B4-099 Overall View of the Heart's Function Flashcards
(125 cards)
1
Q
which layer of the heart wall…
ejection of blood from the heart
A
myocardium
2
Q
which layer of the heart wall…
protection of the heart from mechanical trauma
A
pericardium
3
Q
which layer of the heart wall…
stabilize the heart within the thoracic cavity
A
pericardium
4
Q
which layer of the heart wall…
functions as a lubricant to decrease friction
A
pericardium
5
Q
which layer of the heart wall…
prevent excessive dilation of the heart
A
pericardium
6
Q
which layer of the heart wall…
provides a smooth surface for blood flow
A
endocardium
7
Q
which layer of the heart wall…
releases substances that control heart development
A
endocardium
8
Q
the closure of the AV valves is heard as a
A
lub
9
Q
S1
A
closure of AV valves
10
Q
the closure of SL valves is heard as a
A
dub
11
Q
S2
A
closure of SL valves
12
Q
the mitral valve has […] cusps
A
2
13
Q
capacity to respond to an electrical impulse
A
excitability
14
Q
ability to initiate electrial impulse
A
automatism
15
Q
capacity to maintain
A
rhymicity
16
Q
ability to transmit the electrical stimulus to all areas of the heart
A
conductivity
17
Q
transient lack of the cardiac cells to respond to stimulus
A
refractoriness
18
Q
capacity of heart muscle to contract
A
contractility
19
Q
difference in voltage between the intracellular compartment and the external medium
A
resting membrane potential
20
Q
cardiac cells can trigger a change in membrane potential, which will lead to
A
cardiac contraction
21
Q
- depolarization to repolarization
- all or none response
A
action potential
22
Q
return to the cell resting potential
A
repolarization
23
Q
rapid change in resting membrane potential
A
depolarization
24
Q
how is cardiac action potential different from skeletal muscle?
A
- is it self generating
- it can be conducted directly from cell to cell
- it has relatively long duration
25
atrial and ventricular cardiomyocytes and purkinje fibers have a [...] response
fast
| action potential
26
SA and AV nodes have a [...] response
slow
| action potential
27
phase 4
pre action potential
28
phase 0
upstroke of action potential
29
phase 1
transient repolarization
30
phase 2
plateau phase
31
phase 3
repolarizing phase
32
in the SA and AV nodes, the action potential only has [...] phases
3
| 4, 0, 3
33
in ventricular myocytes, the action potential has [...] phases
all 5
34
different in nodal and myocardial ventricular cells
depolarizing current
35
in the SA and AV nodes, the depolarizing current is the
calcium current
36
in ventricular myocytes, the depolarizing current is the
sodium current
37
important for excitation-contraction of the heart
calcium current
38
the repolarizing current in all areas of the heart is the
potassium current
39
sodium channels are [...] gated
voltage
40
slow response action potential is [...] dependent
calcium
| SA and AV node
41
fast response action potential is [...] dependent
sodium
| cardiomyocytes, bundle of His, perkinje fibers
42
cardiac chronotropism
* automatism
* the capacity of the heart to produce electical impulses
43
automatism depends on the
SA node
44
does not have a stable resting potential
SA node
45
# name the phase/location:
* slow depolarization
* pacemaker potential due to increased Na+ conductance
* funny sodium current is responsible for heart's automaticity
phase 4
SA node
46
# name the phase/location:
upstroke of action potential due to inward calcium current
phase 0
SA node
47
# name the phase/location:
not present in nodal cells
phase 1/2
48
# name the phase/location:
* repolarizing phase
* caused by increased K+ conductance
* leads to outward K+ current
phase 3
SA node
49
* most negative potential in SA node
* normally about 50mV
MDP
| maximum diastolic potential
50
if the SA node is no longer function, cardiac excitation will be driven by
AV node
51
the action potential of AV node is similar to SA node, but the slope of phase [...] is less steep
4
52
determines the conduction velocity of the action potential moving through the AV node
magnitude of calcium current
53
responsible for sodium entrance and phase 0 depolarization
funny sodium channels
54
activated during phase 0 to cause depolarization
L-type calcium channels
55
repolarization during phase 3 occurs due to
K+ channels
56
# name the phase/location:
* stable resting potential
* inward rectifier potassium channels
phase 4
myocardial cells
57
# name the phase/location:
upstroke due to voltage gated sodium current
phase 0
myocardial cells
58
# name the phase/location:
* transient repolarization due to K+ moving out of cells
* decrease in Na+ conductance
phase 1
myocardial cells
59
# name the phase/location:
* plateau phase due to balance between Ca+ and K+ currents
* delayed rectifier K+ channels
phase 2
myocardial cells
60
# name the phase/location:
repolarization phase due to K+ outward current driven by delayed rectifier potassium cells
phase 3
myocardial cells
61
* responsible for phase 0 depolarization
* very transient current
voltage gated sodium channels
62
* activated during phase 0
* little change in membrane potential in phase 2
* Ca+ inactivation gates close near end of phase 2
L-type Ca+ channels
63
repolarization during phase 3 occurs due to
K+ channels
64
normal sinus rhythm
60-100 bpm
65
what channel contributes to diastolic depolarization in SA and AV nodes?
funny sodium channel
66
what channel is active during phase 0 of action potential?
voltage gated sodium channel
67
what channels are open during phase 2 of action potential?
