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A&P Fall '24 > Test 4 - (10/21) Cardiac Lecture 2 > Flashcards

Test 4 - (10/21) Cardiac Lecture 2 Flashcards

1
Q

We have _____ vagus nerves that innervate the heart.

A

Two

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2
Q

The right vagus nerve innervates _____, the tips of the left vagus nerve innervate _____

A

R - SA node
L - AV node

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3
Q

The majority of the parasympathetic innervation will be at what area of the heart?

A

The pacemaker areas of the heart

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4
Q

What is happening with parasympathetic innervation from the vagus nerve?

A

Main emphasis of the parasympathetic innervation is the suppression of the activity of pacemaker cells in the nodal areas

There is a small amount of innervation from the branches of the vagus nerve that extend past the nodal area.

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5
Q

Does the vagus nerve extend past the AV and SA node?

A

Yes, branches of the vagus nerve do extend past the nodal area

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6
Q

How does sympathetic innervation differ from parasympathetic innervation?

A

Sympathetic is more widespread in the heart.

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7
Q

Describe the innervation from the sympathetic chain.

A

Has some innervation at the nodal areas.

Has thick connections with the atrial muscle tissue as well as the ventricular muscle tissue

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8
Q

What is the primary catecholamine that is released from the sympathetic nerves at the heart? What receptor will this interact with?

A

Norepi.
Beta

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9
Q

Acetylcholine will primarily bind to what receptor

A

mACh-R

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10
Q

What has the most innervation at the nodal area of the heart?

A

Parasympathetic nervous system

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11
Q

What kind of AP would this be?

A

ventricular muscle cell/ventricular conduction system

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12
Q

What are the phases for the following?
Blue:
Pink:
Green:
Orange:
Yellow:
Purple:

A

Blue: 4
Pink: 0
Green: 1
Orange: 2
Yellow: 3
Purple: 4

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13
Q

Hot pink

A

Sympathetic chain

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14
Q

Blue

A

sympathetic nerves

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15
Q

Green

A

Left vagus nerve

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16
Q

Orange

A

AV node

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17
Q

Purple

A

SA node

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18
Q

Red

A

Right vagus nerve

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19
Q

Why do we call these fast AP?

A

Because phase 0 is very steep. Once it starts it shoots up

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20
Q

What is the resting membrane potential in a ventricular myocyte?

A

-80

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21
Q

What is a ventricular myocyte

A

Ventricular muscle cell

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22
Q

If our resting membrane potential is -80mV and the peak is +20mV. What is the amount of depolarization we get?

A

100mV

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23
Q

What does an EKG show us?

A

A sum of all the current between a electrodes placed on the body.

Measure the current that is flowing as our heart beats.

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24
Q

The magnitude of deflection in an EKG is _____

A

about 1.5mV

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25
Q

The magnitude of deflection in an EKG is _____ and in a ventricular muscle cell AP it is ______.

A

1.5mV
100mV

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26
Q

The subendocardium is the deepest part of the ______ muscle wall. mainly _______

A

Ventricular
left ventricle

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27
Q

Compared to the left ventricular wall, the right ventricular wall is _____

A

Much more narrow

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28
Q

What part of the heart is most prone to infarction or ischemia?

A

Subendocardium (L ventricle)

29
Q

The _____ to the surface you are in terms of the heart layers, the less likely you are to have ischemia

A

Closer

30
Q

What is different about K channels in the heart vs other cells in regards to AP?

A

Typically K channels open in response to depolarization but in the heart they actually close in response to incoming cations.

31
Q

The K channels that close in the heart during an AP are called what? What causes them to close?

