copyright © 2009 pearson education, inc., publishing as benjamin cummings heart continued

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Heart Continued


Review Blood Flow


Coronary Circulation Blood in the heart chambers does not nourish the

myocardium (heart muscle) The heart has its own nourishing circulatory system

consisting of Coronary arteries—branch from the aorta to supply the

heart muscle with oxygenated blood Cardiac veins—drain the myocardium of blood Coronary sinus—a large vein where all of the cardiac

veins come together on the posterior of the heart, receives blood from cardiac veins


Coronary Circulation Blood empties into the right

atrium via the coronary sinusBlood from the heart enters the coronary arteries through a branch at the base of the aorta.


Coronary Circulation Angina pectoris:

-Chest pain due to inadequate supply of oxygen to the muscle

-Indication some degree of coronary vessels blockage

Myocardial infarction:

- Medical term for heart attack

-Heart cells die from lack of blood supply

-Usually caused by blockage of one of the coronary arteries


The Heart: Conduction System Intrinsic conduction system (nodal system)

Heart muscle cells contract, without nerve impulses, they use nodes

http://www.dailymotion.com/video/xhp35u_argosy-medical-animation-sectioned-heart_tech

Heart beat sounds: “lub dub”

Sounds are made by the closing of the valves

Lub is the AV valves closing

Dub is the SA valves closing


The Heart: Conduction System Special tissue:

Sinoatrial node = SA node (“pacemaker”), in right atrium

Atrioventricular node = AV node, at junction of the right atrium near the interatrial septum

Atrioventricular bundle = AV bundle in the interventricular septum

Bundle branches in the interventricular septum

Purkinje fibers spread within the ventricle wall muscles


SA node (sino-atrial node) acts as the heart’s

“pacemaker” cells whose primary

function is electrical conduction, not contractility

the action potential produced by its depolarization spreads across the atria

(remember that action potential is the movement of molecules across the membranes of cells to create electrical current)


Heart Contractions Impulse spreads to

the AV node Then the atria

contract impulse passes

through the AV bundle, bundle branches, and Purkinje fibers

the ventricles contract


Heart Contraction http://highered.mcgraw-hill.com/sites/0072495855/

student_view0/chapter22/animation__conducting_system_of_the_heart.html


Heart Contractions

Figure 11.6


The Heart: Cardiac Cycle

The cardiac cycle refers to 1 complete heart beat

Normally .8 sec for 1 cardiac cycle

Cardiac cycle includes: Systole = contraction Diastole = relaxation

Relates to the ventricles, unless otherwise stated


Heart ContractionsNormal Heart Rate: 75 beats/min Tachycardia—rapid heart rate over 100 beats per

minute (tachy= fast) Bradycardia—slow heart rate less than 60 beats

per minutes (brady= slow)


Filling Heart Chambers: Cardiac Cycle


The Heart: Cardiac Cycle Cardiac cycle—events of one complete heart beat

Mid-to-late diastole—blood flows from atria into ventricles

Ventricular systole—blood pressure builds before ventricle contracts, pushing out blood

Early diastole—atria finish refilling, ventricular pressure is low

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/animation__the_cardiac_cycle__quiz_1_.html

copyright © 2009 pearson education, inc., publishing as benjamin cummings heart continued

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