Chapter 3-Cardiovascular Flashcards
(121 cards)
1
Q
Blood vessel with extensive elastic tissue and smooth muscle
A
Artery
2
Q
Blood volume contained in arteries
A
Stressed volume
3
Q
Site of highest resistance in cardiovascular system
A
Arterioles
4
Q
Regulates arteriolar resistance
A
Autonomic nervous system
5
Q
ANS receptirs found on arterioles of skin, splanchnic, and renal circulation
A
a1-Adrenergic receptors
6
Q
ANS receptors found on arterioles of skeletal muscle
A
B2-adrenergic receptors
7
Q
Blood vessel with largest total cross-sectional and surface area
A
Capillaries
8
Q
Characteristic of capillary wall
A
Consist of a single layer of endothelial cells surrounded by basal lamina
9
Q
Formed from merged capillaries
A
Venules
10
Q
Contain the highest proportion of the blood in the cardiovascular system
A
Veins
11
Q
Blood volume contained in veins
A
Unstressed volume
12
Q
ANS receptors found in veins
A
a1-Adrenergic receptors
13
Q
Formula of velocity of blood flow
A
v=Q/A
Q=blood glow (ml/min)
A=cross-sectional area
14
Q
Blood flow is analogous to which law
A
Ohm’s law for electrical circuits
15
Q
Blood flow formula
A
Q=∆P/R
∆P=pressure gradient
R=total peripheral resistance
16
Q
Equation that gives factors that change the resistance of resistance
A
Poiseuille’s equation
17
Q
Resistance is directly proportional to which factors
A
Viscosity of blood
Length of vessel
18
Q
Resistance is inversely proportional to which factor
A
Fourth power of the vessel radius
19
Q
Resistance illustrated by the systemic circulation
A
Parallel resistance
20
Q
[T or F] When an artery is added in parallel, the total resistance increases
A
False-the total resistance decreases
21
Q
[T or F] In parallel resistance, the total resistance is less than the resistance of any of the individual arteries
A
True
22
Q
[T or F] In parallel resitance, the pressure is the same in each parallel artery
A
True
23
Q
Resistance illustrated by arrangement of blood vessels within a given organ
A
Series resistance
24
Q
[T or F] In series resistance, as blood flows throught the series of blood vessels, the pressure increases
A
False-the pressure decreases
25
Value which predicts whether blood flow will be laminar or turbulent
Reynolds' number
26
[T or F] As blood viscosity decreases, turbulence increases
True
27
[T or F] Increased blood velocity decreases turbulence
False- increased blood velocity increases turbulence
28
Is a consequence of the fact that adjacent layers of blood travel at different velocities within a blood vessel
Shear
29
[T or F] Velocity of blood is zero at the wall and highest at the center of the vessel
True
30
[T or F] shear is highest at the wall and lowest at the center of the vessel
True
31
Describes the distensibility of blood vessel
Capacitance
32
Factor inversely related to capacitance
Elastance (or stiffness)
33
Formula of capacitance
C=V/P
V=volume
P=Pressure
34
Capacitance is directly proportional to __ and inversely proportional to __
Volume; Pressure
35
[T or F] Capacitance is much greater for arteries than for veins
False- capacitance is much greater for veins than for arteries
36
[T or F] Capacitance of the arteries decreases with age.
True
37
Where the largest decrease in pressure occurs in the cardiovascular system
Arterioles (site of highest resistance)
38
Mean pressure in the Aorta
100 mmHg
39
Mean pressure in the vena cava
4 mmHg
40
Highest arterial blood pressure during a cardiac cycle
Systolic pressure
41
When is systolic pressure measured
After the heart contracts (systole) and blood is ejected into the arterial system
42
Lowest arterial pressure during a cardiac cycle
Diastolic pressure
43
When is diastolic pressure measured
When the heart is relaxed (diastole) and blood is returndd to the heart via the veins
44
Difference between the systolic and diastolic pressures
Pulse pressure
45
Most important determinant of pulse pressure
Stroke volume
46
[T or F] Decreases in capacitance cause decreases in pulse pressure
False- decreases in capacitance cause increases in pulse pressure
47
Used to estimate left atrial pressure
Pulmonary wedge pressure
48
What does P wave represent?
