Ch 18: Cardiovascular System Flashcards
(161 cards)
1
Q
What is the difference between the right and left sides of the heart?
A
Right: receives oxygen-poor blood from tissues
Left: receives oxygenated blood from lungs
2
Q
Where does the right side of the heart pump to?
A
Pumps to lungs to get rid of CO2, pick up O2 via pulmonary circuit
3
Q
Where does the left side of the heart pump to?
A
Pumps to body tissues via systematic circuit
4
Q
What are the receiving chambers of the heart?
A
- Right atrium
2. Left atrium
5
Q
What is the difference between right and left atrium?`
A
Right: receives blood returning from systematic circuit
Left: receives blood returning from pulmonary circuit
6
Q
What are the pumping chambers of heart?
A
Right and left ventricles
7
Q
What is the difference between the right and left ventricles?
A
Right: pumps blood through pulmonary circuit
Left: pumps blood through systemic circuit
8
Q
Where is the heart located?
A
Mediastinum
2/3 of heart is left of the midsternal
9
Q
Compare the base and apex of the heart
A
Base: leans toward right shoulder
Apex points toward left hip
10
Q
What is the approximate size of the heart?
A
Size of fist
11
Q
What are the 2 pericardium of the heart?
A
- Superficial fibrous pericardium
2. Deep 2-layered serous pericardium
12
Q
What is the purpose for superficial fibrous pericardium?
A
Protects, anchors to surrounding structures and prevents overfilling
13
Q
What are the 2 layers of serous pericardium?
A
- Parietal
2. Visceral
14
Q
What portion of the heart does the parental layer line?
A
Internal surfaces of fibrous pericardium
15
Q
What portion of the heart does the visceral layer (epicardium) line?
A
External surface of the heart
16
Q
What separates the 2 serous pericardium layers?
A
Pericardial cavity
17
Q
What is the purpose of the pericardial cavity?
A
Decreases friction
18
Q
What is pericarditis?
A
Inflammation of pericardium
19
Q
What is cardiac tamponade?
A
Excess fluid sometimes compresses heart that limits pumping ability
20
Q
What does pericarditis cause?
A
Roughens membrane surfaces increasing pericardial friction and rubbing
21
Q
What are the 3 layers of the heart wall?
A
- Epicardium
- Myocardium
- Endocardium
22
Q
What is the epicardium?
A
Visceral layer of serous pericardium
23
Q
What is myocardium?
A
Spiral bundles of contractile cardiac muscle cells
24
Q
What is the endocardium?
A
Lines heart chambers that covers valves, consists of endothelial lining of blood vessels
25
Describe the characteristics of the cardiac skeleton
Crisscrossing interlacing layer of connective tissue
26
What is the purpose of the cardiac skeleton?
1. Anchors cardia muscle fibers
2. Supports great vessels and valves
3. Limits spread of action potentials to specific paths
27
Where are the locations of four chambers?
2 superior atria
| 2 inferior ventricles
28
What separates the atria?
Interatrial septum
29
What separates the ventricles?
Interventricular septum
30
What is an auricle?
Appendages that increase atrial volume
31
Where are the auricles located?
Left and right atrium
32
What is the purpose for auricles?
Contribute to propulsion of blood
33
What are the 3 veins that empty into the right atrium?
Superior vena cava, inferior vena cave, coronary sinus
34
How many pulmonary veins go into the left atrium?
4
35
What is the purpose for the papillary muscles?
Anchors chordae tendinae to prevent inversion or prolapse of mitral and tricuspid valves on systole
36
Where does the right ventricle pump blood?
Pulmonary trunk
37
Where does the left ventricle pump blood?
Aorta
38
What is the purpose of atrioventricular valves?
Prevents back flow into atria when ventricles contract
39
What are 2 AV valves?
```
Tricuspid valve (right)
Mitral valve (left)
```
40
What are the purposes for chordae tendineae?
1. Anchors cusps to papillary muscles
2. Hold valve flaps in closed position
3. Ensure undirectional blood flow through heart
4. Open and close in response to pressure changes
41
What is the purpose for semilunar valves?
Prevents back flow into ventricles when ventricles relax by opening and close in response to pressure changes
42
What are the 2 SL valves?
1. Aortic semilunar valve
| 2. Pulmonary semilunar valve
43
What is incompetent valve?
When blood backflows so heart re-pumps blood over and over
44
What occurs during vavular stenosis?
Stiffs flaps that constrict opening to where the hear must exert more force to pump blood
45
Why would the left ventricle of the heart have a thicker cell wall than the right?
Pumping with great pressure do to greater after load
46
How are valves replaced?
Mechanical, animal, cadaver valves
47
Describe the route of the pulmonary circuit
Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium
48
Describe the route of the systemic circuit
Left atrium → mitral valve → left ventricle → aortic semilunar valve → aorta → systemic circulation
49
What is the difference between pulmonary and systemic circuit?
