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\author{jjovann}
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  /Title (chapter-9-4.pdf)
  /Creator (Cheatography)
  /Author (jjovann)
  /Subject (Chapter 9.4 Cheat Sheet)
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        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Chapter 9.4 Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{jjovann} via \textcolor{DarkBackground}{\uline{cheatography.com/67730/cs/17726/}}}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}jjovann \\
  \uline{cheatography.com/jjovann} \\
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 31st October, 2018.\\
   Page {\thepage} of \pageref{LastPage}.
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  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to Change in Stimulus Strength}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Recruitment works on size principle \newline % Row Count 1 (+ 1)
–Motor units with smallest muscle fibers recruited first  \newline % Row Count 3 (+ 2)
–Motor units with more, and larger, fibers recruited if more force is required \newline % Row Count 5 (+ 2)
–Largest motor units activated only for most powerful contractions where maximal force is needed% Row Count 7 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Twitch and Treppe Contractions}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Isotonic (concentric) and isometric contractions}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Isotonic Contractions}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Muscle changes in length and moves load \newline % Row Count 1 (+ 1)
–Thin filaments slide \newline % Row Count 2 (+ 1)
•Isotonic contractions either concentric or eccentric: \newline % Row Count 4 (+ 2)
–Concentric contractions \newline % Row Count 5 (+ 1)
—muscle shortens and does work \newline % Row Count 6 (+ 1)
–Eccentric contractions \newline % Row Count 7 (+ 1)
—muscle generates force as it lengthens \newline % Row Count 8 (+ 1)
•The negative rep% Row Count 9 (+ 1)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Motor Unit: The Nerve-Muscle Functional Unit}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Neuron \newline % Row Count 1 (+ 1)
–Functional unit of the nervous systems \newline % Row Count 2 (+ 1)
•Cell that communicates to others (neurons or targets) via the release of neurotransmitters \newline % Row Count 4 (+ 2)
•Nerve \newline % Row Count 5 (+ 1)
–Bundles of axons (electrical signal relaying portions of neurons) \newline % Row Count 7 (+ 2)
•Ex: Sciatic nerve% Row Count 8 (+ 1)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Tension Increase due to Frequency Increase}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Why continued: \newline % Row Count 1 (+ 1)
•During tetanic contraction, the successive APs each release Ca from the SR before much of the Ca from the previous AP can be pumped back into the SR. \newline % Row Count 5 (+ 4)
–This results in persistent elevation of sarcoplasmic Ca concentration \newline % Row Count 7 (+ 2)
»This prevents a decline in the number of available binding sites on the thin filaments by keeping them unblocked \newline % Row Count 10 (+ 3)
–Results in many more cross-bridges formed and power strokes which equals more tension \newline % Row Count 12 (+ 2)
–Another cause \newline % Row Count 13 (+ 1)
•Lower tension in single twitches are also a result of the elasticity of muscle tendons and the protein Titan \newline % Row Count 16 (+ 3)
–These must stretch/compress before tension produced from the contractile units is transferred  \newline % Row Count 18 (+ 2)
»Like a bungee cord or spring \newline % Row Count 19 (+ 1)
–Because a single twitch is so brief, the cross-bridge activity is already declining before force has been fully transferred through the elastic structures \newline % Row Count 23 (+ 4)
–This is less of a factor during tetanic stimulation because of the long duration of cross-bridge activity and force generation% Row Count 26 (+ 3)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to Change in Stimulus Frequency}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Wave (temporal) summation \newline % Row Count 1 (+ 1)
–Increased stimulus frequency (muscle does not completely relax between AP stimuli)  second contraction of greater force \newline % Row Count 4 (+ 3)
