Cardiac Flashcards
1
Q
What is the cardiovascular system?
A
The hardware that transports blood, consisting of the heart (pump) and blood vessels (pipes).
2
Q
What are the two functions of the heart as a dual pump?
A
The right side pumps oxygen-poor blood to the lungs (pulmonary circuit), and the left side pumps oxygen-rich blood to the body (systemic circuit).
3
Q
What does the right side of the heart do?
A
It receives oxygen-poor venous blood and pumps it to the lungs for gas exchange via the pulmonary circuit.
4
Q
What does the left side of the heart do?
A
It receives oxygen-rich blood from the lungs and pumps it to the body for gas, nutrient, and hormone delivery via the systemic circuit.
5
Q
What are the size, shape, and position characteristics of the heart?
A
It is a hollow, four-chambered muscular pump, shaped like a clenched fist, located in the thoracic cavity between the lungs, and protected by the sternum and ribs.
6
Q
What are the key structural features of the heart’s shape?
A
It is cone-shaped, with an inferior apex that tilts left and a broad superior base where vessels attach.
7
Q
What do surface landmarks help define?
A
The four ‘corners’ of the heart.
8
Q
How can you locate the 2nd rib?
A
By finding the sternal angle (Angle of Louis).
9
Q
What are the three parts of the sternum?
A
Manubrium, body, and xiphoid process.
10
Q
What is the Angle of Louis?
A
A divot between the manubrium and sternum body.
11
Q
How do you palpate the sternal angle?
A
Start at the suprasternal notch, move down the manubrium to feel the divot at the sternum body.
12
Q
What defines the superior border of the heart?
A
From the 2nd left costal cartilage to the superior border of the 3rd right costal cartilage.
13
Q
What defines the inferior border of the heart?
A
From the 6th right costal cartilage to the 5th left intercostal space at the midclavicular line.
14
Q
What defines the right border of the heart?
A
From the 3rd right costal cartilage to the 6th right costal cartilage.
15
Q
What defines the left border of the heart?
A
From the 5th left intercostal space at the midclavicular line to the inferior border of the 2nd left costal cartilage.
16
Q
What is the pericardial sac?
A
A loose-fitting sac that encloses the heart.
17
Q
What are the functions of the pericardial sac?
A
Isolates the heart, resists overexpansion, reduces friction, and anchors the heart.
18
Q
What is the pericardial cavity?
A
A thin space inside the sac containing pericardial fluid.
19
Q
What is the function of pericardial fluid?
A
Lubricates the heart and reduces friction.
20
Q
What are the two layers of the pericardium?
A
Fibrous pericardium (outer, tough, inelastic) and serous pericardium (inner, thin).
21
Q
What are the two layers of the serous pericardium?
A
Parietal pericardium (fused to fibrous layer) and visceral pericardium (epicardium, on the heart).
22
Q
What is pericarditis?
A
Inflammation of the pericardium that roughens the serous lining, causing audible friction.
23
Q
What is cardiac tamponade?
A
Fluid buildup in the pericardial cavity compressing the heart, reducing its pumping ability.
24
Q
How is cardiac tamponade treated?
A
By removing excess fluid with a syringe.
25
What are the three layers of the heart wall?
Epicardium (outer), myocardium (middle), and endocardium (inner).
26
What is another name for the epicardium?
Visceral pericardium.
27
What is the myocardium?
The thick, muscular middle layer, thickest around the left ventricle.
28
What is the endocardium?
The smooth inner lining of chambers and valves, continuous with endothelium.
29
What are the atria?
The two superior chambers that receive venous blood returning to the heart.
30
What type of blood does the right atrium receive?
Deoxygenated blood from the systemic circuit.
31
What three vessels drain into the right atrium?
Superior vena cava, inferior vena cava, and coronary sinus.
32
What does the superior vena cava drain?
The upper body (above the diaphragm).
33
What does the inferior vena cava drain?
The lower body (below the diaphragm).
34
What does the coronary sinus drain?
Venous blood from the myocardium.
35
What are the two internal parts of the right atrial wall?
A smooth posterior wall and an anterior wall with pectinate muscles.
