Cardiovascular- Physiology

Question 1

Do Purkinje fibers and the Bundle of His undergo action potentials that resemble ventricular muscle tissue or pacemaker cells?

Answer 1

Ventricular Muscle Tissue

Question 2

What occurs during phase 0 of ventricular action potential?`

Answer 2

Fast acting sodium channels open and sodium floods into the cell

Question 3

What occurs during phase 1 of ventricular action potential?

Answer 3

Voltage-gated potassium channels open and potassium goes down its concentration gradient and leaves the cell.

Question 4

What occurs during phase 2 of ventricular action potential?

Answer 4

Voltage-gated calcium channels open and calcium enters the cell directly balancing potassium current.

Question 5

What occurs during phase 3 of ventricular action potential?

Answer 5

Calcium channels close and potassium continues to flow out of the cell.

Question 6

What occurs during phase 4 of ventricular action potential?

Answer 6

Voltage-gated potassium channels are closed but high potassium permeability. So potassium is leaking into the cell and sodium and calcium are exiting

Question 7

What occurs during phase 0 of pacemaker action potential?

Answer 7

L-type calcium channels open and calcium enters the cell

Question 8

What occurs during phase 3 of pacemaker action potential?

Answer 8

L-type calcium channels close and potassium channels open allowing for the exit of positively charged potassium

Question 9

What occurs during phase 4 of pacemaker action potentials?

Answer 9

Early in phase 4- low potassium current and funny current occurs allowing sodium to enter the cell.
Late in phase 4- T-type calcium channels open allowing calcium to enter cell.

Question 10

What two tissues make up pacemaker action potentials?

Answer 10

SA and AV node

Question 11

What seven drugs can cause a severe decreased in potassium which can lead to prolonged QT?

Answer 11

Some Risky Meds Can Prolong QT:
Sotalol 
Risperidone
Macrolides
Chloroquines
Protease Inhibitors (-navir)
Quinidine 
Thiazides

Question 12

What is torsades de pointes likely to progress to?

Answer 12

Ventricular fibrillation

Question 13

How do you treat torsades de pointes?

Answer 13

Magnesium sulfate

Question 14

What causes congenial long QT?

Answer 14

It is an inherited disorder of myocardial repolarization, typically due to ion channel defects; this leads to increased risk of sudden cardiac death due to torsades de pointes

Question 15

What is Romano-Ward Syndrome?

Answer 15

A congenital long QT syndrome. It is autosomal dominant and produces a pure cardiac phenotype (no deafness)

Question 16

What is Jervell and Lange-Nielsen Syndrome?

Answer 16

A congenital long QT syndrome. It is autosomal recessive and also results in sensorineural deafness.

Question 17

Describe Wolff-Parkinson-White Syndrome.

Answer 17

Most common type of ventricular pre-excitation syndrome. Abnormal fast accessory conduction pathway from atria to ventricle (Bundle of Kent) bypass the rate-slowing AV node.

Question 18

What would the electrocardiograph look like for a patient with Wolff-Parkinson-White Syndrome?

Answer 18

It would have a shortened PR interval due to a delta wave

Question 19

What can Wolff-Parkinson-White syndrome lead to?

Answer 19

reentry circuit which can then lead to supraventricular tachycardia