intro and electrophysiology

Question 1

What are the two basic cell types in the heart

Answer 1

• myocardial cells
• conducting cells

Question 2

the branching network of myocardial cells is called a

Answer 2

syncytium

Question 3

what are the types of conducting cells

Answer 3

• pacemaker cells
• electrical conducting cells
  
  • bundle branches
  • purkinje fibers

Question 4

myocardial cells are surrounded by a membrane called

Answer 4

a sarcolemma

Question 5

special contact points where the myocardial cells connect are called

Answer 5

intercalated disks

• house gap junctions

Question 6

what structure hold myocardial cells together during contraction

Answer 6

desmosomes

Question 7

electrical impulses in the atria must travel through to get to the ventricles

Answer 7

specific conduction pathways

Question 8

what provides a support structure for the AV and semilunar valves and seperates the upper pumping chambers from the lower chambers

Answer 8

plate of fibrous connective tissue that lies between the atria and ventricles

Question 9

where are the two main baroreceptors found

Answer 9

• aorta
• carotid arteries

Question 10

information from baroreceptors and chemoreceptors is transmitted to the cardioregulatory center in the

Answer 10

medulla oblongata

Question 11

4 functions of sympathetic stimulation on heart

Answer 11

1. increased pacemaker firing
2. increased impulse conduction through heart
3. increased force of contraction
4. coronary vasodilation

Question 12

2 functions of parasympathetic stimulation on heart

Answer 12

1. decreased rate of SA node pacemaker firing
2. decreased rate of impulse conduction through AV node

Question 13

what are the 4 key properties of myocardial cells

Answer 13

1. automaticity
2. excitability
3. conductivity
4. contractility

Question 14

the ability of certain cells to produce an electrical impulse without outside nerve stimulation

Answer 14

automaticity

Question 15

the ability to respond to an electrical stimulus

Answer 15

excitability

Question 16

the ability to transmit an electrical stimulus from cell to cell

Answer 16

conductivity

Question 17

the ability to contract when electrically stimulated

Answer 17

contractility

Question 18

function of pacemaker cells

Answer 18

have the ability to spontaneously generate an impulse at a certain rate

Question 19

function of electrical conducting cells

Answer 19

• carry the electrical impulses to the appropriate regions of the heart

Question 20

List the 3 pacemaker cells and their intrinsic rate

Answer 20

• SA node: 60-100 bpm
• AV node: 40-60 bpm
• purkinje fibers: 20-40 bpm

Question 21

where are the SA node and AV node located in the heart

Answer 21

• SA node: posterior right atrium
• AV node: low right atrium

Question 22

list conduction pathway through heart

Answer 22

• SA -> AV- > bundle of HIS -> right and left bundle branches (left -> anterior and posterior fascicles) -> purkinje fibers: spread throughout myocardium

Question 23

what are primary charges inside and outside of myocardial cell in polarized state

Answer 23

• resting state
• negatively charged ions INSIDE cell
• Positively charged ions OUTISDE cell

Question 24

depolarization occurs when what ions enter the cell

Answer 24

• positive ions
  
  • Na+
  • Ca²⁺

Question 25

what happens during repolarization

Answer 25

* after depolarization * positive ions (Na+, Ca2+, K+) leave the cells and interior cells returns to its negatively charged state

Question 26

list two types of refractory periods

Answer 26

1. absolute refractory period: following depolarization, cells is resistant to further depolarization 2. relative refractory period: in the late phase of repolarization, a very strong electrical stimulate will cause depolarization

Question 27

bipolar leads have what electrodes

Answer 27

* positive and negative electrodes

Question 28

unipolar leads have what electrodes

Answer 28

only a positive electrode

Question 29

list the bipolar leads

Answer 29

* the limb leads

Question 30

what are the limb leads

Answer 30

* I, II, III

Question 31

list the unipolar leads

Answer 31

* chest/precordial leads * augmented limb leads

Question 32

list the chest/precordial leads

Answer 32

V1-V6

Question 33

list the augmented limb leads

Answer 33

* aVR: right arm * aVL: left arm * aVF: foot

Question 34

lead I goes from

Answer 34

* right arm (-) to left arm (+)

Question 35

lead II goes from

Answer 35

* right arm (-) to left leg (+)

Question 36

lead III goes from

Answer 36

* Left arm (-) to left leg (+)

Question 37

movement toward a positive electrode appears as what on the ECG tracing

Answer 37

upright, above the baseline

Question 38

movement away from a positive (toward a negative) electrode appears as what on the ECG tracing

Answer 38

below the baseline

Question 39

ECG records the sum of all the small directional electrical currents, these are called ? and their sum is called _?_

Answer 39

1. vectors 2. electrical axis

Question 40

P wave represents

Answer 40

atrial depolarization

Question 41

QRS complex represents

Answer 41

ventricular depolarization

Question 42

T wave represents

Answer 42

ventricular repolarization

Question 43

atrial repolarization is hidden in the

Answer 43

QRS wave