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66 Cards in this Set

  • Front
  • Back
S.A. node heart rate
72-75 bpm
A.V. node heart rate
50-60 bpm
Beats per minute when ventricles are causing the contractions
30-40 bpm
Factors that increase heart rate
painful stimuli
hypoxia (not enough oxygen)
thyroid hormones
breathing in
Factors that decrease heart rate
breathing out
Normal heart rate
60-100 bpm
less than 60 bpm
greater than 100 bpm
(+) or (-) strength or force of contraction
Factors that have a positive inotropic effect
Frank Starling's law of the heart
Frank Starling's law of the heart
the greater the filling during diastole, the greater the force of contraction during systole
Epinephrine and norepinephrine
Caffeine and theophylline
Drug used for cardiac failure derived from foxglove plant
Chronotropic (+) or (-)
The rate of contraction
Dromotropic (+) or (-)
The rate of conduction of impulse
How do nerves affect cardiac pumping (2 ways)
1. Changing the heart rate - chronotropic
2. Changing the strength of contraction - inotropic
Sympathetic control of heart
1. Increases rate and force of contraction
2. Maximum sympathetic stimulation = 250 bmp
3. Norepinephrine - increases the permeability of cardiac cells to Na+ and Ca++
Parasympathetic control of heart
1. Decreases the rate and force of contraction
2. Maximum parasympathetic stimulation = 20-30 bpm
3. SA node - right vagus, AV node - left vagus
4. Acetylcholine - increases the permeability of membrane to K+
Stroke volume
The amount of blood pumped out of each ventricle per beat
average = 60-80 mL
Cardiac Output (CO)
Volume pumped by each ventricle per minute

Stroke volume x heart rate
Average person CO
72 bpm x 80 ml/beat = 5.76 L/minute
Factors that cause an increased CO
Increased body temperature
Fick Method (measuring CO)
CO = (oxygen consumption ml/min)/(arterial O2-venous O2)

End up with L/minute
Heart impulse pathway
Impulse starts in SA node
Spreads over atrial muscle fibers -> atrial contractions
Travels through AV bundle and purkinje fibers
Produces coordinated ventricular contractions
Things that can alter heart rate
Sympathetic impulses
Parasympathetic impulses
Body temperature
Stimulus from various exteroceptors
What can cause abnormal cardiac rhythms?
Abnormal rhythms in SA node
Ectopic pacemaker
Blockage of impulses throughout the conduction system
Ectopic pacemaker
Shift of pacemaker activity from SA node to other portions of the conduction system or other parts of the heart
Recording of the electrical activity associated w/ muscle contraction
First wave
Depolarization of atria
QRS complex
Second wave
Depolarization of ventricles
Repolarization of ventricles
Einthoven's triangle
EKG: Electrodes are attached to left shoulder, right shoulder, and left leg
Upper heart chambers
Also called auricles
Lower chambers of heart
Direction of blood flow through heart:
Right atrium
Tricuspid valve
Right ventricle
pulmonary valve
pulmonary arteries
pulmonary vein
left atrium
mitral valve
left ventricle
aortic valve
vena cava
right atrium
Three layers of heart wall
Endocardium - thin layer of endothelium
Myocardium - muscle layer
Epicardium - thin external layer
Sinoatrial node
(SA node)
(natural pacemaker)
Located in posterior wall of atrium, near vena cava
Rhythmical impulses originate in the SA node
Four unique characteristics of SA node
1) First half of the pacemaker potential is result of funny (If) channels
2) Second half of pacemaker potential is the opening of T-type Ca+ channels (decrease funny channels)
3) Once threshold is reached, there's a decrease in T-Ca+ channels and opening of L-Ca+ channels (long lasting Ca+ channels)
4) Falling phase is a result of the opening of K+ channels
Funny (If) channels
Inward Na+ movement
Closure of outward K+ channels
Atrioventricular node (AV node)
Located within the lower right interatrial septum.
Impulse is delayed in the AV node for about a tenth of a second to allow the atria to contract before ventricular contraction
Atrioventriuclar bundle
(AV bundle or bundle of HIS)
Originates in the AV node, dividing into two bundle branches which extend down the tow sides of the interventricular system and branch out to purkinje fibers
Is control of the conduction in the heart an extrinsic or intrinsic system?
Phase of contraction in cardiac cycle
Phase of reaction in cardiac cycle
Auscultatory method
Clinical method of measuring blood pressure, based on the correlation of blood pressure and atrial sounds
Sounds of Korotkoff
the sounds of turbulent blood as heard in a stethoscope during auscultatory method
What does the first blood pressure sound represent?

The second?
First = systolic
Second = diastolic
Pulse pressure
difference between systolic and diastolic pressures
Generally about 40-50 mmHg

Represents pressure difference that drives blood along arteries to the capillaries
What are the 12 different leads?
3 standard limb leads
3 augmented limb leads
6 chest leads
What information do the first two chest leads give? (V1 and V2)
Info about what's happening in the left ventricle
What information do the third and fourth chest leads give? (V3 and V4)
Info about the septum (muscle between ventricles)
What information do the last two chest leads give? (V5 and V6)
Info about what's happening in the right ventricle
Cardiac arrhythmia
Deviations from normal heart rate or from normal electrical activity of the conduction system
What can cause cardiac arrhythmia?
Abnormal rhythmicity of the SA node
Shift of pacemaking function from the
Ectopic or abnormal pacemaker
Abnormal pathway or blockage of impulses in the conduction system
Causes of ectopic or abnormal pacemakers:
Localized areas of ischemia (lack of blood flow)
Areas of heart damage
Dilation of the heart
Toxic irritants (nicotine, caffeine, alcohol)
Lack of sleep
Extremes in body temperature
Changes in body pH
What are the "big three" toxins that affect the heart?
Atrial premature beat
P-wave comes early
Can be normal-looking or introverted
AV nodal premature beat
Originates from an ectopic discharge of the AV node, then proceeds down the Bundle of His
Normal QRS complex, just early
Generally not preceded by a p-wave
Premature ventricular depolarization (PVD or PVC)
Originates from an ectopic pacemaker
Characteristics: no p-wave, wide QRS complex, high voltage, T-wave is usually inverted
May become coupled with one or more normal beat
What does a wide QRS wave indicate?
Conduction through the muscle cells
Bigeminy (relating to PVD's)
One normal end and one PVD
Trigeminy (relating to PVD's)
Two normal ends and one PVD
SA block
Pacemaker temporarily stops for at least one complete cycle, then resumes pacing
p-waves before and after block are identical
Atrial flutter
Originates in an atrial ectopic pacemaker
P-waves are very rapid and coordinated, look similar to each other
2:1, 3:1, 4:1
Treatment = digitalis

Atrial fibrillation
Caused by many ectopic pacemakers in the atria
Uncoordinated or irregular P-waves
Decrease in cardiac output
QRS-T usually looks normal