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91

List 3 structures of micro anatomy of the heart:

1) muscle cells
2) intercalated discs
3) gap junctions (communication pathways)

92

What are 2 similarities between cardiac and skeletal mechanisms of contraction?

1) striated - myosin/actin mechanism
2) T-tubule mechanism - acting on sacroplasmic reticulum

93

What are 3 differences between cardiac and skeletal mechanisms of contraction?

1) T-tumble mechanism - direct diffusion of Ca++ (tubules store larger amounts of Ca++)
2) action potential (cardiac muscle "plateau" / plateau results in much longer time of contraction than skeletal mm)
3) strength of contraction (dependent on extracellular Ca++)

94

The ability of cardiac mm to depolarize and contract is intrinsic and known as:

conduction

95

What are the components of intrinsic conduction system:

1) sinus node = sinistral/ SA node
2) intermodal pathways
3) AV node
4) AV bundle (bundle branches)
5) Left and right bundle branches of Purkinje fibers

96

- Smaller diameter muscle fibers
- Almost no contractile muscle fibers
- Connect directly with atrial muscle (mm) fibers
- Cell membranes naturally "leaky" to Na++ and Ca++ ions (therefore, less negative resting membrane potential than other cardiac mm cells)
- Self excitation
All are features of what?

SA node

97

@ -40mV the __________ are already open.

fast Na++

98

List the following events in order from first occur in got last:
- K+ permeability accompanied by slow Na+ entry decreases
- Slow depolarization: pacemaker potential
- Fast Ca2+ channels open
- Ca2+ permeability increased
-K+ permeability increase
- Ca2+ permeability decreased

- K+ permeability accompanied by slow Na+ entry decreases
- Ca2+ permeability increased
- Fast Ca2+ channels open
- Ca2+ permeability decreased
-K+ permeability increase
- Slow depolarization: pacemaker potential

99

during the very early P (PQRST wave) what occurs?

SA node generates impulse: atrial excitation begins

100

During the p -wave what happens?

impulse delayed at AV node

101

during the q-way what happens?

impulse passes to heart apex; ventricular excitation begins at the bundle branches

102

during the QRS segment what is occuring?

ventricular excitation is complete.

103

Electrical impulses passing through the heart also spread into _____________ and some to the _____________________.

adjacent tissues
surface of the body

104

the p-wave =

atrial depolarization

105

QRS complex =

ventricular depolarization

106

T-wave =

ventricular depolarization

107

List 5 events that occur from the beginning of one heartbeat to the beginning of the next:

1) chambers and vessel blood volume changes
2) chamber and vessel blood pressures changes
3) electrical activity notes
4) heart sounds occur
5) valves open and close

108

The cardiac cycle consists of:

-diastole period of relaxation; heart fill in with blood
- systole: contract ration period, heart ejects blood

109

What is end-diastolic volume (EDV)?

.

110

What is the definition of end-systolic volume (ESV)?

.

111

What is the ejection fraction?

fraction of EDV ejected

112

atrioventricular valves are __________ and aortic and pulmonary valves are ____________ during phase 1. During this phase _____________ filling and _____________ contraction occurs. This happens during mid-to-late ______________.

atrioventricular valves are OPEN and aortic and pulmonary valves are CLOSED during phase 1. During this phase VENTRICULAR filling and ATRIAL contraction occurs. This happens during mid-to-late DIASTOLE.

113

atrioventricular valves are __________ and aortic and pulmonary valves are ____________ during phase 2b. During this phase ___________________________ occurs. This happens during __________________________ (atria in diastole).

atrioventricular valves are CLOSED and aortic and pulmonary valves are OPEN during phase 2b. During this phase VENTRICULAR EJECTION occurs.This happens during VENTRICULAR SYSTOLE (atria in diastole).

114

Phase 2a is _________________________. also ventricular systole (atria in diastole)

isovolumetric contraction

115

During phase 3 _________________________ occurs in early ___________.

Isovolumetric relaxation
early diastole

116

P wave =

spread of depolarization through atrial tissue followed by contraction

117

p wave =

increase in atrial pressure

118

QRS complex : spread of depolarization through ventricular tissue followed by contraction =

ventricular increase pressure

119

T-wave =

repolarization of the ventricles which represents ventricular relaxation.

120

The majority of returning venous blood flows directly from _____________ to _______________.

atrium to ventricle