Ch 18 - The Heart

Front 1

Explain the lubb-dupp valve sounds of the cardiac cycle.

Back 1

"LUB" signals AV valves closing as ventricles contract and pump blood.
"DUB" signals semilunar valves closing as ventricles relaxes and fills with blood again.

Front 2

Where is the stethoscope placement for sounds of aortic semilunar valve?

Back 2

second intercostal space at right sternum margin

Front 3

Where is the stethoscope placement for sounds of pulmonary semilunar valve?

Back 3

left of sternum at second intercostal space

Front 4

Where is the stethoscope placement for sounds of bicuspid valve?

Back 4

Heart apex (in 5th intercostals space at nipple on left)

Front 5

Where is the stethoscope placement for sounds of tricuspid valve?

Back 5

tip of sternum or right margin of sternum

Front 6

Intercalated discs contain what? (2 answers)

Back 6

desmosomes and gap junctions

Front 7

Systole refers to what?

Back 7

Atrial or ventriclar contraction period

Front 8

Diastole refers to what?

Back 8

Ventricles relaxation period

Front 9

When AV valves close, you hear what sound?

Back 9

LUB sound

Front 10

When semilunar valves close, you hear what sound?

Back 10

DUB sound

Front 11

Describe the Phase I (ventricular filling) of the cardiac cycle.

Back 11

Heart at rest, blood is entering both atria and flowing by gravity into both ventricles thru open AV valves.
Both atria contract which completes ventricular filling. Atria relaxes, and AV valves close as ventricles fill.
QRS wave stimulates ventricles

Front 12

Describe the Phase II (ventricular systole) of the cardiac cycle.

Back 12

Ventricles contract, ventricular pressure ejects blood into pulmonary and aortic trunks and forces open both semilunar valves.

Front 13

Describe the Phase III (isovolumetric relaxation) of the cardiac cycle.

Back 13

Ventricles relax, ventricular pressure drops, blood in aorta and pulmonary arteries backflow closing semilunar valves.
Slight rise in pressure in aorta when valve close.

Front 14

State the characteristics of cardiac muscle cells. (3 answers)

Back 14

Interconnected, branched with inetrcalated discs, and contain one or two large pale centrally located nuclei.

Front 15

The desmosomes of cardiac muscle prevent adjacent cells from what?

Back 15

separating during contraction

Front 16

The gap junctions of cardiac muscle allow what?

Back 16

allow ions to pass from cell to cell, transmitting current across the entire heart

Front 17

All cells in any chamber are connected to fasten impulse conduction. What is the significance of this?

Back 17

All cells receive the impulse almost simultaneously and then they all contract together.

Front 18

What are the two nodes in heart generating autorythmicity?

Back 18

SA = pacemaker; AV = back-up pacemaker

Front 19

What originates the action potential of the heart?

Back 19

Sino-Atrial node

Front 20

Explain the function of the nodes.

Back 20

Specialized cardiac muscle cell which produce action potential

Front 21

The atria and ventricle are connected by gap junctions. True or False?

Back 21

False: the AV bundle is the only electrical connection between them.

Front 22

Once current reaches AV node, what is going to happen?

Back 22

AV node depolarizes

Front 23

Once current flows over Purkinje Fibers, what is going to happen?

Back 23

Cardiac muscle conducts cells across both ventricles, and myocardium cause ventricular contraction

Front 24

When does atrial systole occurs?

Back 24

At the end of the P Wave

Front 25

When does ventricular systole occurs?

Back 25

At the end of the QRS Wave

Front 26

What is happening at the same time when ventricular systole?

Back 26

Atrial repolarization

Front 27

What does the straight line mean in EKG?

Back 27

Resting period (relaxation)

Front 28

Name the period when pacemaker sends an impulse causing atrial depolarization?

Back 28

P wave

Front 29

Ventricular depolarization causes ventricles to contract at end of what?

Back 29

QRS wave

Front 30

Name the period when ventricular repolarization producing ventricular diastole.

Back 30

T wave

Front 31

Describe the pacemaker potentials produced by SA node.

