The Heart Flashcards

(93 cards)

1
Q

What body cavity is the heart in?

A

The mediastinum

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2
Q

Where do the base and apex of the heart point?

A

The base points towards the right shoulder and the apex points towards the lower left abdomen.

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3
Q

What are the three layers of the heart?

A

The pericardium, the myocardium, and the endocardium.

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4
Q

What is the pericardium of the heart made of?

A

It is a double walled fibrous sac

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5
Q

What are the layers of the pericardium? What are their functions?

A

Outermost layer: Fibrous pericardium is the thickest layer of the pericardium and protects and anchors the heart as well as prevents overfilling

The inner layer is the serous pericardium and is composed of a parietal layer outside of a visceral or epicardium layer outside of a fluid filled pericardial cavity.

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6
Q

What layer of the heart is the muscle located in?

A

The myocardium.

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7
Q

What are the cardiac muscles wrapped in?

A

Connective tissue wrappings

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8
Q

What are the three functions of cardiac connective tissue wrappings?

A
  1. They reinforce myocardium internally and anchor the muscle fibers
  2. It provides support for vessels and valves
  3. It directs the spread of actions potentials across the heart
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9
Q

What is the composition of the endocardium?

A

it is a layer of endothelium and connective tissue on the inner myocardial surface and is continuous with vessels

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10
Q

What are the two sulci on the heart?

A

The coronary sulcus or atrioventricular groove, and the anterior/posterior interventricular sulcus

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11
Q

What are the three sources of oxygen poor blood into the right atrium?

A
  1. The superior vena cava (above the heart)
  2. The inferior vena cava (below the heart)
  3. The coronary sinus (wall of the blood itself in the coronary sulcus)
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12
Q

What are the 4 veins that carry oxygenated blood?

A

pulmonary veins

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13
Q

What are the small muscles called primarily found in the right atrium?

A

Pectinate muscles

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14
Q

What is the opening between the left and right atrium found in babies called?

A

The foramen ovale

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15
Q

What does the closed foramen ovale become?

A

the fossa ovalis.

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16
Q

What blood vessel does the right ventricle send blood out of?

A

The pulmonary trunk

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17
Q

What blood vessel takes blood from the left ventricle to the body?

A

The aorta

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18
Q

What are the two types of muscle found in the ventricles? What is the differentiating characteristic?

A

Trabeculae carneae
Papillary muscles link the chordae tendineae

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19
Q

What are the two classifications of heart valves?

A

There are two atrioventricular valves and two semilunar valves

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20
Q

What are the names of the atrioventricular valves?

A

The right one is called the tricuspid valve and the left is called the mitral or bicuspid valve.

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21
Q

What are the two semilunar valves called?

A

The valve exiting the right ventricle is the pulmonary valve, and the valve exiting the left ventricle is the aortic valve.

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22
Q

What are the two types of valve problems?

A

Valvular insufficiency is the valves not closing all the way, and stenosis is the stiffening of the valves due to calcification or scar tissue

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23
Q

What has more resistance? The pulmonary blood circuit or the systemic one?

A

The systemic circuit has 5x the resistance.

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24
Q

Which ventricle has thicker walls? By how much?

A

The left ventricle is 3X thicker.

