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360 Cards in this Set
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muscle physiology |
bone. |
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what happens when a muscle contracts?. |
it shortens. |
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when is tension placed on tendons connecting to bones |
when muscles contracts |
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the bone that moves is attached at the ____________ |
muscle insertion |
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the bone that does not move is attached at the __________ |
muscle origin |
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movement is toward the _______ |
insertion |
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flexor muscles _____the angle between two bones at a joint |
decrease |
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extensor muscles _______ the angle between two bones at a joint |
increase |
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define agnoist or prime mover |
the main muscle responsible for movement in a given direction |
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define antagonists |
flexors and extensors that act on the same joint to produce opposite actions |
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Define the action of the Extensor |
increases the angle at a joint |
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Define the action of the flexor |
decreases the angle at a joint |
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Define the action of the abductor |
moves limd away form the midline of the body. |
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define the action of adductor |
moves limb toward the midline of the body |
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define the action of the levator |
moves insertion upward |
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define the action of the depressor |
moves insertion downward |
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define the action of the rotator |
rotates a bone along its axis |
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define sphincter |
constricts an opening |
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structure of skeletal muscles are so that they are surrounded by a__________ |
fibrous epimysium |
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define fibrous epimysium |
The external sheath of connective tissue surrounding a muscle |
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define perimysium |
connective tissue that subdivides the muscle into fascicles |
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define fascicles |
a small bundle or cluster, especially of nerve, tendon, or muscle fibers |
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each fascicle is subdivided into muscle fibers (myofibers) surrounded by what? |
endomysium |
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define endomysium |
the sheath of delicate reticular fibrils surrounding each muscle fiber. |
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define sarcolemma |
plasma membranes in muscle fiber structures |
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muscle fiber structure are multinucleated; form a syncytium
TRUE or FALSE |
TRUE |
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muscle fibers are striated name the 3 bands or lines |
-I bands -A bands -Z lines
|
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describe I bands |
light bands |
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describe A bands |
dark bands |
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describe Z-lines (disks) |
dark lines in the middle of the I bands |
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Define motro units |
a single motor neuron and all the muscle fibers it innervates -all muscle fibers in a motor unit contact at once |
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define graded contractions |
varied contractions strength due to different numbers of motor units beings stimulated |
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what is neuromuscular junction |
site where a motor neuron stimulates a muscle fiber |
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define motor end plate |
area of the muscle fiber sarcolemma where a motor neuron stimulates it using the neurotransmitter, acetylcholine |
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neuromuscular junction = |
ach |
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when ach bind Na+ goes in what channel? |
K , potassium |
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contraction comes from where? |
motor unit recruitment |
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finer muscle control requires _______ motor units |
smaller, (fewer muscle fibers) |
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the eye muscles may have _______muscle fibers/motor units |
23 |
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how many muscle fibers do larger, stronger muscles have? |
thousands |
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control and strength are not tradeoffs
TRUE or FALSE |
FALSE, they are tradeoffs |
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what are striations produced by ? |
produced by thick and thin filaments |
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what kind of filaments do I bands contain? and primarily made up of what? |
I bands contain only thin filaments, primarily of the protein, actin |
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what kind of filaments do A bands contain? what are they made up of? |
-A bands contain all of the thick filament with some thing filament overlap -the thick filament is the protein, myosin |
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where are H bands located? how much thin filament overlap? |
H bands are the center of the A band with no thin filament overlap |
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where are Z discs (lines) found? |
Z discs are found in the center of each I band |
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define sarcomere |
the basic subunt of striated muscle contraction |
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The sarcomere is the area from one ___disc to the next |
Z |
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Define Titin |
protein that runs from the Z disc to the M line and allows elastic recoil |
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Where are M lines found? |
M lines are found in the center of each A band and help hold down thick filaments |
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what 3-D pattern does a sarcomere form? |
hexagonal pattern |
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define silding filament theory |
when a muscle contracts shorten |
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A bands do not ______, but move ______together |
shorten, closer |