Back 31

Unstable resting potentials that continuously depolarizes, initiating AP spread throughout the heart

Front 32

Compare the pacemaker potentials with the neuronal action potentials.

Back 32

Unstable resting potentials that continuously depolarize, drifting slowly toward threshold while neuronal AP maintains a stable resting membrane potential.

Front 33

State the difference in the means of stimulation of contraction between cardiac muscle cells and skeletal muscle cells.

Back 33

Skeletal: each skeletal muscle fiber must be stimulated to contract by a nerve ending.
Cardiac: some cardiac cells (nodes) are self-excitable, initiating both their own depolarization and that of the rest of the heart.

Front 34

State the difference in the organ versus motor unit contraction between cardiac muscle cells and skeletal muscle cells.

Back 34

Skeletal: all cells of a given motor unit are stimulated and contract simultaneously.
Cardiac: all cardiac muscle cells together into a single contractile unit -> either contracts as a unit or doesn't contract at all.

Front 35

Define stroke volume.

Back 35

the amount of blood that ventricle ejects per contraction

Front 36

Define venous return.

Back 36

Venous return (VR) is the amount of blood returning back to the heart and stretching its ventricles.

Front 37

Stroke Volume depends on 4 factors. State them.

Back 37

1. the amount of blood that enters the ventricles.
2. the amount of blood left after they contract.
3. arterial pressure (resistance increases with arterial constriction)
4. force of contraction

Front 38

Explain Starling’s Law of the Heart.

Back 38

• The greater the length of stretched muscle fiber, the greater the contraction
• Increased venous return increases the stretch or resting length -> increases force of contraction

Front 39

Define cardiac output.

Back 39

the amount of blood each ventricle ejects per minute

Front 40

How to calculate the cardiac output?

Back 40

CO = (stroke volume) x (beats/min)

Front 41

When does CO increase?

Back 41

When SV increases or the heart beats faster (or both)

Front 42

Describe the major processes that the body uses to adjust CO.

Back 42

Cardiac reserve – maximum % that cardiac output can be increased beyond normal

Front 43

Increased cardiac muscle conditioning by aerobic exercise results in what?

Back 43

Increase in protein mass per cell and length of muscle cells.

Front 44

What are the factors raise the heart rate?

Back 44

Temperature and emotiona/physical stress

Front 45

Explain the CAC Reflex Pathway.

Back 45

Cardioacceleratory center in medulla -> Sympathetic Nerves thru sympathetic trunk ganglion -> SA & AV nodes & ventricular contractile cells -> norepinephrine -> increase heart rate and force of contraction

Front 46

Explain the CIC Reflex Pathway.

Back 46

Cardio-inhibitory Center in medulla -> Vagus nerve -> Acetylcholine -> SA & AV nodes -> decrease heart rate

Front 47

Define the tachicardia and explain it.

Back 47

Tachycardia is an abnormally fast rate (more than 100 beats/min) that may result from elevated body temperature, stress, drugs, or heart disease.

Front 48

Define the bradycardia and explain it.

Back 48

Bradycardia is a heart rate slower than 60 beats/min, resulting from low body temperature, drugs, or parasympathetic nervous activation.

Front 49

When a stressful situation has passed, parasympathetic division effectively reduces heart rate, mediated by what?

Back 49

Achtylcholine

Front 50

Under the emotional/physical stress (fright, anxiety, exercise), what chemical is released at cardiac synapse?

Back 50

Norepinephirine

Front 51

How to calculate SV?

Back 51

SV = EDV (end diastolic volume) - ESV (end systolic volume)

Front 52

Define EDV.

Back 52

EDV (end diastolic volume) - the amount of blood that collects in a ventricle during diastole.

Front 53

Define ESV.

Back 53

ESV (end systolic volume) - the amount of blood remaining in a ventricle after it has contracted.

Front 54

Define the "preload."

Back 54

The amount of blood that enters the ventricles

Front 55

Anything increasing the volume or speed of venous return increases what? (2 answers)

Back 55

Increase EDV => increase SV and contraction force

Front 56

Why exercise speeds venous return?