36
How does the left atrium differ internally from the right atrium?
Mostly smooth walls, with pectinate muscles only in the auricle.
37
What vessels bring blood to the left atrium?
Four pulmonary veins (two from each lung).
38
Why is blood in the pulmonary veins oxygenated?
It returns from the lungs, but they are still called veins due to flow direction.
39
What separates the atria?
The interatrial septum.
40
Why do atria have thin walls?
They are low-pressure chambers with a light workload.
41
What is the fossa ovalis?
A shallow depression in the interatrial septum, a remnant of the fetal foramen ovale.
42
What was the function of the foramen ovale in fetal circulation?
It bypassed the lungs since they weren’t needed before birth.
43
What are auricles?
Small ear-like extensions of the atria that slightly increase atrial volume.
44
What is the only visible part of the left atrium from the front?
The auricle.
45
What are the ventricles?
The two inferior chambers that act as the true pumps of the heart.
46
Where do ventricles pump blood?
Into arteries that carry blood away from the heart.
47
What type of blood do arteries usually carry?
Oxygenated blood (except the pulmonary arteries).
48
Where does the right ventricle receive blood from?
The right atrium.
49
Where does the right ventricle pump blood?
Into the pulmonary trunk, which branches into the right and left pulmonary arteries.
50
What is unique about the pulmonary arteries?
They carry deoxygenated blood to the lungs for gas exchange.
51
How do the right ventricle walls compare to other heart chambers?
Thicker than atrial walls but thinner than left ventricular walls.
52
Which heart chamber has the greatest workload?
The left ventricle.
53
Where does the left ventricle pump blood?
Into the aorta, supplying the entire body (systemic circuit).
54
Which heart chamber has the thickest walls?
The left ventricle.
55
What separates the left and right ventricles?
The interventricular septum.
56
What gives the internal ventricular walls a 'raked' appearance?
Trabeculae carneae.
57
What do external heart grooves indicate?
Boundaries of the heart chambers, occupied by coronary blood vessels.
58
What is the atrioventricular (coronary) sulcus?
A groove that separates the atria from the ventricles.
59
What are the anterior and posterior interventricular sulci?
Grooves that extend from the coronary sulcus to the apex, marking the division of right and left ventricles.
60
What is the function of heart valves?
Ensure one-way blood flow through the heart.
61
What are heart valve cusps made of?
Fibrous flaps covered with endocardium.
62
How do heart valves open and close?
In response to pressure changes.
63
Where are atrioventricular (AV) valves located?
Between the atria and ventricles.
64
What is the function of AV valves?
Prevent backflow into the atria during ventricular contraction.
65
What is another name for the right AV valve?
Tricuspid valve (has three cusps).
66
What is another name for the left AV valve?
Bicuspid or mitral valve (has two cusps).
67
How are AV valve cusps anchored?
By chordae tendineae ('heart strings') to papillary muscles.
68
What is the function of papillary muscles?
They contract first to stabilize the AV valves during ventricular contraction.
69
Where are semilunar valves located?
Between the ventricles and large vessels.
70
What is the function of semilunar valves?
Prevent backflow into the ventricles when relaxed.
71
Where is the pulmonary semilunar valve located?
Between the right ventricle and pulmonary trunk.
72
Where is the aortic semilunar valve located?
Between the left ventricle and aorta.
73
How do semilunar valves differ from AV valves?
AV valves are between atria and ventricles; semilunar valves are between ventricles and large vessels.
74
What are common causes of valve disorders?
Congenital abnormalities, poor blood supply, infection, and aging.
75
What are the two types of valve disorders?
Incompetent valves and stenotic valves.
76
What is an incompetent valve?
A valve that leaks and doesn’t close properly, causing regurgitation.
77
What is a stenotic valve?
A stiffened valve with narrowed openings, straining the ventricles.
78
What condition is a classic example of a stenotic valve?
Rheumatic heart disease.
79
What causes rheumatic heart disease?
An autoimmune reaction after a streptococcal throat infection.
80
How does rheumatic heart disease damage valves?
Antibodies attack connective tissue in the endocardium and valve cusps, especially the left AV valve.
