Cardiac Potentials Flashcards
RMP - TP SA and AV nodes
-50 to -40
RMP -TP Atrial and Ventricular muscles
-85 to -65
cells with stable RMP
ordinary myocradial cells
cells with unstable RMP
P cells and Purkinje cells
determinants of RMP
permeability of membrane to ions and concentration gradients
main ion determinant of RMP
K high permeability and high concentration gradient
ionic basis of RMP
more positively charged ions outside the cell
RMP of SRAP synonyms
Pacemaker Potential, Spontaneous diastolic depolarization, prepotential
reason for PP accdg to Guyton
Inherent leakiness to Na of nodal cells due to: 1.high concentration of Na outside the cell 2.negative charge inside the cell 3.moderate number of open Na channels
ways by which discharge rate of pacemaker cells may be altered
1.changing rate of diastolic depolarization 2.changing threshold potential 3.changing the level of initial RMP
more negative threshold potenital
sympathetic; faster prod of AP
less negative TP
parasympathetic; longer to reach/slower depol
effect CNS on rate of diastolic depolarization
sympa: increase slope= faster; parasympathetic:dec slope = slower
effect of CNS on level of initial RMP
parasympathetic = more negative = slower AP sympathetic: no effect
FRAP ARP
from onset of phase 0 -> repol to -55mV
FRAP RRP
Durint phase 3 when Na and Ca channels start to recover. from -55mV to end of AP
Supernormal Period
FRAP; lesser stimulus needed for AP, immediately after AP
ARP of ventricle
0.25-0.30 sec
RRP of Ventricle
0.05 sec
ARP of Atria
0.15sec
postrepolarozation refractoriness
RRP way beyond phase 3
60-100 impulses/min
SA node
40-60 impulses/min
AVN
His-purkinje system
25-40 impulses/min
AVN firing rate
40-60 impulses/min
SAN firing rate
60-100 impusles/min
impulse conduction for SA node
0.05m/sec
impulse conduction for interatrial & internodal tracts
1m/sec
impulse conduction for AV node
0.05m/sec
impulse conduction for bundle of His
1m/sec
right and left bundle branches impulse conduction
1m/sec
terminal purkinje network impulse conduction
4m/sec
atrial & ventricular muscle fibers impulse conduction
0.3-0.5 m/sec
