Lab 4

Question 1

What can be the possible directions for cardiac axis?

Answer 1

-30° to +110°

Question 2

Between whch limbs is the potential difference measured with the standard limb leads I/II/III?

Answer 2

I: right and left arm
II: right arm and left leg
III: left arm and left leg

Question 3

What is the effect of stophaninge-G on the stimulus conduction in the AV node?

Answer 3

delays stimulus - negative dromotrophic

Question 4

List the main steps of determining the cardiac axis

Answer 4

• measure R-wave in each lead
• construct vectors
• direction of integral vector = cardiac axis

Question 5

Where is Epinephrine produced?

Answer 5

adrenal medulla

Question 6

What type of acetylcholine receptors are present in the heart?

Answer 6

muscarinic Ach receptors

Question 7

What type of ionchannels does Verpamil block?

Answer 7

Ca2+ channels

Question 8

List 4 of the effects of the acetylcholine on the heart

Answer 8

• negative chronotrophic effect
• negative bathmotrophic effect
• negative dromotrophic effect
• negative inotrophic effect

Question 9

Why does Atropine inhibit the acetylcholine effect on the muscarine Ach receptors?

Answer 9

Atropin binds to the receptors without stimulating

Question 10

Describe a normal PQ segment

Answer 10

Action potential through AV, not enough to create detectable differences - isoelectric line

Question 11

How can the hardness of the pulse be determined?

Answer 11

the power needed to compress it

Question 12

List the reg. waves in the ECG of dogs

Answer 12

P, Q, R, S T

Question 13

Effect of Epinephrine

Answer 13

• positive chronotrphic effect
• positive bathmotropic effect
• positive dromotrophic effect
• positive inotrophic effect

Question 14

Antagonist of Epinephrine

Answer 14

Propanolol

Question 15

Positive waves of ECG in human?

Answer 15

P, R and T

Question 16

Negative waves of the cardiac cycle?

Answer 16

Q, S, and T (except in human and ca.)