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I bands do ________, but_______ filaments do not |
shorten, thin |
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Thin filaments slide toward the _______bond |
H |
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H bands ________ or disappears |
shorten |
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how does a myofiber with all its myofibrils shorten? |
by movement of the insertion toward the origin of the muscle |
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what causes the shortening of the myofibrils? |
caused by the shortening of the sarcomeres -the distance between Z lines (or discs) is reduced |
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how is shortening of the sarcomeres accomplished? |
by sliding of the myofilaments -the length of each remains the same during contraction
|
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sliding of the filaments is produced by what? |
by asynchronous power strokes of myosin cross bridges, which pull the thin filaments (actin over the thick filaments (myosin) |
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What bands remain the same length during contraction? but are pulled toward the origin of the muscle |
the A bands |
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what bands are pulled closer together as the I bands between them shorten? |
Adjacent A bands |
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which bands shorten during contraction as the thin filaments on the sides of the sarcomeres are pulled toward the middle? |
The H bands |
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define thick myofilaments |
composed of the protein myosin |
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define thin myofilaments |
composoed of the protein actin |
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which myofilament has two protein globular heads with actin-binding sites and ATP-binding sites? |
thick myofilament |
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which myofilament has proteins called tropomyosin and troponin that prevent myosin binding at rest? |
thin myofilaments |
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what do tropomyosin and troponin prevent? |
prevent myosin binding at rest |
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when sliding is produced by several cross bridges what is formed between them? |
myosin and actin |
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what does the myosin head serve as during the action of sliding? |
the myosin head serves as a myosin ATPase enzyme, splitting ATP into ADP+P |
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define ATP |
energy |
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define ATPase |
are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion. |
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what allows the head to bind to actin when the muscle is stimulated? |
ATPase breaking down ATO into AD+P |
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define the power stroke |
-pulls the thin filament toward the center |
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what causes the power stroke |
release of P upon binding, cocks the myosin head which produced the power stroke |
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what happens after the power stroke |
ADP is released and a new ATP binds |
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what is released by myosin after ADP is released and a new ATP is binded |
myosin releases actin |
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after myosin is released what happens to ATP? |
ATP is split |
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What happens after ATP is split? |
the myosin head straightens out and rebinds to actin farther back this continues until the sarcomere has shortened |
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what are the steps of the cross bridges |
1. resting fiber; cross bridge is not attached to actin 2. cross bridge binds to actin 3. P is released from myosin head, causing conformational change in myosin 4. power stroke causes filaments to slide; ADp is released 5. A new ATp binds to myosin, allowing it to release from actin 6. ATP is hydrolyzed and phosphate binds to myosin, causing cross bridge to return to its original orientation
|
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F-actin is made up of how many G-actin subunits? |
300-400 G-actin subunits |
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how is F-actin arranged? |
in a double row and twisted to form a helix |
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what physically blocks cross bridges? |
Tropomyosin |
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Define Troponin complex: |
1. Troponin I inhibits binding of myosin 2. Troponin T binds to tropomyosin 3. Troponin C binds to calcium |
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When is Ca^2+ released inside the muscle fiber? |
when muscle cells are stimulated |
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what causes a conformational change in troponin and tropomyosin? |
when Troponin C attaches |
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______is allowed access to form cross bridges with______ |
Mysoin, actin |
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Define SR( sarcoplasmic reticulum) |
modified endoplasmic reticulum that stores Ca^2+ when muscle is at rest |
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where is the most Ca^2+ found in the SR? |
in the terminal cisternae |
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What happens when a muscle fiber is stimulated? |
Ca^2+ diffuses out of calcium release channels (ryanodine receptors) |
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define ryanodine receptors |
-form a class of intracellular calcium channels in various forms of excitable animal tissue like muscles and neurons. -It is the major cellular mediator of calcium-induced calcium release(CICR) in animal cells. |
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what happens at the end of a contraction? |
Ca^2+ is actively pumped bak into the SR |
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define transverese tubules |
narrow membranous tunnels formed from the sarcolemma |
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what opens to the extracellular enironment |
transverse tubules |
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Transverse Tubules are not able to conduct action potentials
TRUE or FALSE |
FALSE, they are able to conduct action potentials |
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where is Acetylcholine released from? |
a motor neuron |
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end plate potentials are _______ |
produced |
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All-or-none event |
action potentials are generated |
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what channels change shape is transverse tubules and causes calcium channels in SR to open? |
