neuromuscular junction
specialized synapse between motor neuron and muscle fiber
neurotransmitter
substance released by presynaptic membrane that stimulates or inhibits the production of action potential in the postsynaptic membrane
