Flashcards in Cardiac Pathophysiology Deck (57):
Describe the location of the heart
-in the mediastium between the 2nd rib and 5th intercostal space.
-2/3rds to the left of the midsternal line and 1/3 to the right.
Describe the layers of the heart and pericardial sac.
-Parietal layer of serous pericardium
-Visceral layer of serous pericardium/Epicardium
What is the purpose of the pericardial sac?
-superficial fibrous pericardium?
-parietal serous pericardium?
-visceral serous pericardium/epicardium
-Pericardial sac- dbl wall, allows for smooth movement. Lubrication, reduces friction.
-Superficial fibrous pericardium: protects, anchors, and prevents overfilling of the heart.
-Parietal serous pericardium and visceral serous pericardium make up the pericardial sac.
-Myocardium: spiral bundles of cardiac muscle cells, the fibrous skeleton of the heart; crisscrossing interlacing layer of CT.
--anchors cardiac muscle fibers
--supports great vessels and valves
--limits spread of action potentials to specific paths.
endocardium: continuous with endothelial lining of blood vessels.
what does a pericardial friction rub sound like?
which layer of the heart accumulates fat as you get older?
What is the purpose of atrial auricles?
-increase atrial volume
what is the coronary sulcus?
-landmark of the heart, "crown" that separates the atria and ventricles.
Atrial walls composed of what type of muscles?
Which vessels enter the right atrium? Left?
-Right: SVC, IFV, and Coronary sinus
-Left: right and left pulmonary veins
which muscle line the ventricles?
which vessels leave the right and left ventricles?
-trabeculae carneae line the ventricular walls
-pulmonary trunk leaves the right ventricle and the aorta leaves the left ventricle.
Equal volumes of blood are pumped to the pulmonary and systemic circuits, true or false.
describe the pressures of the pulmonary circuit and the systemic circuit.
Pulmonary circuit is low pressure.
Systemic circuit is high pressure.
Describe the venous coronary circulation and which parts of the heart they supply.
From coronary sinus, Great cardiac vein wraps around the left ventrical anteriorly and runs down the anterior portion of the left ventricle.
From the coronary sinus, the Middle Cardiac Vein runs posteriorly in the interventricular septum.
From the coronary sinus, the small cardiac vein runs along the right ventricle.
during what period of the cardiac cycle do the coronary arteries receive perfusion?
What is Angina Pectoris?
-thoracic pain caused by a deficiency in blood delivery to the myocardium. Cells are weakened.
-ischemia that occurs over time
-may be exertional that is relieved with rest.
What is an MI?
-prolonged coronary blockage. Cells death, repaired with non-contractive scar tissue
-sudden loss of perfusion
-not relieved with rest
What muscle and tissue anchor the AV valve cusps.
When do you hear heart sounds S1-4
S1 & S2 are heard in everyone
S3- volume overload
S4- some kind of fibrotic change
Fibrous insulator exists between the atrium and ventricles, why?
-give time between atrial and ventricular contraction, keeps everything orderly, allow time for filling of the ventricles.
function of intercalated disks of cardiac muscle?
supports sycronized contraction of cardiac tissue
Contractile tissue of the heart has a long absolute refractory period, why?
-allows proper filling.
What is the Intrinsic cardiac conduction system ?
-network of autorhythmic cells that initiate and distribute impulses to coordinate the depolarization and contraction of heart.
Describe the pathway of electrical conduction of the heart
SA Node...Internodal pathway...AV node...HIS Bundle.....Left and Right Bundle Branches...Purkinje Fibers
*bachmanns bundle runs from the SA node to the left atria.
-have _____ resting
-once threshold has been achieved ____ channels open and produce an action potential.
-Repolarization results from _____ of _____ ______ and opening of voltage-gated K+ channels.
-unstable resting potential.
-inactivation of Ca2+ channels.
Myocardial cells respond to which ion for depolarization?
-influx of Na+ ions into myocardial cells, these are faster.
-mediated by which nerve?
-Vagally mediated by parasympathetics. (keeps SA node in check so its not beating at 100BPM)
- what causes a change between the rate of the SA and AV nodes?
-There are less gap junctions near the AV node, conduction is slower.
What is the only electrical connection between the atria and ventricles?
Atrioventricular Bundle/ HIS Bundle
Purkinje Fibers are located where?
-The His Bundle and both bundle branches are "bundles" of rapidly conducting purkinje fibers.
What is the inherent rate of ventricular foci?
What is happening mechanically with the heart just as the purkinje fibers are being stimulated?
