action potential - ANSWER contraction of these cells initiated by electrical
impulses
SA node - ANSWER primary pacemaker of the heart; initiates all heartbeats and
controls heart rate, fire spontaneously generating action potentials that spread
through contractile myocytes of atria.
AV node - ANSWER impulses sent from SA node, to AV node, slow down a little
to allow the atria to contract, then follow the conduction pathway and spread
through the ventricular myocytes.
3 major uses for action potential - ANSWER K - inside cell
Na - outside cell
Ca - outside cell
- resting membrane potential = (-) on the inside
- maintained by pumps Na, Ca and K channels
depolarization - ANSWER action potential begins with the voltage becoming more
positive. Mainly due to opening of sodium channels that allow Na to flow into the
cell
absolute refractory period - ANSWER after a delay; termination of action potential
occurs
repolarization - ANSWER Potassium channels open, allowing K to leave the cell
and causing the membrane potential to return to negative
,AV bundle ( bundle of HIS) - ANSWER divided into right and left bundle branches
which conduct the impulses toward the apex of the heart
purkinje fibers - ANSWER apex of the heart
P wave - ANSWER SA node fires, electrical signals spread throughout the atria
and cause the atrial to depolarize
PR segment - ANSWER the time signals travel from the SA node to the AV node
QRS complex - ANSWER marks the firing of the SA node to the AV node and
represents ventricular depolarization; atrial repolarization.
Q wave - ANSWER depolarization of the interventricular septum
R wave - ANSWER depolarization of the main mass of the ventricles
S wave - ANSWER last wave of ventricular depolarization at base of the heart
ST segment - ANSWER reflects the plateau in the myocardial action potential,
ventricles contract and pump blood
T wave - ANSWER ventricular repolarization. immediately before ventricular
relaxation of ventricular diastole
aorta - ANSWER rich in oxygenated blood
right coronary artery - ANSWER right descending artery - acute marginal artery
- will supply right atrium and right ventricle and cytoatria ventricular nodes, which
are the conduction systems of the heart
left coronary artery - ANSWER left anterior descending artery and the circumflex
artery
- will supply blood to the left atrium and left ventricle
veins (in coronary blood flow) - ANSWER will leave cardiac muscle cells and will
bring the deoxygenated blood back to the right atrium through the coronary sinus
small cardiac vein - ANSWER from right side joining with coronary sinus
middle cardiac vein - ANSWER from right ventricle joining coronary sinus
, posterior vein - ANSWER from left ventricle joining into coronary sinus bringing
back deoxygenated blood to the right atrium
great cardiac vein - ANSWER comes from front of heart
anterior vein - ANSWER does not join onto the coronary sinus but drains blood
directly to right atrium
endocardium - ANSWER - inter most layer of cardiac wall
- loose connective tissue and simple squamous epithelial tissue
- (simple squamous epithelial tissue)
- regulates contractions
subendocardial layer - ANSWER - lies between the endocardium and myocardium
(2nd innner)
- containing the vessels and nerves of the conducting system of the heart. The
purkinje fibers are located in this layer
- damage to this layer can result in various arrhythmias
myocardium - ANSWER - 2nd to outer layer
- main constituent of the heart and the thickest layer of all 3 layers
- it is a muscle layer that enables heart contractions
- have a single nucleus in the center of the cell
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