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Biology - Chapter 19-29 > Chapter 20 - Cardiovascular System: The Heart > Flashcards

Chapter 20 - Cardiovascular System: The Heart Flashcards

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1
Q

Where is the heart located?

A

It rests on the diaphragm, near the midline of the thoracic cavity

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2
Q

What is the mediastinum?

A

An anatomical region that extend from the sternum to the vertebral column
- from the first rib to the diaphragm and between the lungs

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3
Q

What is the apex of the heart?

A

The pointed tip of the left ventricle

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4
Q

What is the base of the heart?

A

Its posterior surface

  • formed by the atria (upper chambers)
  • mostly the left atrium
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5
Q

Where is the anterior surface of the heart?

A

Deep to the sternum and ribs

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6
Q

Where is the inferior surface of the heart?

A

Between the apex and right border

- rests mostly on the diaphragm

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7
Q

What does the right border of the heart face?

A

Faces the right lung

- extends from the inferior surface to the base

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8
Q

What does the left border of the heart face?

A

Faces the left lung

  • extends from the base to the apex
  • *also called the pulmonary border
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9
Q

What is the pericardium?

A

Membrane that surrounds and protects the heart

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10
Q

What are the two main parts of the pericardium?

A
  1. Fibrous pericardium (superficial layer)

2. Serous pericardium (deep layer)

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11
Q

What is the function of the fibrous pericardium?

A
  • prevents overstretching of the heart
  • provides protection
  • anchors heart to the mediastinum
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12
Q

What is the fibrous pericardium partly fused to?

What does this do?

A

Central tendon of the diaphragm

- facilitates movement of blood by the diaphragm (when deep breathing occurs)

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13
Q

What are the two layers of the serous pericardium?

A
  1. Parietal layer

2. Visceral layer (also called epicardium)

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14
Q

What is the parietal layer of the serous pericardium fused to?

A

Fibrous pericardium

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15
Q

What is the visceral layer of the serous pericardium tightly adhered to?

A

Surface of the heart

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16
Q

What is between the parietal and visceral layers of the serous pericardium?
What is it’s function?

A

Pericardial fluid

- reduces friction between the layers as the heart moves

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17
Q

What is the name of the space that contain pericardial fluid?

A

Pericardial cavity

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18
Q

What are the three layers of the heart wall?

A
  1. Epicardium (outer layer)
  2. Myocardium (middle layer)
  3. Endocardium (inner layer)
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19
Q

What give the heart a smooth, slippery texture at the outermost surface of the heart?

A

The epicardium

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20
Q

What does the epicardium layer contain?

A
  • adipose tissue
  • blood vessels
  • lymphatics
  • vessels that supply myocardium
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21
Q

What is the myocardium layer of the heart responsible for?

A

The pumping action of the heart

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22
Q

What is the myocardium layer composed of?

A

Cardiac muscle tissue

- makes up 95% of the heart wall

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23
Q

What is the function of the endocardium?

A
  • provides a smooth lining for the chambers of the heart
  • covers the values of the heart
  • minimizes surface friction as blood passes through the heart
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24
Q

What are the 4 chambers of the heart?

A
  • Right atria
  • Left atria
  • Right ventricle
  • Left ventricle
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25
Q

What is the function of the atria?

A

Receive blood from veins

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26
Q

What is the function of the ventricles?

A

Pump blood into arteries

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27
Q

What are the auricles?

A

Wrinkled pouch-like structure on the anterior surface of each atrium

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28
Q

What is the function of the auricles?

A

Slightly increases the capacity of an atrium (more blood)

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29
Q

What is the coronary sulcus?

A

Deep groove on the surface of the heart

- encircles most of the heart

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30
Q

What does the coronary sulcus mark?

A

Marks the external boundaries between the superior atria and inferior ventricles

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31
Q

What does a sulcus contain?

A

Contains coronary blood vessels and a variable amount of fat

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32
Q

What three veins supply the right atrium?

A
  1. Superior vena cava
  2. Inferior vena cava
  3. Coronary sinus
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33
Q

What is the interatrial septum?

A

A thin partition between the right and left atria

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34
Q

What is the prominent feature of the interatrial septum?

A

An oval depression - Fossa Ovalis

- in the right atrium

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35
Q

What is the fossa ovalis?

A

Remnant of the foramen ovale

- an opening in the interatrial septum of the fetal heart that normally closes soon after birth

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36
Q

How does blood pass through the tricuspid valve?

