Chapter 18

Question 1

Apex

Answer 1

points toward left hip

Question 2

Apical impulse

Answer 2

palpated between fifth and sixth ribs, just below left nipple

Question 3

Pericardium

Answer 3

double-walled sac that surrounds heart, made up of two layers

Question 4

Parietal layer

Answer 4

lines internal surface of fibrous pericardium

Question 5

Visceral layer (epicardium)

Answer 5

on external surface of heart

Question 6

Fossa ovalis

Answer 6

remnant of foramen ovale of fetal heart

Question 7

ligamentum arteriosum

Answer 7

is a small ligament that is the remnant of the ductus arteriosus formed within three weeks after birth.

Question 8

Auricles

Answer 8

appendages that increase atrial volume

Question 9

Left arterial appendage

Answer 9

place where clots form in A-fib

Question 10

Coronary circulation

Answer 10

delivered when heart is relaxed

Question 11

Coronary arteries

Answer 11

both left and right coronary arteries arise from base of aorta

Question 12

Left Anterior Descending artery

Answer 12

part of left coronary artery and it is the widow maker

Question 13

Intercalated discs

Answer 13

connecting junctions between cardiac cells that contain desmosomes and gap junctions

Question 14

Desmosomes

Answer 14

hold cells together, prevent cells from separating during contraction

Question 15

Gap junctions

Answer 15

allow ions to pass from cell to cell, electrically adjacent cells

Question 16

Similarities with skeletal muscle

Answer 16

SR release Ca2+ and muscle contraction is preceded by depolarizing AP

Question 17

Differences between cardiac and skeletal muscle

Answer 17

heart contacts as a unit and influx of Ca2+ from extracellular fluid triggers Ca2+ release from SR

Question 18

Sequence of excitation

Answer 18

SA node, AV node, bundle of his, purkinje fibers

Question 19

SA inherent rate

Answer 19

100x/minute

Question 20

AV inherent rate

Answer 20

50x/minute

Question 21

Purkinje fibers

Answer 21

depolarize 30x/minute

Question 22

Benefit of longer AP and contraction

Answer 22

sustained contraction ensures efficient ejection of blood and longer refractory period prevents tetanic contractions

Question 23

Positive inotropic

Answer 23

increase contractility

epinephrine and norepinephrine

Question 24

Negative inotropic

Answer 24

decrease contractility

Question 25

Positive chronotropic

Answer 25

increase heart rate

Question 26

Negative chronotropic

Answer 26

decrease heart rate