81
Why is the heart highly fatigue-resistant?
It has a high metabolic rate and requires abundant oxygen and nutrients.
82
How is the myocardium nourished?
By coronary circulation, not by blood inside the heart chambers.
83
What is the function of coronary circulation?
To supply oxygen-rich blood to every myocyte.
84
Where do the right and left coronary arteries arise?
At the base of the aorta.
85
Where do the coronary arteries travel?
In the atrioventricular sulcus, circling the heart.
86
What are the two main branches of the left coronary artery?
The anterior interventricular artery and the circumflex artery.
87
What does the anterior interventricular artery supply?
The interventricular septum and anterior walls of both ventricles.
88
What does the circumflex artery supply?
The left atrium and posterior walls of the left ventricle.
89
Where does the right coronary artery travel?
It passes under the right auricle.
90
What does the right coronary artery supply?
The right atrium, SA node, and AV node.
91
What are the two main branches of the right coronary artery?
The marginal artery and the posterior interventricular artery.
92
Where does the marginal artery run?
Down the lateral right ventricle.
93
What does the marginal artery supply?
The right lateral myocardium.
94
Where is the posterior interventricular artery located?
In the posterior interventricular sulcus.
95
What does the posterior interventricular artery supply?
The posterior walls of the ventricles.
96
Where do coronary arteries lie?
In the epicardium.
97
What do coronary arteries supply?
Coronary capillaries.
98
Where does blood go after the coronary capillaries?
Into the coronary veins.
99
Where do most coronary veins drain?
Into the coronary sinus.
100
Where does the coronary sinus empty?
Into the right atrium.
101
Why is the coronary sinus important in open-heart surgery (OHS)?
It is used to initiate cardioplegia (stopping the heart).
102
What causes angina pectoris?
Temporary myocardial ischemia or stress-induced spasms of atherosclerotic coronary arteries.
103
How does angina feel?
Heaviness or pain in the chest.
104
Why is angina pain referred to the left arm?
C-fiber pain is dull and visceral, referred due to dermatomal sharing.
105
What happens when the myocardium becomes hypoxic?
It relies on anaerobic ATP production, leading to lactic acid buildup.
106
Do myocytes recover from angina-related ischemia?
Yes, they are damaged but recover.
107
What are two major causes of ischemia?
Fatty deposits (atherosclerosis) and blood clots (thrombosis).
108
What causes a myocardial infarction (MI)?
Prolonged coronary artery blockage.
109
How does an MI feel?
Heavy pressure, squeezing pain in the chest, arm, or back.
110
What happens to myocytes during an MI?
They die, causing permanent damage.
111
Why can’t the heart regenerate after an MI?
Adult myocytes are amitotic (do not divide) and are replaced with scar tissue.
112
How can an MI directly cause death?
By severely weakening the myocardium.
113
How can an MI indirectly cause death?
By disrupting heart rhythms, interrupting electrical conduction, and causing fibrillation or cardiac arrest.
114
What is an anastomosis in coronary circulation?
The merging of coronary arteries to provide collateral blood flow.
115
How do anastomoses help prevent myocardial infarction (MI)?
They create redundancy in blood supply, reducing the risk of blockage-related damage.
116
Which coronary arteries merge in anastomoses?
The circumflex artery with the right coronary artery and the anterior interventricular artery with the posterior interventricular artery.
117
What are cardiac muscle cells called?
Myocytes.
118
How are cardiac myocytes similar to skeletal muscle?
They are striated and contract via sliding filaments.
119
How are cardiac myocytes different from skeletal muscle?
They have 1-2 nuclei, are short and branching, are not individually innervated, and pass contraction signals.
120
How does the structure of cardiac myocytes aid function?
Their branching structure allows them to interconnect, forming a network for efficient contraction.
121
What are intercalated discs?
Specialized connections between cardiac myocytes that facilitate synchronized contraction.
122
What are intercalated discs?
Thick connections joining cardiac cells.
123
What are the two main junctions of intercalated discs?
Mechanical and electrical junctions.
124
What are the three features of intercalated discs?
Interdigitating membranes, desmosomes, and gap junctions.