•Additional Ca2+ release from SR with second stimulus stimulates re-unblocking of myosin binding sites and more shortening before full relaxation length is obtained \newline % Row Count 8 (+ 4)
•Continued temporal stimulus frequency unfused (incomplete) tetanus \newline % Row Count 10 (+ 2)
–Produces sustained, but quivering, contraction that increases in successive twitch maximum tension \newline % Row Count 13 (+ 3)
•Once again, to a point% Row Count 14 (+ 1)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Motor Unit}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Muscle fibers that are part of a motor unit are found spread throughout a muscle \newline % Row Count 2 (+ 2)
–A single motor unit activation typically causes weak contraction of that muscle \newline % Row Count 4 (+ 2)
•However, when activated, only the muscle fibers of that motor unit in that muscle are contracting \newline % Row Count 7 (+ 3)
•Motor units in a muscle usually contract asynchronously (not at the same time) \newline % Row Count 9 (+ 2)
–helps prevent, or decrease, overall muscle fatigue% Row Count 11 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Graded Muscle Responses}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Muscle contractions exhibit graded responses \newline % Row Count 1 (+ 1)
–Varying strength of contraction for different demands \newline % Row Count 3 (+ 2)
•Required for proper control of skeletal movement \newline % Row Count 5 (+ 2)
•Responses graded by \newline % Row Count 6 (+ 1)
1.Changing frequency of stimulation \newline % Row Count 7 (+ 1)
2.Changing strength of stimulation \newline % Row Count 8 (+ 1)
•More so, applies to activation of additional motor units activating more muscle fibers in a muscle \newline % Row Count 11 (+ 3)
•APs in motor neurons and muscle fibers do not increase in strength% Row Count 13 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to Change in Stimulus Frequency}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•If successive stimuli are given quickly enough, muscle reaches maximal tension fused(complete) tetany results \newline % Row Count 3 (+ 3)
–Smooth, sustained contraction \newline % Row Count 4 (+ 1)
–No muscle relaxation due to consistently high sarcoplasmic Ca from continued release from SR \newline % Row Count 6 (+ 2)
–Muscle fiber reaches sustained maximum tension \newline % Row Count 7 (+ 1)
–Will eventually lead to muscle fatigue as metabolites accumulate and ionic imbalances form  \newline % Row Count 9 (+ 2)
•During fatigue, muscle cannot contract and tension returns toward zero% Row Count 11 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{•Each muscle connected to at least one motor nerve \newline % Row Count 2 (+ 2)
–Motor nerve contains axons of a few to hundreds of motor neurons \newline % Row Count 4 (+ 2)
–Individual axon of a motor neuron can branch many times before ending at nerve terminals, each nerve terminal making a NMJ with a single muscle fiber \newline % Row Count 8 (+ 4)
•Motor unit = motor neuron and all (four to several hundred) muscle fibers it innervates (controls)% Row Count 11 (+ 3)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{The size principle of recruitment}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Motor unit's response to single action potential of its motor neuron \newline % Row Count 2 (+ 2)
–Results in an AP in the muscle fibers connected through NMJs with that neuron \newline % Row Count 4 (+ 2)
–Produces short period of motor unit's muscle fiber contraction that generates tension \newline % Row Count 6 (+ 2)
•Different strength and duration of twitches in whole muscle can be observed \newline % Row Count 8 (+ 2)
–Due to variations in metabolic properties and enzymes between muscle fiber types \newline % Row Count 10 (+ 2)
–Different whole muscles have differing ratios of muscle fiber types•Simplest contraction (twitch) observable in lab \newline % Row Count 13 (+ 3)
–The tension (force) generated can be recorded by a sensor and graphed as a myogram% Row Count 15 (+ 2)
} \tn 
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Isometric Contractions}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Load greater than tension muscle can develop \newline % Row Count 1 (+ 1)
•Tension increases to muscle's capacity, but muscle neither shortens nor lengthens \newline % Row Count 3 (+ 2)
