Cardiac Muscle - Quiz 1 Flashcards
(73 cards)
1
Q
other names for cardiac muscle cell
A
- cardiac myocyte
- cardiac muscle fiber
2
Q
cardiac muscle cells contain
A
- actin
- myosin
- troponin
- tropomyosin
3
Q
cardiac muscle cells are connected to one another by
A
- intercalated discs
4
Q
intercalated discs contain
A
- desmosomes
- gap junctions
- fasciae adherentes (in transverse portion)
5
Q
intercalated discs contain desmosomes for
A
- strength
6
Q
intercalated discs contain gap junctions for
A
- low resistance pathways for action potential spread through atria and ventricles
7
Q
Gap junctions connect
A
- atrial myocytes with other atrial myocytes
- ventricular myocytes with other ventricular myocytes
8
Q
are atrial myocytes connected to ventricular myocytes
- why?
A
- no
- allows time for ventricles to fill
9
Q
role of nodal and conducting cardiac cells
A
- set electrical rhythm
- make sure electrical spread happens in orderly and regulated fashion
10
Q
which cardiac myocyte has the fastest spontaneous firing
A
- SA node
11
Q
electrical coupling between cardiac cells occurs through
A
- intercalated discs
- gap junctions
12
Q
electrical coupling between cardiac cells allows for
A
- synchronized spread of depolarization
13
Q
what initiates the action potential
A
- SA node
14
Q
what is the SA node also known as
A
- normal pacemaker
15
Q
control of SA node
A
- autonomous
16
Q
external stimulus of SA node
A
- no external stimulus needed
17
Q
spread of action potential pathway
A
- SA node
- internodal tracts
- AV node
- common bundle of His
- left and right bundle branches
- purkinje fibers
18
Q
internodal tracts help spread action potential to
A
- atria
19
Q
atrial depolarization results in
A
- atrial contraction
20
Q
contraction of atria occurs
A
- nearly simultaneously
21
Q
atria connection to ventricles
A
- electrically insulated from ventricles
- except at AV node
22
Q
what is the path for excitation from the atria to the ventricles
A
- AV node
23
Q
speed of AV nodal cells conducting action potential
A
- slow
24
Q
slow conduction of action potentials by AV node allows for
A
- a delay between atrial and ventricular contraction
- allows more time for ventricle to fill with blood
25
what occurs after ventricular depolarization
- ventricular contraction
26
where does contraction start in the ventricles
- starts in the apex then spreads to ventricle walls
27
coordination of contraction of two ventricles
- contract almost simultaneously
28
action potential between heartbeats
- no action potentials
| - pacemaker cells are depolarizing
29
action potentials of myocytes from different regions of the heart
- have different action potentials
30
phase 4 ventricular myocytes action potential
- resting membrane potential
31
phase 0 ventricular myocytes action potential
- rapid depolarization
32
phase 1 ventricular myocyte action potential
- partial repolarization
33
phase 2 ventricular myocytes action potential
- plateau
34
plase 3 ventricular myocyte action potenial
- rapid repolarization
35
channels in phase 4 of ventricular myocyte action potenial
- very leaky IR K channels open
36
channels in phase 0 of ventricular myocyte action potenial
- voltage gated NA+ channels open
| - IR K channels blocked
37
channels in phase 1 of ventricular myocyte action potenial
- transient outward K channels open
- voltage gated L-type Ca channels (DHP receptors) begin to open
- voltage gated Na channels inactivating
38
channels in phase 2 of ventricular myocyte action potenial
- voltage gated L-type Ca channels (DHP receptors) open
- DR K channels opening
- transient outward K channels inactivating
- voltage gated Na+ channels inactivated
39
channels in phase 3 of ventricular myocyte action potenial
- voltage gated L-type Ca channels (DHP receptors) inactivating
- DR K+ open
- transient outward K+ channels inactivated
40
atrial, purkinje, and ventricular cells action potential phase 0 - threshold
- around -75 mv
41
atrial, purkinje, and ventricular cells action potential phase 0 - current
- Na+ current
42
atrial, purkinje, and ventricular cells action potential phase 0 - channels
- voltage-gated Na+ channels
43
atrial, purkinje, and ventricular cells action potential - conduction rates
- high conduction rates
44
atrial, purkinje, and ventricular cells action potential phase 0 called
- upstroke
45
atrial, purkinje, and ventricular cells action potential phases 1 and 2 called
- depolarization
46
atrial, purkinje, and ventricular cells action potential phases 1 and 2 - channels
- Na+ channels inactivate
| - Ca and K channels activate
47
atrial, purkinje, and ventricular cells action potential phase 3 called
- repolarization
48
atrial, purkinje, and ventricular cells action potential phase 3 - channels
- Ca2+ channels inactivate
| - K+ channels continue to open
49
excitation contraction coupling begins with
- membrane depolarized by Na+ entry as action potential begins
50
excitation contraction coupling - depolarization causes
- opening of L-type Ca2+ channels in T-tubules
51
excitation contraction coupling - opening of Ca2+ channels causes
- trigger Ca2+ enters cytosol contributing to cell depolarization
- trigger Ca2+ binds to and open ryanodine receptor calcium channels in the SR
52
excitation contraction coupling - after Ca2+ has been released from the SR
- Ca2+ flows into the cytosol
| - raises Ca2+ concentration
53
excitation contraction coupling - what does Ca2+ bind to
- binds to troponin
| - exposes cross-bridge binding sites on thin filaments
54
excitation contraction coupling - bindings of calcium to troponin causes
- cross bridge cycling
- force generation
- sliding of thick and thin filaments
55
excitation contraction coupling - how does Ca2+ get out of the cell
- Ca2+-ATPase pumps return Ca2+ to SR
| - Na+/Ca2+ exchangers remove Ca2+ from cell
56
excitation contraction coupling - when is the membrane repolarized
- when K+ exits to end the action potential
57
channels in SA node action potentials
- K+ channels
- L-type Ca2+ channels
- HCN channels
- T-type Ca2+ channels
58
K+ channels in SA node action potentials
- IR K channels
| - DR K channels
59
HCN channels in SA node action potentials permeable to
- both Na+ and K+
60
HCN channels in SA node action potentials open at
- negative membrane potentials
61
HCN channels in SA node action potentials close when
- as membrane depolarizes
62
HCN channels in SA node action potentials - current called
- I_f
63
HCN channels in SA node action potentials - sensitive to
- NE
| - EPI
64
T-Type Ca+ channels length of opening
- open when
- transient
| - open only briefly at negative voltages -50 then close
65
cardiac action potentials of SA and AV node - resting membrane potential
- no resting membrane potential
66
cardiac action potentials of SA and AV node phase 0
- upstroke
67
cardiac action potentials of SA and AV node phase 0 upstroke due to
- Ca2+ current
- T-type Ca2+ channels first
- then L-type Ca2+ channels
68
cardiac action potentials of SA and AV node phase 0 - threshold
- higher threshold
| - slower
69
cardiac action potentials of SA and AV node phases 1 and 2
- no phases 1 or 2
70
cardiac action potentials of SA and AV node phase 3 - current
- DR K-current begins quickly then decreases
71
cardiac action potentials of SA and AV node phase 4
- slow depolarization
72
cardiac action potentials of SA and AV node phase 4 - currents
- IR K+ currents open then decrease
| - Ca2+ and I_f currents increase
73
which has the slowest spontaneous firing rate
- ventricular myocyte
