EKG, Test 1, MSState, Joe/ 155 Qs with
Complete Ans/ 2024-2025.
What does an EKG tell us? - Answer: the electrical activity of the heart
What are the primary functions of the heart? - Answer: -To pump blood throughout lungs and
body
-Oxygen and nutrient delivery
-Removal of waste products
-Pulmonary circuit
-Systemic circuit
What kind of rhythm is generate if the SA node is acting as the pacemaker of the heart? -
Answer: Sinus
What kind of rhythm is generated if any other part of the heart is acting as the pacemaker? -
Answer: Ectopic
Page 1 of 24
,Describe the characteristics of the SA node - Answer: -Superior aspect of right atrium (top)
-Natural Pacemaker of the heart (intrinsic rate of 60-99 ppm)
-*leakiest to sodium*
Describe the characteristics of the AV node - Answer: -Located in floor of right atrium
-Delays impulse ~0.1 sec
-Allows time for filling of ventricles and AV valve closure
-Contains pacemaker cells that can initiate the heart beat, if needed (intrinsic rate of 40-60
bpm)
What does chronotropic regulation control? - Answer: HR
What does inotropic regulation control? - Answer: Force of contraction
What channels open up during depolarization? - Answer: Na+
What channels open up during repolarization? - Answer: K+
What is the purpose of the Bundle of HIS? - Answer: -Speeds up impulse and delivers it to
bundle branches
-Contains pacemaker cells that can initiate the heart beat, if needed (intrinsic rate of 40-60
bpm)
What are the Bundle Branches? - Answer: -Right and left branches travel that along the
interventricular septum
-Left bundle branch divides into the anterior and posterior fascicles
Page 2 of 24
, What is the purpose of the Purkinje Fibers? - Answer: Conducts impulse quickly throughout
ventricular myocardium to allow for simultaneous contraction of all parts of ventricles
Describe the State of Polarization - Answer: 1. Polarized- Resting state (RMP,-70mV), No
electrical activity
2. Depolarized- Positively charged ions enter the cell
3. Repolarization- Positively charged ions leave the cell, Return to resting state
How many phases does a non pacemaker cell go through? What is the order? - Answer: -all 5
stages
-4,0,1,2,3
How many phases do pacemaker cell go through? What is the order? - Answer: -only 3
-4,0,3
What are the 5 phases of action potential? - Answer: 1. Phase 4: Resting phase. Ready to
receive stimulus.
-Na+ leaks in during funny currents.
2. Phase 0: Rapid depolarization
-Mainly Na+ entry in non-pacemaker cells
-Mainly Ca++ entry in pacemaker cells
3. Phase 1: Early depolarization
-Rapid inactivation of Na+ channels and a rapid opening and closing of K+ channels, allowing a
brief K+ outflow, making the membrane slightly more negative again
-referred to as the "notch" on the action potential waveform
4. Phase 2: Plateau
-At this time, repolarization begins very slowly as K+ channels open (K+ leaves cell) while Ca++
and Cl- channels open (Ca++ and Cl- enter cell)
5. Phase 3: Rapid repolarization
Page 3 of 24
Complete Ans/ 2024-2025.
What does an EKG tell us? - Answer: the electrical activity of the heart
What are the primary functions of the heart? - Answer: -To pump blood throughout lungs and
body
-Oxygen and nutrient delivery
-Removal of waste products
-Pulmonary circuit
-Systemic circuit
What kind of rhythm is generate if the SA node is acting as the pacemaker of the heart? -
Answer: Sinus
What kind of rhythm is generated if any other part of the heart is acting as the pacemaker? -
Answer: Ectopic
Page 1 of 24
,Describe the characteristics of the SA node - Answer: -Superior aspect of right atrium (top)
-Natural Pacemaker of the heart (intrinsic rate of 60-99 ppm)
-*leakiest to sodium*
Describe the characteristics of the AV node - Answer: -Located in floor of right atrium
-Delays impulse ~0.1 sec
-Allows time for filling of ventricles and AV valve closure
-Contains pacemaker cells that can initiate the heart beat, if needed (intrinsic rate of 40-60
bpm)
What does chronotropic regulation control? - Answer: HR
What does inotropic regulation control? - Answer: Force of contraction
What channels open up during depolarization? - Answer: Na+
What channels open up during repolarization? - Answer: K+
What is the purpose of the Bundle of HIS? - Answer: -Speeds up impulse and delivers it to
bundle branches
-Contains pacemaker cells that can initiate the heart beat, if needed (intrinsic rate of 40-60
bpm)
What are the Bundle Branches? - Answer: -Right and left branches travel that along the
interventricular septum
-Left bundle branch divides into the anterior and posterior fascicles
Page 2 of 24
, What is the purpose of the Purkinje Fibers? - Answer: Conducts impulse quickly throughout
ventricular myocardium to allow for simultaneous contraction of all parts of ventricles
Describe the State of Polarization - Answer: 1. Polarized- Resting state (RMP,-70mV), No
electrical activity
2. Depolarized- Positively charged ions enter the cell
3. Repolarization- Positively charged ions leave the cell, Return to resting state
How many phases does a non pacemaker cell go through? What is the order? - Answer: -all 5
stages
-4,0,1,2,3
How many phases do pacemaker cell go through? What is the order? - Answer: -only 3
-4,0,3
What are the 5 phases of action potential? - Answer: 1. Phase 4: Resting phase. Ready to
receive stimulus.
-Na+ leaks in during funny currents.
2. Phase 0: Rapid depolarization
-Mainly Na+ entry in non-pacemaker cells
-Mainly Ca++ entry in pacemaker cells
3. Phase 1: Early depolarization
-Rapid inactivation of Na+ channels and a rapid opening and closing of K+ channels, allowing a
brief K+ outflow, making the membrane slightly more negative again
-referred to as the "notch" on the action potential waveform
4. Phase 2: Plateau
-At this time, repolarization begins very slowly as K+ channels open (K+ leaves cell) while Ca++
and Cl- channels open (Ca++ and Cl- enter cell)
5. Phase 3: Rapid repolarization
Page 3 of 24
