Cheatography
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Cardiac muscle cheat sheet
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Anatomy Of The Heart
4 chambers: |
left and right atria |
left and right ventricles |
4 heart valves: |
right AV valve (tricuspid) |
left AV valve (bicuspid) |
pulmonary/semilunar valve |
aortic/semilunar valve |
Flow of Blood
Right atrium: |
receives oxygen-poor blood from systemic circulation from inferior and superior vena cavas then pumps blood into right ventricles from right AV valve |
Right ventricle: |
receives oxygen-poor blood from right atrium then pumps blood through the pulmonary valve into pulmonary arteries |
Left atrium: |
receives oxygen-rich blood from pulmonary circulation then into left and right pulmonary veins and pumps blood through the left AV valve into the left ventricle |
Left ventricle: |
receives oxygen-rich blood from left atrium then pumps blood through the aortic valve into the aorta which will go to the rest of the body |
Purpose of Heart Valves
ensures one way blood flow |
when pressure is greater behind valve it opens |
when pressure is greater in front of valve it closes |
has chordae tendineae which prevents valves from everting on itself during ventricular contraction |
Heart Sounds & Definitions
murmurs: |
abnormal heart sounds due to malfunctioning valves |
stenotic valve: |
stiff narrow valve that does not open completely, whistling sound |
insufficient valve: |
valve that does not close properly, swishing sound |
first heart sound (lub) -> closure of AV valve
second heart sound (dup) -> closure of semilunar valve
Regulation Of Cardiac Output
Heart rate: |
regulated by parasympathetic and sympathetic nervous system |
Stroke volume: |
volume of venous blood returning to the ventricles |
Cardiac Output = heart rate X stroke volume
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AP of Pacemaker Cells
Key:
If - Funny Channels
T - Transient Type Calcium Channels
L - Long Lasting Calcium Channels
Pacemaker Definitions And Terms
Nodes: |
specialized cardiac cells capable of pacemaker activity are grouped together to form nodes |
Sinoatrial (SA) Node: |
located in the wall of the right atrium, able to conduct 70 AP for minute |
Atrioventricular (AV) Node: |
located in the at the base of the right atrium, able to conduct 50 AP for minute |
Bundle of HIS |
located at the AV nodes and projects into the left and right ventricles |
Purkinje Fibers |
small fibers that extend from the Bundle of HIS, able to conduct 30 AP for minute |
Interatrial Pathway |
conducts pacemaker activity from the right atrium to the left atrium |
Internodal Pathway |
conducts pacemaker activity from the SA node to the AV node |
Flow of AP
SA node -> AV node -> Bundle of HIS -> Purkinje Fibers |
Heart Walls Definitions
Endocardium: |
thin layer of endothelial tissue lining the interior of each chamber |
Myocardium: |
middle layer of the heart, has intercalated disks with desmosomes and gap-junctions |
Epicardium: |
thin external membrane covering the heart and filled with pericardial fluids to protect the heart |
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Electrocardiogram Waveforms
P-wave: |
depolarization of the atria |
QRS Complex: |
depolarization of the ventricles |
T-wave: |
redepolarization of the ventricles |
Electrocardiogram
PR = AV Nodal Delay
ST = Time when ventricles are contracting & emptying
TP = Time when ventricles are relaxing & filling
Mechanicals Events of the Cardiac Cycle
Systole: |
periods of contraction & emptying |
Diastole: |
periods of relaxing & filling |
End-diastolic volume: |
volume of blood at the end of diastole |
isovolumetric ventricular contraction: |
period of time during contraction where the chambers are closed and the chamber pressure increases |
End-systole volume: |
the amount of blood remaining at the end of systole |
Stroke volume: |
end-diastole volume minus end systole volume |
isovolumetric ventricular relaxation: |
period of time during relaxation when chamber remains closed and the chamber pressure decreases |
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