Exam 1

Question 1

Equation for Work

Answer 1

Work = Pressure X Volume

Question 2

Effective Refractory Period

Answer 2

period of NO AP regardless of signal sent in the heart

Question 3

Relative Refractory Period

Answer 3

period after EFP (near end of plateau phase 2) that requires stronger signal to stimulate another AP – moving subsequent AP closer together

Question 4

Parasympathetic Effects on Heart

Answer 4

Vagal nerve innervates SA node and AV fibers proximal to AV node – vagal stimulation releases ACh which increases permeability of K+ causing hyper polarization

lower resting membrane potential makes it longer for the cell to depolarize therefore less AP firing and lower HR

Question 5

Sympathetic Effects on Heart

Answer 5

NE causes increase in permeability of depolarizing ions (Na and Ca) therefore faster depolarization and increase HR

Question 6

PR interval

Answer 6

atrial depolarization time (beginning of atrial depolarization to beginning to ventricular depolarization)

p wave to beginning of QRS

Question 7

RR interval

Answer 7

time between on heart beat

Question 8

QT interval

Answer 8

full cycle of ventricular contraction from depolarization to repolarization

Question 9

ST interval

Answer 9

Time between end of ventricular depolarization and beginning to ventricular repolarization

Question 10

Rough directions for conductivity of heart

Answer 10

Lead I, Lead II, and aVF

Question 11

V1

Answer 11

right 4th intercostal space

Question 12

V2

Answer 12

left 4th intercostal space

Question 13

V4

Answer 13

5th intercostal space at midclavicular line

Question 14

V3

Answer 14

between V2 and V4

Question 15

V6

Answer 15

5th intercostal space at midaxillary line

Question 16

V4

Answer 16

between V4 and V6

Question 17

Right Axis Deviation

Answer 17

• LV failure

- hypertrophy of right ventricle (thus more current would flow there

Question 18

First Degree AV incomplete block

Answer 18

• DELAY (not block) above bundle of His
• prolonged PR interval that is greater than 0.20 seconds
  (normally 0.16s) but not higher than 0.35 seconds

Question 19

Second degree AV Block

Answer 19

-block above or below bundle of His
- some signals get conducted and some do not
sinus is still firing regularly, so p wave (depolarization) signal may or may not be conducted
-ECG shows periodic drops of heart beat (can be every other or every third)

Question 20

Third Degree AV block

Answer 20

total block at the AV node – leading to Stokes Adam’s Syndrome
- ventricles stop contracting for 30s due to “overdrive suppression”