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Chapter 13
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14
Physiology
Undergraduate 1
03/24/2015

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Term
Heart Structure
Definition
-serves as pump to generate a pressure gradient
-Hollow 4 chambered muscular organ:
-2 atria
-2 ventricles
-septum: divides into 2 separate pumps
-fibrous skeleton: divides into 2
functional syncytium
Term
Two pumps of the heart
Definition
-septum divides into 2 pumps
-interatrial & interventricular

1.Right: receives and pumps blood LOW in oxygen; pumps to lungs (pulmonary)

2.Left: receives and pumps blood high in oxygen; pumps to body (systemic)

*both sides pump together and move equal amounts of blood
*left heart wall is much thicker b/c it has more muscle to do more work
Term
Fibrous Skeleton
Definition
-electrically separates the atria and the ventricles into 2 functional syncytium (doesnt conduct electricity)

-anchors myocardium

-foundation into which valves are placed
Term
Heart Valves
Definition
1.Right and Left AV Valves
-right= tricuspid
-left= bicuspid
-open=allow blood flow into ventricles
-closed=prohibit backflow into atria
2.Aortic and Pulmonary Valves
-open=allow blood out of ventricles
-closed=prohibit backflow into ventricle
Term
Intercalated discs
Definition
-special adaptation for cardiac muscle
-connect individual cardiac cells to form branching fibers

1.desmosomes= rivet cells together
2.gap junctions= rapid ion movement
Term
Myocardium
Definition
-myogenic control=doesnt need nerves to work

-99%= contractile cells
-1%= pacemaker cells/autorythmicity
Term
Pacemaker Cells
Definition
-unstable membrane potential; "drift"

1.SA node
-upper wall of right atrium
-70 to 80 BPM
2.AV node
-lower interatrial septum
-40 to 60 BPM
3.Bundle of His
-upper interventricular septum
-15 to 40 BPM
-bundle branches extend through septum
4.Purkinje Fibers
-walls of myocardium and ventricles
-15 to 40 BM=PM

-SA node is pacemaker for entire heart
-AV node delay is only point of contact between atria and ventricles; it holds
message so atrial tissue has time for systole
-ectopic foci= abnormal HR due to lifestyle choices/stress
Term
Cardiac Cycle
Definition
-events in one complete heartbeat
-systole=wringing/emptying
-diastole=relaxed/filling

Atria:
Diastole Systole Diastole
(filling 100%) (empyting 0.1s) (fill)

Ventricles:
Diastole Diastole Systole
(filling 80%) (filling 20%) (empty 0.4s)

*heart spends more time in diastole
Term
AP in contractile cardiac tissue
Definition
1.Rapid Depolarization (Rapid Na+ influx)
2.Long plateau at peak potential (slow Ca2+ influx)
3.Repolarization (K+ efflux)

-long duration b/c plateau time (250m/sec)
Term
Refractory Period of AP
Definition
-whole time of plateau
-prevents initiation of second AP until resting potential is stored
-no Tetanus possible b/c no temporal summation
Term
Electrocardiogram (ECG or EKG)
Definition
1.P wave= SA node fires & atrial depolarization
2.PR interval= internodal delay
3.QRS= ventricles depolarize & atrial repolarization
4.ST segment=ventricles contracting/emptying
5.T Wave= ventricles repolarize
6.TP interval=ventricles relaxed/filling
Term
HR abnormalities
Definition
-trachycardia= fast HR over 100 BPM
-brachycardia= slow HR under 60 BPM
Term
heart murmurs
Definition
-turbulent flow at abnormal times in cardiac cycle

-narrow/stenotic valve=whistle b/c doesnt open completely and blood is forced through
-insufficient/leaky valve=gurgle b/c doesnt close completely and forces blood backwards
Term
Blood Flow Sequence
Definition
Left Atrium
Bicuspid
Left Ventricle
Aortic Semilunar
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Vena Cava
Right Atrium
Tricuspid
Right Ventricle
Pulmonary Semilunar
Pulmonary Arteries
Lungs
Pulmonary Veins
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