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% Document Info
\author{CooperF04}
\pdfinfo{
  /Title (cardiac-muscle-cheat-sheet-c-forsythe.pdf)
  /Creator (Cheatography)
  /Author (CooperF04)
  /Subject (Cardiac Muscle  C.Forsythe Cheat Sheet)
}

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\noindent
\begin{multicols}{3}
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    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Cardiac Muscle  C.Forsythe Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{CooperF04} via \textcolor{DarkBackground}{\uline{cheatography.com/212853/cs/46339/}}}
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\noindent
\begin{multicols}{3}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}CooperF04 \\
  \uline{cheatography.com/cooperf04} \\
  \end{tabulary}
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Published 13th May, 2025.\\
   Updated 14th May, 2025.\\
   Page {\thepage} of \pageref{LastPage}.
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  Measure your website readability!\\
  www.readability-score.com
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Heart Overview}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Human Blood Circulation}} \newline % Row Count 1 (+ 1)
Double pump action \newline % Row Count 2 (+ 1)
Two circuits \newline % Row Count 3 (+ 1)
{\bf{Pulmonary arteries}} \newline % Row Count 4 (+ 1)
Carry oxygen-poor blood from hearts right half to capillary beds in lungs \newline % Row Count 6 (+ 2)
{\bf{Pulmonary veins}} \newline % Row Count 7 (+ 1)
Return oxygenated blood to heart's left half  \newline % Row Count 8 (+ 1)
Systemic circuit \newline % Row Count 9 (+ 1)
Oxygenated blood is pumped from the heart's left half into body's main arteries \newline % Row Count 11 (+ 2)
{\bf{Aorta}} \newline % Row Count 12 (+ 1)
Blood flows to smaller arteries then capillary beds% Row Count 14 (+ 2)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{The Human Heart}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Lies in thoracic cavity between sternum anteriorly and the vertebrae posteriorly  \newline % Row Count 2 (+ 2)
Apex lies to the left of the sternum and base lies to the right  \newline % Row Count 4 (+ 2)
{\bf{Atria}} \newline % Row Count 5 (+ 1)
Receive blood returning to heart and transfer to lower chambers \newline % Row Count 7 (+ 2)
{\bf{Ventricles}} \newline % Row Count 8 (+ 1)
Pump blood from the heart \newline % Row Count 9 (+ 1)
{\bf{Veins}} \newline % Row Count 10 (+ 1)
Return blood from tissues to the atria \newline % Row Count 11 (+ 1)
{\bf{Arteries}} \newline % Row Count 12 (+ 1)
Carry blood away from the ventricles to the tissues  \newline % Row Count 14 (+ 2)
{\bf{Septum}} \newline % Row Count 15 (+ 1)
Continuous muscular partition that prevents blood mixing from the two sides of the heart  \newline % Row Count 17 (+ 2)
{\bf{Right Half}} \newline % Row Count 18 (+ 1)
Right atrium \newline % Row Count 19 (+ 1)
-Receives deoxygenated blood from head and arms and trunk and legs \newline % Row Count 21 (+ 2)
Right ventricle \newline % Row Count 22 (+ 1)
-Receives deoxygenated from right atrium from AV valve \newline % Row Count 24 (+ 2)
-Pumps into pulmonary artery \newline % Row Count 25 (+ 1)
-Carries to lungs \newline % Row Count 26 (+ 1)
{\bf{Left Half}} \newline % Row Count 27 (+ 1)
Left atrium \newline % Row Count 28 (+ 1)
-Receives blood from right and left pulmonary veins \newline % Row Count 30 (+ 2)
} \tn 
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\vfill
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{The Human Heart (cont)}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{-Well oxygenated  \newline % Row Count 1 (+ 1)
Left ventricle \newline % Row Count 2 (+ 1)
-Receives oxygenated blood from atrium through left AV valve \newline % Row Count 4 (+ 2)
-When contracted blood moves into aorta and is then pushed throughout major arteries of body \newline % Row Count 6 (+ 2)
-Conduction of electrical signals  \newline % Row Count 7 (+ 1)
