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68 Cards in this Set

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Describe some basic facts about the heart. (5)
1. Muscular organ about the size of a fist.
2. Four-chambered double pump.
3. Creates the pressure needed to push blood in the vessels to the lungs and body cells.
4. At rest, the heart of an adult pumps about 5.0L/min of blood.
5. It takes about 1 minute for blood to be circulated to the most distal extremity of the body.
What are the four major heart chambers?
1. Atria - two upper; sometimes called auricles.
2. Ventricles - two lower chambers.
What are the arterioventricular valves of the heart?
1. Right and left arterioventricular valves are between the atria and ventricles.
-right AV valve = tricuspid valve
-left AV valve = mitral valve
What are the pulmonary and aortic valves?
They are valves that also found in the heart, pumping blood out of and back into the heart.
-They are also called seminlunar valves because they have 3 cusps which resemble half moons.
What is the direction of blood flow in the heart?
Right atrium==>Right AV valve (tricuspid)==>right ventricle==>Pulmonary valve==>pulmonary vessels==>left atrium==>left AV valve (mitral)==>Left ventricle==>Aortic valve==>Aorta==>All parts of the body==>superior vena cava and inferior vena cava==>right atrium
What are the three separate layers of the heart wall?
1. Endocardium - a thin layer of endothelium
2. Myocardium - muscle layer (cardiac muscle)
3. Edpicardium - then external layer
What generates and conducts impulses throughout the heart causing rhythmic contractions of the myocardium?
Nodal tissue (specialized cardiac cells)
What are the four structural/functional portions of the cardiac conduction system?
1.Sinoatrial node (SA node aka pacemaker)
2. Atrioventricular node (AV node)
3. Atrioventricular bundle (AV bundle or bundle of HIS)
4. Purkinje fibers
Describe the sinoatrial node.
-normal pacemaker of the heart
-Located within the posterior wall of the right atrium, near the opening of the superior vena cava.
-Rhythmical impulses originate in the SA node and spread through the atria.
What is the process of depolarization/repolarization of the SA node?
1. The first half of the SA node potential is the result of: opening of funny (If) channels, which permits inward sodium movement and the closure of outward potassium channels.
2. The 2nd half of the SA node potential is the opening of T-type calcium channels which allows calcium to enter and a decrease in the funny channels.
3. Once threshold is reached there is a decrease in the T-calcium channels (long-lasting calcium channels).
4. The falling phase is a result of the opening of potassium channels.
Where is the AV node located? What feature of its function is critical to a normal heartbeat?
The AV node is located within the lower right interatrial septum.

Impulses received by the AV node are delayed for about a tenth of a second to allow the atria to contract before ventricular contraction.
Where does the AV bundle originate, and where does it extend?
The AV bundle (bundle of HIS) originates in the AV node, dividing into two bundle branches which extend down the two sides of the interventricular septum.
Where are purkinje fibers located?
Originating from the right and left branches, purkinje fibers extend to the papillary muscles and lateral walls of the ventricles.
How does the cardiac contraction system work?
Impulses start in the SA node ==>spread over atrial muscle fibers producing atrial contraction==>AV node delays the impulse then allows it to travel through the AV bundle and Purkinje fibers, producing coordinated ventricular contraction
Is control of heart conduction intrinsic or extrinsic? What factors may alter the heartbeat rate/force?
Control of the conduction of the heart is intrinsic.

The heartbeat rate can be altered by:
1. Sympathetic and parasympathetic impulses
2. Hormones
3. Body temperature
4. Exercise
5. Emotions
What is the basic cardiac cycle? What are the two major events?
The cardiac cycle is the (1) contraction and emptying and (2) relaxation and filling of the atria and ventricles with blood.

The two major events of the cardiac cycle are systole (contraction) and diastole (relaxation); Mid-diastole and early diastole are also steps.
What are the 4 major steps of the cardiac cycle?
1. Mid-diastole
2. Atriol systole
3. Ventricular systole
4. Early diastole
What is occurring during mid-diastole?
-Atria and ventricles are relaxed
-Tricuspid and mitral valves are open
-Aortic and pulmonary valves are closed
-Blood flows passively from atria into the ventricles, with 65 to 85% of the ventricular filling occurring before the end of this phase.
What occurs during atrial systole?
-Atria contract, and orifices of the venae cavae and pulmonary veins narrow (there is still some regurgitation of blood into the veins).
-There is about 135 mL (on average) of blood in each ventricle.
What are the major steps and "tidbits" about ventricular systole?
1. At the beginning of ventricular contraction, the pressure in the ventricles exceeds atrial pressure and the two AV valves close, causing the first heart sound, "lub."

