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Anatomy And Physiology 2 > Chapter 18: Heart > Flashcards

Chapter 18: Heart Flashcards

0
Q

Left atrium revolves blood from?

A

Returning pulmonary circuit

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1
Q

Right atrium receives blood from?

A

Returning systemic circuit

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2
Q

Right ventricle pumps blood through ?

A

Pulmonary circuit

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3
Q

What is the pericardium?

A

Double walled sac

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4
Q

What does the superfibrous pericardium do?

A

Protects ,
Anchors to surrounding structures ,
And prevents overfilling

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5
Q

Serous pericardium is made up of what 3 layers?

A
  • parietal layer
  • visceral layer
  • pericardial cavity
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6
Q

Parietal layer does:

A

Lines the internal surface of fibrous pericardium

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7
Q

Visceral layer does:

A

On external surface of heart

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8
Q

Pericardial cavity:

A

Fluid filled cavity that separates the two layers

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9
Q

What is pericarditis?

A
  • inflammation of the pericardium
  • roughens membrane surfaces->pericardial friction rub(creaking sound)
  • cardiac tamponade : excess fluid sometimes compressed the heart–> limited pumping ability
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10
Q

What are the three layers of the heart?

A

Epicardium
Myocardium
Endocardium

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11
Q

Epicardium:

A

Is the visceral layer of the serous pericardium

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12
Q

Myocardium:

A
  • spiral bundle of contractile cardiac muscle cells
  • cardiac skeleton : crisscrossing, interlacing layer of connective tissue
    • anchors cardiac muscle fibers
    • supports great vessels and valves
    • limits spread of action potentials to specific paths
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13
Q

Endocardium:

A

Is continuous with endothelial lining of blood vessels.

-it lines the heart chambers, covers cardiac skeleton valves

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14
Q

What is the interatrial septum?

A

Separates the atria

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15
Q

What structure separates the ventricles?

A

Interventricular septum

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16
Q

Heart valves do what?

A
  • Ensure unidirectional blood flow through heart

- open and close in response to pressure changes

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17
Q

Which valves prevent backflow into atria when ventricles contract?

A

The atrioventricular valves

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18
Q

What do the semilunar valves do?

A

-prevent backflow into ventricles when ventricles RELAX

There are two semilunar valves: aortic/pulmonary

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19
Q

What two conditions seriously weaken the heart?

A

Incompetent valve
And

Valvular stenosis

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20
Q

Incompetent valve:

A

Blood backflows so heart repos same blood over and over

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21
Q

Valvular stenosis:

A

Stiff flaps- constrict opening ->heart muscle must exert more force to pump blood

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22
Q

How are weakened heart valves replaced?

A

Mechanical, animal, or cadaver valves

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23
Q

What is the pathway of blood through the heart in the pulmonary circuit?

A

Right atrium> tricuspid valve > right ventricle

  • right ventricle > pulmonary semilunar valves > pulmonary trunk > pulmonary arteries > lungs
  • lungs > pulmonary veins > left atrium
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24
Q

Pathway of blood in systemic circuit?

A

Left atrium> mitral valve > left ventricle

  • left ventricle > aortic semilunar valve > aorta
  • aorta > systemic circuit
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25
Q

What kind of pressure is the pulmonary circuit ?

A

Short , low pressure

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26
Q

What kind of pressure is the systemic circuit ?

A

Long , high-friction circulation

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27
Q

What does the left ventricles thicker wall have to do with pressure?

A

Makes the heart pump with greater pressure

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28
Q

What is the function of blood supply to the heart?

A
  • delivers when heart is RELAXED

- left ventricle receives most blood supply

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29
Q

The coronary circulation contains how many anastomoses ?

A

Many anastomoses (junctions )

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30
Q

What do the anastomoses do for the coronary circulation ?

A
  • provide additional routes for blood delivery

- cannot compensate for coronary artery occlusion

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31
Q

What do cardiac veins do?

A

Collect blood from capillary beds

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32
Q

Angina Pectoris:

A
  • thoracic pain caused by fleeting deficiency in blood delivered to myocardium
  • cells weakened
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33
Q

Myocardial infarction(heart attack):

A
  • due to prolonged coronary blockage

- areas of cell death are repaired with non contractile scar tissue

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34
Q

Intercalated disks:

A

Junctions between cells -anchor cardiac cells

Contains desmosomes and gap junctions

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35
Q

Desmosomes :

A

Prevent cells from separating during contraction

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36
Q

Gap junctions :

A

Allows ions to pass from cell to cell ; electrically couple adjacent cells
–allows heart to be functional syncytium

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37
Q

Cardiac differ from skeletal muscles in 3 ways:

A
  • ~1% of cells have automaticity (autorhythmicity)
    (Do not need nervous system stimulation and can DEPOLARIZE entire heart)
  • all cardiomyocytes contract as unit or none do
  • long absolute refactory period (250 ms) this prevents tetanic contractions
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38
Q

Three similarities cardiac and skeletal muscles have?