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25
Where do the left and right coronary arteries come from? Where are they located?
They come from the base of the aorta and wrap around the coronary sulcus.
26
What does the left coronary artery branch into?
The circumflex artery (around the back) and the anterior interventricular artery.
27
What branches off from the right coronary artery?
The right marginal artery anteriorly, and posteriorly the posterior interventricular artery.
28
What is important about the coronary arteries come from the base of the aorta?
They deliver blood when it is relaxed. When the ventricles are contracting, they constrict the coronary arteries.
29
What are anastomoses in the heart?
They are direct linking of arteries and are important for providing alternative pathways for blood flow.
30
What does angina pectoris mean?
Chest pain
31
What is a myocardial infarction?
A heart attack is a complete blockage and no blood moving to an area of the heart.
32
What four cardiac veins feed into the coronary sinus?
The great cardiac vein (left) Middle cardiac vein (posterior) The small cardiac vein (lower right) The anterior cardiac veins (upper right)
33
What is the biggest difference between skeletal and cardiac muscle cells?
Cardiac muscle has intercalated discs
34
What are the two types of junctions in intercalated discs?
Gap junctions for electrical coupling desmosomes for strong cell to cell adhesion
35
What is the phenomenon that gap junctions allow for?
functional syncytium
36
What are the two types of cardiac muscle?
contractile and autorythmic
37
What percentage of cardiac muscle cells are pacemakers?
roughly 1 percent
38
Is the ECF considered a fast or slow channel?
Slow channel
39
What is the duration of the absolute refractory period of a cardiac muscle vs skeletal? Why?
It is roughly 250ms vs 1-2 ms so the muscle doesn't go titinic
40
Why do circulatory blockages matter more in the heart?
Respiration is purely aerobic
41
What is the depolarization phase of a heartbeat driven by?
voltage gated Na+ channels
42
Why is the plateau of a heartbeat longer?
The calcium influxes at the same rate as potassium goes out.
43
What happens in the repolarization phase?
The potassium channels open and the calcium channels close.
44
What is sinus rhythm
The spontaneous depolarization of the SA node.
45
Where is the SA node found?
The right atrium
46
What are autorhythmic cardiac muscle cells?
cells that are able to spontaneously depolarize
47
What is special about the structure of cardiac muscle cells?
They are unstable because funny sodium channels open at negative membrane potentials plus slow closing potassium channels
48
What is special about action potentials in autorhythmic cells?
They are caused by calcium channels, not sodium channels.
49
What is the order of the intrinsic conduction system of the heart?
1. SA node 2.AV node 3. AV bundle 4. Left and right bundle branches 5. Subendocardial conducting network/Purkinje fibers
50
Why is the SA node considered the pacemaker?
It spontaneously depolarizes the most.
51
Where is the bottleneck in the intrinsic conduction system of the heart?
From the atria to the ventricles
52
What is brachychardia?
Slower than normal HR (<55BPM)
53
What is tachycardia?
Faster than normal HR (>100BPM)
54
What has a dampening effect on HR under resting conditions?
tonic parasympathetic output
55
What does an ECG tracing record?
The electrical tracing of the heart
56
What does a P wave represent?
Atrial depolarization
57
What follows a P wave?
A QRS complex (ventricular depolarization)
58
What follows a QRS complex?
A T wave (ventricular repolarization)
59
Where on an ECG do we see atrial repolarization?
The QRS complex
60
What happens if the SA node is nonfunctional? (junctional rhythm)
The AV node takes over
61
What is ventricular fibrilation?
What is happening in the ventricles is not being controlled by the intrinsic conduction system
62
What are the stages of the cardiac cycle?
Systole (contraction blood OUT) and Diastole (filling with blood) Atrial systole and diastole -> ventricular systole and diastole
63
What is the first phase of the cardiac cycle?
The period of ventricular filling, mid to late diastole. The AV vales are open and the SL valves are closed
64
What happens when ventricles reach 70% capacity?
There is atrial systole to fill the rest of the ventricles, and the AV valves begin to close. The atria begin diastole
65
What is EDV?
End diastolic volume is the filled volume of the ventricles
66
What is the second stage of the cardiac cycle?
The ventricular systole.
67
Describe the cardiac events that lead to the QRS complex and T wave.
The ventricles begin to contract, the AV valves close, there is a period of isovolumetric contraction, and that pressure opens the SL valves for the ventricular ejection (systole) phase.
68
Describe the cardiac events of the isovolumetric relaxation phase
There is an early diastole which decreases pressure in the ventricles, which closes the SL valves
69
What is the timing breakdown of a cardiac cycle?
0.1 sec of atrial systole, 0.3 seconds of ventricular systole, and then 0.4 seconds of quiescent period (atrioventricular diastole)
70
What determines the direction of blood in the heart?
Pressure changes open and close the valves
71
What is the blip in pressure caused by the recoil of the aorta called?
The dicrotic notch
72
Where is the Stroke volume found?
It is the volume pushed out from each ventricle
73
What is the ESV?
The end systolic volume is the volume of blood left over after systole
74
What are the two heart sounds?
The first is caused by the closing of the AV valves at the beginning of ventricular systole The second is the closing of the SL valves at the end of systole
75
What are two reasons for abnormal heartbeat sounds (Heart murmurs)?
Valvular stenosis: Valve doesn't open very well, and higher pitch of sounds when blood is being pushed through Valvular insufficiency: Leakage of blood back instead of silence
76
What is CO?
Cardiac output is the amount of blood pumped by the heart for each ventricle per minute
77
What is the calculation of CO?
It is stroke volume*HR
78
What is the average CO for a healthy male?
5L/min
79
What is the calculation for SV?
Stroke volume is end diastolic volume - end systolic volume
80
How does exercise affect CO?
It increases 4-5 times in well trained people, and 7 times in marathon runners
81
What is the notion of cardiac reserve?
There is a heart capacity to pump more
82
What are 4 determinants of HR?
1. autonomic fibers of the SA node 2. circulating hormones 3. Plasma electrolyte concentrations 4. Body temperature
83
What NT kicks in with the parasympathetic nervous system?
Acetylcholine decreases spontaneous depolarization
84
What is the term for the dominant effect of the parasympathetic NS on the heart in resting conditions?
Vagal tone
85
What is the Frank Starling Law of the heart?
Within defined limits, the heart will pump as much blood as it receives
86
At what stretch is cardiac muscle at rest compared to optimal length?
It is shorter than the optimal length
87
Define preload
The amount of blood entering the heart that is expected to leave
88
What is afterload?
The pressure that ventricles have to overcome to open the semilunar valves. It is the pressure of the aorta/pulmonary trunk
89
How does hypertension affect the heart?
It increases the afterload, therefore the heart has a lower end systolic volume and therefore a decreased SV
90
What are extrinsic influences on stroke volume?
factors outside the heart that change the vigor of contraction without changing the EDV
91
What leads to a stronger contractile reflex?
An increase in Ca++ influx
92
What are two reasons for the Ca++ influx leading to a stronger heart contraction?
1. Sympathetic stimulation increases the strength of contraction as well as rate of contraction 2. Drugs such as digoxin increase contractility
93