Atrial depolarization
49
Span of PR interval
Beginning of the P wave to the beginning of the Q wave
50
What does the PR interval represent?
Initial depolarization of the ventricle
51
Factor affecting PR interval
Conduction velocity through the AV node
52
[T or F] In heart block, the PR interval increases
True
53
Stimulation of the ___ nervous system decreases PR interval while stimulation of the ____ increases PR interval.
Sympathetic; Parasympathetic
54
Part of ECG representing depolarization of ventricles
QRS complex
55
Span of QT interval
Beginning of the Q wave to the end of the T wave
56
Part of ECG representing depolarization and repolarization of the ventricles
QT interval
57
Span of the ST segment
From the end of S wave to the beginining of the T wave
58
Isoelectric segment
ST segment
59
Represents period when ventricles are depolarized
ST segment
60
Represent ventricular repolarization
T wave
61
Determining factor of the resting membrane potential of cardiac muscle
Conductance to K+
62
Maintains ionic gradients across cell membranes
Na+- K+ ATPase
63
Stable testing membrane potential of the ventricles, atria, and the Purkinje system
-90 mV
64
Cause of upstroke in the phase 0 of ventricular action potential
Increased Na+ conductance, resultinvlg in inward Na+ current that depolarizes membrane
65
Phase in ventricular action potential that apporaches equilibrium potential
Phase 0- upstroke
66
Cause of initial repolarization in Phase 1 of ventricular action potential
Outward current due to movement of K+ ions out of the cell and decrease in Na+ conductance
67
Plateau of ventricular action potential
Phase 2
68
Cause of plateau of action potential
Transient increase in Ca2+ conductance, resulting in inward Ca2+ current and bu an increase in Ca2+ conductance- outward and inward currents are approx. Equal
69
Phase of repolarization of ventricular action potential
Phase 3
70
Cause of repolarization of ventricular action potential
Large outward K+ current (Ik) from high K+ conductance
71
Phase of resting membrane potential
Phase 4
72
In phase 0, the membrane potential approaches the __ equilibrium potential
Na+
73
In phase 4, membrane potential approaches the __ resting potential
K+
74
[T or F] SA node has a stable resting potential
False. SA node has an unstable resting potential.
75
[T or F] SA node exhibits automaticity.
True.
76
Latent pacemakers
AV node and His-Purkinje systems
77
Order of intrinsic rate of phase 4 depolarization
SA node > AV node > His-Purkinje
78
Cause of upstroke in phase 0 of SA node action potential
Inward Ca2+ current from Increased in Ca2+ conductance.
79
[T or F] Phases 1 and 2 are not present in the SA node action potential.
True
80
Phase of repolarization in SA node action potential
Phase 3
81
Phase that accounts for the pacemaker activity of the SA node
Phase 4- slow depolarization
82
Cause of slow depolarization of SA node
Inward Na+ (If) current from increased Na+ conductance.
83
[T or F] If is turned on by repolarization of the membrane potential during the preceding action potential
True
84
[T or F] Upstroke of the action potential in the AV node is the result of an inward Ca+ current, as in SA node
True
85
Reflects the time required for excitation to spread throughout cardiac tissue
Conduction velocity
86
Factor affecting conduction velocity
Size of the inward current during the upstroke
87
Conduction velocity is fastest in ___ and slowest in ___.
Purkinje system; AV node
88
Ability of cardiac cells to initiate action potentials in response to inward, depolarizing current
Excitability
89
Reflects the time during which no action potential can be initiated, regardless of how much inward current is supplied
Absolute refractory period (ARP)
90
When does the absolute refractory period occur?