Pressure builds by closing all valves; no blood can enter or leave the ventricles, hence the name isovolumetric ventricular contraction phase.

When pressure on the right side exceeds diastolic pressure in the pulmonary artery (10 mmHg) and the left exceeds diastolic pressure in the aorta (80 mmGH), the pulmonary and aortic valves open and ventricular ejection begins.

Under normal resting conditions, pressure reaches 24 mmHg on the right and 120 mmHg on the left.

*Stroke volume, blood volume ejected from either ventricle, is 70 to 80 mL. 30 to 50 mL remains in either ventricle, this volume = end-systolic volume.
What are the major steps in early diastole?
Ventricles begin to relax and the pressure drops rapidly.
Pulmonary/aortic valves close, preventing backflow into the ventricles from the arteries (causes the second heart sound, "dub").
The tricuspid and mitral valves open, and blood begins to flow from the atria into the ventricles.
How does one measure blood pressure in clinic? How is it done?
The auscultatory method is based on the correlation of blood pressure and atrial sounds.
What is the process of the auscultatory method with regards to detecting systolic and diastolic pressure?
Pump the cuff.
Because the cuff is pumped, it stops blood flow. Slowly, the pressure of the cuff is lowered, and when systolic pressure in the artery exceeds cuff pressure, a spurt of blood passes through the artery with each heartbeat and heard in the stethoscope called sounds of Korotkoff. The first sound is systolic pressure; the last sound occurs when the cuff pressure is equal to the diastolic pressure (occurs as cuff pressure is slowly released and no more sound is heard).
*Read the cuff pressure @ systolic and diastolic readings to obtain pressure.
How is pulse pressure recorded?
Assume:
Systolic pressure = 120 mmHg
Diastolic pressure = 80 mmHg
==> Pulse pressure = 120/80 (systolic/diastolic)

Pulse pressure (Delta-P) = systolic-diastolic; in this case pulse pressure is 40 mmHg
How does arteriosclerosis effect blood pressure? How does this effect blood flow?
Arteriosclerosis increases total peripheral resistance, raising diastolic pressure to the point that systolic pressure is insufficient to move blood. It is the difference in systolic and diastolic pressures that moves blood, not the relative values.
Arterial pressure increases with age; arteriosclerosis appears to be associated with it.
What are some factors that increase heart rate?
1. Excitement
2. Anger
3. Painful Stimuli
4. Hypoxia
5. Exercise
6. Epinephrine
7. Norepinephrine
8.Thyroid hormones
9. Fever
10. Inspiration
What are some factors that decrease heart rate?
1. Expiration (slow exhaling)
2. Fear (?)
3. Grief
What is the average heart rate of the SA node? The AV node? The ventricles?

What is a normal heart rate? Bradycardia? Tachycardia?
SA Node = 72 to 75 bpm
AV node = 50-60 bpm
Ventricles = 30-40 bpm

Normal heart rate: 60-100 bpm
Bradycardia: <60 bpm
Tachycardia: >100 bpm
What does Inotropic (+/-) mean?
Inotropic refers to the strength of force of a contraction.
What are some factors that have only a positive inotropic effect?
1. Frank Starling's law of the heart: greater the filling during diastole, the greater the force of contraction during systole (less bpm facilitates greater filling).
2. Catecholamines - Epi and NE
3. Xanthines - Caffeine, theophylline
4. Digitalis - drug used for cardiac failure
What is Frank Starling's law of the heart?
The greater the filling during diastole, the greater the force of contraction during systole (less bpm facilitates greater filling).
What are two other factors involved in the heart's contraction besides inotropic?
1. Chronotropic (+/-) => rate of contraction (same factors listed for inotropic)
2. Dromotropic (+/-) => rate of conduction of impulse
How do nerves effect cardiac pumping?
1. Change the heart rate ==> chronotropically.
2. Changing the strength of the contraction ==>inotropic
How does the sympathetic division of the ANS effect cardiac pumping?
1. Increases the rate and force of contraction.
2. Maximum sympathetic stimulation = 250 bpm
3. NE increases the permeability of cardiac cells to sodium and calcium ions.
How does the parasympathetic division of the ANS effect cardiac pumping?
1. Decreases the rate and force of contraction
2. Maximum parasympathetic inhibition = 20-30 bpm
3. SA node - right vagus, AV node - left vagus
4. Acetylcholine - increases the permeability of the membrane to potassium.
What is stroke volume? What is the average stroke volume?
The amount of blood pumped out of each ventricle per beat.