voltage gated calcium channels |
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when clacium is released what does it bind to? |
troponin C |
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steps of skeletal muscle contraction and relaxation |
1. a nerve impulse traels down and axon and causes the release of acetylcholine. 2. ACH caues the impulse to spread across the surface of the sarcolemma 3. the nerve impulse enters the T tubules and sarcoplasmic Reitculum, stimulating the release of calcium ions 4. calcium ions combine with troponin, shifting troponin and exposing the myosin bindinf sites on the actin 5. ATP breaks down ADP+P. the released energy activates the myosin cross bridges and results in the sliding of thing actin myofilaments. 6. the sliding of the myofilamens draws the Z lines towards each other, the sarcomere shortens, the muscle fibers contract and therefore muscle contracts 7. ACh is inactivated by Acrytcholinesterase, inhibiting the nerve impulse conduction across the sarcolemma 8.nerve impulse is inhibited calcium ions are acitvely transportes back into the ST, using the energy from the earlier ATp breakdown 9.the low Calcium concentration causes the myosin cross brdiges to seperate from the thin myolifalments and the actin myofilaments return to their releaxed position. 10.sarcomeres return to heir resting lengths, muscle fibers relax and the muscle relaxes |
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excitation contraction coupling summary |
1. somatic neuron releases ACh
SARCOLEMA 2. binds to nicotinic ACh receptors, open ligand (chemically)- gated channels 3.Na+ diffuses in, producing depolarizing stiumuls 4. Action potentials produced
TRANSVERESE TUBULES 1. Action potentials conducted along transverse tubules 2. action potentials open voltage-gated Ca^2+ channels
SR 1.Ca^2+ release channels in SR open 2. Ca^2+ diffuses out into sacroplasm
MYOFIBRILS 1.Ca^2+ binds to troponin, stimulating contraction
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define troponin |
a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle. |
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describe muscle relaxation |
-action potentials cease -calcium release channels close -Ca^2+-ATPase pumps move Ca^2+ back into SR (ATP) -No more Ca^2+ is available to bind to troponin C -Tropomyosin moves to block the myosin heads from binding to actin |
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Where do you see Ca2+ involved in muscle contractions? |
1. in the Pre-Synaptic 2. Excitation Coupling 3.(relaxtion) ATPase pumps |
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define a twitch |
when a muscle quickly contracts and relaxes after a single electrical shock of sufficient voltage |
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how do you increase the strength of a twitch? |
you increase the voltage |
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define summation |
when a second shock is applied immediately after the first, the second twitch will partially piggyback the first |
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define latent perio of a twitch |
time between stimulusand the contraction (excitatio-contraction coupling to the attachement of myosin cross bridges to actin) |
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Define graded contraction |
stronger contractions result in recruitment of more fibers, until all fibers are contracting |
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Define tetanus |
is a medical condition characterized by a prolonged contraction of skeletal muscle fibers |
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define incomplete tetanus |
increasing the frequency of electrical shocks decreases the relaxtion time between twitches |
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Define complete tetanus |
at a certain frequency there will be no relaxation, just a smooth sustained contraction. |
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Define Treppe |
the graduated series of increasingly vigorous contractions that results when a corresponding series of identical stimuli is applied to a rested muscle |
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list the Treppe steps |
1. as the voltage is increased, the number of muscle fibers used in vitro increases 2. this will reach a maximum value when all muscle fibers are stimulated 3.if a fresh muscle is stimulated with several shocks at maximum voltage, each will be progressively stronger. 4. when recorded, this will produce a staircase effect |
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describe Force Velocity curve |
for muscle contract they must generate force that is greater than opposing forces
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the greater the froce, the _____ the contraction |
slower |
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define isotonic contractions |
muscle fibers shorten when the tension produced is just greater than the load |
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define concentric contraction |
a muscle fiber shortens when force is greater than load |
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define eccentric contraction |
a muscle may actually lengthen, despite contraction, if the load is too great |
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what does eccentric contraction allow after a full concentric contraction |
allows you to lower a weight gently |
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define isometric contraction |
muscles can't be shorten becuase the load is oo great |
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can isometric contraction be voluntary? |
yes |
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what has to happen to concontractile parts of the muscle when it contracts? |
it must be pulled tight |
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describe a tendon |
-elastic, resist distension, snap back to resting length -absorb some of the tension as muscles contracts
|
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what is muscle strength determined by? |
-number of fibers recruited to contract -freq of stimulation -thickness of each muscle fiber (thick is stronger) -initial length of the fiber at rest |
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when the tension is maximal, what are the sarcomeres? |
at normal resting length |
|
increasing sarcomere length, increases muscle tension
TRUE or FALSE |
FALSE, increasing sarcomere length, decreases muscle tension |
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are there fewer or more interactions between myosin and actin, with an increasing sarcomere length, and decreasing muscle tension |
fewer |
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What happens to muscle tension when the sarcomere length decreases? why does it happen |
decreases muscle tension -because the fiber gets shorter and thicker |
|
when the sarcomere length decreases and the muscle tension decreases.