125
What is the function of interdigitating membranes?
They interlock myocytes like laced fingers for strong connections.
126
What is the function of desmosomes in cardiac muscle?
They provide mechanical stability and prevent separation during contraction.
127
What is the function of gap junctions?
They electrically connect cells, allowing ions to pass and transmitting action potentials.
128
How does cardiac muscle generate energy?
Almost exclusively through aerobic respiration.
129
Why is cardiac muscle resistant to fatigue?
Due to its rich supply of myoglobin, glycogen, and large mitochondria.
130
How do cardiac T-tubules and sarcoplasmic reticulum (SR) differ from skeletal muscle?
T-tubules are wider and farther apart, and the SR is simpler, smaller, and lacks terminal cisternae.
131
What does it mean that the heart is myogenic?
It generates its own stimulus for contraction.
132
What are pacemaker cells?
Specialized cardiac cells that originate contraction signals.
133
How does the autonomic nervous system (ANS) affect heart rhythm?
It modifies rhythm but does not create it.
134
What does it mean that pacemaker cells are autorhythmic?
They spontaneously depolarize at regular intervals.
135
What is the function of the cardiac conduction system?
It controls the route and timing of electrical conduction for chamber coordination.
136
Where is the sinoatrial (SA) node located?
In the right atrium near the superior vena cava.
137
What is the function of the SA node?
It acts as the heart’s pacemaker, initiating each heartbeat and setting heart rate.
138
Where does the SA node send signals?
Through the atria to the AV node.
139
Where is the atrioventricular (AV) node located?
Near the right AV valve.
140
What is the function of the AV node?
It acts as the electrical gateway to the ventricles.
141
What is the AV bundle (Bundle of His)?
The pathway through which signals leave the AV node.
142
What are the right and left bundle branches?
Divisions of the AV bundle that extend down the interventricular septum.
143
Where do the bundle branches travel?
They descend toward the apex and terminate in the Purkinje fibers.
144
What are Purkinje fibers?
Fibers that arise from the bundle branches and spread throughout the ventricles.
145
Where do Purkinje fibers distribute signals?
They turn upward and spread through the ventricles, including the papillary muscles.
146
Which part of the ventricles contracts first?
The papillary muscles.
147
Does the autonomic nervous system (ANS) generate the heartbeat?
No, it only modifies the heart rate and force of contraction.
148
Which nerve provides parasympathetic innervation to the heart?
The vagus nerve (cardio-inhibitory).
149
What areas does the parasympathetic system supply?
The SA node, AV node, and atrial myocardium (minor influence).
150
What is the effect of parasympathetic stimulation on the heart?
It decreases heart rate.
151
What areas does the sympathetic system supply?
The SA node, AV node, coronary arteries, and cardiac myocytes.
152
What are the effects of sympathetic stimulation?
Increases heart rate and force of contraction.
153
Where do all autonomic nerves serving the heart pass through?
The cardiac plexus on the trachea.
154
When does heart development begin?
Around day 20–21 as a pair of endothelial tubes.
155
When do the heart tubes fuse into a single tube?
Around day 20.
156
When does the heart start pumping?
Around day 22.
157
What structural changes occur by day 22?
Four bulges appear in the developing heart.
158
What major heart developments occur in month 2?
The heart divides into chambers and forms septa and valves.
159
When do most congenital heart defects occur?
During month 2, when chambers, septa, and valves form.
160
What is the most common congenital heart defect?
Ventricular septal defect (VSD).
161
What causes VSD?
Failure of the superior interventricular septum to form, leaving a hole between ventricles.
162
What interatrial connection exists before birth?
The foramen ovale, which allows blood flow between atria.
163
What is the purpose of the foramen ovale in fetal circulation?
It bypasses the lungs by allowing blood to flow between the atria.
164
What happens if the foramen ovale fails to close at birth?
It results in an atrial septal defect (ASD).
165
Is an atrial septal defect always dangerous?
Sometimes benign; a portion of the population has a pro-patent defect.
166
What are the effects of an ASD?
Inadequate oxygenation of tissues (ischemia) and increased ventricular workload.