Average stroke volume in the ventricles separately is 60-80 mL, so 120-160 mL total pumped by both ventricles.
What is the cardiac output?

What is the average CO per person?
The stroke volume (SV) x Heart rate (HR), the volume pumped by each ventricle per minute.

Average Person: 5.76 L/min
Athlete: 5.4 L/min
Asthenic person: 5.5 L/min
What are some factors that would cause an increased CO?
Anxiety, eating, exercise, increased body temperature, and pregnancy.
What is the Fick method for measuring CO?
It measures CO as well as oxygen consumed per unit of time.

CO=oxygen consumption (mL/min)/(aterial oxygen - venous oxygen in mL/L)
What does an EKG monitor? How does a normal electrical impulse spread throughout the heart?
An EKG monitors electrical impulses in the brain. Impulses start in the SA node, then are delayed in the AV node, travel down the AV bundles into the Purkinje fibers, producing coordinated ventricular contractions.
What does it mean that the heart is an intrinsic system?
What are some factors that may effect the heart rate?
The heart can beat on its own without any outside influence, but some factors can still influence the heart rate.

Some factors are sympathetic/parasympathetic impulses, hormones, body temperature, exercise, drugs, emotions, and stimulation from various exteroceptors.
What are some ectopic cardiac rhythms caused by?
-Abnormal rhythms in the SA node
-Shift of pacemaker activity from SA node to some other part of the conduction system.
-Blockages of impulses throughout the conduction system.
What is bradycardia? Tachycardia?
1. Slowed heart rate (<60bpm)
2. Accelerated heart rate (>100bpm)
What does the EKG record? What are the three major events?
An EKG records the electrical activity associated with muscle contraction.
1. P wave = depolarization of the atria.
2. QRS complex = depolarization of the ventricles
3. T wave = repolarization of the ventricles
What is Einthoven's triangle in reference to an EKG?
It is an EKG fromed by attaching electrodes the left shoulder, right shoulder, and left leg.
How many different EKG's are there? Into what categories are they broken down? (You will have to learn where the electrodes are placed on each of these leads, because we can't display them with this aid). What is the point of having different leads?
There are 12 different leads: 3 standard limb leads, 3 augmented limb leads, and 6 chest leads.

Different leads allow physicians to obtain a more complete picture of the heart to make a more accurate diagnosis if there is a heart condition.
What is the standard limb lead used in class?

Which parts of the heart to the different chest leads give you?
Lead 2 is the lead we use most often in class.

V1, V2 = more information about the right ventricle.
V3, V4 = more information about the septum.
V5, V6 = more information about the left ventricle.
What is a cardiac arrhythmia? What are some causes of a cardiac arrhythmia?
Cardiac arrhythmia is a deviation from normal heart rate or from normal electrical activity of the conduction system.

