Intro Flashcards
(40 cards)
What is systole?
Period of contraction, force generation and blood.
What is diastole?
Period of relaxation, filling with blood, readying for next systole
Is blood volume constant or does it change?
It is always constant
-volume increases it one area, it has to decrease in another
Left arterial fibrillation would most greatly affect filling of which heart chamber?
-left ventricle
Describe the specialized conducting system in the heart and what it is it responsible for?
- highly modified monocytes, no contraction (only action potentials), connected by gap junctions
- responsible for rhythmic excitation and coordinated contraction of heart muscle.
The heart is auto rhythmic and modulated by what?
ANS
Dysregulation of the heart leads to what?
Arrhythmia and altered pump function
What node is the first to depolarize?
The sinus node (right atria)
What does the sinus node do?
- pacemaker of the heart
- connected by gap junctions to atrial cardiomyocytes
- causes arterial contraction
What does the atrioventricular node do?
- carries AP from atria to ventricles
- has fewer gap junctions
- has reduced conduction velocity(slower to depolarize)
- allows atria to fully contract before ventricles do
The AV bundle is also called what?
Bundle of His
What do the bundle branches do?
There is a left and right and they feed each ventricle
What does the perkinje system do?
- they are large diameter cells
- speeds conduction to ventricular monocytes
Where does contraction occur?
Ventricular myocytes
Contraction occurs in what direction?
From the apex to the base of the heart
Coordination of depolarization allows for what?
Maximal blood ejection
All of the heart is auto-rhythmic, but do they all depolarize at the same time?
Nope. They all have an unstable RMP, but they all have different depolarization rates.
Why is the SA node the pacemaker of the heart>
- it is the fastest to depolarize
- it fires while others are still slowly depolarizing
What is the other location that can serve as the pacemaker if something happens to the SA node??
The AV node
When would an ectopic pacemaker override the SA node?
-the SA node slows and the ectopic location is faster
The heart is primarily under what control?
Parasympathetic
In what two ways is the heart rate modulated?
- Altering SA node firing rate
2. Altering conduction through the AV node
Sympathetic: what kind of chronotrope and what does it do? What kind of receptors?
- positive chronotrope
- increases HR
- increases funny current
- increases calcium current
- Beta 1 receptors
Parasympathetic: what kind of chronotrope? What does it do? What kind of receptors?
- Negative chronotrope
- reduces HR
- decreases funny current
- decreases calcium current
- increase potassium current
- M2 receptors