Right atrioventricular valve

A

Passes from the RIGHT ATRIUM into the RIGHT VENTRICLE

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37
Q

What forms most of the anterior surface of the heart?

A

The right ventricle

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38
Q

What are the chordae tendineae connected to?

A

Tendonlike cords

- tricuspid valve connects to chordae tendineae, which connects to papillary muscles

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39
Q

What are papillary muscles?

A

Cone-shaped trabeculae carneae (raised bundles of cardiac muscle fibres)

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40
Q

What is the interventricular septum?

A

How the RIGHT VENTRICLE is separated from the LEFT VENTRICLE

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41
Q

How does blood pass through the pulmonary valve?

A

Blood passes from RIGHT VENTRICLE through the pulmonary valve into the pulmonary trunk (large artery)

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42
Q

What does the pulmonary trunk divide into?

What does it service?

A

Divides into right and left pulmonary arteries

- carries blood to the lungs

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43
Q

What is the mnemonic to aid in remembering the function of arteries and veins?

A

Arteries carry blood AWAY from the heart

Artery = Away

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44
Q

What forms most of the base of the heart?

A

Left atrium

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45
Q

What is the bicuspid valve?
(Mitral valve)
(Left atrioventricular valve)

A

Blood passes from the LEFT ATRIUM into the LEFT VENTRICLE

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46
Q

Which chamber is the thickest in the heart?

A

The left VENTRICLE

- forms the apex of the heart

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47
Q

How does blood pass through the aortic valve?

A

Blood passes from the LEFT VENTRICLE through the aortic valve into the ascending aorta

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48
Q

What happens to some of the blood in the aorta?

A

Flows into coronary arteries

- carry blood to the heart wall

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49
Q

Which ventricle has a thicker muscular wall?

Why?

A

LEFT ventricle

- pumps blood a greater distance in the body and under greater resistance

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50
Q

What does the fibrous skeleton of the heart consist of?

A

Consists of 4 dense connective tissue rings that surround the valves of the heart, fuse with one another, and merge with the interventricular septum

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51
Q

What is the function of the fibrous skeleton of the heart?

A
  • forms structural foundation
  • prevents overstretching
  • serves as a point of insertion for bundles of cardiac muscle fibres
  • acts as an electrical insulator between the atria & ventricles
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52
Q

What are the atrioventricular (AV) valves?

A
  1. Tricuspid valve

2. Bicuspid valve

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53
Q

What happens with regards to blood flow when the ventricles are relaxed?

A
  • ventricles relaxes, papillary muscles are relaxed

- blood moves from a higher pressure in the atria to a lower pressure in the ventricles through the open AV valves

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54
Q

What happens with regards to blood flow when the ventricles contract?

A
  • pressure of the blood drives the cusps upwards, closes their openings
  • papillary muscles contract which tighten chordae tendineae
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55
Q

What are the semilunar (SL) valves?

A
  1. Aortic valve

2. Pulmonary valve

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56
Q

What do the SL valves allow?

What do the SL valves prevent?

A

Allow - Ejection of blood from the heart into arteries

Prevent - backflow of blood into ventricles

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57
Q

When do the semilunar valves open?

A

When pressure in the ventricles exceeds the pressure in the arteries

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58
Q

Which heart valve is most commonly replaced?

A

Aortic valve

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59
Q

What kind of circulation does the left side of the heart pump?

A

Systemic circulation

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60
Q

What is systemic circulation?

A

Circulation of bright red OXYGENATED (oxygen-rich) blood from the lungs

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61
Q

Describe the flow of blood in systemic circulation.

A

LEFT side of heart receives oxygenated blood from the lungs

  • ejects blood into aorta
  • from aorta, divides into separates streams; smaller systemic arteries
  • into arterioles, into systemic capillaries
  • unloads oxygen into cells
  • enters systemic venule, into systemic veins
  • flows into RIGHT atrium
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62
Q

What kind of circulation does the right side of the heart pump?

A

Pulmonary circulation

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63
Q

What is pulmonary circulation?

A

Circulation of dark-red DE-OXYGENATED blood returning from systemic circulation

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64
Q

Describe the flow of blood in pulmonary circulation.

A
  • blood ejected from the RIGHT ventricle flows into pulmonary trunk
  • branches into pulmonary arteries (carry blood to lungs)
  • dump CO2, pick up oxygen
  • flows from capillaries, into veins
  • returns to LEFT atrium
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65
Q

What is coronary (cardiac) circulation?

