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study guide chapter 6

contractility ability of skeletal muscle to shorten with force
excitability capacity of skeletal muscle to respond to a stimulus
extensibility ability to be stretched
elasticity ability to recoil to their original resting length after they have been stretched.
epimysium connective tissue sheath that surrounds the skeletal muscle.
Fascia another connective tissue located outside the epimysium that surrounds and separates muscles.
perimysium loose connective tissue that surrounds fascicle
muscle fasciculi numerous visible bundles that the muscles are composed of.
fibers single muscle cells that the fasciculi are composed of.
endomysium connective tissue sheath that surrounds fibers
myofibrils threadlike structure that extends from one end of the fiber to the other
actin myofilaments thin myofilaments
myosin myofilaments thick myofilaments
sarcomeres basic structural and functional unity of the muscle
Z line attachment site for actin
I band light area on each side of the Z line that consists of actin
A band extends the length of the myosin and is the darkest central region in each sarcomere.
H zone light area in the center of each sarcomere
M line dark staining band anchored in the center of the sacromere
resting membrane potential change difference across the membrane
action potential the brief reversal back of the charge
Motor neurons nerve cells that carry action potentials to skeletal muscle fibers
axons enter the muscles and branches
neuromusclular junction or synapse each branch that connects to the muscle froms ____ near the center of the cell
motor unit single motor neuron and all the skeletal muscle fibers it innervates
single muscle many motors unit form ___
presynaptic terminal enlarged nerve terminal
Synaptic cleft space between the presynaptic terminal and the muscle cell.
postsynaptic terminal muscle fiber
synaptic vesicles secrete a neurotransmitter
acetylcholine neurotransmitter that diffuses across synaptic cleft and binds to the postsynaotic terminal causing change in the postsynaptic cell.
acetylcholinesterase enzymes that break down acetylcholine released into the synaptic cleft between the neuron and muscle cell
sliding filament mechanism sliding of actin myofilaments past myosin myofilaments during contraction
muscle twitch contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers.
threshold point in which the muscle fiber will contract mazimally
all-or-none response phenomenon of threshold
lag phrase time between applicatin of the stimulus to a motor neuron and the beginning of a contraction
`contraction phase time of contraction
relaxation phase time during which the muscle relaxes
tetany where the muscle remains contracted without relaxing.
recruitment increase in number of mototr units being activated
adenosine triphosphate (ATP) needed for energy for muscle contraction
ATP produced in the mitochondria, short-lived and unstable, it degenerates to the more stable ADP plus phosphate.
ADP more stable enegry
Creatine phosphate high-energy molecules that muscle cells can store
anaerobic respiration without oxygen
aerobic respiration with oxygen and is more efficient
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 results when ATP is used during muscle contraction faster than it can be produced in the muscle cells
two types of muscle contractions Isometric Isotonic
Isometric (equal distance) length of the muscle does not change, but the amount of tension increases during the contraction process
Isotonic (equal tension) the amount of tension produced by the muscle in constant during contraction, but the length of the muscle changes
muscle tone refers to constant tension produced by muscles of the body for long periods of time. (Keeps head up and back straight)
fast-twithch fibers Well adapted to perform anaerobic metabolism. contract quickly and fatigue guickly. (White meat of a chicken's breast)
slow-twitch fibers contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism (Dark meat of a duck's breat; legs of a chicken)
origin the most stationary end of the muscle. (head)
insertion end of the muscle undergoing the greatest movement
belly portion of muscle between the origin and the indertionsynergists
synergists muscles that work together to accomplish movements
antagonists muscles that work in opposition to one another
prime mover among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the _____
Muslces named according to their location, size, orientation of fibers, shape, origin, insertion, and function, etc.
Muscles help what? to produce heat essential for maintenance or normal body tempeature
What is each muscle fiber? single cylindrical cell containing several tissue
Cytoplasm of each fiber is__ filled with myofibils
Myofibrils consist of ? to major protein fibers -actin myofilaments -myosin myofilaments
Actin and Myosin myofilaments from what? highly ordered units called sarcomeres
neuromusclular junction formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane
muscle contraction occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten
During sliding filament mechanism... H and I bands shorten, but the A bands do not change in length
If successive stimuli are given... you get successive twitches that occur so frequently the muscle does not have time to fully relax
during period of inactivity.. energy contained in ATP is used to synthesize creatine phosphate.
Points of attachment of each muscle origin and insertion
two characteristics of skeletal Muscle -Four Major Functional Characteristics -Structure
outside of most cell membranes is... positively charged compared to the inside of the cell memeberane, which is negatively charged.
Created by: Godrules1



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