Back 56

Both increased sympathetic nervous system activity & the squeezing action of the skeletal muscles compresses the veins => decreases the volume of blood in veins => return more blood to the heart

Front 57

Depolarization wave travels across the heart from cell to cell via ion passage thru what?

Back 57

Gap junctions

Front 58

Due to sodium influx, the inner membrane of autorhythmic cells gradually become what? Then, what occurs?

Back 58

Inner membrane becomes less negative and generate the pacemaker potential

Front 59

When threshold is reached in autorhythmic cells, what is going to happen? (2 phases)

Back 59

Calsium channels open and calcium rushes into the mambrane -> produces depolarization and reverses membrane potential (the inner membrane potential is now positive)

Front 60

Reversal of membrane potential of autorhythmic cells triggers what?

Back 60

Opening of potassium channels, resulting in rapid efflux of potassium

Front 61

Potassium efflux produces what?

Back 61

repolarization

Front 62

For contractile cells of heart, what causes depolarization and reversal of membrane potential?

Back 62

Rapid influx of sodium

Front 63

Why slow calcium influx results in producing a plateau in the action potential tracing?

Back 63

Few potassium channels are open and decline potassium efflux

Front 64

What produces plateau phase during action potential of contractile cells?

Back 64

Calcium surge across the sarcolemma prolongs the depolarization potential. Simultaneously, few potassium channels are open, which also prolongs the plateau and prevents rapid repolarization.

Front 65

Rapid potassium efflux results in what?

Back 65

Repolarization

Front 66

Internodal pathway is the link between what and what?

Back 66

SA node and AV node

Front 67

AV bundle (bundle of His) is the link between what and what?

Back 67

Atria and ventricles

Front 68

What convey the impulse down the interventricular septum?

Back 68

Bundle branches

Front 69

A sudden drop in blood volume (after you lost a lot of blood) causes what?

Back 69

Lower the venous return -> decrease SV -> compensated for by an increase in symapthetic activity which increases Heart rate -> CO is unchanged

Front 70

Rise in blood pressure increase Heart rate. True or False?

Back 70

False: decrease Heart rate

Front 71

This valve sounds are heard in 2nd intercostal space at right sternal margin.

Back 71

Aortic valve

Front 72

This valve sounds are heard in 2nd intercostal space at left sternal margin.

Back 72

Pulmonary valve

Front 73

This valve sounds are heard over heart apex (in 5th intercostal space)

Back 73

Mitral valve

Front 74

This valve sounds are heard in right sternal margin of 5th intercostal space.

Back 74

Tricuspid valve

Front 75

Functional Syncticuim means that all cells in the heart....?

Back 75

All cells in the heart receive the impulse almost simultaneously and all contract together.

Front 76

The role of the atrioventricular node (AV node) is ... ?

Back 76

slow down impulses so that the atria can contract to fill the adjacent ventricles with blood.

Front 77

Nodal cardiac cells are periodically permeable to what?

Back 77

Sodium ions

Front 78

What is going to happen after current from Bundle of His fibers flow?

Back 78

The Purkinje fibers of AV node depolarize the contractile cells of both ventricles.

Front 79

What ion influx causes depolarization in autorhythmic cells AP?

Back 79

Calcium

Front 80

When is the peak of muscle tension caused by AP of cardiac muscle cells?

Back 80

Just after the plateau phase ends

Front 81

When does SR (sarcoplasmic reticulum) release calcium to cause cardiac muscle cells to contract?

Back 81

Once calcium starts to influx from ECF during plateau period

Front 82

Thyroxine increase/decrease heart rate.

Back 82

Increase HR

Front 83

Why chronically hyperthyroid individuals may develop a heart disease?

Back 83

It enhances the effect of epinephrine and norepinephrine on the heart.

Front 84

Faster heart rate increase/decrease EDV.

Back 84

Decrease EDV since there is less time for ventricular filling

Front 85

More blood remaining in the ventricles after systole result in increased/decreased ESV and increased/decreased SV.

Back 85

Increased ESV and reduced SV