A

The network of blood vessels that supply the heart

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66
Q

What is the function of the coronary arteries?

Where do they branch from?

A

Supply oxygenated blood to the myocardium

- right and left coronary arteries branch from ascending aorta

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67
Q

What is the function of the coronary veins?

A

The de-oxygenated blood from the myocardium drains into a large vascular sinus (coronary sinus)
- empties into the right atrium

68
Q

What are the principal tributaries that carry blood into the coronary sinus?

A
  1. Great cardiac vein
  2. Middle cardiac vein
  3. Small cardiac vein
  4. Anterior cardiac veins
69
Q

What is the coronary sinus?

Where is it located?

A

A wide venous channel, that receives blood from the coronary veins and empties into the right atrium of the heart
- the posterior surface of the heart

70
Q

What are the 10 steps of systemic and pulmonary circulaton?

A
  1. Right atrium (de-oxygenated blood)
    - tricuspid valve
  2. Right ventricle
    - Pulmonary valve
  3. Pulmonary trunk and pulmonary arteries
  4. Pulmonary capillaries (exchange 02 & CO2)
  5. Pulmonary veins (oxygenated blood)
  6. Left atrium
    - bicuspid valve
  7. Left ventricle
    - aortic valve
  8. Aorta and systemic arteries
  9. Systemic capillaries (exchange 02 & CO2)
  10. Superior and inferior vena cava and coronary sinus
    * repeats from 1.
71
Q

Describe the histology of cardiac muscle.

A
  • 50-100 micrometers long
  • 14 mincrometers wide
  • 1 centrally located nucleus (some have 2)
  • exhibit branching
72
Q

What are intercalated discs?

A

Irregular transverse thickenings of the sarcolemma

- separate opposing ends of cardiac muscle cells

73
Q

What is the function of desmosomes?

A

Holds cardiac muscle fibres together

74
Q

What is the function of gap junctions in cardiac muscle cells?

A

Allows muscle action potentials to conduct from one muscle fibre to its neighbours
- allows entire myocardium of the atria/ventricles to contract as a single, coordinated unit

75
Q

What are autorhythmic fibers?

A

The source of the rhythmical electrical activity of the heart

76
Q

What do autorhythmic fibers generate?

A

Repeatedly generate action potentials that trigger heart contractions

77
Q

What are the two important functions of autorhythmic fibers?

A
  1. Act as a pacemaker

2. Form the cardiac conduction system

78
Q

What is the cardiac conduction system?

A

A network of specialized cardiac muscle fibres that provide a path for each cycle of cardiac excitation to progress through the heart

79
Q

What does a pacemaker do?

A

Sets the rhythm of electrical excitation that causes contraction of the heart

80
Q

What is the pacemaker potential?

A

Spontaneous depolarization

81
Q

What is the sinoatrial node?

Where is it located?

A

Small body of specialized muscle tissue that acts as a pacemaker by producing a contractile signal at regular intervals
- in the wall of the right atrium

82
Q

What are the steps involved in the propagation of cardiac action potentials through the conduction system?

A
  1. Sinoatrial (SA) node
  2. Atrioventricular (AV) node
  3. Atrioventricular (AV) bundle
  4. Right and left bundle branches
  5. Purkinje fibers
83
Q

How do action potentials propagate through the sinoatrial (SA) node?

A
  • when the pacemaker potential reaches threshold, it triggers an action potential
  • action potential at SA node propagates throughout both atria via gap junctions
  • following the action potential, the two atria contract at the same time
84
Q

How do action potentials propagate through the atrioventricular (AV) node?

A
  • at the AV node, the action potential slows considerably

- this delay provides time for the atria to empty their blood into the ventricles

85
Q

What is special about the action potential propagation at the atrioventricular (AV) bundle?

A

Only site where action potentials can conduct from the atria to the ventricles

86
Q

What happens to the action potential at the right and left bundles?

A

The bundle branches extend through the interventricular septum toward the apex of the heart

87
Q

What happens to the action potential when it reaches the Purkinje fibers?

A

Purkinje fibers rapidly conduct the action potential from the apex to the remainder of the ventricular myocardium
- the ventricles contract, pushing blood upwards

88
Q

What acts as the natural pacemaker of the heart?

A

SA node

  • do not have a stable resting potential
    • nerve impulses and hormones modify the timing and strength of each heartbeat, BUT they do not establish the fundamental rhythm
89
Q

What is an artificial pacemaker?