–Cross bridges generate force but do not move actin filaments% Row Count 5 (+ 2)
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Principles of Muscle Mechanics}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Same principles apply to contraction of a single fiber as well as the whole muscle \newline % Row Count 2 (+ 2)
•Contraction produces muscle tension \newline % Row Count 3 (+ 1)
–Force exerted on load or object to be moved \newline % Row Count 4 (+ 1)
•Force and duration of contraction vary in response to stimuli of different frequencies and intensities \newline % Row Count 7 (+ 3)
•Contraction may, or may not, shorten muscle \newline % Row Count 8 (+ 1)
–Isometric contraction \newline % Row Count 9 (+ 1)
–Isotonic contraction% Row Count 10 (+ 1)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to Change in Stimulus Strength}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Recruitment (multiple motor unit summation) controls force of contraction of a whole muscle \newline % Row Count 2 (+ 2)
•Subthreshold stimuli  \newline % Row Count 3 (+ 1)
– a stimulus that is too weak to illicit activation of any motor units in a muscle \newline % Row Count 5 (+ 2)
–no observable contractions or tension \newline % Row Count 6 (+ 1)
•Threshold stimulus: the stimulus strength that causes first observable muscle contraction (activation of a motor unit) and generation of tension \newline % Row Count 9 (+ 3)
•Maximal stimulus  \newline % Row Count 10 (+ 1)
– strongest stimulus that increases contractile force of whole muscle to its maximum% Row Count 12 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Contraction Strength of Twitches}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Threshold stimuli produces twitch \newline % Row Count 1 (+ 1)
•"Muscle fiber obeys an all-or-none law" contracting to its maximum or not at all \newline % Row Count 3 (+ 2)
–not a necessarily a true statement since twitches can vary in strength \newline % Row Count 5 (+ 2)
•depends upon Ca2+ concentration, previous stretch of the muscle, temperature, pH, and hydration \newline % Row Count 7 (+ 2)
•AP (action potential) in muscle cell occurs much faster than actual contraction \newline % Row Count 9 (+ 2)
–2 milliseconds vs. up to 100 milliseconds respectively \newline % Row Count 11 (+ 2)
–Thus a second AP  may be initiated during the period of mechanical activity of the muscle fiber% Row Count 13 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Muscle Twitch}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Three phases of muscle twitch \newline % Row Count 1 (+ 1)
–Latent period: events of excitation-contraction coupling  \newline % Row Count 3 (+ 2)
•Action potential must cause all of the events we discussed in the previous lectures for muscle fibers to shorten \newline % Row Count 6 (+ 3)
•no "visible" shortening or tension of the muscle  \newline % Row Count 8 (+ 2)
–Period of contraction: sarcomere shortening from cross bridge formation and power stroke produce visible tension (External tension) \newline % Row Count 11 (+ 3)
•Visible shortening and tension of muscle \newline % Row Count 12 (+ 1)
–Period of relaxation: Ca2+ reentry into SR; tension declines to zero \newline % Row Count 14 (+ 2)
•Muscle contracts faster than it relaxes% Row Count 15 (+ 1)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Principles of Muscle Mechanics}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{•Contraction may/may not shorten muscle \newline % Row Count 1 (+ 1)
–Isometric contraction: no shortening; muscle tension increases but does not exceed load  \newline % Row Count 3 (+ 2)
•Same length \newline % Row Count 4 (+ 1)
–Isotonic contraction: muscle shortens because muscle tension exceeds load \newline % Row Count 6 (+ 2)
•Same tension, or tone, once load exceeded% Row Count 7 (+ 1)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Muscle Tone}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•Constant, slightly contracted state of all muscles \newline % Row Count 2 (+ 2)
•Due to spinal reflexes  \newline % Row Count 3 (+ 1)
–Groups of motor units are alternately activated in response to input from stretch receptors in muscles \newline % Row Count 6 (+ 3)
•Keeps muscles firm, healthy, and ready to respond% Row Count 8 (+ 2)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to Change in Stimulus Strength}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{•During recruitment, muscle contracts more vigorously as stimulus strength increases above threshold \newline % Row Count 3 (+ 3)