A

Inward rectifying K channels

The inward movement of cations

32
Q

The amplitude of the QRS complex is

A

1.5mV

33
Q

Why is the magnitude of deflection in the ventricular AP so much bigger than that of the EKG

A

We lose a lot of the voltage in our tissue because of the high resistance in the tissue, not all of our body conducts electricity very well

34
Q

Someone with COPD will have a much _____ QRS complex

A

Lower

35
Q

During depolarization, the inside of the cell is more _____ and the outside is more ____

A

positive
negative

36
Q

Negative electrons on the outside of a cell will want to go to ____

A

areas that are positively charged

37
Q

Lead one is a _____ electrode that is placed on _____. It is measuring a depolarization wave that is moving ______ the ______ electrode that is placed on _____

A

positive
left chest.
Towards.
positive.
left chest

38
Q

If we see electrons moving towards the positive lead that shows a _____ deflection in the meter. If electrons are moving away from that positive lead that would show up as ______ deflection

A

positive
negative

39
Q

The conduction system is very ____ in the heart wall

A

deep

40
Q

Depolarization in the heart happen from ______ to _____

A

Inside (deep) to outside (superficial)

41
Q

Repolarization in ventricular muscle starts in more ______ structures and then goes to ______

A

Superficial
deep

42
Q

Repolarization in the heart moves the _____ way of depolarization

A

opposite

43
Q

P wave is ____

A

Depolarization of the atria

44
Q

QRS is

A

depolarization of the ventricles

45
Q

T wave is

A

ventricular repolarization

46
Q

Why does T wave show a positive deflection even though it repolarizes in the opposite direction

A

the epicardium repolarizes before the endocardium.

47
Q

If there is an area of a heart that is ischemic what will happen in regards to AP?

A

It will be depolarized constantly, cant reset itself after AP.

48
Q

In the pacemaker area of the heart the AP can _____

A

look different

49
Q

Pacemaker of the heart

A

SA node

50
Q

Why is the SA node called the pacemaker of the heart?

A

The tissue at the SA node goes from resting membrane potential to threshold potential in the shortest amount of time

51
Q

Normal resting HR for our class?

A

72 BPM

51
Q

What is the resting membrane potential (Vrm) for a healthy SA nodal cell?

A

-55mV

52
Q

What is threshold potential for a healthy SA nodal cell?

A

-40mV

53
Q

In the SA nodal cell what causes the hefty positive slope in phase 4 from Vrm to threshold?

A

Ca and Na leak channels as well as HCN channel

54
Q

What does HCN channel stand for?

A

Hyperpolarization + cyclic nucleotide mediated channel

55
Q

When do HCN channels open up in the SA nodal cells?

A

When we get back to Vrm following AP

56
Q

What ions move through HCN channels?

A

Fairly nonspecific for positively charged ions (cations) primary is Na and secondary is Ca

57
Q

In the heart when we have norepi binding to a beta receptor we have _____ (relating to HCN channels)

A

Increase in cAMP

58
Q

cAMP is a _______. A stands for ____

A

Cyclic nucleotide
Adenoside

59
Q

When we have a normal amount of Beta activity we should have a normal amount of _____ channels operating in phase ______ in nodal tissue

A

HCN
4

60
Q

If we give someone a beta agonist what will it do to the heart rate? what does cAMP have to do with this?

A

The HR will increase because there will be an increase in cAMP and that will cause more HCN channels to open

61
Q

HCN channels can open due to what?

A

Repolarization (hyperpolarization)
or increase in cAMP

62
Q

If we have more HCN channels opening what would that do to the slope of phase 4?

A

make it steeper

63
Q

More HCN channels would cause a _____ slope in phase 4 and cause _____ AP due to ____

A

steeper
earlier
reaching threshold potential faster

64
Q

Beta antagonist (atenolol) given what would that do for slope and HCN channels and HR

A

Less HCN channels. slope isnt as steep. later AP. slower HR

65
Q

If we have lots of ACh around what will that do in terms of nodal tissue AP?

A

will bind to mACh-R, opening up K channel, K will leave and make cell more negative and that could lower our Vrm. Slope can be the same but phase 4 will be longer so slower HR.

will also lower cAMP

66
Q

if we have small amounts of K around what would that do to HR?

A

slightly higher Vrm, hit threshold faster. increase HR.

67
Q

How can Ca slow down our HR in nodal tissue specifically?

A

A slight increase in Ca and actually change our threshold potential and make it more positive..making phase 4 longer and that will slow down HR

68
Q

Reduced Ca levels in the blood can _____ HR by _____

A

Increase
lowering threshold potential

A&P Fall '24 (12 decks)

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