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When sodium ion channels open and allow an influx of Na+ ions this increase in positivity inside the cell membrane is known as ___
Depolarization
When K+ ions leak out through the cell membrane in order to restore the resting membrane potential this process is known as _______
repolarization
When excess K+ leaves the cell and the inside becomes more negative than the resting membrane potential the process is known as
hyperpolarization
Name four important structures for the conduction system of the heart
SA node (Sinoatrial node), AV Node (atrioventricular node), Bundle of His (AV bundle), Purkinje fibers
The SA node is located in the ___ ____
right atrium
The pacemaker of the heart is another name for the _____ node
Sinoatrial node
What type of cells make up the SA node
cardiac muscle cells
The cells of the SA node can automatically generate ____ ____ which trigger repeated beating of the heart
electrical impulses
Artificial _____ replace the SA node and generate action potentials
pacemakers
What is the full name for AV Node
atrioventricular node
The AV node sits at the top of the _________ _____
atrioventricular septum
The AV node is composed of a specialized group of cardiac muscle cells which serve as _____ ____ in order to protect the ventricles from beating too rapidly
auxiliary pacemakers
In normal function conditions, the path through the AV node is the _____ route of conduction from the atria to the ventricles
only
The Bundle of His is also called the ___ bundle
AV
The AV bundle travels down the ____ ____
interventricular septum
The first part of the AV bundle ____ conduction of action potentials
slows
The ____ ____ creates a delay between the atrial and ventricular contractions
AV bundle
There are ___ and ___ bundle branches
left and right
The AV bundle branches break into a dispersed network of fibers called the _____ _____
perkinje fibers
Purkinje fibers carry action potentials to _____ _____
ventricular myocardium
The ventricles contract at the ____ first
apex
When the SA node depolarizes, Na+ rushes in and travels through the _____ ____ between cells
intercalated discs
Electrical activity rapidly travels from the ____ node to the ___ node through internodal pathways
SA node to AV node
The AV node is responsible for slowing conduction across the atria to the _____
ventricles
T/F --When the depolarization has spread throughout the atria they contract together
True
T/F – The right atrium and right ventricle contract simultaneously
False
From the AV node the depolarization wave moves through the ______ conducting system to the apex of the heart
ventricular
T/F -- As the action potential travels through the Bundle of His and the Bundle branches the ventricles contract
False
T/F – The ventricles begin to contract at the apex of the heart
True
The _______ septum houses the Bundle of His and the Bundle branches which are part of the conduction system
interventricular
The depolarization wave spreads ____ from the apex of the ventricular myocardium
upward
The filling of the chambers with blood is a _____ process
passive
As the chambers fill with blood the _____ within the chamber increases
pressure
_____ relieves the pressure within the chambers
contraction
Only ____ to ____% of the blood in the ventricles is ejected when they contract
40-60%
Only ____ to ____% of the blood in the atria is ejected when they contract
80-85%
The cardiac cycle creates the ______
heartbeat
A complete cycle of contraction and relaxation of the heart (pump) is called a ____ ____
cardiac cycle
What are the two main parts of a cardiac cycle
systole and diastole
Systole is the cycle of ______
contraction
Diastole is the cycle of ______
relaxation
Define systole
the contraction of a chamber of the heart that drives blood out of the chamber
When _____ in the ventricle exceeds that within the respective atria the AV valves are forced shut
pressure
The closing of the AV valves creates the first ____ _____
heart sound
_____ ______ is a period of systole during which all four of the valves are closed
isovolumetric contraction
Isovolumetric contraction is also called ___ or the “lub” noise
S1
When the ventricular pressure _____ that in the arteries (includes the aorta and the pulmonary artery), the ______ valves are forced open
exceeds, semilunar
The _____ phase is rapid and is followed by a decrease in ventricular and arterial pressures
ejection
When the pressure in the aorta and pulmonary artery is greater than the pressure in the respective ventricles the ______ valves _____
semilunar valves shut
The second heart sound is caused by the _____ valves closing
semilunar
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