Electrical Properties of the Heart and Conduction System

Question 1

SA Node

Answer 1

Sinoatrial Node. Normal site of origin of the electrical impulse. The hearts natural pacemaker. SA node travels through the right and left atria resulting in the atrial contraction.

Question 2

AV Node

Answer 2

Atriocentricular node. Transiently slows electrical impulse.

Question 3

Bundle of His

Answer 3

A continuation of the AV node. Bundle branches procede the Bundle of His.

Question 4

Pukinje Fibers

Answer 4

Fibers that go to the left and right ventricles.

Question 5

Excitability

Answer 5

The ability of cells to respond to electrical impulses.

Question 6

Conductivity

Answer 6

The ability of cells to conduct electrical impulses.

Question 7

Intrinsic Automaticity

Answer 7

The ability to generate an impulse to contract without the need of a nerve stimulus. (CARDIAC CELLS)

Question 8

Chronotropic State

Answer 8

Hearts rate of contraction (monitored by various systems in the body)

Question 9

Dromotropic State

Answer 9

Hearts rate of electrical conduction (monitored by various systems in the body)

Question 10

Inotropic State

Answer 10

Hearts strength of contraction (monitored by various systems in the body)

Question 11

Chemoreceptors

Answer 11

Detect chemical changes in the blood.

Question 12

Baroreceptors

Answer 12

Sense the pressure in the heart or arteries.

Question 13

Contractility

Answer 13

Strength of heart muscle contraction.

Question 14

Parasympathetic Stimulation

Answer 14

Slows heart by affecting AV node

Question 15

Sympathetic Stimulation

Answer 15

Alpha OR Beta effects; depending on what nerve receptor is stimulated.

Question 16

ALPHA effects

Answer 16

Alpha receptors are stimulated resulting in vasoconstriction

Question 17

BETA effects

Answer 17

Beta receptors are stimulated resulting in increased inotropic,dromotropic, and chronotropic states.

Question 18

Epinephrine

Answer 18

Hormone that has a greater stimulatory effect on BETA receptors.

Question 19

Norepinephrine

Answer 19

Hormone that has a greater stimulatory effect on ALPHA receptors.

Question 20

Electrolytes

Answer 20

IONS. Charged chemicals.

Question 21

Na+

Answer 21

Sodium. Concentration is greater OUTSIDE of the cell.

Question 22

K+

Answer 22

Potassium. Concentration is greater INSIDE of the cell.

Question 23

Ca2+

Answer 23

Calcium.

Question 24

Electrical Potential

Answer 24

Cellular Electrical Charged difference across the membrane. Measured in Millivolts.

Question 25

Resting Cell

Answer 25

Negative Electrical Pote - Extracellular space is more positively charged than the intracellular space.

Question 26

Polarized State

Answer 26

Resting cells normally have a NET negative charge with respect to the outside of the cell.

Question 27

Depolerization

Answer 27

Heart cell gets a stimulus from the conduction system. Sodium (Na+) rushes in, along with some calcium (Ca2+). Changing the charge of the cell. Makes the intracellular slightly positive charged.

Question 28

Repolarization

Answer 28

The process in which the cell can get back to the POLERIZED state (net negative).Depolerization slows down…Potassium (k+) starts to flow out of the cell, and the sodium potassium pump starts to activate based on the charge needs of the cell to keep it at a polarized state (net negative).

Question 29

Absolute Refractory Period

Answer 29

EARLY phase of repolarization when the cell contains a large concentration of ions that it cannot be stimulated to depolerize.

Question 30

Relative Refractory Period

Answer 30

LATE stage of repolarization, cells are able to respond to a stronger stimulus.

Question 31

ECG

Answer 31

Electrocardio gram a graphic recording of the electrical activity of the heart

Question 32

P wave

Answer 32

Occurs first. Represents the electrical impulse through the atria

Question 33

P-R

Answer 33

Flat line between the p and r… Represents the time delay within the AV node

Question 34

QRS

Answer 34

QRS complex. Represents the DEPOLARIZATION of the ventricle contraction.

Question 35

ST segment

Answer 35

The pause after the QRS complex. This is where repolarization is beginning.

Question 36

T

Answer 36

Represents completion of REPOLARIZATION.

Question 37

Cardiac Cycle

Answer 37

From contraction of the myocardium to the next contraction

Question 38

Systole

Answer 38

Ventricular contraction. Blood is pumped to the body (systemic) and lungs (pulmonary) via contraction of the ventricles.

Question 39

Afterload

Answer 39

Pressure in the AORTA.

Question 40

Stroke volume

Answer 40

Amount of blood ejected into the aorta from the left ventricle per contraction

Question 41

Cardiac output

Answer 41

Expressed as the volume of blood pumped through the circulatory system in one minute. LITERS PER MINUTE

Heart rate X stroke volume = cardiac output (lpm)