Cardiophysiology Winden

Question 1

Ionotropy

Answer 1

• The force of contraction
• positive or negative ionotropic

Question 2

Chronotropy

Answer 2

• Rate
• Positive or negative

Question 3

Dromotropy

Answer 3

• Conduction velocity

Question 4

What are the 2 types of cardiac muscle cells?

Answer 4

• Condusting System
  
  • Controls and coordinates heartbeat
• Contractile cells
  
  • Produce contractions that propel blood
• Both are myocytes

Question 5

Trachycardia

Bradycardia

Arrhythmia

Dysrhythmia

Question 6

Conducting system cells function

Answer 6

• Controls and coordinates heartbeat
• Initiates and distributes electrical impulses that stimulate contraction
• Automaticity

Question 7

Contractile cells function

Answer 7

• Produce contraction to propel blood
• Purkinje fibers distribute stimulus to contractile cells
  *

Question 8

Cardiac contraction and calcium

Answer 8

• Contraction produced by calcium ion concentration around myofibrils
• 20% of Ca ions required are extracellular (cardiac muscle very sensitive to extracell Ca)
  
  • enter plasma mebrane during plateau phase
• Arrival of extracell Ca triggers SR to release Ca reserves
• As calcium channels close Intracell ca is absorbed or pumped out

Question 9

Where does the heart get aerobic energy from

Answer 9

• Mitochondrial breakdown of fatty acids and glucose
• Oxygen from circulating hemoglobin
• Cardiac muscles store oxygen in myoglobin

Question 10

Components of conducting system

Answer 10

• SA node
• Internodal pathways
• AV nodes
• AV bindle
• Bundle branches
• Purkinje fibers

Question 11

Prepotential

Answer 11

• AKA pacemaker potential
• Resting potential of conducting cells
  
  • gradually depolarizes toward threshold
• SA node depolarizes first, establishing heart rate

Question 12

SA Node location and features

Answer 12

• In posterior wall of right atrium
• Contains pacemaker cells
• Connected to AV node by internodal pathways
• Begins atrial activation

Question 13

AV node

Answer 13

• In floor of right atrium
• Stimulus spreads across atrial surfaces and reaches AV node

Question 14

AV bundle location and action

Answer 14

• In septum
• Carries impulse to left and right bundle branches
  
  • which conduct to Purkinje fibers
• And to the moderator band
  
  • Which conducts to papillary muscles

Question 15

Purkinje fibers action

Answer 15

• Distribute impulse through ventricles
• Atrial contraction is completed
• Ventricular contraction begins

Question 16

P Wave

Answer 16

Atria depolarize

Question 17

QRS complex

Answer 17

Ventricles depolarize

Question 18

T wave

Answer 18

Ventricles repolarize

Question 19

P-R Interval

Answer 19

From start of atrial depolarization

Tostart of QRS complex

Question 20

Q-T interval

Answer 20

From ventricular depolarization

To ventricular repolarization

Question 21

Which portion of ECG is the only isoelectric period when the entire ventricle is depolarized?

Answer 21

S-T segment

Question 22

Cardiac cycle is the period…

Answer 22

• Period between start of one heartbeat and beginning of the next
• Includes both contraction and relaxation

Question 23

What are the 2 phases of cardiac cycle

Answer 23

• Within any one chamber (atrial or ventricular)
  
  • Systole (contraction)
  • Diastole (relaxation)

Question 24

Atrial Systole steps

Answer 24

• Atrial systole
  
  • Atrial contraction begins
  • Right and left AV valves are open
• Atria eject blood into ventricles
  
  • Filling ventricles
• Atrial systole ends
  
  • AV valves close
  • Ventricles contain max blood volume
  • Known as end-diastolic volume

Question 25

Ventricular Systole Steps

Answer 25

• Ventricles contract and build pressure
  
  • AV valves close cause isovolumetric contraction
• Ventricular Ejection
  
  • Ventricular pressure exceeds vessel pressure opening the semi-lunar valves allowing blood to leave
  • Amount of blood ejected is called Stroke Volume
• Ventricular pressure falls
  
  • Semi-lunar valves close
  • Ventricles contain End-Systolic Volume, about 40% of end diastolic volume

Question 26

Ventricular Diastole

Answer 26

• Ventricular pressure is higher than atrial pressure
  
  • All heart valves are closed
  • Ventricles relax (isovolumetric relaxation)
• Atrial pressure is higher than ventricular pressure
  
  • AV valves open
  • Passive atrial filling
  • Passive ventricular filling