Module 10 Muscular System Flashcards
my/o
muscle
sarc/o
flesh
sthen/o
strength
origin
attachment of a muscle to a bone or structure that does not move when the muscle contracts
insertion
attachment of a muscle to a bone or structure that DOES move when the muscle contracts
intrinsic muscle
muscle that has its origin and insertion located in the same body region
extrinsic muscle
muscle that has its origin located in a region different from that of its insertion; ex. sternocleidomastoid
fixator
a muscle that holds an origin stable for another muscle
synergists
muscles that have the same action
prime mover
the main muscle that performs the action, helped by synergists
antagonist
a muscle that has an opposing action
sarcolemma
muscle cell’s cell membrane
sarcoplasmic reticulum
muscle cell’s ER
myofibrils
a bundle of myofibrils make up a muscle fiber
single muscle structure (smallest to largest)
individual muscle cell (muscle fiber) is surrounded by endomysium; muscle fibers are grouped together to form a fascicle which is surrounded by perimysium; fascicles together make up the muscle which is surrounded by epimysium
fascia
tough, fibrous tissue that does not allow for expansion; forms muscle compartments and separates muscle from the hypodermis
sarcomere
section of myofibril extending from one z line to the next; the overlapping of the myofilaments near the center of the sarcomere is what causes the striated appearance of skeletal muscle tissue
myosin
several hundred protein molecules that make up thick myofilaments; includes: actin, tropomyosin, and troponin
5 physiological characteristics of muscles
- excitability- ability to be stimulated by a nerve to contract
- conductivity
- contractility- can shorten with force
- extensibility- can be stretched; muscles are stretched by the contraction of other muscles
- elasticity
neuromuscular junction
shows excitability; nerve ending and muscle cell don’t touch, instead receptors with specific shape are located on the muscle cell
Acetylcholine
(ACh) neurotransmitter released for skeletal muscle tissue that signals the muscle cell to contract
threshold
minimum amount of ACh required in receptors for the muscle to react; creates an all or nothing response
synaptic cleft
AKA synapse; indentation in the muscle cell that forms a gap where the nerve ending meets the muscle; allows receptors to communicate between nerve ending and muscle cell
muscle twitch
contraction of one muscle cell due to one nerve impulse
phases of muscle twitch- 1. latent phase
muscle cell has not shorted during this phase; nerve impulse comes down the neuron; ACh is released and fits into the receptors; sarcoplasmic reticulum releases Ca+; Ca+ binds to troponin; tropomyosin shifts position to expose the active sites; myosin grabs ahold of actin
phases of muscle twitch- 2. contraction phase
myosin pulls (power stroke; the muscle cell shortens
phases of muscle twitch- 3. relaxation phase
myosin lets go; muscle goes back to its shape because it is elastic
phases of muscle twitch- 4. refractory phase
Ca+ is actively transported back to the sarcoplasmic reticulum and the muscle produces acetylcholinesterase; muscle appears to be relaxed
tetany
sustained muscle contraction due to frequency of nerve impulses that come and complete their latent phases before the muscle cell can even begin to enter the relaxation phase from the first nerve impulse