A

A device that sends out small electrical currents to stimulate the heart to contract
- consists of a battery and an impulse generator

90
Q

What are the three steps involved in how an action potential occurs in cardiac contraction fibres?

A
  1. Depolarization
  2. Plateau
  3. Re-polarization
91
Q

Which muscle fibres are the “working” contractile fibres?

A

Atrial and ventricular muscle fibres

92
Q

Describe what is occurring during the depolarization stage in a ventricular contractile fibre action potential.

A

Rapid depolarization due to Na+ inflow when voltage-gated “fast” Na+ channels open
- resting membrane potential of -90mV

93
Q

Describe what is occurring during the plateau stage in a ventricular contractile fibre action potential.

A

Plateau (maintained depolarization) is due to Ca+2 inflow when voltage-gated “slow” Ca+2 channels open and K+ outflow when some K+ channels open

  • lasts about 0.25 secs
  • membrane potential just above 0mV
94
Q

Describe what is occurring during the re-polarization stage in a ventricular contractile fibre action potential.

A

Repolarization due to closure of Ca+2 channels and K+ outflow when additional voltage-gated K+ channels open
- outflow of K+ restores the negative resting membrane potential (-90mV)

95
Q

What is the refractory period?

A

Time interval during which a second contraction cannot be triggered
- lasts longer in cardiac muscle than the contraction itself

96
Q

Why can tetanus never occur in cardiac muscle?

A

Tetanus (maintained contraction) would cause blood flow to cease

  • atria and ventricles depend on alternation contraction
  • it is prevented by the long refractory period of cardiac muscle
97
Q

What is an electrocardiogram?

ECG or EKG

A

A composite record of action potentials produced by all the heart muscle fibres during each heartbeat

98
Q

What is an electrocardiograph?

A

The instrument used record the changes in a ECG

99
Q

What are the 4 things that can be determined by an ECG or EKG?

A
  1. If the conducting pathway is abnormal
  2. If the heart is enlarged
  3. If certain regions of the heart are damaged
  4. Cause of chest pain
100
Q

What are the three waves that appear with each heartbeat?

A
  1. P wave
  2. QRS complex
  3. T wave
101
Q

What is the P wave?

A

First wave

- small upward deflection on the ECG

102
Q

What does the P wave represent?

A

Represents atrial depolatization

- spreads from the SA node through contractile fibres in both atria

103
Q

What is the QRS complex?

A

Second wave

- begins as a downward deflection, continues as a large, upright, triangular wave and ends as a downward wave

104
Q

What does the QRS complex represent?

A

Represents the rapid ventricular depolarization

- as the action potential spreads through ventricular contractile fibres

105
Q

What is the T wave?

A

Third wave

- dome-shaped upward deflection

106
Q

What does the T wave represent?

A

Represents ventricular re-polarization

- occurs just as the ventricles are starting to relax

107
Q

What are the 6 steps in a ECG wave?

A
  1. Depolarization of atrial contractile fibers produces P wave
  2. Atrial systole (contraction)
  3. Depolarization of ventricular contractile fibres produces QRS complex
  4. Ventricular systole (contraction)
  5. Repolarization of ventricular contractile fibres producdes T wave
  6. Ventricular diastole (relaxation)
    * page 778
108
Q

What does systole refer to?

A

Refers to the phase of contraction

109
Q

What does diastole refer to?

A

Refers to the phase of relaxation

110
Q

What does a cardiac cycle include?

A

All the events associated with one heartbeat

  • systole and diastole of the atria
  • systole and diastole of the ventricles
111
Q

What occurs during atrial systole?

A

Atria are contracting (atrial systole)

Ventricles are relaxed (ventricular diastole)

112
Q

What are the 4 steps involved in atrial systole?

A
  1. Depolarization of the SA node causes atrial depolarization (P wave)
  2. Atrial systole - atria contract, force blood through the open AV valves into the ventricles
  3. Atrial systole contributes final 25mL of blood to each ventricle
    - end of atrial systole is also the end of ventricular diastole
  4. QRS complex marks the onset of ventricular depolarization
113
Q

What is the end-diastolic volume (EDV)?

A

The blood volume at the end of diastole (relaxation period)

- about 130mL

114
Q

What occurs during ventricular systole?

A

Ventricles are contracting (ventricular systole)

Atria are relaxed (atrial diastole)

115
Q

What are the 4 steps involved in ventricular systole?