A
  • depolarization opens few voltage-gated fast Na+ channels on sarcolemma->
    • reversal of membrane potential from -90 mV to +30 mV
    • brief Na channels close rapidly.

-depolarization wave down T tubules > SR to release Ca2+ ->

  • excitation-contraction coupling occurs.
    • -Ca2+ binds troponin> filaments slide
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39
Q

Muscle contraction differences between cardiac and skeletal?

A
  • depolarization wave also opens slow Ca2+ channels in sarcolemma > SR to release Ca2+
  • Ca2+ surge prolongs the depolarization phase (plateau)
  • action potential and contractile phase last much longer (allow blood ejection from heart)

-repolarization result of inactivation of Ca2+ channels and opening of voltage-gated K + channels
( Ca2+ pumped back to SR and extracellulary)

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40
Q

Does cardiac muscle have many mitochondria ?

A

Yes

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41
Q

Why does cardiac muscle have many mitochondria?

A

-Great dependence on aerobic respiration

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42
Q

Cardiac cell imbalance?

A

Ischemic cells> anaerobic respiration > lactic acid

  • -high H+ concentration > high Ca2+ concentration
    - gap junction close > fatal arrhythmias
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43
Q

Coordinated heartbeat is a function of:

A
  • presence of gap junctions
  • intrinsic cardiac conduction system : (network of non contractile autorhythmic cells) and (initiate and distribute impulses > coordinated depolarization and contraction of heart
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44
Q

Pacemaker (autorhythmic cells):

A

✳️have unstable resting membrane potentials (pacemaker potentials or prepotentials ) due to opening of slow Na+ channels)
-continuously depolarize
✳️at threshold, Ca2+ channels open
✳️explosive Ca2+ influx produces the rising phase of the action potential
✳️repolarization results from inactivation of Ca2+ channels and opening of voltage-gated k+ channels

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45
Q

Three parts of action potential?

A

Pacemaker potential
Depolarization
Repolarization

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46
Q

Pacemaker potential:

A

Repolarization closes K+ channels and opens slow Na+ channels ➡️ ion imbalance

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47
Q

Depolarization :

A

Ca2+ channels open ➡️ huge influx➡️rising phase of action potential

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48
Q

Repolarization:

A

K+ channels open➡️efflux of K+

49
Q

How long does it take the cardiac pacemaker cells to go across heart?

A

~220 ms

50
Q

What is the sequence of excitation ?

A 
▪️sinoatrial node ➡️
▪️atrioventricular node ➡️
▪️atrioventricular bundle ➡️
▪️right and left bundle branches ➡️
▪️subendocardial conducting network
(Purkinje fibers)
51
Q

Sinoatrial node(sequence of excitation )?

A
  • pacemaker of the heart in right atrial wall
  • depolarizes faster than rest of myocardium
  • generates impulses about 75X/minute (sinus rhythm)
    • inherent rate of 100X/minute tempered by extrinsic factor)

-impulse spreads across atria and to AV node

52
Q

Atrioventricular node(sequence of excitation)?

A
  • in inferior interatrial septum
  • delays pulses aprox. 0.1 second
    • because fibers are smaller diameter= fewer gap junctions
      - allows atrial contraction prior to ventricular contraction

-inherent rate of 50X/minute in absence of SA node input

53
Q

Atrioventricular bundle(sequence of excitation)?

A
  • in superior interventricular septum
  • only electrical connection between atria and ventricles
    • atria and ventricles not connected via gap junction
54
Q

Right and left bundle branches (sequence of excitation)?

A
  • two pathways in interventricular septum

- carry impulses toward apex of heart

55
Q

Subendocardial conducting network (sequence of excitation)?

A

-Complete pathway through interventricular septum into apex and ventricular walls

  • more elaborate on left side of heart
  • AV bundle and subendocardial conducting network depolarize 30X/minute in absence of AV node input

-ventricular contraction immediately follows from apex toward atria

56
Q

Defects in intrinsic conduction system cause what?

A

▪️arrhythmias

▪️fibrillation

57
Q

Arrhythmias :

A
  • irregular heart rhythms

- uncoordinated atrial and ventricular contractions

58
Q

Fibrillation:

A

Rapid, irregular contractions; useless for pumping blood ➡️ circulation cease➡️ brain death ➡️ defibrillation to treat

59
Q

Fasiculation:

A

Visible muscle tremors

60
Q

What does a defective SA node cause?

