Cardiac Rhythm

Question 1

autonomic NS controls

Answer 1

• rate of impulse
• speed of conduction
• strength of contraction

Question 2

cardiac conduction system

Answer 2

• SA node —> AV node —> Bundle of HIS —> Lt/Rt bundle branches —> purkinje fibres

Question 3

sinus node

Answer 3

• primary pacemaker
• 60-100 bpm

Question 4

av junction

Answer 4

• 40-60 bpm

Question 5

purkinje fibres

Answer 5

• <40 bpm

Question 6

depolarization

Answer 6

• Cells increase permeability
• Na+ floods into cells
• inside + compared to outside

Question 7

repolarization

Answer 7

• slower movement of ions across membrane returns cell to polarized state

Question 8

P wave

Answer 8

• atrial contraction (1st 1/2 Rt 2nd 1/2 Lt)

Question 9

Q wave

Answer 9

• initial phase of depolarization

Question 10

R wave

Answer 10

• depolarization of main mass of ventricles

Question 11

S wave

Answer 11

• depolarization at base of heart (purkinje)

Question 12

QRS complex

Answer 12

• combo or Q R S
• ventricular depolarization
• 0.04-0.10 seconds

Question 13

T wave

Answer 13

• ventricular repolarization

Question 14

PR interval

Answer 14

• start of atrial depol to start of ventricular depolarization
• delay at AV for filling
• 0.12-0.20 seconds

Question 15

QT interval

Answer 15

• start of ventricular depol to end of repol

Question 16

ST segment

Answer 16

• end of QRS to start of T
• end of depol to start of repol

Question 17

sinus rhythm

Answer 17

• normal = 60-100 bpm
• bradycardia = <60 bpm
• tachycardia = >100 bpm

Question 18

shockable rhythms

Answer 18

• ventricular fibrillation
• ventricular tachycardia

Question 19

non shockable rhythms

Answer 19

• PEA
• asystole

Question 20

peaceable rhythms

Answer 20

• heart block (2nd and 3rd degree)
• bradycardia