–This applies to stimulation of the motor nerve with an electrode that applies voltage \newline % Row Count 5 (+ 2)
•Shocking the motor nerve \newline % Row Count 6 (+ 1)
•Contraction force of whole muscle precisely controlled by recruitment \newline % Row Count 8 (+ 2)
–Recruitment (multiple motor unit summation) \newline % Row Count 9 (+ 1)
–Used to increase the force of a muscle contraction by activating additional motor units of that muscle \newline % Row Count 12 (+ 3)
•Each muscle fiber capable of generating a certain amount of force \newline % Row Count 14 (+ 2)
•More active motor units = more muscle fibers shortening and pulling = more force generation \newline % Row Count 16 (+ 2)
•Beyond maximal stimulus no increase in force of contraction \newline % Row Count 18 (+ 2)
–Why?% Row Count 19 (+ 1)
} \tn 
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{stimulus intensity and muscle contraction}}  \tn
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\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/jjovann_1540997611_9.4 img 3.jpg}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Response to change in Stimulus}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/jjovann_1541007656_9.4 img 1.jpg}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Motor Units}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{•Fine control \newline % Row Count 1 (+ 1)
–Produce small, finely controlled movements \newline % Row Count 2 (+ 1)
–small motor units can contain as few as 10-20 muscle fibers \newline % Row Count 4 (+ 2)
–eye muscles \newline % Row Count 5 (+ 1)
–Larynx muscles \newline % Row Count 6 (+ 1)
•Strength control \newline % Row Count 7 (+ 1)
–Produce large, strong movements \newline % Row Count 8 (+ 1)
–gastrocnemius muscle can have as many as 2000 muscle fibers in a motor unit% Row Count 10 (+ 2)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Tension Increase due to Frequency Increase}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{•Why is tetanic tension so much greater than single twitch tension? \newline % Row Count 2 (+ 2)
–Isometric tension produced by muscle fiber at any moment depends mainly on the total number of cross bridges undergoing power stroke. \newline % Row Count 5 (+ 3)
•A single AP in a skeletal muscle fiber briefly releases enough calcium to saturate troponin C making all of the myosin sites on the thin filament initially available. \newline % Row Count 9 (+ 4)
•However, the binding of the energized myosin head to the myosin binding site takes time \newline % Row Count 11 (+ 2)
–During this time, the Ca that was released by the SR is being pumped back into it by the SR calcium ATPases (SERCA pumps) \newline % Row Count 14 (+ 3)
•Thus, after a single AP and Ca release, the sarcoplasmic Ca concentration begins to decrease and the troponin/tropomyosin complex starts to re-block a lot of the binding sites before many of the actin/myosin cross-bridges can be formed% Row Count 19 (+ 5)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Contraction Strength of Twitches}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/jjovann_1541008292_9.4 img 4.jpg}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Twitch and Treppe Contractions}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{•Muscle stimulation at variable frequencies of APs–low frequency (up to 10 stimuli(AP)/sec) \newline % Row Count 2 (+ 2)
•each stimulus produces an identical twitch response \newline % Row Count 4 (+ 2)
•Max tension produced from each twitch remains equal \newline % Row Count 6 (+ 2)
–moderate frequency (between 10-20 stimuli/sec) \newline % Row Count 7 (+ 1)
•each twitch has time to recover but develops more tension than the one before (treppe phenomenon) \newline % Row Count 10 (+ 3)
–Not enough time between stimuli for sarcoplasmic calcium to return to full resting levels \newline % Row Count 12 (+ 2)
»thus calcium not completely put back into SR \newline % Row Count 13 (+ 1)
–Increase in sarcoplasmic Ca2+ concentration with each successive AP stimulation = longer unblocking = more cross bridge formation and power strokes= increase in tension produced \newline % Row Count 17 (+ 4)
»...To a certain point% Row Count 18 (+ 1)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}