what happens to fluid pressure and what happens to the distance between the actin and the myosin? |
-the fluid pressure is increased -the distance between the actin and myosin is increased |
|
how is energy distributed? between Myosin ATPase and Ca2+ |
Myosin ATPase 70% Ca2+ 30%
|
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what is the role of the calcium pump |
to actively return calcium to the SR at a 30% clip |
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where do muscles get thier energy at rest and mild exercise |
from the aerobic respiration of fatty acids |
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where do muscles get their energy for moderate exercise: |
from glycogen stores |
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where do muscles get their energy fro heavy exercise |
from blood glucose |
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as exercise intesnsity and duration increase, ______channels are inserted into the sarcolemma to allow glucose into cells |
GLUT4 |
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where are GLUT4 found? |
only found in muscle cells and adipose tissues |
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what is the time for anaerobic of moderate to heavy exercise |
45-90 seconds |
|
anaerobic allows time to increase what? |
oxygen supply |
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what is another name for maximal oxygen uptake |
aerobic capacity, or V02 max |
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what determines whether a given execise is light, moderate, or heavy for a given person |
-a persons age, sex, size, and atheltic training |
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what age group and sex does aerobi capacity the highest? |
for males and younger people |
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what is another name for lactate threshold |
anaerobic threshold |
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what is lactate threshold |
another way to determine exercise intensity for a given person |
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what % of maximal oxygen uptake rises as blood lactate levels occurs |
occurs at about 50-70% V02max |
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need for ____ increases during exercise |
glucose |
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more GLUT4 receptors in __________membrane |
plasma |
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when blood glucose drops, where does the body get more glucose from? and how ? |
from the liver, through hydrolysis og glycogen and through gluconeogenesis |
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define oxygen debt |
when a person exercises, oxygen is withdrawn from reserves in hemoglobin and myoglobin |
|
phosphocreatine |
molecule that serves as a rapidly mobilizable reserve of high-energy phosphates in skeletal muscle and the brain |
|
when are phosphocreatine stores replenished? |
when at rest |
|
how is creatine produced? |
by the liver and the kidneys or obtained throught the diet |
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when is creatine supplements bad for the liver? |
whens its used for long periods of time bad |
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define slow twitch (type 1) |
slower contraction speed; can sustain contraction for long periods witout fatigue -rich capillary supply -more mitochondria -more respiratory enzymes -more myoglobin |
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slow twitch muscles have _____oxidative capacity, so are called ______ oxidative fibers |
high, slow |
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due to high myoglobin content found in slow twitch fibers are also called ____ fibers |
red |
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where are slow twitch fibers found? |
in postural muscles |
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define fast twitch fibers (type IIX) |
-faster contraction speed -fatigue fast -fewer capillaries -mitochondira -respiratory enzymes -less myoglobin |
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what is another name for fast twitch fibers? |
white fibers |
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fast twitch fibers have more glycogen stores and are called fast glycolytic fibers
TRUE or FALSE |
TRUE |
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where are fast twitch muscles found? |
stronger muscles |
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what are fast oxidative fibers intermediate (type IIA) ? |
fast-twitch but with high oxidative capacity; |
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why do people vary greatly in the percentage of fast-or slow-twitch fibers in thier muscles |
result of genetics and training |
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what are the Z line thickness characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-wide -intermediate -narrow |
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Glycogen content characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-low -intermediate -high
|
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Resistants to fatigue characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-high -intermmediate -low
|
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capillaries characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-many -many -few |
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myoglobin content characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-high -high -low
|
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respiration characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-aerobic -aerobic -anaerobic
|
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oxidative capacity characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-high -high -high
|
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twitch rate characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-slow -faster -fastest
|
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diameter characteristics for slow oxydative, fast oxidative, and fast Glycolytic types? |
-small -intermediate -large |
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muscle fatigue |
reduced ability to generate force |
|
what is muscle fatigue due to? |
-accumulation of extracellular K+, reducing membrane potential -short duration -depletion of stored glycogen -reduced SR calcium release -lactic acid accumulation and lower pH -increased concentration of PO4 due to phosphocreatine breakdown -lack of ATP -buildup of ADP -fatigue of upper motor neurons (in the CNS), called central fatigue |