-Causes heart to contract  \newline % Row Count 8 (+ 1)
-Begins at SA node (sinoatrial node) \newline % Row Count 9 (+ 1)
-Found near Right atrium  \newline % Row Count 10 (+ 1)
{\bf{Pacemaker}} \newline % Row Count 11 (+ 1)
Spreads through both atria and causes it to contract  \newline % Row Count 13 (+ 2)
Spreads then to AV node \newline % Row Count 14 (+ 1)
Relays impulse to bundle of HIS  \newline % Row Count 15 (+ 1)
Charge is distributed  \newline % Row Count 16 (+ 1)
{\bf{Cardiac myocytes}} \newline % Row Count 17 (+ 1)
Mechanical pumping  \newline % Row Count 18 (+ 1)
{\bf{Autorhythmic cells}} \newline % Row Count 19 (+ 1)
Initiate and conduct electrical impulses  \newline % Row Count 20 (+ 1)
Pacemaker activity \newline % Row Count 21 (+ 1)
Fire action potential% Row Count 22 (+ 1)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Complete Circuit of Blood Flow}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Blood returning from systemic circulation enters right atrium via two large veins: \newline % Row Count 2 (+ 2)
{\bf{Venae cavae }} \newline % Row Count 3 (+ 1)
-Returning blood from above and the other returning blood from below heart level \newline % Row Count 5 (+ 2)
-Deoxygenated blood flows from right atrium into right ventricle \newline % Row Count 7 (+ 2)
-Pumps out through pulmonary artery  \newline % Row Count 8 (+ 1)
{\bf{Pulmonary veins}} \newline % Row Count 9 (+ 1)
-Blood returning to left atrium from both lungs% Row Count 10 (+ 1)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Atrioventricular and Semilunar Valves}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Atrioventricular Valves between the Atria and Ventricles}} \newline % Row Count 2 (+ 2)
AV valves are positioned between atrium and ventricle on the right and left sides  \newline % Row Count 4 (+ 2)
Let blood flow from atria into the ventricles during ventricular filling  \newline % Row Count 6 (+ 2)
Prevent backflow of blood \newline % Row Count 7 (+ 1)
Right AV valve \newline % Row Count 8 (+ 1)
Tricuspid valve \newline % Row Count 9 (+ 1)
3 cusps or leaflets \newline % Row Count 10 (+ 1)
Left AV valve \newline % Row Count 11 (+ 1)
Bicuspid valve \newline % Row Count 12 (+ 1)
2 cusps \newline % Row Count 13 (+ 1)
{\bf{Semilunar Valves between the Ventricles and Major arteries}} \newline % Row Count 15 (+ 2)
Aortic and pulmonary valve \newline % Row Count 16 (+ 1)
-Forced open when left and right ventricular pressures exceed the pressure in the aorta and pulmonary artery during ventricular contraction and emptying% Row Count 20 (+ 4)
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Components of the Heart}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Heart walls}} \newline % Row Count 1 (+ 1)
Endothelium \newline % Row Count 2 (+ 1)
-Thin, inner layer \newline % Row Count 3 (+ 1)
-Unique type of epithelial tissues that lines entire circulatory system \newline % Row Count 5 (+ 2)
Myocardium \newline % Row Count 6 (+ 1)
-Middle layer \newline % Row Count 7 (+ 1)
-Composed of cardiac muscle and constitutes bulk of heart wall \newline % Row Count 9 (+ 2)
Epicardium \newline % Row Count 10 (+ 1)
-Thin, external layer \newline % Row Count 11 (+ 1)
-Covers the heart \newline % Row Count 12 (+ 1)
{\bf{Intercalated discs}} \newline % Row Count 13 (+ 1)
Desmosomes  \newline % Row Count 14 (+ 1)
-Adhering junction that mechanically holds cells together \newline % Row Count 16 (+ 2)
Gap junctions \newline % Row Count 17 (+ 1)
-Areas of low electrical resistance that allow action potentials to spread from one cardiac cell to adjacent cells \newline % Row Count 20 (+ 3)
{\bf{Pericardial sac}} \newline % Row Count 21 (+ 1)
Membranous sac that encloses heart \newline % Row Count 22 (+ 1)
Double-walled \newline % Row Count 23 (+ 1)
Two layers \newline % Row Count 24 (+ 1)
Tough, fibrous covering \newline % Row Count 25 (+ 1)
Attaches to the connective tissue partition that separates the lungs  \newline % Row Count 27 (+ 2)
Secretory lining \newline % Row Count 28 (+ 1)
Thin pericardial fluid \newline % Row Count 29 (+ 1)