A
  1. Ventricular depolarization causes ventricular systole
    - pressure rises in the ventricles, AV valves are forced shut
  2. Continued contraction of the ventricles causes pressure to increase sharply
    - SL valves open - ventricular ejection occurs
  3. Left ventricles ejects 70 mL into aorta, Right ventricles ejects about 70 mL into pulmonary trunk
  4. T wave marks the onset of ventricular repolarization
116
Q

What happens during isovolumetric contraction?

A

For about 0.05 seconds, both the SL and AV valves are closed

- all four valves are closed, so ventricular volume remains the same

117
Q

When does isovolumetric contraction occur?

A

During ventricular systole

- as ventricular systole begins, pressure rises inside the ventricles and pushes the AV valves shut

118
Q

What is ventricular ejection?

A

The period when the SL valves are open

- blood is ejected from the heart

119
Q

What is the end-systolic volume (ESV)?

A

The volume of blood in a ventricle at the end of contraction (systole) and the beginning of filling (diastole)

  • the lowest volume of blood in the ventricle at any point in the cardiac cycle.
  • about 60 mL
120
Q

What is the stroke volume?

A

Volume ejected per beat from each ventricle

- approx. 70mL

121
Q

What is the formula for calculating stroke volume?

A

SV = EDV - ESV

Stroke Volume = End-diastolic volume - End-systolic volume

122
Q

What happens during the relaxation period?

A

Both the atria and ventricles are relaxed

- as the heart beats faster and faster, relaxation period becomes shorter and shorter

123
Q

What happens during ventricular diastole?

A

Ventricles relax

  • pressure within the chambers fall
  • blood in the aorta and pulmonary trunk begins to flow backwards toward the regions of lower pressure in the ventricles
124
Q

What happens during isovolumetric relaxation?

A

During ventricular diastole, after the SL valves close there is a brief interval when ventricular blood volume does not change
- all 4 valves are closed

125
Q

When does ventricular filling occur?

A

As the ventricles continue to relax, the pressure falls quickly

  • ventricular pressure drops below atrial pressure
  • AV valves open
  • ventricular filling begins
126
Q

How many heart sounds are there?

How many can be heard with a stethoscope?

A

During each cardiac cycle there are 4 heart sounds

- only S1 and S2 can be heard

127
Q

Describe S1.

When does it occur?

A

Lubb sound

  • louder and longer than S2
  • caused by blood turbulence associated with the closure of the AV valves soon after ventricular systole begins
128
Q

Describe S2.

When does it occur?

A

Dupp sound

- caused by blood turbulence associated with closure of the SL valves at the beginning of ventricular diastole

129
Q

What are S3 and S4 due to?

A

S3 - blood turbulence during rapid ventricular filling

S4 - blood turbulence during atrial systole

130
Q

What is a heart murmur?

A

Abnormal sound

  • consists of clicking, rushing or gurgling
  • heard before, between or after normal heart sounds
131
Q

Cardiac cycle relating to pressure changes.

See page 780

A

Review diagram on page 780.

132
Q

What is cardiac output (CO)?

A

The volume of blood ejected from the left ventricle (or the right ventricle) into the aorta (or pulmonary trunk) each minute

133
Q

What is the formula for calculating cardiac output (C0)?

A

Cardiac output = stroke volume x heart rate

CO (mL/min) = SV (mL/beat) x HR (beats/min)

134
Q

What is the cardiac reserve?

A

The difference between a person’s maximum cardiac output and cardiac output at rest
- typically 4-5x the resting value

135
Q

What 3 factors regulate stroke volume and ensure that the L and R ventricles pump equal volumes of blood?

A
  1. Pre-load - degree of stretch on the heart before it contracts
  2. Contractility - forcefulness of contraction of individual ventricular muscle fibres
  3. After-load - pressure that must be exceeded before ejection of blood from the ventricles can occur
136
Q

A greater pre-load (stretch) on cardiac muscle increases what?

A

The force of contraction

137
Q

What is the Frank-Starling law of the heart?

A

Equalizes the output of the R and L ventricles

- keeps the same volume of blood flowing to both systemic and pulmonary circulations

138
Q

What 2 factors determine EDV (end-diastolic volume)?

A
  1. Duration of ventricular diastole

2. Venous return

139
Q

What is venous return?

A

The volume of blood returning to the right ventricle

140
Q

What is contractility?

