EKG 1A.4

Question 1

cardiac conduction (electrical activity) results in

Answer 1

the mechanical beating of the heart

Question 2

what is the mechanical beating of the heart created by

Answer 2

electrical impulses moving throughout the conduction system

Question 3

the movement of 3 types of ions determines all aspects of cardiac ___,___,____

Answer 3

depolarization, contraction, and repolarization

Question 4

cell to cell conduction is called

Answer 4

depolarization

Question 5

depolarization through the myocardium is carried by what ions?

Answer 5

Na+ ions

Question 6

depolarization may be considered an advancing of

Answer 6

wave of positive charges within the heart’s myocytes

Question 7

what conduction is due to the slow movement of Ca+ ions

Answer 7

AV node conduction

Question 8

what produces myocardial contraction

Answer 8

the release of free Ca2+ ions into the interiors of the myocytes

Question 9

repolarization is due to the….

Answer 9

outflow of K+ ions from the myocytes

Question 10

normal heart rate

Answer 10

60-100 bpm

Question 11

bradycardia heart rate

Answer 11

less than 60 bpm

Question 12

tachycardia heart rate

Answer 12

greater than 100 bpm

Question 13

where is the SA node?

Answer 13

located in the wall of the right atrium

Question 14

the SA node gives origin spontaneously to

Answer 14

rhythmical impulses that spread in all direction through the cardiac muscle of the atria
as a result, the atrial muscle contracts

Question 15

where is the AV node located?

Answer 15

lower part of the right atrium just above the attachment of the septal cusp of the tricuspid valve

Question 16

through the AV node, where is the impulse conducted?

Answer 16

impulse is conducted from the atria to the ventricles

Question 17

what is the speed of conduction through the AV node and why?

Answer 17

very slow which will allow sufficient time for the atria to empty their blood into the ventricles completely

Question 18

what is another name for AV bundle?

Answer 18

bundle of his

Question 19

what is the only pathway that connects the myocardium of the atria to the myocardium of the ventricles electrically?

Answer 19

AV bundle/ bundle of his

Question 20

what does the bundle of his break into?

Answer 20

descended through the fibrous skeleton and through the membranous part of the ventricular septum.
it divides into two branches (RBB and LBB)
at this point, they become continuous with the fibers of the purkinje plexus

Question 21

what is sympathetic innervation?

Answer 21

cardiac accelerator nerves to an alpha adrenergic receptor

Question 22

what is the neurotransmitter for sympathetic innervation

Answer 22

norepinephrine

Question 23

what kind of receptor does norepinephrine have?

Answer 23

adrenergic receptor

Question 24

what is the effects of sympathetic innervation?

Answer 24

increase HR and myocardial contractility by increasing rate of spontaneous depolarization in nodes and increasing calcium inflow to the cell

Question 25

sympathetic nervous system stimulation causes

Answer 25

constriction of arteries

Question 26

SNS stimulation cause: (4)

Answer 26

• positive inotropic state (increased contractility)
• positive chronotropic state (increased frequency)
• positive dromotropic state ( increased conduction velocity)
• positive bathmotropic state (increased irritability)

Question 27

sympathetic innervation is thoracolumbar or craniosacral?

Answer 27

thoracolumbar

Question 28

parasympathetic innervation (vagus nerve) is thoracolumbar or craniosacral?

Answer 28

craniosacral

Question 29

where are sympathetic innervation located?

Answer 29

atria, ventricles, SA node and AV node

Question 30

where are parasympathetic innervation located?

Answer 30

atria, SA node and AV node

Question 31

what is the neurotransmitter for parasympathetic innervation?

Answer 31

acetylcholine

Question 32

what kind of receptor does acetylcholine have?

Answer 32

cholinergic receptor

Question 33

what effects does parasympathetic innervation have?

Answer 33

decrease HR and myocardial contractility by slowing rate of spontaneous depolarization in nodes and decreasing calcium inflow to cell

Question 34

parasympathetic nervous system stimulation causes

Answer 34

dilation of arteries

Question 35

neurons of the ANS are ___-____ neurons

Answer 35

post-ganglionic neurons

Question 36

at rest, the interior of myocytes is

Answer 36

negative (polarized)

Question 37

the ECG records a baseline Calle d

Answer 37

“the isoelectric line”

Question 38

if the EKG shows an isoelectric line, there is

Answer 38

no potential difference on a resting cell

Question 39

in resting myocyte, what is the potential difference

Answer 39

there is no potential difference between points on the cell surface

Question 40

if the positive electrode is in an area of electropositivity, there is an

Answer 40

upward deflection on the EKG

Question 41

what is the absolute refractory period

Answer 41

a period during which the cardiac excitability is totally cancelled

Question 42

what does the absolute refractory period coincide with?

Answer 42

systole (contraction) of the cardiac muscle

therefore, another contraction would never occur except after completion of the systole

Question 43

what does absolute refractory period help prevent

Answer 43

tetanisation of cardiac muscle

Question 44

what is relative refractory period

Answer 44

a period that follows the absolute period and the excitability begins to recover gradually until it reaches its normal value

Question 45

what does the relative refractory period coincide with>

Answer 45

the period of rapid repolarization following the plateau