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Muscles Ch. 6

4 characteristics of muscles? contractility, excitability, extensibility, elasticity
what is an epimysium? connective tissue sheath surrounding each skeletal muscle
myofibrils threadlike structure that extends from one end of the fiber to the other
2 major kinds of protein fibers actin myofilaments and myosin myofilaments
actin thin myofilaments
myosin thick myofilaments
sacromeres joined end to end to form the myofibril; formed by actin and myosin; basic structural and functional unit of muscle
I band on each side of the Z line; consists of actin
A band extends the length of the myosin
H zone in the center of each sarcomere.
positive and negative charge? positive- outside of cell membrane. negative- inside of cell membrane
resting membrane potential charge difference across the membrane
action potential brief reversal of back of the charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers.
synapse (neuromuscular junction) near center of cell; formed by each branch that connects to the muscle.
fascia connective tissue outside the epimysium
perimysium surrounds fasciculi; is loose connective tissue
fibers single muscle cells that create fasciculi
endomysium connective tissue sheath surrounding each muscle fiber
cytoplasm of each fiber myofibrils
resting membrane potential charge difference across the membrane
Action potential brief reversal of the charge
motor nuerons nerve cells that carry action potentials to skeletal muscle fibers
Synapse near center of cell
another word for synapse neuromuscular junction
motor unit single motor neuron and all skeletal muscle fibers it innervates
how is a synapse formed? an enlarged nerve terminal resting in an indentation of the muscle cell membrane.
presynaptic terminal enlarged nerve terminal
synaptic cleft space between the presynaptic terminal and the muscle cell
muscular fiber postsynaptic terminal
what does each presynaptic terminal include? synaptic vessels
synaptic vessels secret a neurotransmitter called what? acetylcholine
what does acetylcholine do? diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell.
acetylcholinesterase enzyme that breaks down acetylcholine
what happens when sarcomeres shorten? the muscle shortens
how does muscle contraction occur? actin and myosin myofilaments slide past each other
sliding filament mechanism sliding of actin myofilaments past myosin myofilaments during contraction
What bands shorten? H and I
What bands stay the same? A bands
Muscle Twitch contraction of an entire muscle in response to a stimulus
tetany muscle remains contracted without relaxing
threshold a muscle fiber won't contract until it reaches this level
all-or-none-response a muscle fiber won't contract, but when it does, it does maximally
lag phase time between application of the stimulus to a motor neuron and the beginning of a contraction
contraction phase time of contraction
relaxation phase time where muscles relax
recruitment increase in number of motor units being activated
ATP is needed for what needed for energy for muscle contraction
where is atp produced? in the mitochondria
What is ADP adenosine diaphosphate
True or False? It is necessary for muscle cells to constantly produce ATP true
creatine phosphate high-energy molecule stored when at rest
Can muscles store ATP at rest no
energy contained in ATP is used to synthesize what? creatine phosphate
anaerobic respiration without oxygen
aerobic respiration with oxygen
anaerobic example lifting weights
aerobic example swimming
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
fast-twitch fibers contract quickly and fatigue quickly
slow-twitch fibers contract more slowly and are more resistant to fatigue
origin most stationary end of muscle
insertion end of muscle undergoing the greatest movement
belly portion of muscle between the origin and the insertion
true or false? Some muscles have multiple origins or head true
synergists muscles that work together to accomplish specific movements
anatgonists muscles that work in opposition to each other
prime mover in a group of synergists, it's one muscle that plays a major role in accomplishing the desired movement
how are muscles named? according to location, size, shape, orientation of fibers, origin, insertion, and function
occipitofrontalis raises eyebrows
orbicularis oculi closes eyelids and causes "crows feet"
orbicularis oris puckers the lips
zygomaticus smiling muscle
levator labii superioris sneering
depressor anguli oris frowning
mastication chewing
sternocleidomastoid lateral neck muscle and prime mover
Created by: arnelso8



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