Cardiac Flashcards
Rate-setting slow response cardiac tissue will depolarize independent of autonomic influence. However, in the presence of sympathetic stimulation, what is the physiologic process that increases heart rate?
lower depolarization threshold
Parasympathetic stimulation of rate-setting tissue results in:
K+ channels opening.
The primary difference between fast response and slow response cardiac action potentials is that:
Fast response potentials are approximately 300 msec in duration.
The term “inward rectifier” is another name for:
K+ channels open at rest.
Open ___ channels are responsible for maintaining voltage in resting state.
Potassium (K+)
After an electrical stimulus is generated by the atrioventricular (AV) node, which ion channels open to affect the depolarization stage 0?
Na+
Cardiac contraction occurs when calcium channels open and calcium influx occurs. What is the stimulus that opens calcium channels?
Depolarization from Na+ influx
In contractile cells, what is happening to Na+ channels in phase 3?
h gates recover.
Which ion is not generally regarded to be a factor in fast response action potentials?
cl-
Which of the following is a unique feature of action potentials in atria?
The plateau phase is not as prominent as fast response cells.
Among the variety of tissue types found in cardiac muscle, which type has the greatest ability to beat autonomously?
Sinoatrial (SA) node tissue
One of the consequences of ischemic myocardium is coronary artery disease (CAD). This can lead to dysrhythmia because it:
Depolarizes myocardium.
The specialized rapid conduction tissue that is important to ventricular muscle contraction is known as:
The His-Purkinje System.
The conduction block phenomenon characterized by slow conduction and unidirectional block is known as:
A re-entry block.
Contraction of cardiac cells occurs as a consequence of filament sliding and binding. Which of the filaments is anchored onto Z bands of the sarcomere?
Actin