P: short-low pressure circulation
S: long, high-friction circulation
50
Compare the anatomy of the 2 ventricles
Left ventricle wall is 3x thicker than right
51
Compare the volumes of blood that are pumped to the pulmonary and systematic circuit
Equal volumes fo blood is pumped
52
When would blood supply be pumped to the heart?
1. Delivered when heart is relaxed
| 2. Left ventricle receives most blood supply
53
What is the purpose of the anastomoses?
1. Provide additional routes for blood delivery
| 2. Cannot compensate for coronary artery occulusion
54
Identify the difference between left and right coronary artery
Left: supply left atrium and left ventricle
Right: supply right and most of right ventricle
55
What are the cardiac veins?
Collect blood from capillary beds
56
What is the coronary sinus?
Empties into right atrium formed by merging cardiac viens
57
What cardiac veins the coronary sinus empties into?
1. Great cardiac vein
2. Middle cardiac vein
3. Small cardiac vein
58
What is angina pectoris?
Thoracic pain caused by fleeting deficiency in blood delivery to myocardium causing cells to weaken
59
What is myocardial infarction?
Caused by prolonged coronary blockage where areas of cell death repaired with non contractile scar tissue
60
What are the junctions between cardiac cells?
Intercalated discs
61
What is purpose of desmosomes in the cardiac muscle?
Prevent cells from separating during contraction
62
What is the purpose of gap junctions in the cardiac muscle?
Allows ions to pass from cell to cell electrically couple adjacent cell allowing the heart to function as a single unit?
63
What is the term for behaving as a single coordinated unit?
Functional syncytium
64
Describe the structure of cardiomyocytes
Striated, short, branched, fat interconnected containing a central nuclei
65
What are the components of the cardiac muscle?
1. Cardiomyocytes
2. T tubules
3. Simple SR
4. Large mitochondria
66
How are cardiac muscles similar to the skeletal muscle?
1. Depolarization opens few voltage-gated fast Na+ channels in sarcolemma causing a reversal in membrane potential
2. Depolarization wave down T tubule allowing SR to release Ca2+
3. Excitation-contraction coupling occurs when Ca2+ binds to troponin and filaments slide
67
How are cardiac muscles different from skeletal?
1. Autorhythmicity
2. All cardiomyocytes contract aș a unit
3. Long absolute refractory period preventing tetanic contractions
4. Depolarization wave also opens slowing Ca2+ channels in sarcolemma causing SR to release its Ca2+
5. Ca2+ surge prolongs the depolarization phase (plateau)
6. Action potential and contractile phase last much longer allowing blood ejection from heart
7. Repolarization result of inactivation of Ca2+ channels and opening of voltage-gated K+ channels where Ca2+ is pumped back into SR and extracellularly
68
Describe the action potential of the cardiac muscle cells
1. Depolarization is due to Na+ influx through fast voltage-gated Na+ channels. A positive feedback cycle rapidly opens many Na+ channels, reversing the membrane potential. Channel inactivation ends this phase.
2. Plateau phase is due to Ca2+ influx through slow Ca2+ channels. This keeps the cell depolarized because few K+ channels are open.
3. Repolarization is due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its resting voltage.
69
Why does the cardiac muscle have so many mitochondria?
1. Greater dependence on aerobic respiration
| 2. Little anaerobic respiration ability
70
What can be used by the heart that is derived from the skeletal muscles?
Lactic acid
71
What is the pathway when ischemic cells are present?
Ischemic cells → anaerobic respiration → lactic acid → high [H+] → high [Ca2+] → mitochondrial damage → decrease ATP production → Gap junctions close → fatal arrhythmias
72
What NS can alter heart rhythm?
ANS
73
Does the heart need nervous stimulus stimulation to depolarize and contract?
No
74
What factors cause coordinated heartbeat?
1. Presence of gap junctions
| 2. Intrinsic cardiac conduction system
75
Describe the intrinsic cardiac conduction system
1. Network of non contractile (autorhythmic) cells
| 2. Initiate and distribute impulses → coordinated depolarization and contraction of heart
76
Describe the mechanism for pacemaking
1. Pacemaker potential: Repolarization closes K+ channels and opens slow Na+ channels causing ion imbalance. Unstable resting membrane potential is due to opening of slow Na+ channels and closing of K+ (continual depolarization)
2. Depolarization: action potential releases threshold opening Ca2+ channels causing an influx raising the action potential
3. Repolarization occurs by the inactivation of Ca+ channels and K+ efflux brings membrane potential back to negative
77
What are sequences of excitation?
