Question | Answer |
Contractility | the ability of skeletal muscle to shorten with force |
Excitability | the capacity of skeletal muscle to respond to a stimulus |
Extensibility | the ability to be stretched |
Elasticity | the ability to recoil to their original resting length after they have been stretched |
Epimysium | connective tissue sheath that surrounds each skeletal muscle |
Fascia | another connective tissue located outside the epimysium; it surrounds and separates the muscle |
Perimysium | loose connective tissue that surrounds fasciculi |
Fasciculi (Fascicle) | numerous visible bundles that make up muscle |
Endomysium | connective tissue sheath that surrounds each muscle fiber |
Muscle Fiber | a single cylindrical cell containing several nuclei |
Myofibril | a threadlike structure that extends from one end of the fiber to the other |
Myofibrils consist of 2 major kinds of protein fibers... | actin & myosin (myofilaments) |
Sarcomere | highly ordered units created by actin & myosin myofilaments, which are joined end to end to form the myofibril |
The basic structural & functional unity of the muscle | Sarcomere |
Each Z line is the site for... | actin |
I bands consist of... | actin |
The H zone consists of only... | myosin |
Resting Membrane Potential | the charge difference across the membrane between the inside (-) & the outside(+) |
Action Potential | the brief reversal back of the charge when a muscle is stimualated |
Motor Neurons | nerve cells that carry action potentials to skeletal muscle fibers |
Neuromuscular Junction (Synapse) | what is formed when each branch connects to the muscle near the center of the cell |
Motor Unit | a single motor neuron and all the skeletal muscle fibers it innervates |
Presynaptic Terminal | the enlarged nerve terminal |
Synaptic Cleft | the space between the presynaptic terminal and the muscle cell |
Postsynaptic Terminal | the muscle fiber |
Synaptic Vesicles | secrete neurotransmitters called acetylcholine |
Acetylcholine | diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell |
Acetylcholinesterase | an enzyme that breaks down acetylcholine |
Muscle Twitch | a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers |
Threshold | the point at which the muscle fiber will respond to a stimulus |
Contraction Phase | the time of contraction |
Lag Phase | the time between application of a stimulus to a motor neuron & the beginning of a contraction |
Relaxation Phase | the time during which the muscle relaxes |
Tetany | where the muscle remains contracted without relaxing |
Recruitment | the increase in number of motor units being activated |
ATP is needed for... | energy for muscle contraction |
Origin | the most stationary end of the muscle |
Insertion | the end of the muscle undergoing the greatest movement |
Belly | the portion of the muscle between the origin & the insertion |
Anaerobic Respiration | respiration without oxygen |
Fast-Twitch Fibers | contract quickly & fatigue quickly. (ex. white meat from a chicken's breast) |
Slow-Twitch Fibers | contract more slowly & are more resistant to fatigue (ex. dark meat of a duck's breast or the legs of a chicken) |
Synergists | muscles that work together to accomplish specific movements |
Antagonists | muscles that work in opposition to one another |
Nomenclature | how most muscles are characterized (ex. size, location, orientation of fibers, shape, origin, insertion, function, etc.) |
Occipitofrontalis | raises the eyebrows |
Orbicularis oculi | closes the eyelid |
Orbicularis oris | pucker/ "kissy face" |
Buccinator | flattens the cheeks |
Zygomaticus | smiling muscle |
Levator labii superioris | sneering |
Depressor anguli oris | frowning |
Mastication | 4 pair of chewing muscles |
Intrinsic Tongue Muscles | changes the shape of the tongue |
Extrinsic Tongue Muscles | moves the tongue |