LAB Final Part 3 (Muscle) Flashcards
what is required for muscle function?
the physical interaction of protein filaments
what is muscle activity a response to?
input from the nervous system
what does muscle cell contraction rely on?
interaction
how should muscle cell contraction rely on interaction?
1) between thin filaments (mainly of actin)
2) and thick filaments (staggered arrays of myosin)
what does verebrate skeletal muscle move?
bones and the body
what is vertebrate skeletal muscle characterized by?
a hierarchy of smaller and smaller units
characteristics of skeletal muscle
1) bundle of long fibers, each a single cell running parallel to the length of the muscle
2) each muscle fiber itself a bundle of smaller myofibrils arranged longitudally
what is skeletal muscle also called and why?
striated muscle because the regular arrangement of myofilaments creates a pattern of light and dark bands
what is the functional unit of a muscle called and what is it bordered by?
a sacomere, bordered by z lines where thin filaments attach
thin and thick filaments slide past each other longitudinally, powered by the myosin molecules
sliding-filament model
what does the sliding filaments rely on?
interactions between actin and myosin
what does the sliding filament cause actin and myosin to do?
1) the head of a myosin binds to an actin filament formign a cross bridge
2) pulling the thin filament toward the center of the sacomere
what does muscle contraction require?
repeated cycles of binding and release
what generates the ATP needed to sustain muscle contraction?
glycosis and aerobic respiration
with muscle energy store glycogen as?
glucose polymer.
what is glucose used in cellular respiration to make?
ATP
what does creatine poshpate do for muscle energy?
gives up phosphate to ADP to form ATP
Actin-Myosin contraction cycle (4) (AAMC)
1) ATP binds to myosin head causing it to detach from actin (low-energy)
2) ATP is hyrdolyzed into ADP and P, this makes myosin in high energy state (high-energy)
3) mysoin head form cross bridge with actin
4) conformational change occurs in myosin causing it to move the actin filament
what happens to Tropomyosin (regulatory protein) and the troponin complex a set of additional proteins?
binds actin stands on thin filaments when a muscle fibers at rest
what happens when tropomyosin and troponin bind actin strands on thin filaments when a muscle fiber is at rest?
it prevents actin and myosin from interacting
what needs to occur in order for a muscle fiber to contract?
myosin-binding sites must be uncovered
when does myosin-binding sites uncover in order for a muscle fiber to contract?
when calcium ions (Ca2+) bind to the troponin complex and expose the myosin-binding sites
when does muscle fiber contraction occur?
when the concentration of Ca2+ is high
when does muscle fiber contraction of a muscle stop?
when the concentration of Ca2+ is low
what is the stimulus leading to a contraction of a muscle fiber?
an action potential
how is an action potential created through the contraction of a muscle fiber? (3) (FSA)
1) from a motor neuron that make a synapse with the muscle fiber
2) the synaptic terminal of the more neuron releases the neurotransmitter acetycholine
3) Acetycholine depolarizes the muscle, causing it to produce an action potential
once the action potential is now in the muscle cell what happens?
travel to the interior of the muscle fiber along transverse tubues (T)
what does the action potential along the T tubules cause the sacroplasmic reticulum (SR) to release?
Ca2+
when the SR releases Ca2+ what does the Ca2+ bind to?
the troponin complex on the thin filaments
what does the binding of the Ca2+ and the troponin complex expose and what does it allow?
myosin-binding sites and allows the cross-bridge cycle to proceed
when motor neuron input stops what happens? (3) (MTR)
1) the muscle cell relaxes
2) transport proteins in the SR pump Ca2+ out of the cytosol
3) regulatory proteins bound to thin filaments shift back to the myosin-binding sites
formerly called Lou Gehrig’s disease, interferes with the excitation of skeletal muscle fibers; usually fatal
Amytrophic lateral sclerosis (ALS)
an autoimmune disease that attacks acetycholine receptors on muscle fibers; treatments exist for this disease
myasthenia gravis
what is contraction of a whole muscle?
graded
what does it mean when a whole muscle is graded?
the extent and strength of its contraction can be the voluntarily altered
2 basic mechanisms by which the nervous system produced graded contractions (VV)
1) varying the number of fibers that contract
2) varying the rate at which fibers are stimulated
in vertebrates what may each motor neuron snyapse with?
multiple muscle fibers
how many motor neurons is each fiber controlled by?
only one
consists of a single motor neuron and all the muscle fibers it controls
motor unit
what does recruitment of multiple motor neurons result in?
stronger contractions
what does a twitch result from?
a single action potential in a motor neuron
what do more rapidly delivered action potentials produce?
a graded contraction by summation
a state of smooth and sustained contraction produced when motor neurons deliver a volley of action potentials
tetanus
what are the types of skeletal muscles classified by? (2) (SS)
1) the source of ATP power the muscle activity
or
2) the speed of muscle contraction
what does oxidative fibers rely mostly on and why?
aerobic respiration to generate ATP
what do oxidative fibers have?
many mitochondria, a rich blood supply and a large amount of myoglobin
a protein that binds oxygen more tightly than hemoglobin
myoglobin
what does glycolytic fibers use as their primary source of ATP?
glycolysis
what do glycolytic fibers have less of than oxidative fibers and what do they do differently?
myoglobin and tire more easily
what is the light meat of poultry and fish composed of?
glycolytic fibers
what is the dark meat of poultry and fish composed of?
oxidative fibers
what do slow-twitch fibers do?
contract more slowly but sustain longer contractions
what are all slow-switch fibers?
oxidative
what do fast-twitch fibers do?
contract more rapidly but sustain shorter contractions
what can fast-twitch fibers be?
either glycolytic or oxidative
what type of fibers do most skeletal muscles contain in varying ratios?
both slow-twitch and fast-twitch fibers
what do some vertebrates have compared to humans?
muscles that twitch at rates much faster
in producing its characteristic mating call what can the male toadfish do?
contract and relax certain muscles more than 200 times per second
what do verterbrates have in addition to skeletal muscle?
cardiac muscle and smooth muscle
what is cardiac muscle found and what does it consist of?
found only in the heart and consists of striated cells electrically connected by intercalated disks
what can cardiac muscle generate?
action potentials without neural input
where is smooth muscle found?
mainly in walls of hollow organs such as those of the digestive tract
what are contraction in the smooth muscle and what also may they be inititated by?
relatively slow and may be inititated by the muscle themselves
what may contraction be caused by in smooth muscle?
stimulation from neurons in the autonomic nervous system
what does Ca2+ regulate in smooth muscle?
the contraction of smooth muscle but different than skeletal muscle
