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Exam 1
Chapter 18 Part 2
44
Anatomy
Undergraduate 3
09/13/2011

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Cards

Term
Is stimulated by nerves and is self-excitable (automaticity)
Contracts as a unit
Has a long (250 ms) absolute refractory period
Definition
Heart Muscle
Term
Use calcium influx (rather than sodium) for rising phase of the action potential (prolonging contracture)
Definition
Autorhythmic cells:
Term
generates impulses about 75 times/minute
Definition
Sinoatrial (SA) node
Term
node delays the impulse approximately 0.1 second
Definition
Atrioventricular (AV)
Term
Impulse passes from atria to ventricles via the
Definition
atrioventricular bundle (bundle of His)
Term
carry the impulse toward the apex of the heart
Definition
Bundle branches
Term
carry the impulse to the heart apex and ventricular walls
Definition
Purkinje fibers
Term
Heart is stimulated by the
Definition
sympathetic cardioacceleratory center
Term
Heart is inhibited by the
Definition
parasympathetic cardioinhibitory center
Term
corresponds to depolarization of SA node error Depolarisation of the atria!!!!
Definition
P wave
Term
corresponds to ventricular depolarization
Definition
QRS complex
Term
corresponds to ventricular repolarization
Definition
T wave
Term
Heart sounds (lub-dup) are associated with closing of heart valves
First sound occurs as
Definition
AV valves close and signifies beginning of systole
Term
Heart sounds (lub-dup) are associated with closing of heart valves
Second sound occurs when
Definition
SL valves close at the beginning of ventricular diastole
Term
contraction of heart muscle
Definition
Systole
Term
relaxation of heart muscle
Definition
Diastole
Term
Phases of the Cardiac Cycle

mid-to-late diastole
Definition
Ventricular filling
Term
Phases of Cardiac Cycle:

AV valves are open, then
Definition
atrial systole occurs
Term
Phases of Cardiac Cycle:

Rising ventricular pressure results in..
Definition
in closing of AV valves(1)
Term
early diastole
Ventricles relax
Backflow of blood in aorta and pulmonary trunk closes semilunar valves
Definition
Isovolumetric relaxation
Term
brief rise in aortic pressure caused by backflow of blood rebounding off semilunar valves
Definition
Dicrotic notch
Term
is the amount of blood pumped by each ventricle in one minute
Definition
Cardiac Output
Term
is the product of heart rate (HR) and stroke volume (SV)
Definition
Cardiac Output
Term
is the amount of blood pumped out by a ventricle with each beat (or stroke)
Definition
SV
Term
is the difference between resting and maximal CO
Definition
Cardiac Reserve
Term
= end diastolic volume (EDV) minus end systolic volume (ESV)
Definition
SV
Term
= amount of blood collected in a ventricle during diastole
Definition
EDV
Term
= amount of blood remaining in a ventricle after contraction
Definition
ESV
Term
amount ventricles are stretched by contained blood
Definition
Preload
Term
cardiac cell contractile force due to factors other than EDV
Definition
Contractility
Term
back pressure exerted by blood in the large arteries leaving the heart
Definition
Afterload
Term
is the critical factor controlling stroke volume
Definition
Preload, or degree of stretch, of cardiac muscle cells before they contract
Term
Agents/factors that decrease contractility include:
Definition
Increased extracellular K+
Calcium channel blockers
Term
chronotropic factors increase heart rate
Definition
Positive
Term
chronotropic factors decrease heart rate
Definition
Negative
Term
is activated by stress, anxiety, excitement, or exercise
Definition
Sympathetic nervous system (SNS)
Term
is mediated by acetylcholine and opposes the SNS
Definition
Parasympathetic nervous system (PNS)
Term
dominates the autonomic stimulation, slowing heart rate and causing vagal tone
Definition
PNS
Term
a sympathetic reflex initiated by increased blood in the atria


Stimulates baroreceptors in the atria, causing increased SNS stimulation
Definition
Atrial (Bainbridge) reflex
Term
Two Hormones that increase heart rate
Definition
epinephrine and thyroxine
Term
must be maintained for normal heart function
Definition
Intra- and extracellular ion concentrations
Term
Fetal heart structures that bypass pulmonary circulation
Definition
Foramen ovale

Ductus arteriosus
Term
connects the two atria
Definition
Foramen Ovale
Term
connects pulmonary trunk and the aorta
Definition
Ductus arteriosus
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