```
Sinoatrial node →
Atrioventricular node →
Atrioventricular bundle →
Right and left bundle branches →
Subendocardial conducting network (Purkinje fibers)
```
78
What is function of Sinoatrial node?
1. Pacemaker of heart in right atrial wall
2. Depolarizes faster than rest of myocardium
3. Generates impulses about 75x/minute (sinus rhythm)
79
What is the function of the Atrioventricular node?
1. Delays impulses approximately 0.1 seconds
2. Smaller fibers that have fewer gap junction
3. Allows atrial contraction prior to ventricular contraction
80
What is the inherent rate of the AV node?
50x/minutes in absence of SA node input
81
What is the inherent rate SA node?
100X/minute tempered by extrinsic factors
82
What is the AV bundle (bundle of His)?
Only electrical connection between atria and ventricle because they are not connected by gap junctions
83
What is the purpose of the right and left bundle branches?
Carry impulses toward apex of heart
84
What is the subendocardial conducting network (Purkinje fibers)?
1. Complete pathway through interventricular septum into apex and ventricular walls
2. More elaborate on left side of heart
85
What are the inherent rate of the (Purkinje fibers)
AV bundle and subendocardial conducting network depolarize 30X/minute in absence of AV node input
86
Describe the intrinsic cardiac conduction system
1. SA nodes generates impulse
2. Impulse pause at the AV node
3. AV bundle connects the the atria to the ventricles
4. The bundle branches conduct the impulses through the inter ventricular septum
5. The subendocardial conducting network depolarizes the contractile cells of both ventricles
87
What occurs during an arrhythmia?
Irregular heart rhythms caused by uncoordinated atrial and ventricular contractions
88
What occurs during a fibrillation?
Rapid, irregular contractions useless for pumping blood, circulation ceases and brain death
89
What treats fibrillation?
Defibrillation
90
What is abnormal pacemaker
Ectopic focus caused by defective SA node
91
What is an extrasystole?
Ectopic focuse sets high rate causing premature contraction
92
What is a heart block?
Few (partial) or no (total) impulses reach ventricles caused by a defective AV node
93
How is a heart block treated?
Artificial pacemaker
94
How is heartbeat modified?
ANS via cardiac centers in the medulla oblongata
95
How does the sympathetic NS modify heartbeat?
increase rate and force
96
How does the parasympathetic NS modify heartbeat?
decrease rate
97
How does the Cardioacceleratory center modify heartbeat?
Sympathetic – affects SA, AV nodes, heart muscle, coronary arteries
98
How does the Cardioinhibitory center modify heartbeat?
Parasympathetic – inhibits SA and AV nodes via vagus nerves
99
What is a Electrocardiogram?
Composite of all action potentials generated by nodal and contractile cells at given time
100
What are the 3 waves of an ECG?
1. P wave
2. QRS complex
3. T wave
101
What occurs in the P wave?
Depolarization of SA node in atria: atrial depolarization
102
What occurs in the QRS complex?
Ventricular depolarization and atrial repolarization
103
What occurs during the T wave?
Ventricular repolarization
104
What is the P-R interval?
Beginning of atrial excitation to beginning of ventricular excitation
105
What is the S-T segment?
Entire ventricular myocardium depolarized
106
What is the Q-T interval?
Beginning of ventricular depolarization through ventricular repolarization
107
Describe the mechanism of an electrocardiograph
1. Atrial depolarization caused by the SA node (P wave)
2. Completion of atrial depolarization where impulse is delayed at the AV node
3. Ventricular depolarization at apex. Atrial depolarization (QRS complex)
4. Ventricular depolarization is complete
5. Ventricular depolarization begins at apex (T wave)
6. Ventricular repolarization is complete
108
What causes the sound of heart (lub-dub)?
1. First as AV valves close; beginning of systole
2. Second as SL valves close; beginning of ventricular diastole
3. Pause indicates heart relaxation
109
What are heart murmurs?
Abnormal heart sounds; usually indicate incompetent or stenotic valves
110
What is the cardiac cycle?
Blood flow through heart during one complete heartbeat: atrial systole and diastole followed by ventricular systole and diastole
Series of pressure and blood volume changes
111
What is the difference between systole and diastole?
S: contraction
D: relaxation
112
What occurs during ventricular filling?
1. AV valves are open; pressures
2. 80% of blood passively flows into ventricles
3. Atrial systole occurs, delivering remaining 20%
113
What is the end diastolic volume?
Volume of blood in each ventricle at end of ventricular diastole
114
What occurs during ventricular systole?
1. Atria relax; ventricles begin to contract
2. Rising ventricular pressure → closing of AV valves
3. Isovolumetric contraction phase (all valves are closed)
115
What occurs in the ejection phase of ventricular systole?
Ventricular pressure exceeds pressure in large arteries, forcing SL valves open
116
What is end systolic volume?
