Cardiovascular System - Lecture 6 Flashcards
What kind of coupling is found in the heart?
excitation - contraction coupling
What are the 5 steps involved in contraction of cardiac muscle after there is depolarization of the plasma membrane?
- opening of plasma membrane L type Ca channels in T-tubules
- flow of calcium in cytosol
- calcium binds to calcium ryanodine receptors on the sarcoplasmic reticulum
- flow of calcium into the cytosol
- cytosolic calcium concentration increases
What is the calcium concentration transient sensitive to?
voltage
Mechanical activity always ___ electrical activity and can have complete dissociation.
lags
What is the normal sinus rhytm?
70 bpm
What is bradycardia?
abnormally slow rhythm (<60 bpm)
What is tachycardia?
abnormally fast rhythm (>100 bpm)
What happens during respiratory sinus arrhythmia?
sinus rate increases as you breathe in and slows as you breathe out
What is pathological sinus tachycardia?
at rest and heart rate >100 bpm
What is blocked during an AV block?
the AV node
How can you treat AV blocks?
with pacemakers
What are premature ventricular complexes?
heartbeats that begin in one of the ventricles (ectopic pacemaker)
What are ectopic pacemakers?
pacemaking sites that can originate in tissues that are beating out of sync with the normal rhythm of the heart
What 2 conditions can premature ventricular complexes produce?
ventricular parasystole and ventricular tachycardia
Is ventricular parasystole dangerous?
no, it is often untreated