A

▪️Ectopic focus

▪️extrasystole

61
Q

Ectopic focus:

A
  • abnormal pacemaker

- AV node may take over ; sets junction all rhythm (40-60bpm)

62
Q

Extrasystole:

A
  • ectopic focus sets high rate

- can be from excessive caffeine or nicotine

63
Q

Defective AV node may cause what?

A

▪️heart block

▪️artificial pacemaker to treat

64
Q

Heart block:

A
  • Few(partial) or no (total) impulses reach ventricles

- ventricles beat at intrinsic rate –too slow for life

65
Q

What is the heartbeat modified by?

A

▪️Heartbeat modified by ANS via cardiac centers in medulla oblongata.
-sympathetic =⬆️ rate and force
-parasympathetic =⬇️rate
▪️cardioacceleratory center- sympathetic affects SA,AV, heart muscle , coronary arteries
▪️cardioinhibitory center - parasympathetic inhibits SA AV nodes via vagus nerves

66
Q

Electrocardiogram:

A

Composite of all action potentials generated by nod and contractile cells at given time

67
Q

Three waves in electrocardiograph?

A

P wave
QRS complex
T wave

68
Q

P wave:

A

Depolarization SA node ➡️atria

69
Q

QRS complex:

A

Ventricular depolarization and atrial repolarization

70
Q

T wave:

A

Ventricular repolarization

71
Q

P-R interval:

A

Beginning of atrial excitation to beginning of ventricular excitation

72
Q

S-T segment:

A

Entire ventricular myocardium depolarizes

73
Q

Q-T interval:

A

Beginning of ventricular depolarization through ventricular repolarization

74
Q

What are the two heart sounds?

A

Lub-dub

75
Q

Heart sound one:

A

As AV valves close, beginning of systole

76
Q

Heart sound 2:

A

as semilunar valves close, beginning of ventricular diastole

77
Q

Heart murmur:

A

Abnormal heart sounds ; usually indicate incompetent or stenotic valves

78
Q

What is the cardiac cycle(mechanical events)?

A
  • blood glow through the heart during one complete heartbeat; atrial systole and diastole followed by ventricular systole and diastole
  • systole : contraction
  • diastole : relaxation
  • series of pressure and blood volume changes
79
Q
  1. Ventricular filling:
A

Takes place in mid to late diastole

▪️AV valves are open ; pressure low
▪️80% of blood passively flows into ventricles
▪️atrial systole occurs ;delivering remaining 20%
▪️end diastolic volume : volume of blood in each ventricle at end of ventricular diastole

80
Q
  1. Ventricular systole:
A

▪️atria relax; ventricles begin to contract
▪️rising ventricular pressure ➡️ closing of AV valves
▪️isovolumetric contraction phase(all valves are closed)
▪️in ejection phase , ventricular pressure exceeds pressure in large arteries, forcing SL valves to open
▪️end systolic volume ; volume of blood remaining in each ventricle after systole

81
Q
  1. Isovolumetric relaxation :
A

Early diastole

▪️ventricles relax ; atria relaxed and filling
▪️backflow of blood in aorta and pulmonary trunk closes SL valves
-causes dicrotic notch (brief rise in aortic pressure as blood rebounds off closed valve)
-ventricles totally closed chambers
▪️when atrial pressure exceeds that in ventricles ➡️ AV valves open ; cycle begins again at step 1

82
Q

Cardiac output:

A

▪️volume of blood pumped by each ventricle in one minute
▪️CO= heart rate x stroke volume

 -number of beats per minute 
 - volume of blood pumped out by one ventricle with each beat  ▪️normal 5.25 L/minute
83
Q

Cardiac output at rest:

A

▪️CO (ml/min) = HR (75beats/min) x SV (70ml/ beat) = 5.25 L/min
▪️CO increases if either/ both SV OR HR increased
▪️maximal CO is 4-5 times resting CO nonathletic people
▪️maximal CO May reach 35 L/min in trained athletes
▪️cardiac reserve- difference between resting and maximal CO

84
Q

Cardiac reserve:

A

Difference between resting and maximal CO

85
Q

regulation of stroke volume:

A

▪️SV= EDV-ESV

  - EDV affected by length of ventricular diastole and venous pressure 
  - ESV affected by arterial BP and force of ventricular contraction
86
Q

What 3 main factors affect SV?

