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Physiology for Pharmacy > Cardiology 2: Electrical and Mechanical Activity > Flashcards

Cardiology 2: Electrical and Mechanical Activity Flashcards

1
Q

cells of the heart, like neurons, are excitable and generate ___

A

AP

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2
Q

rate of AP generation determines _____ and initiates ___

A

heart rate; muscle contractionn

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3
Q

AP is a result of changes in ___

A

membrane potential

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4
Q

membrane potential is determined by the balance in inward ___ ions and outward ___ ios

A

na and Ca; K

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5
Q

changes in membrane potentia are reliant and what type of ion channels?

A

voltage-gated

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6
Q

what are the 5 phases of cardiac ap?

A 
Phase 0: upstroke
Phase 1: early repol
Phase 2: plateau
Phase 3: repol
Phase 4: resting
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7
Q

describe what is happening in the upstroke phase 0

A

there is rapid influx of Na through fast Na channels which are quick to open but also quick to inactivate

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8
Q

describe what is happening in early repolarization (phase 1)

A

there is a brief efflux of K through transient outward K channels

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9
Q

describe what is happening in the plateau phase and the ion channels involved

A

influx of Ca through long-lasting (L-type) ca channels, this is counterbalanced by the efflux of K through delayed rectifier K channels (reason for plateau)

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10
Q

t/f long-lasting Ca channels open and inactivate slower than Na channels

A

true

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11
Q

describe what is happening in the repolarization (phase 3)

A

there is increased opening of delayed K rectifier channels and the Ca channels inactivate, so the efflux of + is greater than influx and cell repolarizes

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12
Q

describe what is happening during rest (phase4) What membrane potential is held? What happens to residual Na/ca ions during this time>

A

inward rectifying K channels open, making cells almost exclusively permeable to K, so membrane potential is held close to K’s equilibrium value ~90mV. residual Na and ca are removed

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13
Q

in what three ways can Na and Ca be removed from the cell during the resting phase? What are the ratios of exchange and which of these methods requires ATP?

A

Na removed by Na/K pump (3Na out : 2K in) ATP
Ca removed by Na/Ca exchanger (3 Na in : 1ca out) No ATP
Ca removed by Ca pump (ATP)

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14
Q

what are 4 important difference between AP of the sinoatrial node compared to the atria and ventricles?

A
  1. slower upstroke
  2. smaller amplitude
  3. no early repolarization
  4. no resting potential
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15
Q

why does the sinoatrial AP have a slower uptake and smaller amplitude?

A

the lack of fast Na channels (driven by slow L-type Ca channels)

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16
Q

the upstroke of sinoatrial node ap is driven by what type of channels?

A

slow L-type ca channels

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17
Q

why does the sinoatrial ap not have early repolarization?

A

lacks transient outward k channels

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18
Q

why does the sinoatrial ap not have a resting potential?

A

it has automaticity (self-excitation) due to diastolic depolarization

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19
Q

what causes the diastolic depolarization in SA Ap? 2 channels involved

A
  1. Na influx through inward hyperpolarization-activated “funny channels”
  2. Ca influx through transient T-type ca channels
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20
Q

inward hyperpolarisation-activated funny channels and transiet T type Ca channels are olnly found in the ___

A

SA node

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21
Q

are there inward rectifying K channels in the SA node?

A

no

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22
Q

what makes funny channels funny?

A

as cell becomes more - causes more depol (?)

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23
Q

differences in pacemaker cells results in diastolic depolarization which is essential for cell ___

A

automaticity

24
Q

excitation of the heart is initiated in the ___

25
excitation travels cell-cell across the atria through ____
gap juntion
26
excitation is delayed at the ___
AV node
27
why is excitation delayed at they AV node?
want ventricles to fill with blood before excited
28
excitation continues through fast conduction system composed of ____ cells, resulting in rapid excitation of the ventricles
Purkinje
29
Purkinje fibers reach into all parts of the ventricles, what is the point of this?
allows heart to contract as one
30
the is a ring of fibrous tissue between the A and V that electrically ____ that atria from ventricle
isolates
31
what does an ECG measure?
the projection of the heart's electrical activity onto surface of the body
32
in an ECG, recording electrodes or "leads" are connected at specific locations on the body to measure the _____ between 2 points
potential difference
33
what 2 points are most commonly used for ECG?
right arm and left leg
34
the Q-T interval is a measure of
how rapidly ventricle is excited and how long it takes to repolarize
35
what does the P wave represent?
atrial excitation
36
what does q represent?
exciation enters purkinje, beginning of ventricle excitation
37
what does p-R interval represent?
AV delay
38
what does the QRS represent?
ventricle excitation
39
what does the S-T interval represent?
AP plateau
40
what does the T wave represnt>?
ventricular repolarization
41
what is the path of normal excitation of the heart?
SA --> A --> AV node --> [Delay] --> Purkinje --> ventricle
42
t/f each part of the heart has a unique shaped curve of activity
true
43
excitation triggers highly efficient contraction of the heart muscle which is dependent on the ___ of the cardiac cell
structure
44
cardiac muscle is striated due to ___
regular arrangement of contractile proteins (actin and myosin) in the sarcomere
45
the actin and myosin generate force for contraction through ___
cross-bridge cycling
46
Z line
site of actin attachment
47
M line
site of myosin attachment
48
I band
actin filaments
49
A band
myosin filament s
50
titin
tethers myosin to Z line
51
filament buldles called ____ are surrounded by the ____ which stores Ca
myofibrils; SR
52
the SR is closely associated with ____ which are invaginations of the membrane at the Z bands
T tubules
53
T tubules are filled with ____ fluid
extracellular
54
mitchondria make up ____% of the heart's volume
30
55
the abundance of mitochondria in the heart cells provide cells with high ____ capacity
oxidative
56
when calcium enters _____ receptors in the SR it riggers large efflux of Ca from SR to allow for cross bridge cycling
ryanodine
57
relaxation of muscle occurs when Ca is removed from cytosol in what 3 ways?
1. SECRA takes back into SR (most) 2. Na Ca exchanger 3. ca pump

Physiology for Pharmacy (39 decks)

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