Section B - 12. 3, 4

Question 1

The heart is enclosed in a fibrous sac called the _____

Answer 1

Pericardium

Question 2

A fibrous layer is closely affixed to the heart called the _____

Answer 2

Epicardium

Question 3

The wall of the heart is called the _____

Answer 3

Myocardium

Question 4

The inner surface of the cardiac chambers as well as the inner wall of all blood vessels is lined by a thin layer of cells named the _____

Answer 4

Endothelium

Question 5

The ventricles are separated by the _____

Answer 5

interventricular septum

Question 6

Between the atrium and ventricle in each half of the heart are the _____ _____, which permit blood flow from _____ to _____ but not backward

Answer 6

Atrioventricular (AV) valves, atrium, ventricle

Question 7

The right AV valve is called the _____ valve, because it has _ flaps

Answer 7

Tricuspid, 3

Question 8

The left AV valve is called the _____ valve, because it has _ flaps

Answer 8

Bicuspid valve, 2

Question 9

A valve is pushed open and blood flows from atrium to ventricle when…

Answer 9

Blood pressure in an atrium is greater than in the corresponding ventricle

Question 10

Condition in which the AV valves are pushed up and open backward into the atria when ventricles are contracting

Answer 10

Prolapse

Question 11

Valves are fastened to muscular projections called _____ of the ventricular walls by fibrous strands called. _____

Answer 11

Papillary muscles, chordae tendineae

Question 12

The openings of the right ventricle into the pulmonary trunk and of the left ventricle into the aorta contain valves called _____ and _____. They are also called _____ valves

Answer 12

Pulmonary, aortic, semilunar

Question 13

Path of blood flow (4 sections)

Answer 13

(1) Aorta, arteries, arterioles, capillaries, venules, veins, venae cavae. (2) Right atrium, right AV valve, right ventricle, pulmonary valve. (3) Pulmonary trunk, pulmonary arteries, pulmonary arterioles, capillaries of lungs, pulmonary venules, pulmonary veins. (4) left atrium, left AV valve, left ventricle, aortic valve

Question 14

Only _% of muscle cells are replaced yearly

Answer 14

1%

Question 15

The cycling of force-generating cross-bridges is activated when…

Answer 15

APs propagate along cell membranes, and Ca2+ enters the cytosol

Question 16

Cells with specialized features essential for normal heart excitation constitute a network called the _____ _____

Answer 16

conduction system

Question 17

The receptors for norepinephrine on cardiac muscle are mainly _____

Answer 17

beta-adrenergic

Question 18

The arteries supplying the myocardium are the ____ _____ , and the blood flowing thru them is the _____ _____ _____

Answer 18

coronary arteries, coronary blood flow

Question 19

Pumping of blood requires that the ____ contract first, followed by the _____

Answer 19

atria, ventricles

Question 20

contraction of the cardiac muscle is triggered by…

Answer 20

depolarization of the plasma membrane

Question 21

____ _____ interconnect myocardial cells and allow APs to spread from one cell to another

Answer 21

Gap junctions

Question 22

Initial depolarization arises in a group of conducting system cells called the _____ _____, located in..

Answer 22

Sinoatrial (SA) node, right atrium near the entrance of the superior vena cava

Question 23

The AP spreads from the _____, throughout the _____ and into and throughout the _____

Answer 23

SA node, atria, ventricles

Question 24

Heart rate is determined by…

Answer 24

the discharge rate of the SA node

Question 25

The AP is conducted rapidly from the _____ to the _____ through _____ _____

Answer 25

SA node, AV node, internodal pathways

Question 26

Conducting system fibers are called

Answer 26

Bundle of His

Question 27

The only electrical connection between the atria and ventricles is constituted by the ____ and ____

Answer 27

AV node and bundle of His

Question 28

large diameter, rapidly conducting cells connected by low resistance gap junctions are called ____ ____

Answer 28

purkinje fibers

Question 29

The resting membrane is much more permeable to ____ than ____

Answer 29

K+, Na+

Question 30

The depolarizing phase of the AP is mainly due to …

Answer 30

the opening of voltage gated Na+ channels

Question 31

____ ____ entry depolarizes the cell and sustains the opening of more ____ channels in a ____ feedback fashion

Answer 31

sodium ion, Na+, positive

Question 32

Membrane potential order (illustration)

Answer 32

Na+ enters (depolarization), transient K+ exit, Ca2+ enters and K+ exits (plateau), K+ exits (depolarization)

Question 33

Reasons for continued depolarization of the membrane at a plateau of 0 mV;

Answer 33

K+ permeability declines below resting value due to closure of K+channels, large increase in the cell membrane permeability to Ca2+ occurs

Question 34

Gradual depolarization of the SA node is called a ____ ____, and it…

Answer 34

pacemaker potential, brings the membrane potential to threshold, at which point an AP occurs

Question 35

Three ion channel mechanisms contributing to pacemaker potential;

Answer 35

1. progressive reduction in K+ permeability, 2. channels that open when the membrane potential is at negative values, 3. a type of Ca2+ channel that opens briefly but contributes inward Ca2+ current and an important final depolarizing boost to the pacemaker potential.

Question 36

The depolarization phase of a nodal cell is caused by ____ influx through ____ ____ channels

Answer 36

Ca2+, L-type Ca2+

Question 37

Cardiac excitation through the AV node is slow because…

Answer 37

APs propagate more slowly along nodal-cell membranes than in other cardiac cells

Question 38

AV conduction disorder causes

Answer 38

autorhythmic cells in the bundle of his and purkinje network, no longer driven by SA node, begin to initiate excitation at their own inherent rate and become the pacemaker for the ventricles

Question 39

ECG electrodes detect…

Answer 39

currents being conducted through body fluids around the heart by APs occurring in myocardial cells

Question 40

P wave

Answer 40

first deflection, corresponding to current flow during atrial depolarization

Question 41

QRS complex

Answer 41

second deflection, result of ventricular depolarization

Question 42

T wave

Answer 42

result of ventricular repolarization

Question 43

____ ____ is usually not evident on the ECG because it occurs at the same time as ____ ____

Answer 43

Atrial repolarization, QRS complex

Question 44

The small amount of extracellular ___ entering through ___ channels during the plateau of the AP triggers the release of a larger quantity of ___ from the ___ receptors in the sarcoplasmic reticulum membrane

Answer 44

Ca2+, L-type Ca2+, Ca2+, ryanodine

Question 45

Contraction ends when ___ is returned tot he sarcoplasmic reticulum and extracellular fluid bu ___ ___ and ___ ___

Answer 45

Ca2+, Ca2+ ATPase pumps, Na+/CA2+ countertransporters

Question 46

The inability of the heart to generate tetanic contractions is the result of the long ___ ___ ___ of cardiac muscle - the period during and following an AP when the membrane cannot be re-excited

Answer 46

Absolute refractory period