* L-type calcium channel
* K+ delayed rectifier channel
68
what channel maintains high K+ permeability during phase 4 of action potential?
K+ inward rectifier channel
69
what channel contributes to phase 1 of action potential?
K+ transient outward channel
70
the funny sodium channel opens with
repolarization
71
Na+ channels open in response to
depolarization
72
voltage gated sodium channels have 3 main conformational states
1. closed
2. open
3. inactivated
73
Na+ channels have two separate gates
1. activation gate
2. inactivation gate
74
at resting membrane potential, the voltage gated sodium channel is
closed
75
[...] opens the activation gate of the voltage gates sodium channel
depolarization
76
at full depolarization, the [....] gate of the voltage gated sodium channel closes
inactivation
77
the activation gate opens [fast or slow]
fast
78
the inactivation gate opens [fast or slow]
slow
79
in hyperkalemia, the resting membrane potential is more positive than normal.
This causes
* decreased voltage gated sodium current
* decreased excitability of heart cells
80
the magnitude of the voltage gated sodium current in the cardiac myocytes will determine
1. threshold potential
2. amplitude of action potential
3. rate of rise of action potential
4. conduction velocity
81
the L type Ca+ channel has activation and inactivation curves that overlap called
calcium window
82
the magnitude of L-type calcium current in the SA and AV nodes will determine
1. threshold potential
2. amplitude of action potential
3. rate of rise of action potential
4. conduction velocity
83
conduction velocity in the AV node will determine the
duration of PR segment on ECG
84
K+ delayed rectifier cells open upon
depolarization
| very slow to allow depolarization to finish
85
lowest conduction velocity
AV node
86
cardiac muscle cells are rectangular shaped cells connected by
intercalated discs
87
* protein lined tunnels
* allow direct transmission of the depolarizing current from cell-to-cell so they contract in unison
gap junctions
88
because of the way gap junctions function, cardiac muscle cells are said to be
electrically coupled
89
period in which the cardiac cells is unable to intiate anothe action potential
refractory period
90
refractory period allows for
complete emptying of the heart
91
heart muscle contraction is reffered to as
inotropism
92
process by which the electrical activation of the cardiac myocytes leads to the activation of contraction
cardiac excitation contraction coupling (ECC)
93
increases inotropy and stroke volume
calcium
94
Frank-Starling's Law
the energy of contraction is proportional to the initial length of the cardiac muscle fiber
95
stroke volume increases when
preload is increased
96
as preload increases, sarcomere length
increases
| allows more cross bridging during systole
97
increased sarcomere length allows
more cross bridges to form during systole
98
increasing EDV allow more overlap of
thick and thin filaments
| more crosslinking
99
* all cardiac valves are closed with no blood flow
* pressure in ventricles is low
isovolumic relaxation
| diastole
100
mitral and tricuspid valves open, pulmonic valves are closed
ventricular filling
| diastole
101
during ventricular filling, the pressure in the ventricles drops below
that of the atria
102
* all cardiac valves are closed with no blood flow
* ventricular pressure raises
* atrial pressure raises
isolvolumic contraction
| systole
103
aortic and pulmonic valves are open; mitral and tricuspid are closed
ejection
| systole
104
when the heart rate is high, [...] is shortened the most
diastole
105
the AV node will not conduct beyond
230 bpm
106
Ejection fraction=
stroke volume/
EDV
107
normal value for EDV
120-140 mL
108
normal value for ESV
40-60 mL
109
normal value for SV
60-100 mL
110
normal value for ejection fraction
0.5-0.7
111
normal value for cardiac output
5.0-6.0 L/min
112
normal value for cardiac index
2.6-4.2 L/min/m2 of body surface area
113
way to normalize values for cardiac output to differences in body size
cardiac index
114
# myocardial action potential
* rapid upstroke and depolarization
* voltage gated Na+ channels open
phase 0
115
# myocardial action potential
* initial repolarization
* inactivation of voltage gated Na+ channels
* voltage gated K+ channels begin to open
phase 1
116
# myocardial action potential
* Ca+ influx through voltage gated Ca+ channels balances K+ efflux
* Ca+ influx triggers Ca+ release from sarcoplasmic reticulum and myocyte contraction
phase 2
| Ca+in =K out causes pla**two**
117
# myocardial action potential
* rapid repolarization
* massive. K+ efflux due to opening of delayed rectifier K+ channels
* closure of voltage gated K+ channels
phase 3
118
# myocardial action potential
* resting potential
* high K+ permeability through K+ channels
phase 4
119
myocardial action potential occurs in all cardiac myocytes except
SA and AV node
120
# pacemaker action potential
* upstroke
* opening of L type Ca+ channels
* results in slow conduction velocity
phase 0
121
# pacemaker action potential
* repolariztion
* inactivation of Ca+ channels
* increased activation of K+ channels
* increase K+ efflux
phase 3
122
# pacemaker action potential
* slow spontaneous diastolid depolarization due to funny sodium current
phase 4
123
neurotransmitters that decrease the rate of diastolic depolarization and HR
* ACh
* adenosine
124
neurotransmitters that increase depolarization and HR
chatecholamines
125
increases the chance that funny sodium channels are open and thus increases HR
sympathetic stimulation
