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BSC 105 CH.6 Muscles

anatomy muscle notes

a threadlike structure that extends from one end of the fiber to the other myofibrils
cytoplasm of each fiber is filled with myofibrils
surrounds fibers; a connective tissue sheath endomysium
single muscle cells fibers
surrounds fascicles; a loose connective tissue perimysium
visible bundles in the muscle fascicle
connective tissue located outside the epimysium; surrounds & seperates fascia
connective tissue sheath surrounding skeletal msucles epimysium
ability to recoil to their original resting length after they have been stretched elasticity
the ability to be stretched extensibility
the capacity of skeletal muscle to respond to a stimulus excitability
the ability of skeletal muscle to shorten with force contractility
thin myofilaments actin myofilaments
thick myofilaments myosin myofilaments
actin & myosin myofilaments form highly ordered units that are joined end to end to form the myofibril sarcomeres
each z-line is an attachment site for actin
I-band consists of actin
A-band extends the length of the myosin
Nerve cells that carry action potentials to skeletal muscle fibers motor neurons
the space between the presynaptic terminal and the muscle cell is the synaptic cleft
where the muscle remains contracted without relaxing tetany
a muscle fiber will not respond to stimulus until that stimulus reaches a level called threshold
the time between the application of a stimulus to a motor neuron and the beginning of a contraction is the lag phase
the time of contraction is the contraction phase
the time during which the muscle relaxes is the relaxation phase
the increase in number of motor units being activated is called recruitment
without oxygen anaerobic respiration
with oxygen (more efficient) aerobic respiration
the 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 oxygen debt
results when ATP is used during muscle contraction faster than it can be produced in the muscle cells muscle fatigue
two types of muscle contractions isometric & isotonic
the length of the muscle does not change, but the amount of tension increases during the contraction process. (equal distance) isometric
the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes. (equal tension) isotonic
constant tension produces by muscles of the body for long periods of time. keeps head up and back straight muscle tone
contract quickly and fatigue quickly. well adapted to perform anaerobic metabolism. fast-twitch-fibers
contract more slowly and are more resistant to fatigue. they are better suited for aerobic metabolism slow-twitch fibers
the most stationary end of the muscle. (head) origin
the end of the muscle undergoing the greatest movement insertion
the portion of the muscle between the origin and the insertion is the belly
muscles that work together to accomplish specific movements are called synergists
muscles that work in opposition to one another are called antagonists
if one muscle plays the major role in accomplishing the desired movement, it is the prime mover
raise the eyebrows occipitofrontalis
closes the eyelids and causes "crow feet" wrinkles in the skin at the lateral corners of the eye orbicularis oculi
puckers the lips orbicularis oris
flattens the cheeks. trumpeter's muscle buccinator
smiling muscle zygomaticus
sneering levator labii superioris
frowning depressor anguli oris
chewing mastication
4 pairs of mastication muscles 2 pair of ptyergoids, temporalis, and masseter
change the shape of the tongue intrinsic tongue muscle
move the tongue extrinsic tongue muscle
lateral neck muscle and prime mover. rotates & abducts the head sternocleidomastoid
muscles help to produce heat essential for maintenance of normal body temperature true
each muscle fiber is a single cylindrical cell containing several nuclei true
there are 3 major kinds of protein fibers false
the sarcomere is the basic structural and functional unit of the muscle true
each sarcomere extends from one z-line to another z-line
on each side of the z-line is a light area called an i-band
the a-band extends the length of the myosin
in the center of each sarcomere is another light area called the h-zone
a dark staining band called the m-line
the muscle fiber is the postsynaptic terminal
each presynaptic terminal contains synaptic vessels
each synaptic vessel secretes a neurotransmitter called acetylcholine
acetylcholine causes a change in the postsynaptic cell
the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzyme acetylcholinesterase
occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten muscle contraction
the sliding of actin myofilaments past myosin myofilaments during contraction is called sliding filament mechanism
a contraction of an entire muscle is response to a stimulus that causes the action potential in one or more muscle fibers muscle twitch
a msucle fiber will not respond to stimulus until the stimulus reaches a level called threshold
the muscle fiber will contract maximally all-or-none response
the time of contraction is the contraction phase
the increase in number of motor units being activated is called recruitment
needed for energy for muscle contraction ATP
produced the mitochondria ATP
Created by: madisonwilburn