A
What is the function of the pericardium?
- anchors the heart
- acts as a constraint to enable ventricular interaction
- lubrication (pericardial fluid)
What anchors AV valves to the papillary muscles?
Chordae tendinae
Regarding the action potential of the myocardial contractile cells, what happens during:
- depolarization
-plateau
-repolarization
- Na+ moves in.
-Ca++ moves in, stays depolarized
- K+ moves out
What are the effects of pacemaker cells being more depolarized? (modulation of heart rate by the sympathetic nervous system)
- they are closer to threshold
- will reach threshold faster
- increased heart rate
A heart beat of 60 to 120bmp is called:
Sinus rhythm
Function of the surface coronary arteries.
Prevent compression during contraction
What is stenosis?
- Narrowing of the heart valve.
- faulty opening (decreased ejection)
What is the average bpm of the AV node?
40bpm
what are the effects of the pacemaker being hyperpolarized? (modulation of heart rate by the parasympathetic nervous system)
- further from threshold
- takes longer to reach threshold
- slower heart rate (normal resting condition)
A heart rate of more than 100bpm is called:
Tachycardia
Function of heart valves.
Prevent back-flow of blood.
What are the internal symptoms of insufficiency or regurgitation?
- backflow of blood
-decreased forward ejection
What allows for more efficient ejection and produced diastolic suction for more efficient filling.
Ventricular torsion
- atrial depolarization
- initiates atrial contraction
A heart rate of less than 60 bpm is called:
When are the pulmonary/aortic valves open?
The pulmonary/aortic valves are open in systole (ventricular contraction)
When is stenosis heard?
- Whistling heard when valve should be open
What type of cell generates and spreads action potentials? (includes pacemaker cells and conduction cells)
Autorhythmic Cells
On an ECG, what does the QRS complex represent?
- ventricular depolarization and atrial repolarization
- initiates ventricular contraction
What is Heart Block?
- interruption in conduction system
-impulses from atria can't always reach ventricles
-normal P waves, fewer QRS
When are the atrio-ventricular valves open?
The AV valves are open during diastolic filling
When is insufficiency heard?
Whirring heard when valve should be closed.
Why is there a long refractory period for cardiac muscle?
The long refractory period prevents tetanus and allows for relaxation and diastolic filling each beat
On an ECG, what does the T wave represent?
- ventricular repolarization
- initiates ventricular relaxation
What are the effects of ventricular fibrillation?
No organized pattern of depolarization
- no organized contraction
-no ejection
-leads to death