Begins with the upstroke of the action potential and ends after the plateau
91
Period during which a conducted action potential cannot be elicited
Effective refractory period
92
Period during which an action potential can be elicited, but more than the usual inward current is required
Relative refractory period
93
A __ chronotropic effect decreases heart rate by decreasing firing rate of the SA node
Negative
94
A positive dromotropic effect ___ conduction velocity through the AV node and __the PR interval
Increases, decreases
95
The nurotransmitter for parasympathetic vagal innervation if the SA node, atria, AV node is __ which acts at __ receptors
Acetylcholine; muscarinic
96
Parasympathetic effects on heart rate
Decreases heart rate by decreasing rate of phase 4 depolarization through decreased If
97
Parasympathetic dromotropic effect
Decreases conduction velocity through AV node through decreased inward Ca2+ current and increased outward K+ current
98
__ is the neurotransmitter exerting sympathetic effect in the heart acting through the __ receptors
Norepinephrine; B1
99
Sympathetic chronotropic effect
Increases heart rate through uncreased If
100
Sympathetic dromotropic effect
Increases conduction velocity through AV nofr through increased inward Ca2+ current
101
Contractile unit of the myocardiac cell
Sarcomere
102
Maintain cell-to-cell cohesion
Intercalated disks
103
Low-resistance paths between cells that allow for rapid electrical spread ofaction potentials and accounts for electrical syncytium
Gap junctions
104
[T or F] Mitochondria are more numerous in skeletal muscle than in cardiac muscle.
False
105
Form dyads with the sarcoplasmic reticulum and carry action potentials into the cell interior
T tubules
106
Site of storage and release of Ca2+ for excitation-contraction coupling
Sarcoplasmic reticulum
107
During the plateau of the action potential, inward Ca2+ current occurs through these channels
Dihydropyridine receptors
108
Ca2+ release channels in the SR
Ryanodine receptors
109
Steps in excitation-contraction coupling of myocardial cell
Action potential sprewds through T tubules.
During plateau of action potential, inward C2+ current occurs through L-type Ca2+ channels.
Ca2+ entry triggers release of more Ca2+ from SR.
Intracellular [Ca2+] rises.
Ca2+ binds to troponin C, removing the inhibition of actin and myosin binding.
Actin and myosin bind, thich and thin filaments slide past each other, the myocardial cell contracts.
Relaxatjon occurs when Ca2+ is reaccumulated by the SR by an active Ca2+-ATPase pump.
110
Amount of Ca2+ released from SR depends on
Amount of Ca2+ previously stored in the SR
| Size of inwatd Ca2+ current during action potential
111
Intrinsic ability of cardiac muscle to develop force at a given muscle length
Inotropism
112
Contractibility can be estimated by the __
Ejection fraction
113
Positive staircase or Bowditch staircase (or Treppe)
Increased heart rate increases the force of contraction in a stepwise fashion as the intracellular [Ca2+] increases cumulatively over several beats.
114
The beat that occurs after an extrasystolic beat has increased force of contraction because extra Ca2+ entered the cells.
Postextrasystolic potentiation
115
Mechanisms by which sympathetic stimulation increase force of contraction
Increase inward Ca2+ current during plateau.
| Increases activity of Ca2+ pump of the SR
116
Increase the force of contraction by inhibiting Na+ K+-ATPase in the myocardial cell membrane
Cardiac glycosides/digitalis
117
Parasympathetic stimulation ___ the force of cintractuon in the atria
Decreases
118
Afterload for the left ventricle
Aortic pressure
119
Afterload for the right ventricle
Pulmonary artery pressure
120
Determines the maximum number of cross-bridges that can form between actin and myosin
Sarcomere length
121
Frank-Starling relationship
Increases in end-diastolic volume can cause an increase in ventricular fiber length, which produces am increase in developed tension.