|
what are some factors that can lead to adaptation to endurance exercise training? |
-increased ability to use fatty acids as fuel and increased intracellular triglyceride storage -increased lactate threshold -decreased in type IIX and increase in type IIA muscle fibers -decreased insulin sensitivity -increase in number of mitochondria |
|
what are the effects of endurance training on skeletal muscles |
-improved ability to obtain ATP from oxidative phosphorylation -increased size and number of mitochondria -less lactic acid produced per given amount of exercise -increased myoglobin content -increased intramuscular triglyceride content -increased lipoprotein lipase (enzyme needed to utilize lipids form blood) -increased proportion of energy derived from fat; less from carbs -lower rate of glycogen depletion during exercise -improved efficiency in extracting oxygen from blood -decreased number of type IIX (fast glycolytic) fibers; increased number of type IIA (fast oxidative) fibers |
|
what are some characteristics of muscle decline with aging |
-reduced muscle mass (type II fibers) -reduction in capillary blood supply -fewer satellite cells |
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how can muscle decline with age be prevented or slowed down |
- can be helped with strength training -can be helped with endurance training - increased myostatin production |
|
define myostatin |
inhibits muscle differentiation and growth production - protein family that inhibits muscle differentiation and growth in the process known as myogenesis. |
|
define satellite cells |
-cells that can fuse to damaged muscle cells and repiar them or fuse to each other to form new muscle fibers |
|
where are satellite cells found |
in skeletal muscles, near muscle fibers |
|
define myostatin |
a paracrine regulator that inhibits satellite cells |
|
what 3 proteins does myostatin require to serve as muscle fiber scaffolding |
-titin -nebulin -obscurin |
|
define titin |
giant protein that functions as a molecular spring which is responsible for the passive elasticity of muscle. |
|
define nebulin |
an actin-binding protein which is localized to the thin filament of the sarcomeres in skeletal muscle. |
|
define obscurin |
may have a role in the organization of myofibrils during assembly and may mediate interactions between the sarcoplasmic reticulum and myofibrils. |
|
define hypertrophy |
type II muscle fibers become thicker due to increased amount of actin and myosin (more sarcomeres) |
|
what is the advantage of thicker fibers due to adaptation to strength training |
thick fibers can split into two fibers, which can also increase in size |
|
what proteins are required to maintain thicker fibers that split into two fibers that can also increase in size |
-titin -nebulin -obscurin |
|
describe lower motoneurons (motor neurons) |
neurons whose axons innervate skeletal muscles- also called the "final common pathway" in the control of skeletal muscles |
|
describe higher (motor neurons)motoneurons |
neurons in the brain that are involved in the control of skeletal movements and that act by facilitating or inhibiting (usually by way of interneurons) the activity of the lower motoneurons |
|
describe alpha neurons |
lower motoneurons whose fibers innervate ordinary (extrafusal) muscle fibers |
|
descirbe gamma motoneurons |
lower motoneurons whose fibers innervate the muscle spindel fibers (intrafusal fibers) |
|
describe agoinst/antagoinst |
a pair of muscles or muscle groups that insert on the same bone, the agonist being the muscle of reference |
|
describe synergist |
a muscle whose action facilitates the action of the agonist |
|
describe ipsilateral/contralateral |
Ipsilateral- located on the same side or the side of reference contralateral- located on the opposite side |
|
describe afferent/efferent |
afferent- sensory neurons efferent -motor neurons |
|
in skeletal muscle striated ______ and ______ arranged in sarcomeres |
actin, myosin |
|
in skeletal muscles well-developed _____ and tranverse tubules |
(SR) Sarcoplasmic Reticulum |
|
Skeletal Muscle contains troponin in the _____ filaments |
thin |
|
in skeletal muscle what is released into the cytoplasm form SR |
Ca2+ |
|
skeletal muscle cannot _________ without nerve stimulation; denervation resultsin muscle _______ |
contract,atrophy |
|
in skeletal muscles fibers are stimulated _______ and have no ___junctions |
independently,gap |
|
cardiac muscle are striated and have _____ and ______ arranged in sarcromeres |
actin, myosin |
|
cardiac muscle have moderately developed SR and ______ |
transverse tubules |
|
cardiac muscle contains _____ in thin filaments |
troponin |
|
in cardiac muscle _____ enters cytoplasm from SR and extracellular fluid |
Ca2+ |
|
cardiac muscle can contract without nerve stimulation; action potentials originate in _________cells of heart |
pacemaker |
|
in cardiac muscle ________junctions present as intercalated discs |
gap |
|
smooth muscle is not striated; more ____ than ____; ________inserts into dense bodies and cell membranes |
actin, myosin, actin |
|
smooth muscle poorly developed _________ and no _________ |
SR, tranverse tubules |
|
smooth muscle contains calmodulin, a protein that, when bound to Ca2+, activates the enzyme myosin light-chain______________ |
kinase. |
|
in smooth muscle Ca2+ enters cytoplasm from extracellular fluid, sacroplamsmic reticulum, and perhaps_____________ |
mitochondria |
|
smooth muscle maintains tone in absence of nerve stimulation; visceral smooth muscle produces pacemaker potentials; denervation results in ______to stimulation |
hypersensitivity |
|
smooths muscles's _______junctions present in most smooth muscles |
gap |
|
what happens to calcium when smooth muscle relax? |
calcium is pumped out to SR using ATPase active transport pumps. |
|
in smooth muscle relaxation calmodulin dissociates from ______light chain kinase |
myosin |
|
in smooth muscle relaxation phosphate groups are stripped away from the myosin by __________ |
myosin phosphatase |
|
list excitation-contraction coupling in smooth muscle |
1. begins with rise in intracellular calcium conconcentrations 2. calcium binds to calmodulin (no troponin in smooth muscle) 3. myosin light chain kinase phosphorylates myosin light chains 4.stimulation is graded. more stimulation allows in more calcium, which allows stronger contractions 5. contractions are slow and sustained |
|
in the beginning of the excitation-contraction coupling in smooth muscle where does the calcium come from? |
