Exam #3 - heart stuff Flashcards
(24 cards)
The sinoatrial (SA)
node (pacemaker)
generates impulses.
Heart contraction step 1
The impulses
pause (0.1 s) at the
atrioventricular
(AV) node.
Heart contraction step 2
The atrioventricular
(AV) bundle
connects the atria
to the ventricles.
Heart contraction step 3
The bundle branches
conduct the impulses
through the
interventricular septum.
Heart contraction step 4
The Purkinje fibers
depolarize the contractile
cells of both ventricles
Heart contraction step 5
– Delays impulses approximately 0.1 second
– Depolarizes 50 times per minute in the absence of
SA node input
Atrioventricular (AV) node
Only electrical connection between the atria and
ventricles
Atrioventricular (AV) bundle (bundle of His)
Two pathways in the interventricular septum that
carry the impulses toward the apex of the heart
Right and left bundle branches
– Cause the apex of the heart, the papillary muscles
and the ventricular walls to depolarize
Purkinje fibers
heart sounds are caused by what opening and closing
valves
↑↑ The cardioacceleratory center innervates the SA and
AV nodes, heart muscle, and coronary arteries
through _____ neurons
sympathetic
↓↓ The cardioinhibitory center inhibits SA and AV
nodes through __________ fibers in the vagus nerve
parasympathetic
wave of depolarization of SA node
P wave
wave of ventricular repolarization
T wave
When the heart is contracting
Systole
When the heart is relaxing
Diastole
volume of blood in the left ventricle
at the end of ventricular diastole
End Diastolic Volume (EDV)
volume of blood remaining in the left
ventricle after systole
End Systolic Volume (ESV)
volume of blood ejected from the left
ventricle (EDV-ESV)
Stroke Volume (SV)
Volume of blood pumped each
minute (ml/min)
Cardiac Output (Q)
Factors that affect SV
- Preload
- Contractility
- Afterload
stretch of the heart immediately
before contraction
Preload
force of contraction
Contractility
back pressure of blood on the
semi-lunar valves
Afterload