1. Abnormal rhythmicity of the SA node.
2. Shift of pacemaking function from SA node to another area of the heart (ectopic pacemaker).
3. Abnormal pathway or blockage of impulses in the conduction system.
What are some of the major causes of ectopic pacemaker?
1. Localized areas of ischemia (lack of blood flow to an area of the heart)
2. Localized areas of heart damage.
3. Dilation of the heart
4. Toxic irritants (nicotine, caffeine, alcohol)
5. Lack of sleep
6. Anxiety
7. Extremes in body temperature
8. Changes in body pH
Describe the abnormal atrial premature beat.
-Premature depolarization of the SA node or of an ectopic pacemaker
-some of the P waves are normal, some are abnormal
-usually have little clinical significance, may precede flutter or fibrillation
Describe the AV nodal premature beat.
-originates from an ectopic discharge of the AV node, then proceeds down the bundle of His
-normal QRS complex
-generally not preceded by a P wave.
Describe a premature ventricular depolarization - PVD or PVC
-originates from an ectopic pacemaker in the ventricles
-No P wave; wide QRS complex; high voltage; T wave usually inverted; usually a pause after the PVD; feels like a skipped beat
-PVD may become coupled with one or more normal beats; bigeminy = one normal and one PVD; trigeminy = two normal and one PVD
-may be dangerous and can lead to fibrillation if lasting more than 6-7/min
Describe an SA block.
-pacemaker temporarily stops for at least one complete cycle, then resumes pacing normally. (impulse doesn't make it to the ventricles)
-P waves before and after block are identical
Describe a Type 1/first degree/incomplete AV block.
-characterized by a prolonged PR interval, 0.2-0.3 seconds
-consistently prolonged interval in each cycle.
-can be caused by digitalis or vagal stimulation
Describe a Second Degree/Type 1/Mobitz's Type 1/ Wenckeback AV block.
-PR intervals lengthen progressively until a ventricle beat is dropped (6 to 8 per minute)
-can be caused by digitalis.
Describe a Second Degree/Type 2/Mobitz's Type 2 AV block.
-Present when it takes 2 or more atrial impulses to stimulate the ventricles
-usually 2:1, 3:1, or 4:1
-may be caused by myocardial infarction or myocarditis
-may lead to a 3rd degree block
Describe a third degree/complete AV block.
-occurs when none of the atrial impulses stimulate the AV node
-ventricles are paced independently from the atria.
-the ventricular rate is slower than the atrial rate of contraction
-don't need to know visual EKG
Describe an 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 is digitalis
Describe an atrial fibrillation.
-caused by multiple ectopic pacemakers in the atria
-uncoordinated/irregular P waves
-decrease in cardiac output
-QRS-T usually look normal.
Describe a ventricular flutter.
-caused by a single ectopic pacemaker in the ventricles.
-usually has a smooth sine wave appearance
-because it is so fast, it is extremely dangerous.
-heart does not fill properly => decreased cardiac output
-often leads to ventricular fibrillation
-decreased coronary blood flow.
Describe aventricular fibrillation.
-caused by many ventricular ectopic pacemakers.
-uncoordinated, chaotic twitching, "bag of worms"
-blood pressure drops
-unless stopped death will occur in a short time
-blood not pumping that much
What is a myocardial infarction? What are some possible causes? What is a bypass?
-caused by lack of blood flow to an area of the heart (ischemia).
-possibly caused by thrombus formation and blockage of vesicles
-can be caused by spasms in the coronary arteries, without total occlusion
-can be due to vessel narrowing caused by atherosclerosis
-area becomes electrically dead
-bypass = device that "bypasses" the infarction
What are the three phases - the classical triad - of a myocardial infarction?
1. Ischemia
2. Injury
3. Infarction
What is ischemia's EKG in relation to a myocardial infarction?
-shown as a symmetrical inversion of the T wave
-most pronounced in chest leads
-caused by delay in the recovery at the eipcardial regions
-altered repolarization
What is injury's EKG in relation to a myocardial infarction?
-ST elevation means infarction is fresh (acute)
What is is an infarction's EKG?
-significant Q wave - much wider than normal
-Q may be 1/3 of the height of the QRS
-may last for many years after the infarction
-some drugs can cause effects similar to this significant Q
What are some clinical information about a myocardial infarction?
-Pain: heavy/crushing, may radiate to neck, jaw, back, shoulder, and left arm
-Nausea and vomiting may occur
-Catecholamines are released
-Blood sugar usually increases
-Cardiac troponins (troponin I and torponin T) are found in the blood
-Enzymes may be released (creatine kinase - CK, and lactic dehydrogenase - LDH)
-amount of troponin and creatine kinase in the blood are usually correlated with the severity of the infarction
What are some treatments for a myocardial infarction?
-Aspirin
-heparin
-sublingual nitroglycerine
-morphine sulfate
-oxygen administration