-Provides lubrication to prevent friction between the layers as they glide with heart beats% Row Count 31 (+ 2)
} \tn 
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Pacemaker Potentials}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Sinoatrial node (SA node)}} \newline % Row Count 1 (+ 1)
Small, specialized region in the right atrial wall near the opening of the superior (upper) vena cava \newline % Row Count 4 (+ 3)
Controls pacemaker potential  \newline % Row Count 5 (+ 1)
{\bf{Atrioventricular node (AV node)}} \newline % Row Count 6 (+ 1)
Small bundle of specialized cardiac muscle cells located at the base of the right atrium near the septum, just above the junction of the atria and ventricles \newline % Row Count 10 (+ 4)
{\bf{Bundle of His/Atrioventricular bundle}} \newline % Row Count 11 (+ 1)
Tract of specialized cells that originates at the AV node and enters the septum between the ventricles \newline % Row Count 14 (+ 3)
Divides to form the right and left bundle branches that travel down the septum, curve around the tip of the ventricular chambers, and travel back toward the atria along the outer walls \newline % Row Count 18 (+ 4)
{\bf{Purkinje fibers}} \newline % Row Count 19 (+ 1)
Small terminal fibers that extend from the bundle of His and spread throughout the ventricular myocardium, much like small twigs of a tree branch% Row Count 22 (+ 3)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Cardiac Muscle Excitation}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{The spread of cardiac excitation is coordinated to ensure efficient pumping}} \newline % Row Count 2 (+ 2)
Atrial excitation and contraction should be complete before the onset of ventricular contraction \newline % Row Count 4 (+ 2)
Excitation of cardiac muscle fibers should be coordinated to ensure that each heart chamber contracts as a unit to pump efficiently  \newline % Row Count 7 (+ 3)
Fibrillation \newline % Row Count 8 (+ 1)
Random, uncoordinated excitation and contraction of cardiac cells \newline % Row Count 10 (+ 2)
The pair of atria and pair of ventricles should be functionally coordinated so that both members of the pair contract simultaneously  \newline % Row Count 13 (+ 3)
{\bf{Atrial Excitation}} \newline % Row Count 14 (+ 1)
The interatrial pathway extends from the SA node within the right atrium to the left atrium  \newline % Row Count 16 (+ 2)
The internodal pathway extends from the SA node to the AV node \newline % Row Count 18 (+ 2)
{\bf{Ventricular Excitation}} \newline % Row Count 19 (+ 1)
Impulse travels rapidly down the septum via the right and left branches of the bundle of His and throughout the ventricular myocardium via the Purkinje fibers% Row Count 23 (+ 4)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Action Potential in Cardiac Contractile Cells}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{p{5.377cm}}{\vspace{1px}\centerline{\includegraphics[width=5.1cm]{/web/www.cheatography.com/public/uploads/cooperf04_1747102754_Screenshot 2025-05-12 at 7.18.20 PM.png}}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Cardiac Muscle Excitation}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{The action potential of cardiac contractile cells shows a characteristic plateau}} \newline % Row Count 2 (+ 2)
{\bf{A long refractory period prevents tetanus of cardiac muscle}} \newline % Row Count 4 (+ 2)
Rapidly repetitive stimulation that does not let the muscle fiber relax between simulations results in a sustained, maximal contraction known as tetanus  \newline % Row Count 8 (+ 4)
In contrast, cardiac muscle has a long refractory period because of the prolonged plateau phase of the action potential \newline % Row Count 11 (+ 3)
Cardiac muscle cannot be restimulated until contraction is almost over, precluding summation of contractions and tetanus of  cardiac muscle% Row Count 14 (+ 3)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
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% That's all folks
\end{multicols*}

\end{document}