Lecture 3 Content Flashcards
The right bundle and left posterior bundle are made of:
Purkinje Cells
What are some aspects of the purkinje system
- they are located on the inner ventriculat wall
- they have fast conduction due to having many gaps at the intercalated disks
- they have few sarcomeres
The sinus node (SA) is a _____
pacemaker
Why is the sinus node (SA) node a pacemaker
it has a faster discharge rate
What happends if the SA node fails?
the AV node takes over, if AV fails then the ventricular escape happens
What does the AV node do?
it DELAYS cardiac impluse by a total of 0.16s
A-V His bundle
is a one way conducting path between AV node and AV bundle
What effects does the PSNS have on HR?
- release of Acetylcholine innervates the SA node and AV junction fibers, this causes hyperpolarization and increased K+ permeability in response to acetylcholine, ultimately slowing heart rate down.
What effects does the SNS have on HR?
-Release of nor-epi causes increased SA dicharge causing a faster HR .
-increasing Na+ and Ca2+ permeability leads to more positive resting potential and a faster rate of conduction
How does an EKG work?
Cardiac impluses spread currents into tissues, electrodes are placed on skin and eletctric potentials are recorded.
The P-R interval is
the time between the beginning of atrial contraction and the beginning of ventricular contraction
Tachycardia is
a fast heart rate >100BMP
Bradycardia is
Slow hear rate <60BPM
Atrial fibrilation is
irregular, fast HR due to irregular cardaic impluses at AV node. no clear P wave and pumping eficiency is decreased by 20-30 percent. can lead to blood clots in atria which is fatal
What ion “leaking in” node cell start action potential?
Sodium (Na+)
