WCHS Mr. Alasti PLTW HBS Human Body Systems 3.1.3 Stayin Alive

What does the conduction system do?

Moves an electrical signal through the muscle to coordinate contraction and relaxation

What do electrical signals trigger in terms of heart chambers?

The rhythmic squeezing of the heart chambers to move blood throughout the body

What does routine monitoring of electrical signals provide medical professionals?

A measure of overall heart health

What is an extreme fix for arythmia?

An AED machine

True or False: You have to stop the heart before you can fix it

True

AED (Automated External Defibrilator)

A simple-to-use device that can analyze and interpret electrical signals within the heart and determine whether providing an electrical shock or a series of shocks to the heart may help restore the heart to a normal rhythm

EKG (Electrocardiogram)

Graphical recording of the electrical activity occurring within the heart during contraction and relaxation

Deflections

Downward or upward changes

What does a typical EKG tracing consist of?

Deflections and three recognizable waves (P wave, QRS complex, and T wave) created by a change in voltage

What can the overall pattern in an EKG provide information about?

Heart conditions such a as irregular heartbeat, blocked arteries, heart damage, and heart attacks (myocardial infarctions)

What does the cardiac conduction system consist of?

The human heart, which contains four more components: the SA node, AV node, Bundle of His, and Purkinje fibers

SA Node (Sinoatrial Node)

Natural pacemaker of the heart, located in the right atrium, next to the entrance of the superior vena cava

How are electrical signals that begin in the SA node passed along?

Through a conduction system that causes the chambers of the heart to contract rhythmically

What do electrical impulses spread throughout, and what does it cause?

They spread throughout the atria, causing them to contract

AV Node (Atrioventricular Node)

Located near the center of the heart, where the two atria and two ventricles are close to each other; it also delays the electrical impulses from the SA node to the ventricles, allowing the ventricles to fill with blood from the atria

Where does the AV node pass electrical signals to?

The Bundle of His, or the AV Bundle

Bundle of His (AV Bundle)

Split into right and left branches, which conduct impulses to the apex of the heart

Purkinje Fibers

Pass the signals from the Bundle of His upwards around the ventricles, where the signals stimulate the ventricles to contract

What happens to blood when the ventricles contract?

It gets pushed to the pulmonary arteries and the aorta

What happens during an EKG when the atria are full of blood?

The SA node fires, spreading an electrical signal throughout the atria, causing the atria to depolarize and contract, which is shown by the P wave

PQ Interval

How long it takes for the electrical signals to travel from the SA node to the AV node

What happens throughout the QRS complex?

The ventricles depolarize and prepare to contract, while the atria repolarize at the same time; this cannot be seen on an EKG because the QRS complex masks this repolarization

ST Interval

Shows when the ventricles contract

T-Wave

Shows when the ventricles repolarize or relax and prepare for the next cycle that repeats with every heartbeat

Proper sequence of a normal heart’s electrical conduction series

SA node →AV node →Bundle of His →Purkinje fibers

P-R Interval

Time from the beginning of the P wave to the start of the QRS complex, measured in milliseconds/seconds

QRS Complex

Time from the Q deflection to the S deflection measured in milliseconds/seconds

Q-T Interval

Time from the Q deflection to the end of the T wave, measured in milliseconds/seconds

Heart Rate Equation (bpm)

(1 beat/__ seconds)(60 seconds/1 minute)= # of beats/minutes

What can abnormalities in the shape of the wave or in the timing of each segment in an EKG indicate?

That something is wrong with the conduction system, or that an area of cardiac tissue has died (myocardial infarction)

What is one of the most important diagnostic tools for monitoring the health of the heart?

EKG analysis

What can the pattern or rate detected in an EKG provide in emergencies?

Critical information about how to help a patient

Heart Arrhythmia

An irregular heartbeat caused when the electrical signals that coordinate the heart’s beat misfire

Tachycardia

When the heart is beating too quickly

Bradycardia

When the heart is beating too slowly

Fibrillation

Abnormal contraction of the chambers of the heart

What happens during fibrillation?

The normal pattern of the EKG is lost, and the heart is unable to function effectively as a pump

Artificial Pacemaker

An electronic device that stimulates the heart with electrical impulses to maintain or restore a normal rhythm in people with a slow heart rate or heartbeats that pause