-only some come from SR -most come through plasma membrane after voltage-gated calcium channels are opened |
|
when myosin light chain kinase phosphorylates myosin light chains, how does contraction happen? |
myosin forms cross bridges with actin to initiate contraction |
|
what is "latch state"? |
Allows smooth muscle to keep tone under low ATP hydrolysis conditions, bc it surrounds many hollow organs that need constant tone bc cross bridges are still formed. |
|
cardiac and smooth muscles are voluntary or involuntary |
involuntary |
|
what are cardiac and smooth muscles regulated by? |
ANS (autonomic nervous system) |
|
like skeletal muscle, contraction in smooth muscles are due to _________ cross bridges stimulates by _________ |
myosin/actin, calcium |
|
cardiac muscle are not striated
TRUE or FALSE |
FALSE, cardiac muscle are striated |
|
_____ and actin filaments form sarcomeres |
myosin |
|
_______ occurs by means of sliding thin filaments |
contraction |
|
unlike skeletal muscles fibers, cardiac muscle fibers are ________, ________, and ___________ via gap junctions called intracalated discs |
short, branched, connected |
|
define myocardium |
is a mass of cardiac muscle cells connected to each other via gap junctions |
|
action potentials that occur at any cell in a myocardium can ___________ all the cells in the myocardium |
stimulate |
|
myocardium behaves a multi functional unit
TRUE OR FALSE |
FALSE, myocardium behaves a single functional unit |
|
where are the myocardium located in the heart? |
the atria of the heart compose one myocardium, and the ventricles of the heart compose another myocardium |
|
how can cardiac muscle produce action potentials automatically? (without innervation) |
begin in a region called the pacemaker |
|
heart rate is influenced by what? |
autonomic innervation and hormones |
|
unlike skeletal muscle, the voltage-gated calcium channels are not directly connected to ________channels in the SR |
Calcium |
|
in cardiac and smooth muscles calcium acts as a _______messenger to open SR channels |
second |
|
what is another name for when calcium acts as a second messanger |
calcium-induced calcium release |
|
what is slower then calcium-induced calcium release? |
excitation-contraction coupling |
|
where is smooth muscle found |
in blood vessel walls, bronchioles, digestive organs, urniary and reproductive tracts |
|
how does smooth muscle propel content of its organs? |
usings peristaltic waves |
|
smooth muscle contains no what? |
sarcomeres |
|
smooth muscle contain large amounts of what two proteins? |
actin and myosin |
|
smooth muscles have what length of actin filaments? what are they attached to ? |
long actin filaments, dense bodies |
|
how are myofilaments arranged? and what can they form with actin ? |
myosin filaments are stacked vertically and can form cross bridges |
|
what does the arrangment of myosin filaments in smooth muscle allow? |
allows contractions, even when greatly stretched |
|
single unit smooth muscles |
multiple gap junctions that make neighboring cells behave as a unit. |
|
most smooth muscle are a multiunit
TRUE or FALSE |
FALSE, most smooth muscles are single unit |
|
single unit smooth muscles display pacemaker acitivity moderated by _____ or _______ innervatoin |
stretch, autonomic |
|
in single unit smooth muscles Muscarinic ACh receptors respond by closing _____channels |
K+, potassium |
|
multi-unit smooth muscles |
require individual nerve innervation (no pacemaker activity) |
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multi-unit smooth muscles have few or no gap junctions
TRUE or FALSE |
TRUE |
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smooth muscles arrector pili in skin and ciliary uslces in _____ are mulit -unit |
eyes |
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autonomic innervation |
neuroransmitter is released along the length of an autonomic neuron from varicosities |
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where are the receptors proteins located on the smooth muscles? |
on the entire surface of smooth muscles |
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autonomic innervation forms synapses en passant
TRUE or FALSE |
TRUE |
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lower motor neurons(motoneurons) |
cell bodies in ventral horn of spinal cord or in the brain stem |
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how do skeletal muscles travel to the spinal nerves? |
by way of the ventral root |
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Skeletal muscles are influenced by sensroy feedback from _____ and _______ |
muscles, tendons |
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name the skeletal muscle sensory organs |
-intrafusal fibers -extrafusal fibers -golgi tendon organs -muscle spindle apparatus |
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muscles that are made of thin muscle cell are called |
intrafusal fibers |
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regular muscle fibers are called |
extrafusal fibers |
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golgi tendon organs |
respond to tension a muscle puts on a tendon |
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muscle spindle apparatus |
respond to muscle length |
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in a muscle spindle apparatus a muscle that reuquires more control have ______ spindles |
more |
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in a muscle spindle stretching a muscle causes spindles to ______ |
stretch |
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muscle spindle apparatus contains ______ muscle cells called intrafusal fibers |
thin |
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name two types of intrafusal fibers |
nuclear bag fibers- nuclear chain fibers
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define nuclear bag fibers |
nuclei in loose central aggregates |
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define nuclear chain fibers |
nuclei in rows |
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alpha or gamma are going to innervate intrafusal |
gabba |
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two types of sensroy cell wrap around fibers |
primary (annulospiral) secondary (flower-spray) |
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define primary (annulosprial) |
most stimulated at the beginning of the stretch |
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define secondary (flower spray) |
respond more during sustained stretch |
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what is an alpha motorneuron? |
