Heart Flashcards
(124 cards)
1
Q
A
2
Q
What controls the beating of the heart?
A
Action potentials.
3
Q
What is the primary pacemaker of the heart?
A
Sinoatrial (SA) node.
4
Q
What are the three main pacemakers in the heart?
A
SA node, AV node, Purkinje fibers.
5
Q
What is the typical firing rate of the SA node?
A
60-100 beats per minute.
6
Q
What is the typical firing rate of the AV node?
A
40-60 beats per minute.
7
Q
What is the typical firing rate of the Purkinje fibers?
A
20-40 beats per minute.
8
Q
Which pacemaker dominates under normal conditions?
A
SA node (highest frequency wins).
9
Q
How do cardiomyocytes communicate?
A
Via intercalated discs and gap junctions.
10
Q
What is electrotonic conduction?
A
Passive spread of electrical signals between cardiac cells.
11
Q
Which part of the heart has the slowest conduction velocity?
A
AV node (5 cm/sec).
12
Q
Which part of the heart has the fastest conduction velocity?
A
Purkinje fibers (3-500 cm/sec).
13
Q
What is the role of the AV node in conduction?
A
Delays signal to allow ventricular filling.
14
Q
What are HCN channels and where are they found?
A
Hyperpolarization-activated cyclic nucleotide-gated channels in pacemaker cells.
15
Q
What is the function of HCN channels?
A
They generate pacemaker currents (If) to regulate heart rate.
16
Q
How does sympathetic stimulation affect heart rate?
A
Increases it by increasing HCN channel activity.
17
Q
How does parasympathetic stimulation affect heart rate?
A
Decreases it by reducing HCN channel activity.
18
Q
What ion primarily drives depolarization in SA node action potentials?
A
Calcium (Ca²⁺).
19
Q
What ion primarily drives depolarization in ventricular action potentials?
A
Sodium (Na⁺).
20
Q
What is the plateau phase in ventricular action potentials?
A
A prolonged depolarization due to Ca²⁺ influx.
21
Q
Why is the plateau phase important?
A
Prevents tetanus and allows coordinated contraction.
22
Q
What is the origin of the ECG signal?
A
The electrical activity of the heart.
23
Q
What does the P wave represent on an ECG?
A
Atrial depolarization.
24
Q
What does the QRS complex represent?
A
Ventricular depolarization.
25
What does the T wave represent?
Ventricular repolarization.
26
What is sinus tachycardia?
A fast heart rate due to increased sympathetic activity.
27
What is sinus arrhythmia?
Normal heart rate variation with breathing.
28
What is an ectopic pacemaker?
An abnormal pacemaker outside the SA node.
29
What are two common disorders of impulse conduction?
Conduction block and reentry.
30
What is reentry in cardiac electrophysiology?
A self-sustaining loop of electrical activity causing arrhythmias.
31
What is Wolff-Parkinson-White (WPW) syndrome?
A reentry arrhythmia due to an abnormal accessory conduction pathway.
32
Question
Answer
33
What is the main function of the cardiovascular system?
Transport oxygen, nutrients, and waste.
34
What determines blood pressure?
Cardiac output and vascular resistance.
35
What is cardiac output?
Heart rate × stroke volume.
36
How is heart rate regulated?
By autonomic nervous system (sympathetic and parasympathetic).
37
What effect does sympathetic stimulation have on heart rate?
Increases heart rate and contractility.
38
What effect does parasympathetic stimulation have on heart rate?
Decreases heart rate.
39
What is stroke volume?
The amount of blood ejected per heartbeat.
40
What factors influence stroke volume?
Preload, afterload, and contractility.
41
What is preload?
The volume of blood filling the ventricles before contraction.
42
What is afterload?
The resistance the heart must overcome to eject blood.
43
What determines vascular resistance?
Vessel diameter, blood viscosity, and vessel length.
44
What is the primary site of vascular resistance regulation?
Arterioles.
45
How does vasoconstriction affect blood pressure?
Increases blood pressure.
46
How does vasodilation affect blood pressure?
Decreases blood pressure.
47
What is the role of baroreceptors?
Detect changes in blood pressure and regulate autonomic output.
48
Where are baroreceptors located?
Carotid sinuses and aortic arch.
49
What happens when blood pressure drops?
Baroreceptors activate sympathetic response to increase BP.
50
What happens when blood pressure increases?
Baroreceptors activate parasympathetic response to lower BP.
51
What is the function of the renin-angiotensin-aldosterone system (RAAS)?
Regulates blood pressure and fluid balance.
52
What does renin do?
Converts angiotensinogen to angiotensin I.
53
What does angiotensin II do?
Causes vasoconstriction and stimulates aldosterone release.
54
What does aldosterone do?
Increases sodium and water retention to raise blood pressure.
55
What is the role of the kidneys in blood pressure regulation?
Adjust blood volume via urine output.
56
What is mean arterial pressure (MAP)?
The average blood pressure during a cardiac cycle.
57
How is mean arterial pressure calculated?
MAP = (SBP + 2×DBP) ÷ 3.
58
What is hypertension?
Chronically high blood pressure (≥140/90 mmHg).
59
What is hypotension?
Abnormally low blood pressure (<90/60 mmHg).
60
How does exercise affect cardiovascular regulation?
Increases heart rate, stroke volume, and vasodilation in muscles.
61
What is the role of nitric oxide (NO) in blood vessels?
