Medical Terminology Simplified

Conduction Pathway of the Heart

5–72 Primary responsibility for initiating the heartbeat rests with the (1) sinoa-

trial (SA) node,also known as the pacemaker of the heart.The SA node is a small

region of specialized cardiac muscle tissue located on the posterior wall of the

(2)right atrium (RA).Label these two structures in Figure 5–6.

5–73 Write the abbreviations for

sinoatrial:__________

right atrium:__________

5–74 The CF electr/orefers to electricity. Electric/al and electr/ic both mean

pertaining to ____________________.

5–75 The electric/al current generated by the heart’s pacemaker causes the atrial walls

to contract and forces the flow of blood into the ventricles. The wave of electricity moves

to another region of the myo/cardi/um called the (3) atrioventricular (AV) node. Label

the structure in Figure 5–6 to learn about the conduction pathway of the heart.

5–76 Identify the words in Frame 5–79 that mean

pertaining to the atrium and ventricles:

__________ / _____ / ____________________ / __________

pertaining to electricity:____________________ / __________

pertaining to the atrium:__________ / __________

5–77 Write the abbreviations for

atri/o/ventricul/ar:__________

sino/atri/al:__________

5–78 The AV node instantaneously transmits impulses to the (4) bundle of His,

a bundle of specialized fibers that transmits those impulses to the right and left

(5) bundle branches.Label the structures in Figure 5–6.

5–79 From the right and left bundle branches, impulses travel through the

(6) Purkinje fibersto the rest of the ventricul/ar my/o/cardi/um and bring about

ventricul/ar contraction. Label the Purkinje (pŭr-KĬN-jē) fibers in Figure 5–6.

Boldfaceindicates a word root or combining form. Blueindicates a suffix. Pinkindicates a prefix.

174 CHAPTER 5• Cardiovascular and Lymphatic Systems

SA

RA

atri/o/ventricul/ar

ā-trē-ō-vĕn-TRĬK-ū-lăr

electric/al

atri/al

Ā-trē-ăl

electricity

AV

SA