Chapter 15: Heart

Question 1

base

Answer 1

• broadest part of the heart
• upper right
• where the great vessels enter and leave the heart

Question 2

apex

Answer 2

• point of maximum impact
• where the strongest beat can be felt or heard
• location of apical pulse
• left midclavicular line at the 5th intercostal space

Question 3

pericardium

Answer 3

double walled sac surrounding the heart
- fibrous pericardium
- serous pericardium

Question 4

endocardium

Answer 4

• innermost layer of heart wall
• lines the heart’s chambers, covers valves
• thin layer of squamous epithelial cells

Question 5

myocardium

Answer 5

• middle layer of heart wall
• thickest layer
• composed of cardiac muscle
• performs the work of the heart

Question 6

epicardium

Answer 6

• outer layer of heart wall
• closely integrated with the myocardium
• a.k.a. visceral layer
• squamous epithelial cells

Question 7

atria

Answer 7

• primarily reservoirs
• receive blood from body or lungs
• walls not very thick

Question 8

ventricles

Answer 8

• serve as pumps
• generate a lot of force
• thick walls
• left ventricle walls are thicker

Question 9

tricuspid valve

Answer 9

prevents backflow from right ventricle to right atrium

Question 10

mitral (bicuspid) valve

Answer 10

prevents backflow from left ventricle to left atrium

Question 11

pulmonary valve

Answer 11

prevents backflow from pulmonary artery to right ventricle

Question 12

aortic valve

Answer 12

prevents backflow from aorta to left ventricle

Question 13

heart sounds

Answer 13

1. aortic area
2. pulmonic area
3. Erb’s point area
4. tricuspid area
5. mitral area

Question 14

“widow-maker”

Answer 14

left anterior descending artery (LAD)

Question 15

coronary sinus

Answer 15

• where most cardiac veins empty
• returns blood to right atrium

Question 16

intercalated discs

Answer 16

join together cardiac cells

Question 17

gap junctions

Answer 17

allow impulses to pass quickly from one cardiac cell to the next

Question 18

pacemaker cells

Answer 18

generate action potentials to stimulate contraction

Question 19

automaticity

Answer 19

unique ability of cardiac muscle to contract without nervous stimulation

Question 20

rhythmicity

Answer 20

heart’s ability to beat regularly

Question 21

sinoatrial (SA) node

Answer 21

• heart’s primary pacemaker
• where normal cardiac impulses arise
• fires at 60-80 bpm

Question 22

atrioventricular (AV) node

Answer 22

• relays impulses from the atria to the ventricles
• impulse slows to allow the atria time to contract completely
• fires at 40-60 bpm

Question 23

AV bundle (bundle of His)

Answer 23

• impulse picks up speed
• branches into right and left bundle branches

Question 24

Purkinje fibers

Answer 24

• distribute impulses to muscle cells of both ventricles
• fire at 20-40 bpm

Question 25

ECG

Answer 25

- electrocardiogram - composite recording of all the action potentials produced by nodal and myocardial cells

Question 26

normal sinus rhythm

Answer 26

- ECG that appears normal - impulse originates from the SA node