innervate extrafusal (contracting) muscle fibers |
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what is a gamma motoneurons? |
innervate intrafusal (active stretch) muscle fibers |
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alpha and gamma are both stimulated by which motoro neurons? |
upper motor neurons at the same timecoacti |
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coactivation |
both types of motor neurons alpha nad gamma are stimulated by upper motor neurons at the same time |
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skeletal muscle are usually referred to as _____ and are controlled by descending motor pathways under ______Control |
voluntary, conscious |
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define a reflex |
a skeletal muscle contracting unconsciously in response to a certain stimuli |
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monosynaptic stretch reflex? |
simplest reflex |
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in monosynaptic strecth reflex it only involves a sensroy neuron synapsing on a motor neuron in the ________cord |
spinal |
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one synapse equals |
monosynaptic |
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muscle stretch reflex |
maintains optimal length of skeletal muscles |
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whats the name of a stimiulation by stiking the patellar ligament |
knee jerk reflex |
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golgi tendon organs |
constantly monitor tension in tendons |
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_____ inhibits motor neuron |
interneuron |
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disynaptic reflex involves how many synapses? |
two |
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golgi tendon organs steps |
1. tension on tendon activates sensroy neuron 2. sensroy neuron stimulates interneruon 3. interneuron inhibits motoneuron 4. tension on tendon is reduced |
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what is a reciprocal innervation in knee-jerk-reflex |
when interneurons are stimulated in the spinal cord to inhibit antagonisttic musles on that limb |
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define double reciprocal innervation |
a more complex reflex that requires contorl of muscles on the contralateral limb |
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reciprocal innervation |
1. muscle stretch activates spindle apparatus 2. agonist muscle contracts in stretch reflex 3. antagoinst muscle relaxes |
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define crossed extensor reflex |
type of double reciprocal innervation seen when you step on a tack |
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steps for crossed extensor reflex |
1. flexor contracts and extensor relaxes to withdraw foot 2. extensor contracts and flexor relaxes in contralateral leg to support weight |
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upper motor neuron control pecentral gyrus |
sends neurons through pyramidal tracts (contralateral) by the lateral and ventral cotricospinal tracts |
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neurons through extrapyamidal tracts |
reticulospinal tracts |
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define reiculopspinal tract |
inhibition of lower motorneurons |
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define cerebellum |
receives information from muscle spindles and Golgi tandon organs as well as other senses |
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what inhibits regions of the basal nuclei, red nucei, and vestibular nuclei? |
cerebellum |
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define basal nuclei |
also act to inhibt motor activivty through the rubrospinal tract |
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define Babinski's reflex |
extension of the great tow when the sole of the foot is storked along the lateral border |
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Spastic paralysis |
high muscle tone and hyperactive stretch reflexes; flexion of arms and extension of legs |
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Hemiplegia |
paralysis of upper and lower limbs on one side- commonly produced by damage to motor tracts as they pass through internal capsule (such as cerbrovascular accident-stoke) |
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paraplegia |
paralysis of the lower limbs on both sides as a result of lower spinal cord damage |
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quadriplegia |
paralysis of upper and lower limbs on both sides as a result of damage to upper region of the spinal cord or brain |
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chorea |
random uncontrolled contractions of different muscle groups( as in Saint Vitus dance) as a result of damage of basal nuclei |
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resting tremor |
shaking of limbs at rest; disappears during voluntary movements; produced by damage to basal nuclei |
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intention tremor |
oscilltions of the arm following voluntary reaching movements; produced by damage to cerebellum |
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1. The stretch reflex is a ____________ reflex because the sensory neuron synapses directly with the motor neuron and does not use an interneuron involving spinal cord interneurons. |
monosynaptic
The stretch reflex is a monosynaptic reflex because it involves only one synapse within the CNS. Striking the patellar ligament with a mallet is an example of a monosynaptic stretch reflex. You may review the monosynaptic stretch reflex in detail in Section 12.5: Neural Control of Skeletal Muscles of the text. |
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As opposed to the upper motor neurons, the lower motor neurons have their cell bodies located in the ________________. |
spinal cord as opposed to the brain |
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the maximum rate of oxygen consumption in the body |
aeriobic capacity |
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the percentage of the ocygen uptake at which a signaificant rise in blood level occurs |
lactate thresholdre |
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reversible, exercise induced reduced ability in the muscle to generate force |
muscel fatigue |
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Muscle contraction is caused by |
actin filaments sliding past myosin filaments.