Volume of blood remaining in each ventricle after systole
117
What occurs during isovolumetric relaxation?
1. Ventricles relax; atria relaxed and filling
2. Backflow of blood in aorta and pulmonary trunk closes SL valves
3. When atrial pressure exceeds that in ventricles → AV valves open; cycle begins again at step 1
118
What is a dicrotic notch?
Brief rise in aortic pressure as blood rebounds off closed valve
119
What is the cardiac output?
Volume of blood pumped by each ventricle in one minute
120
What is the equation of CO?
CO = heart rate(bpm) (HR) × stroke volume (volume of blood pumped out by one ventricle with each beat (SV)
121
What is the normal CO?
5.25L/min
122
What is cardiac reserve?
Difference between resting and maximal CO
123
What is the maximal CO of trained athletes?
35L/min
124
What is equation to calculate stroke volume?
SV = EDV – ESV
EDV affected by length of ventricular diastole and venous pressure
ESV affected by arterial BP and force of ventricular contraction
125
What are the factors that affect SV?
Preload
Contractility
Afterload
126
What is preload?
Degree of stretch of cardiac muscle cells before they contract (Frank-Starling law of heart)
127
What is the important factor stretching cardiac muscle?
Venous return
128
What is venous return?
The amount of blood returning to heart
129
What is the purpose for venous return?
1. Slow heartbeat and exercise increase venous return
| 2. Increased venous return distends (stretches) ventricles and increases contraction force
130
What is a length-tension relationship?
At rest, cardiac muscle cells shorter than optimal length
131
What is contractility?
Contractile strength at given muscle length, independent of muscle stretch and EDV
132
How is contractility increased?
1. Sympathetic stimulation → increased Ca2+ influx → more cross bridges
2. Positive inotropic agents
133
What are examples of positive inotropic agents?
Thyroxine, glucagon, epinephrine, digitalis, high extracellular Ca2+
134
How is contractility decreased?
Negative inotropic agents such as Acidosis, increased extracellular K+, calcium channel blockers
135
What is factor increases heart rate?
Positive chronotropic factors
136
What factor decreases heart rate?
Negative chronotropic factors
137
What is afterload?
Pressure ventricles must overcome to eject blood
138
What can increase afterload?
Hypertension resulting in increased ESV and reduced SV
139
How is the Sympathetic NS activated?
Emotional or physical stressors
140
What hormone cases increased contractility to fire pacemakers more rapidly?
Norepineriphine
141
How does norepinephrine increase contractility?
Binds to β1-adrenergic receptors increasing HR
| Increasing contractility; faster relaxation
142
What hormone slows down heart rate?
Acetylcholine hyperpolarizes pacemaker cells by opening K+ channels → slower HR
143
What is vagal tone?
Parasympathetic dominant influence
144
What occurs during an Atrial (Bainbridge) reflex?
1. Stretch of atrial walls stimulates SA node → increasing HR
2. Also stimulates atrial stretch receptors, activating sympathetic reflexes
145
How is the Atrial (Bainbridge) reflex?
Sympathetic reflex initiated by increased venous return, hence increased atrial filling
146
What are the hormones that increases heart rate and contractility?
1. Epinephrine
| 2. Throxine
147
What maintains normal heart function?
Intra- and extracellular ion concentrations
148
What is hypocalcemia?
Depression of the heart
149
What is hypercalcemia?
Increase in HR and contractility
150
What is hyperkalemia?
Alters electrical activity → heart block and cardiac arrest
151
What is hypokalemia?
Feeble heartbeat; arrhythmias
152
Wha is tachycardia?
Abnormally fast heart rate (>100 beats/min)
153
What is bradycardia?
Heart rate slower than 60 beats/min
154
What are the factors that increase HR?
1. Age
2. Gender
3. Exercise
4. Body temperature
155
What is congestive heart failure?
1. Progressive condition; CO is so low that blood circulation inadequate to meet tissue needs
2. Reflects weakened myocardium
156
What causes weakened myocardium?
1. Coronary atherosclerosis—clogged arteries
2. Persistent high blood pressure
3. Multiple myocardial infarcts
4. Dilated cardiomyopathy (DCM)
157
What is pulmonary congestion?
Left side fails → blood backs up in lungs
158
What is peripheral congestion?
Right side fails → blood pools in body organs → edema
159
What is the treatment for heart congestion?
Removing fluid, reducing afterload, increasing contractility
160
What are the 2 types of congenital heart defects?
1. Mixing of oxygen-poor and oxygen-rich blood, e.g., septal defects, patent ductus arteriosus
2. Narrowed valves or vessels → increased workload on heart, e.g., coarctation of aorta
161
What is tetralogy of fallot?
Both types of disorders present: Mixing of oxygen-poor and oxygen-rich blood and narrowed valves or vessels
