16 Electrophysiology of the Heart

Question 1

-this allows the cardiac muscle fibers to act as a functional syncytium so that the atria and ventricles can contract as a unit

-provides low resistance for the spread of excitation from one cell to another

Answer 1

gap junctions

Question 2

Type of muscle that is involuntary and striated

Answer 2

Cardiac muscle

Question 3

____ muscle fibers are shorter and less circular than ____ muscle fibers.

Answer 3

Cardiac

skeletal

Question 4

-Adjacent cardiac myocytes are joined end to end by ____

-contain desmosomes and gap junctions

Answer 4

intercalated discs

Question 5

What hold cells together

Answer 5

Desmosomes

Question 6

In cardiac muscle cells, action potentials are conducted from ____ while in skeletal muscle cells, action potentials are conducted along the length of a ____

Answer 6

cell to cell

single fiber

Question 7

Propagation is slow in this muscle because of gap junctions and the small diameter of fibers

Answer 7

cardiac muscle

Question 8

Propagation is fast in this muscle because of the larger diameter fibers

Answer 8

skeletal muscle

Question 9

The movement of extracellular Ca2+ through the plasma membrane and T tubules into sarcoplasm stimulates the release of Ca2+ from the sarcoplasmic reticulum

Answer 9

calcium-induced calcium release (CICR)

Question 10

What are the Action Potential stages in Cardiac Muscle

Answer 10

Depolarization

Plateau

Repolarization

Refractory period

Question 11

refers to all events associated with blood flow through the heart from the start of one heartbeat to the beginning of the next

Answer 11

The Cardiac Cycle

Question 12

During a cardiac cycle, each
heart chamber goes through two divisions

Answer 12

systole

diastole

Question 13

This represents ventricular filling

Answer 13

Diastole

Question 14

This represents ventricular contraction/ejection

Answer 14

systole

Question 15

Which valve closure causes the “lub” heart sound

Answer 15

Atrioventricular valves (tricuspid & mitral valve)

Question 16

Which valve closure causes the “dub” heart sound

Answer 16

Semilunar valves (pulmonary & aortic valves)

Question 17

involves listening to body sounds, usually with a stethoscope

Answer 17

Auscultation

Question 18

The first heart sound is produced when the ventricles ____ and the ____ valves close

Answer 18

contract

AV

Question 19

The second heart sound is produced when ventricular ____ begins and the ____ valves close

Answer 19

relaxation

semilunar

Question 20

It is a prolonged series of auditory vibrations emanating from the heart or blood vessels that may occur at different times during the cardiac cycle

Answer 20

Cardiac murmurs

Question 21

What are the 3 Cardiac murmurs

Answer 21

Systolic murmurs

Diastolic murmurs

Continuous murmurs

Question 22

murmurs (between S1 and S2) result as blood regurgitates through incompetent AV (mitral and tricuspid) valves, or as blood is ejected through the semilunar (aortic and pulmonary) valves or a ventricular septal defect.

Possible causes of this murmur include aortic stenosis, pulmonic stenosis, mitral insufficiency, tricuspid insufficiency, interventricular septal defect, interatrial septal defect, and functional (physiologic) murmurs and Tetralogy of Fallot.

Answer 22

Systolic murmurs

Question 23

A murmur heard after S2 is designated as diastolic. While pure diastolic murmurs are extremely rare in dogs and cats, they are not uncommon in horses. These murmurs are observed in mitral or tricuspid stenosis, pulmonic insufficiency, aortic insufficiency, and innocent diastolic murmurs.

Answer 23

Diastolic murmurs

Question 24

This murmur is continuous during systole and diastole. In the patent ductus arteriosus (PDA), the fundamental pathophysiologic event is the shunting of blood through the patent duct. The flow direction is usually from the left (aorta) to the right (pulmonic artery) side because of the pressure gradient, but with larger ducts, which are uncommon, the flow ceases or can even be from the right to the left side (so-called reversed PDA).

Answer 24

Continuous murmurs

Question 25

-Record of electrical events in the myocardium that can be correlated with mechanical events

-With each beat, an electrical impulse (or “wave”) travels through the heart

Answer 25

electrocardiogram (ECG)

Question 26

electrical voltages generated by the heart are recorded by the ____ from the surface of the body. P, Q, R, S, and T waves are reflected

Answer 26

electrocardiograph

Question 27

(wave) is the spread of depolarization through the atria, and this is followed by atrial contraction

Answer 27

P wave

Question 28

(waves) represent the depolarization of the ventricles (contraction of the ventricles)

Answer 28

QRS waves

Question 29

(wave) shows the repolarization of the ventricles

Answer 29

T wave

Question 30

interval that extends from the start of atrial depolarization to the start of ventricular depolarization (QRS complex) contract and begins to relax

Answer 30

PR interval or PQ interval

Question 31

interval that is the time required for ventricles to undergo a single cycle of depolarization and repolarization. This interval can be lengthened by electrolyte disturbances, conduction problems, coronary ischemia, and myocardial damage

Answer 31

Q-T interval