Heart Exam 2

impulse delayed at

AV node

dysrhythmia

Abnormal heart rhythm

Systole

Contraction of the heart

internodal pathways

Interconnect the SA Node with the AV Node, conducts impulses throught to the atrial working cells.

Depolarization

K+ rushes out of cell through slow potassium channels

Caleb's heart allows oxygenated and deoxygenated blood to mix. Based on your knowledge of the heart and the great vessels, describe other anatomical abnormalities that cause the mixing of oxygenated and deoxygenated blood. Would more or less blood circulate to the lungs?

Less blood would be circulated to the lungs because Caleb is breathing harder to try to get more O2 in his body. Less pressure to pump blood due to the hole.

3 main waves of ECG

P, QRS complex, T

Waves and complexes

P, QRS, T

Segments

PR, ST

Intervals

PR, ST, QT

In a normal ECG wave tracing, atrial depolarization is hidden by

QRS complex

diastole

Relaxation of the heart

1st step of the intrinsic conduction system

SA node activity and atrial activation begin (60-100 action potentials per minute at rest), time= 0

impulse pathway

SA node, internal pathway, AV node, AV bundle (bundle of His), right and left bundle branches, Purkinje fibers

One of the problems that worried Tiffany was that Caleb seemed to be breathing too hard all the time. Let's consider how this symptom is related to his heart defect. Describe what would happen to the blood volume and pressure entering the pulmonary circuit as a result of his VSD.

The total amount of blood would be more. The heart is working harder to pump because the hole causes less pressure.

right and left bundle branches

Two pathways in interventricular septum Carry impulses toward apex of heart

In Caleb's heart, what color would the blood be within the right and left ventricles?

a mix of red and blue due to the whole in between both ventricles

atrioventricular (AV) node

a node of specialized heart muscle located in the septal wall of the right atrium; receives impulses from the sinoatrial node and transmits them to the atrioventricular bundle

PR (segments)

atrial contraction

P wave

atrial depolarization

SA node generates impulse:

atrial excitation begins

1st step of heart mechanical movement

atrial systole begins: atrial contraction forces a small amount of additional blood into relaxed ventricles

2nd step of heart mechanical movement

atrial systole ends, atrial diastole begins

the p wave represents _____ depolarization, which leads to atrial _____

atrial, contraction

the intrinsic conduction system consists of

autorhythmic cardiac cells

Where do you think would be the best place to auscultate Caleb's abnormal heart sound?

between the left and right ventricles

P-Q interval much longer than normal indicates

blockage in the normal conduction pathway

Heart Block

blocked AV node, slows or prevents ventricular depolarization

Right ventricles have what color blood

blue (deoxygenated)

Based on the location of Caleb's defect, what part of the conductive system might be at risk for abnormalities?

bundle branches/bundle of his

"DUB"

closing of semilunar valves at end of systole/beginning of diastole

"LUB"

closing of the AV valves at the beginning of systole

ECG shows and measures

conductive system and electrical activity (not muscle contraction), used to detect if the electrical conduction pathway within the heart is normal and if any damage has been done to the heart

atrioventricular (AV) bundle

conducts the impulse to the ventricles

unlike skeletal muscle, cardiac muscle

contracts on its own

relies on _____ conduction to move blood

electrical

pacemaker cells are not part of the nervous system, it is its own

electrical system

Plateau

extracellular Ca2+ enters cytosol through slow calcium channels

Purkinje fibers

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract

conducting cells

found in the internal pathways

pacemaker cells

found in the sinoatrial (SA) node and atrioventricular (AV) nodes

the intrinsic conduction system coordinates heart activity by determining the direction and speed of ______. This leads to a coordinated heart contraction.

heart depolarization

blood flows from

higher to lower pressure

autorhythmic cardiac cells

initiate and distribute electrical impulses throughout the heart

repolarization

initiated relaxation of muscle (diastole)

depolarization

initiates contraction of muscle (systole)

Rapid depolarization

massive influx of Na+ through fast sodium channels

Q-T segment much longer than normal may indicate

myocardial damage

specialized cardiac cells:

pacemaker cells (autorhythmic) and conducting cells

sinoatrial (SA) node

pacemaker of the heart

ventricular excitation completion involves

purkinje fibers

Tachycardia

rapid heart rhythm (>100bpm), normal when exercising, abnormal at rest

Left ventricles have what color blood

red (oxygenated)

PR (interval)

signal from SA to AV

Bradycardia

slow heart rhythm (<60bpm), can be caused from damaged SA node

What would it mean if one of the peaks was off, missing or looked abnormal?

something is wrong in the atrial, electrical impulses (the ventricles) after AV nodes

2nd step of the intrinsic conduction system

stimulates spreads across the atrial surfaces and reaches the AV nodes (P waves: atrial depolarization), elapsed time= 50msec

pacemaker cells are the reason why

the heart still beats on its own when removed from body

5th step of the intrinsic conduction system

the impulse is distributed by purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed, and ventricular contraction begins. Purkinje fibers. (QRS complex: completion of ventricular depolarization), elapsed time= 225msec

4th step of the intrinsic conduction system

the impulse travels along the interventricular septum within the AV bundle and the bundle branches to the purkinje fibers and; by the moderator band, to the papillary muscles of the right ventricle. Moderator band. (G waves: beginning of ventricular depolarization), elapsed time= 175msec

Bachmann's bundle

the structure that relays the electrical impulse from the SA node to the left atrium in a normal heart

3rd step of the intrinsic conduction system

there is a 100-msec delay at the AV node. Atrial contraction begins. AV bundle and bundle branches. (P-R Intervals: conduction through AV node and AV bundle), elapsed time= 150msec

two types of ECG variations that might signal abnormalities

variation of wave height (elevated or depressed) and/or normal time intervals

ST (segments)

ventricular contraction

ST (interval)

ventricular contraction and recovery

T wave

ventricular depolarization

QRS complex

ventricular depolarization and atrial repolarization

QT interval

ventricular depolarization and repolarization

5th step of heart mechanical movement

ventricular diastole-early: as ventricles relax, pressure in ventricles drops; blood flows back against cusps of semilunar valves and forces them closed. Blood flows into the relaxed atria

6th step of heart mechanical movement

ventricular diastole-late: all chambers are relaxed. ventricles fill passively

impulse passes to heart apex:

ventricular excitation begins (bundle branches)

3rd step of heart mechanical movement

ventricular systole-1st phase: ventricular contraction exerts enough pressure on the blood to close AV valves but not enough to open semilunar valves

4th step of heart mechanical movement

ventricular systole-2nd phase: as ventricular pressure rises and exerts pressure in the arteries, the semilunar valves open and blood is ejected