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Which of the following statements about H zones and I bands is TRUE? |
the H zones contain only myosin, while the I bands contain only actin
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During muscle contraction |
the A band remains the same and the I band narrows.
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1. Each somatic motor neuron, together with all of the muscle fibers it innervates, is called a ____________. |
motor unit |
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An action potential enters a muscle cell ______________________. |
by the T-tubules.
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What structures do the calcium ions bind to when muscle contraction is initiated? |
the troponin molecule. |
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Cross bridges form between _________________. |
the actin filaments and the myosin heads. |
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A person who sprints for 45 seconds obtains most of their energy from |
muscle glycogen.
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What happens to the amount of muscle glycogen used for energy as exercise continues? |
it decreases
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After 3 hours of exercise what are the main sources of energy? |
blood glucose and plasma free fatty acids
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Where are most plasma free fatty acids obtained from? |
hydrolysis of stored fat
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What happens to the amount of plasma free fatty acids used for energy as exercise continues? |
they increase
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The inhibition of motor neurons of antagonist muscles during stretch reflexes is called ______________________. |
reciprocal inhibition |
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1. Skeletal muscles are able to generate their greatest force during a contraction when their length is ____________ of their normal resting length. |
100-120%
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1. Cells adapt to endurance training by increasing their numbers of mitochondria
true or false |
true |
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Endurance training is improved when muscles reduce the amount of muscle glycogen they use for energy
true or falset |
true |
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Resistance training results primarily in an increase in Type I fibers
true or false |
false |
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An increase in muscle size (hypertrophy) is the result of an increase in the number of muscle fibers
true or false |
false |
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If a muscle is already at about 80% of its resting length, it cannot be stimulated to contract any more because __________________. |
the Z lines abut against the thick filaments and cannot go any further |
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During contraction of a muscle, calcium ions bind to... |
the troponin molecule.
|
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The bond between the actin and myosin head is broken when... |
an ATP molecule binds to the myosin head.
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Energy is released when... |
ATP is broken down into ADP and phosphate. |
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Which of the following shortens in length during during skeletal muscle contraction? |
I bands |
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intermediate glycogen content has what type of fiber |
type IIA |
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few capillaries has what type of muscle fiber? |
type IIX |
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wide Z line thickness has what type of muscle fiber? |
Type I |
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. Smooth muscles cells have a striated appearance
true or false |
false |
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The ratio of thin to thick filaments in smooth muscle is about 16:1
true or false |
true |
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Thin filaments in smooth muscles attach to Z discs
true or false |
false |
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Smooth muscle cells are capable of producing graded depolarizations and contractions
true or false |
true |
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Smooth muscle contractions are fast and operate on the all-or-none principle
true or false |
false |
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muscle tenison causes shortening |
concentric contraction |
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Muscle tension does not cause shortening of the muscle |
isometric contracction |
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Lengthening contraction |
eccentric contraction |
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Each actin filament is composed of _________________________. |
two strands of actin molecules wrapped together.
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As actin and myosin filaments slide past each other during muscle contraction, |
neither actin nor myosin filaments shorten.
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Which of the following statements about the "heads" of the myosin molecules is TRUE? |
they can attach to different sites on the actin filament
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the nervous system regulates skeletal muscle contraction by receiving constant _______feddback |
sensory |
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the tension a muscle exerts on its tendons is deetermined by _____ tendon organsgol |
golgi |
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the muscel spindle _______ provides input on muscle length |
apparatus |
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the thin muscle cell within the connective tissue sheath are called __________ |
intrafusual fibers |
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the muscle fibers which inset into the tendons of the muscle are called____ fibers |
extrafusal |
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The sequence for skeletal muscle contraction is... |
increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross-bridges, resulting in contraction.
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Which of the following statements is true concerning calcium ions? |
in smooth muscle it binds with calmodulin.
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Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions.
true or false |
true |
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The structures responsible for monitoring muscle tension in the tendons during muscle contraction are: |
Golgi tendon organs
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