Causes vasodilation and lowers vascular resistance.
62
What is the role of the vagus nerve in heart regulation?
Carries parasympathetic signals to slow heart rate.
63
Question
Answer
64
What are the three main types of blood vessels?
Arteries, veins, and capillaries.
65
What is the primary function of arteries?
Distribute oxygenated blood from the heart to tissues.
66
What is the primary function of veins?
Return deoxygenated blood to the heart.
67
What is the primary function of capillaries?
Exchange of gases, nutrients, and waste.
68
What is hemodynamics?
The study of blood flow properties in the circulatory system.
69
How does blood pressure change as it moves through circulation?
It decreases from arteries to veins.
70
Why does blood pressure drop across capillaries?
Due to increased cross-sectional area and resistance.
71
What is vascular resistance?
The force opposing blood flow in vessels.
72
What factors determine vascular resistance?
Vessel diameter, blood viscosity, and vessel length.
73
How does vessel diameter affect resistance?
Smaller diameter increases resistance.
74
What is compliance in blood vessels?
The ability of a vessel to expand and accommodate blood volume.
75
Which blood vessels have the highest compliance?
Veins.
76
Why do veins act as blood reservoirs?
They have high compliance and store large blood volumes.
77
What happens to compliance with aging?
It decreases due to arterial stiffening.
78
What is the function of arterioles?
Regulate blood flow and resistance through vasoconstriction and vasodilation.
79
What regulates arteriole diameter?
Autonomic nervous system and local metabolic factors.
80
What is microcirculation?
Blood flow through small vessels, from arterioles to capillaries and venules.
81
What are the three types of capillaries?
Continuous, fenestrated, and discontinuous.
82
Where are continuous capillaries found?
In muscle, skin, and the blood-brain barrier.
83
What is the primary function of fenestrated capillaries?
Facilitate filtration in kidneys and absorption in intestines.
84
Where are discontinuous capillaries found?
In the liver, spleen, and bone marrow.
85
What are Starling forces?
Forces regulating fluid movement across capillaries.
86
What are the two primary Starling forces?
Hydrostatic pressure and oncotic (osmotic) pressure.
87
What happens when hydrostatic pressure exceeds oncotic pressure?
Filtration occurs, moving fluid out of capillaries.
88
What happens when oncotic pressure exceeds hydrostatic pressure?
Reabsorption occurs, moving fluid into capillaries.
89
What is the blood-brain barrier?
A selective barrier that restricts passage of substances into the brain.
90
What is the main function of cerebral circulation?
To regulate blood flow based on metabolic demand.
91
What is the role of nitric oxide (NO) in blood vessels?
It acts as a vasodilator to regulate blood pressure.
92
What is pulse wave velocity (PWV)?
A measure of arterial stiffness.
93
Why does arterial stiffening increase blood pressure?
Reduced compliance leads to higher resistance.
94
Question
Answer
95
What is the primary function of the cardiovascular system?
Transport oxygen, nutrients, and waste.
96
What are the two main components of blood pressure regulation?
Cardiac output and vascular resistance.
97
What is cardiac output?
The volume of blood pumped by the heart per minute.
98
How is cardiac output calculated?
Heart rate × stroke volume.
99
What is stroke volume?
The amount of blood ejected by the heart per beat.
100
What factors influence stroke volume?
Preload, afterload, and contractility.
101
What is preload?
The volume of blood filling the ventricles before contraction.
102
What is afterload?
The resistance the heart must overcome to eject blood.
103
What is the Frank-Starling mechanism?
Increased stretch leads to stronger contraction.
104
What is vascular resistance?
The force opposing blood flow in blood vessels.
105
What is the primary site of vascular resistance control?
Arterioles.
106
How does vasoconstriction affect blood pressure?
Increases blood pressure.
107
How does vasodilation affect blood pressure?
Decreases blood pressure.
108
What is the role of baroreceptors in blood pressure regulation?
Detect blood pressure changes and adjust autonomic output.
109
Where are baroreceptors located?
Carotid sinuses and aortic arch.
110
What happens when blood pressure drops?
Baroreceptors activate sympathetic response to increase BP.
111
What happens when blood pressure increases?
Baroreceptors activate parasympathetic response to lower BP.
112
What is the renin-angiotensin-aldosterone system (RAAS)?
A hormone system regulating blood pressure and fluid balance.
113
What does renin do?
Converts angiotensinogen to angiotensin I.
114
What does angiotensin II do?
Causes vasoconstriction and stimulates aldosterone release.
115
What does aldosterone do?
Increases sodium and water retention to raise blood pressure.
116
What is mean arterial pressure (MAP)?
The average blood pressure during a cardiac cycle.
117
How is mean arterial pressure calculated?
MAP = (SBP + 2×DBP) ÷ 3.
118
What is hypertension?
Chronically high blood pressure (≥140/90 mmHg).
119
What is hypotension?
Abnormally low blood pressure (<90/60 mmHg).
120
What is the effect of sympathetic stimulation on the heart?
Increases heart rate and contractility.
121
What is the effect of parasympathetic stimulation on the heart?
Decreases heart rate.
122
How does nitric oxide (NO) regulate blood vessels?
Causes vasodilation and lowers vascular resistance.
123
What is autoregulation in the cardiovascular system?
The ability of tissues to regulate their own blood flow.
124
How does exercise impact cardiovascular regulation?
Increases heart rate, stroke volume, and vasodilation in muscles.