A

Preload
Contractibility
After load

87
Q

Preload:

A

Degree of stretch of cardiac muscle cells before they contract (Frank-Starling law of heart)
▪️cardiac muscle exhibits a length -tension relationship
▪️at rest, cardiac muscle cells shorter than optimal length
▪️MOST IMPORTANT factor stretching cardiac muscle is VENOUS RETURN - amount of blood returning to the heart.
-slow heartbeat and exercise increase venous return
-increased venous return distends (stretches ) ventricles and increases contraction force

88
Q

Contractibility:

A

Contractile strength at given muscle length, independent of muscle stretch and EDV
▪️Increased by: sympathetic stimulation ➡️ increased Ca2+ influx➡️more cross bridges
-positive inotropic agents : thyroxine, glucagon, epinephrine, digitalis, high extracellular Ca2+

▪️decreased by negative inotropic agents
- acidosis, increased extracellular K+ , calcium channel blockers

89
Q

After load:

A

Pressure ventricles must overcome to eject blood

90
Q

What is the result of hypertension increasing after load?

A

Resulting in increased ESV and reduced SV

91
Q

Positive chronotropic factors do what to heart rate?

A

⬆️ heart rate

92
Q

Negative chronotropic factors do what to heart rate?

A

⬇️ heart rate

93
Q

How is the sympathetic nervous system activated?

A

By emotional or physical stressors

94
Q

Which hormone causes sympathetic nervous system to activate?

A

Norepinephrine

95
Q

What does norepinephrine do in the sympathetic nervous system?

A

Causes pacemaker to fire more rapidly (increases Contractility)

  • binds to B1- adrenergic receptors ➡️ increase HR
  • ⬆️ Contractility ; faster relaxation
    - offsets lower EDV de to decreased fill time
96
Q

Which hormone in the parasympathetic nervous system effects the heart rate?

A

Acetylcholine

97
Q

What does acetylcholine do in the parasympathetic nervous system ?

A

Hyperpolarizes pacemaker cells by opening the K+ channels ➡️ slower HR

  • little to no effect on Contractility
  • heart at rest exhibits Vaal tone
    • parasympathetic dominant influence
98
Q

What is the atrial (brain bridge ) reflex?

A

Sympathetic reflex initiated by increased venous return, hence increased Atrial filling

  • stretch of atrial walls stimulates the SA node ➡️ increase HR
  • also stimulates atrial stretch receptors, activating sympathetic reflexes
99
Q

What two hormones affect chemical regulation of heart rate?

A

Epinephrine
And

Thyroxine

100
Q

Epinephrine chemical regulation for heart rate?

A

From adrenal medulla increased heart rate and Contractility

101
Q

Thyroxine for chemical regulation of heart rate?

A

Increases heart rate; and enhances effects of norepinephrine and epinephrine

102
Q

Intra- and extracellular ion concentrations must be maintained for normal heart function ? True or false

A

True

103
Q

Hypocalcemia:

A

Depresses heart

104
Q

Hypercalcemia:

A

Increased HR and Contractility

105
Q

Hyperkalemia:

A

Alters electrical activity ➡️heart block and cardiac arrest

106
Q

Hypokalemia:

A

Feeble heartbeat arrhythmias

107
Q

Does a fetus have a faster or slower heart rate?

A

Faster

108
Q

Does a male or females heart beat faster?

A

Female

109
Q

Does exercise increase heart rate?

A

Yes

110
Q

Does body temperature increase heart rate?

A

Yes

111
Q

Tachycardia:

A

Abnormally fast heart rate over 100bpm

112
Q

Bradycardia:

A

Slow heart rate less than 60 bpm.
-results in inadequate blood flow

-desirable for endurance training

113
Q

Congestive heart failure (CHF):

A

▪️progressive condition ; CO is so low that blood circulation is inadequate to meet tissue needs
▪️reflects weakened myocardium caused by :
-coronary atherosclerosis (clogged arteries)
- persistent HBP
-multiple myocardial infarcts
-dilated cardiomyopathy (DCM)

114
Q

What is pulmonary congestion?

A

Left side fails ➡️ blood backs up in Lungs

115
Q

Peripheral congestion :

A

Right side fails ➡️ blood pools in body organs ➡️ edema

116
Q

What are the four Embryonic heart chambers?

A

Sinus venous
atrium
Ventricle
Bulbus cordis

117
Q

What does the ductus arteriosus do in fetal hearts?

A

Connects pulmonary trunk to aorta

-remnant- ligamentum arteriosum in adult

118
Q

Congenital heart defects:

A

▪️most common heart defects treated by surgery
▪️two types: mixing of oxygen-port and oxygen-rich blood (septal , patent duct)
And

Narrowed valves or vessels ➡️ increased workload on heart (coarctation of aorta)
▪️tetralogy of fallot : both types of disorders present

119
Q

4 age related changes that affect the heart?

A

▪️sclerosis and thickening of valve flaps
▪️decline in cardiac reserve
▪️fibrosis of cardiac muscle
▪️atherosclerosis

Anatomy And Physiology 2 (7 decks)

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