-the AV valves are just closing as the perkinje fibers are being stimulated and preparing for ventricular contractions.
What are some consequences of defects in the intrinsic conduction system?
-uncoordinated atrial and ventricular contractions
Defective SA node may result in?
AV node defect?
-AV node takes over
Av Node defect:
-partial or total heart block
-few or no impulses from SA node reach the ventricles.
Extrinsic Innervation of the Heart:
-sympathetic effects on heart
-parasympathetic effects on heart
Sympathetic: "gas pedal," Cardioacceleratory center innervates SA, AV nodes, myocardial cells, and coronary arteries through sympathetic neurons
Parasympathetic: "break pedal", cardioinhibitory center inhibits the SA and AV nodes through the vagus nerve.
*controls rate but not contractility of the vessels.
Describe whats happening during each wave on EKG.
-why do we not see atrial repolarization?
p: atrial depolarization & SA node
QRS: ventricular depolarization
T: ventricular repolarization
-we dont see atrial repolarization because its masked by the QRS complex.
What does the...
-PR interval tell you
-ST segment (whats happening)
PR interval tells how the atria and ventricles are communicationg, should be 0.21
ST: time between ventricular depolarization and repolarization
QT: total time its takes from ventricular depolarization to ventricular repolarization.
When would you have a junctional rhythm?
when the SA node is nonfunctional. on EKG P waves are absent and the heart is paced at 40-60BPM
What do the sounds "lubb" "dupp" represent?
-Lubb: S1, occurs during ventricular systole, AV valves closing
-Dupp: S2, occurs during ventricular diastole, semilunar valves closing
How do you treat torsades de point?
-magnesium sulfate, will bring you back to sinus rhythm
Heart murmurs are indicative of what kind of problem?
When does ventricular filling take place?
-mid to late diastole, the AV valves are open, 80% of blood passively flows into the ventricles.
End diastolic volume: what is this?
-the volume of blood in each ventricle at the end of ventricular diastole.
What is occuring during ventricular systole?
-atria relax and ventricles begin to contract.
-rising ventricular pressure results in AV Valves closing
-isovolumetric contraction phase (all valves are closed)
-in ejection phase, ventricular pressure exceeds pressure in the large arteries, forcing the SL valves open.
What is End systolic Volume?
-the volume of blood remaining in each ventricle after ventricular systole
Isovolumetric relaxation occurs when?
in early diastole. (ventricles relax)
-backflow of blood in the aorta and pulm trunk closes SL valves and cases dicrotic notch
What is dicrotic notch?
-brief rise in aortic pressure
what is cardiac output? How do you calculate this?
-the volume of blood pumped by each ventricle in one minute.
-CO= HR x Stroke Volume
Maximal CO is _____ times resting CO in nonathletic peaople
What is cardiac reserve?
-the difference between resting and maximal CO
How do you calculate Stroke Volume?
-What are the three main factors that effect SV?
Stroke Volume = EDV-ESV
1.) Preload (end diastolic)
3.) Afterload (End systolic)
What is ejection fraction?
-what is a normal EF?
-what is the best way to look at EF?
-measurement of ventricular systolic function
-normal is 60%
-echocardiogram is teh best way to look at the EF
Regulation of Stroke Volume
--what will increase the preload
-Preload: degree of stretch of cardiac muscle before they contract (Frank-starling law of the heart)
-slow heartbeat and exercise increase venous return
*increased venous return stretches the ventricles and increases contraction force.
Increased preload ____ SV
Increase afterload _____ SV.
Increasing contractile state increases _____.
Increased preload increases stroke volume
Increased afterload decreases SV
Increasing contractile state increases SV.
Regulation of Stroke Volume:
-contractile strength at a given muscle length, independent*? of muscle stretch and EDV.
-positive inotropes: increase contractility, increased Ca2+ influx d/t sympathetic stimulation. Hormones (thyroxine, glucagon, and epi)
-Negative inotropic agents decrease contractility; acidosis, increased extracellular K+, calcium channel blockers.
What is afterload?
pressure that must be overcome for ventricles to eject blood.
Describe the sympathetic effects on heart rate? Parasympathetic?
-releases NE causing increase sinus node discharge leading to increases rate of conduction and contraction in atria and ventricles
*positive inotropic and chronotropic
-releases Ach hyperpolarizing pacemaker cells by opening K+ channels, opposing sympathetic effects. ONLY EFFECTS RATE!!! (Chronotropic)
What is the Atrial Reflex?(Bainbridge)
-sympathetic reflex initiated by increased venous return, stretch of atrial walls stimulates the SA node to fire