question | Answer |
contractility | ability of skeletal muscles to shorten with force |
contractility | ability of skeletal muscles to shorten with force |
excitability | capacity of skeletal muscles to respond to a stimulus |
excitability | capacity of skeletal muscles to respond to a stimulus |
extensibility | ability to be stretched |
extensibility | ability to be stretched |
elasticity | ability to recoil to their original resting length after they have been stretched |
elasticity | ability to recoil to their original resting length after they have been stretched |
epimysium | skeletal muscle surrounded by a connective tissue sheath |
epimysium | skeletal muscle surrounded by a connective tissue sheath |
fascia | another connective tissue located outside the epimysium |
a muscle is composed of numerous visible bundles called | fasciculi |
fasciculi are surrounded by loose connective tissue called | perimysium |
muscle fibers | muscle cells |
muscle fibers | muscle cells |
each muscle fiber is a single cylindrical cell connecting several | nuclei |
endomysium | a connective tissue sheath that surrounds fibers |
myofibrils | a threadlike structure that extends from one end of the fiber to the other. |
myofibrils | a threadlike structure that extends from one end of the fiber to the other. |
actin myofilaments | thin myofilaments |
actin myofilaments | thin myofilaments |
myosin myofilaments | thick myofilaments |
myosin myofilaments | thick myofilaments |
actin myofilaments resemble | 2 minute strands of pearls twisted together |
actin myofilaments resemble | 2 minute strands of pearls twisted together |
myosin myofilaments resemble | bundles of minute golf clubs |
myosin myofilaments resemble | bundles of minute golf clubs |
sarcomeres | ordered units joined end to end to form the myofibril |
basic structural and functional unit of the muscle | sarcomere |
each sarcomere extends from what to what | z line to z line |
each sarcomere extends from what to what | z line to z line |
on each side of the z line is a light area called a ____, that consists to actin | I band |
on each side of the z line is a light area called a ____, that consists to actin | I band |
in the center of each sarcomere is another light are called the ____, which consists of only myosin | H zone |
what is the A band | darker central region of each sarcomere |
dark staining band in the center of the sarcomere | M line |
in the center of each sarcomere is another light are called the ____, which consists of only myosin | H zone |
the outside of most cell membranes are | positively charged |
dark staining band in the center of the sarcomere | M line |
the inside of most cell membranes are | negatively charged |
resting membrane potential | charge difference across the membrane |
action potential | brief reversal back of a charge |
the outside of most cell membranes are | positively charged |
motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
axons enter the muscles and branch. each branch that connects to the muscle forms a _______, or ____ near the center of the cell. | neuromuscular junction; synapse |
the inside of most cell membranes are | negatively charged |
motor unit | a single motor neuron and all the skeletal muscle fibers it innervates |
action potential | brief reversal back of a charge |
motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
axons enter the muscles and branch. each branch that connects to the muscle forms a _______, or ____ near the center of the cell. | neuromuscular junction; synapse |
motor unit | a single motor neuron and all the skeletal muscle fibers it innervates |
presynaptic terminal | enlarged nerve terminal |
synaptic cleft | the space between the presynaptic terminal and the muscle cell |
postsynaptic terminal | muscle fiber |
each presynaptic terminal contains | synaptic vesicles |
synaptic vesicles secrete a neurotransmitter called | acetycholine |
muscle contraction | occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten |
sliding filament mechanism | the sliding of actin myofilaments past myosin myofilaments during contraction |
between the H, the I ,and the A band, which one does not shorten in length? | the A band |
muscle twitch | a contraction of an entire muscle in response to a stimulus |
a muscle fiber will not respond to stimulus until the stimulus reaches a level called | threshold |
all-or-more response | the phenomenon of the threshold |
lag phase | the time between application of a stimulus to a motor neuron and the beginning of a contraction |
contraction phase | the time of contraction |
relaxation phase | the time during which the muscle relaxes |
tetany | where the muscle remains contracted without relaxing |
recuitment | the increase in number of motor units being activated |
ATP | needed for energy for muscle contraction |
ATP produces | mitochondria |
adenosine triphosphate | ATP |
adenosine diphosphate | ADP |
creatine phosphate | high-energy molecule |
anaerobic respiration | without oxygen |
aerobic respiration | with oxygen |
oxygen debt | amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells. |
muscle fatigue | when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
isometric | equal distance |
isotonic | equal tension |
muscle tone | constant tension produced by muscles of the body for long periods of time |
fast-twitch fibers | contract quickly and fatigue quickly |
slow-twitch fibers | contract more slowly and are more resistant to fatigue |
origin | head |
insertion | the end of the muscle undergoing the greatest movement |
synergists | muscles that work together to accomplish specific movements |
antagonists | muscles that work in opposition to one another |
prime mover | one muscle that plays the major role in accomplishing the desired movement |
2 tongue muscles | extrinsic and intrinsic |
sternocleidomastoid | prime neck muscle |
mastication | chewing |
kissing muscles | orbicularis oris and buccinator |
occipito frontalis | raises eyebrows |
orbicularis occilu | closes eyelid |
zygomaticus | smiling |
levator labii superioris | sneering |
depressor angulioris | frowning |