A

The strength of contraction at any given preload

141
Q

What are positive inotropic agents?

A

Substances that increase contractility

- promote inflow of Ca+2, strengthens the force of the next contraction

142
Q

What are negative inotropic agents?

A

Substances the decrease contractility

- increased K+ levels

143
Q

What happens to the duration of diastole as the heart rate increases?

A

Diastole is shorter; smaller EDV

- ventricles may contract before adequately filled

144
Q

When does ejection of blood from the heart begin?

A

When pressure in the R ventricle exceeds the pressure in the pulmonary trunk and when the pressure in the L ventricle exceeds the pressure of the aorta

145
Q

What is the after-load?

A

The pressure that must be overcome before a semilunar valve can open

146
Q

What happens to stroke volume if there is an increase in after-load?

A

Stroke volume decreases

- more blood remains in the ventricles at the end of systole

147
Q

What condition can increase after-load?

A

Hypertension (elevated blood pressure)

148
Q

Where is the cardiovascular center?

What does it do?

A

In the medulla oblongata

- nervous system regulation of the heart

149
Q

What are the main receptors that send information to the cardiovascular center?

A
  1. Proprioceptors
  2. Chemoreceptors
  3. Baroreceptors
150
Q

What do proprioceptors monitor?

A

Monitor the position of the limbs and muscles

- send nerve impulses at an increased frequency during activity

151
Q

What do chemoreceptors monitor?

A

Changes in the blood

152
Q

What do baroreceptors montior?

A

The stretching of major arteries and veins caused by the pressure of blood flowing through them

153
Q

What do sympathetic cardiac accelerator nerves trigger?

A

The release of norepinephrine

- binds to beta 1 receptors on cardiac muscle fibres

154
Q

Where do the neurons for the sympathetic cardiac accelerator nerves extend from and to?

A

Sympathetic neurons extend from the medulla oblongata into the spinal cord
- from thoracic region of spinal cord into the SA node, AV node and most portions of the myocardium

155
Q

What happens after the sympathetic cardiac accelerator nerves release norepinephrine?

A
  1. SA and AV nodes, norepinephrine speeds the rate of spontaneous depolarization (heart rate increases)
  2. Artria and ventricles, norepinephrine enchances Ca+2 entry (increases contractility, increased stroke volume)
156
Q

How do parasympathetic nerve impulses reach the heart?

A

Right and left vagus (X) nerves

157
Q

What do vagus (X) nerves release?

What happens after that release?

A

Acetylcholine

- decreases the heart rate by slowing the rate of spontaneous depolarization in autorhythmic fibres

158
Q

What are the major hormones that affect the heart?

A
  1. Epinephrine and norepinephrine - increase heart rate and contractility
  2. Thyroid hormones - enhance cardiac contractility and increase heart rate
159
Q

What is tachycardia?

A

An elevated resting heart rate

- caused by excessive thyroid hormone release (hyperthyroidism)

160
Q

What are the three major ions that affect the ability of the heart to contract?

A
  1. K+
  2. Ca+2
  3. Na+
    - high levels of K+ or Na+ decrease heart rate and contractility
    - Na+ blocks Ca+2, decreasing the force of contraction
    - Ca+2 speeds the heart rate and strengthens the heartbeat
161
Q

What are the other major factors that influence the resting heart rate?

A

Age, gender, physical fitness, body temperature

162
Q

What is bradycardia?

A

A resting heart rate under 50 beats/minute
- beneficial effect of endurance type training, b/c a slowly beating heart is more energy efficient than one that beats more rapidly

163
Q

What is arteriosclerosis?

A

A thickening of the walls of arteries and loss of elasticity

164
Q

What is atherosclerosis?

A

A form of arteriosclerosis

- progressive disease characterized by the formation of lesions in the walls of large and medium-sized arteries

165
Q

What is ventricular fibrillation (VF or V-fib)?

A

Most deadly arrhythmia

  • contractions of the ventricular fibres are completely asynchronous so that the ventricles quiver instead of contract
  • ventricular pumping stops
  • blood ejection ceases and circulatory failure and death occur unless there is medical interventrion
166
Q

What is cardiac arrest?

A

Cessation of an effective heartbeat

- heart may be completely stopped or in V-fib

167
Q

What is a heart palpitation?

A

A fluttering of the heart or an abnormal rate or rhythm of the heart
- individual is aware

Biology - Chapter 19-29 (11 decks)

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