dysrhythmias

Question 1

2 ways to change the refractory period

Answer 1

1. change the AP duration

2. blockade of Na channels to recover from inactivation

Question 2

what does the Na/Ca exchanger rely on

Answer 2

concentrations

Question 3

what does active Arrhythmogenesis rely on?

Answer 3

automaticity

Question 4

effect of Ach on phase 4 diastolic depolarization of nodal cells

Answer 4

increased potassium current, reduces slope of phase 4

Question 5

effect of NE on phase 4 diastolic depolarization of nodal cells

Answer 5

increased calcium and funny current, increases slope of phase 4

Question 6

effect of hypokalemia on phase 4 diastolic depolarization of nodal cells

Answer 6

decreased potassium current, increases slope of phase 4

Question 7

effect of mild hyperkalemia on phase 4 diastolic depolarization of nodal cells

Answer 7

increased maximum diastolic potential, increases slope of phase 4

Question 8

effect of severe hyperkalemia on phase 4 diastolic depolarization of nodal cells

Answer 8

significantly depolarized membrane potential, cells become inexcitable

Question 9

what are delayed after depolarizaton (DAD) due to?

Answer 9

cytosolic and/or SR calcium overload

Question 10

what are early after depolarizaton (EAD) due to?

Answer 10

occur earlier (towards end of phase 2/beginning of phase 3); due to altered ion flux during plateau phase

Question 11

what characterizes EAD?

Answer 11

prolonged action potential duration

Question 12

what can result in prolonged APD?

Answer 12

1. reduced K current
2. incr Ca
3. incr Na-Ca exchanger activity
4. incr later Na current

Question 13

in comparison to EAD, DAD is only due to concentrations of what ion?

Answer 13

Ca (thus occurs during phase 4)

Question 14

EAD are associated with ____HR, DAD are associated with _____HR

Answer 14

EAD are associated with low HR, DAD are associated with high HR

Question 15

short PR interval characterized by signal that can reenter atria via accessory pathway and depolarize AV node - what syndrome?

Answer 15

Wolff-Parkinson-White Syndrome

Question 16

passive arrhythmias are generally due to?

Answer 16

cardiac remodeling–>changes in gap jxns, changes in cellular structure

Question 17

role of gap jxns in AV node

Answer 17

there are less–>signal moves slower

Question 18

if there is tissue damage, the AP duration will be ________ after passing thru damaged area

Answer 18

if there is tissue damage, the AP duration will be shorter after passing thru damaged area

Question 19

what is the refractory period dependent on?

Answer 19

Na channels