Lecture 6 Test 4

Question 1

When should you not see any electrical activity on your EKG?

Answer 1

Before the P wave and after the T wave.

Question 2

If you have a current of injury on your left ventricle sub endocardium what would you see on the EKG?

Answer 2

Positive deflections before the P wave and after the T wave.

Question 3

What can the TP segment tell you?

Answer 3

If there’s a depression or elevation.

Question 4

If you have an infarct on the left wall thickness of the ventricle what would you see?

Answer 4

A bigger vector, going towards the right arm. Negative deflection on Lead II

Question 5

What does a negative deflection on the ST segment tell you?

Answer 5

ST elevation = infarct

Question 6

If you’re looking at leads V2 with a negative deflection?

Answer 6

This is an anterior injury

Question 7

If your axis is pointed straight up what does it mean?

Answer 7

You have an infarction on the Apex of the heart

Question 8

What does it mean if V2 has a positive deflection?

Answer 8

Posterior injury

Question 9

Positive deflection on V2 with the Mean axis pointed straight up means?

Answer 9

Posterior apex injury.

Question 10

General rule of thumb, ischemia is usually on the ……… and infarct

Answer 10

• little sliver on the left side
• Whole left wall

Question 11

Fast Na channel: at rest
Inactivation gate
Activation gate

Answer 11

• H gate (inside) open
  -M gate (outside) closed

Question 12

Fast Na channel: depolarization

Answer 12

• M gate (activation) opens
• H gate (inactivation) open for a brief time and closes

Question 13

Fat Na channel: repolarize

Answer 13

• M gate closes
• H gate opens

Question 14

T/F: you need repolarization before being able to do another Fast Na Channel depolarization

Answer 14

True

Question 15

L-type Ca Channel gates:
inactivation gate (inside)
Activation gate (outside)

Answer 15

• F gate
• D gate

Question 16

resting Fast Na channel gates are

Answer 16

M gate is closed and H gate is open

Question 17

resting L-type channel gates are

Answer 17

D gate is closed and F gate is open

Question 18

What causes the L type channel to open?

Answer 18

Voltage dependent and when threshold is reached but opens and closes slower than fast Na channels

Question 19

L Type channel: depolarized

Answer 19

D gate opens while F gate is open but closes slowly

Question 20

L type channel: repolarized

Answer 20

D gate is closed, F gate is closed

Question 21

SA node resting Vrm and threshold Vrm

Answer 21

-55 Vrm

-40 Vrm

Question 22

SA node AP speed is dependent on the ______ slope of the phase 0

Answer 22

L type

Question 23

are there Na leaky channels and HCN on the SA node phase 4

Answer 23

yes

Question 24

Are there any fast Na leaky channel on the phase 0 slope of the SA node?

Answer 24

No

Question 25

Are there any VG or fast Na channels on the nodal tissues?

Answer 25

No

Question 26

What's another theory in regards to VG Na channels on the SA node?

Answer 26

The Vrm is -55 (not negative enough) so maybe it is not able to function

Question 27

Purkinjie: Fast Na channel phase 4 is.....

Answer 27

pretty much horizontal

Question 28

Purkinjie: Fast Na channel phase 0 slope is

Answer 28

straight up and down

Question 29

Purkinjie: What happens when the Vrm is more positive? from -80 Vrm to -60Vrm

Answer 29

You start to lose some fast Na channels and the slope decreases and the height decrease

Question 30

Purkinjie: What happens if the Vrm is more positive than the fast Na channels can handle?

Answer 30

the AP will look more like a slow AP because there's no Na channels involved

Question 31

What happens when we have no Na involved in the AP?

Answer 31

the heart won't pump as well but we tend to rely on the Ca channels.

Question 32

Purkinjie: If we have a really positive Vrm...... maybe due to?

Answer 32

NA and Ca channels won't work = no AP Hyperkalemia Acidosis MI

Question 33

What does lidocaine (-caine) do for our APs?

Answer 33

decreases the slope of phase 0

Question 34

What's the difference with phase 4 of the purkinjie fibers and SA node?

Answer 34

Phase 4 - SA node is leaky to Ca channels - AV node is 2nd leaky to Ca channels - Purkinjie has no leaky Ca channels

Question 35

T/F: Fast Na channels can trigger Ca channels to open.

Answer 35

True

Question 36

mACh-R in a (SA) heart cell when activated

Answer 36

causes K+ to efflux to reduce Vrm

Question 37

SA node: we have a second set of mACh-R that has an a-subunit that's inhibitory and attached to?

Answer 37

adenylyl cyclase that turns ATP to cAMP.

Question 38

What happens to the secondary mACh-R when the main mACh-R is activated?

Answer 38

it is inhibited

Question 39

SA node: Beta receptors with an a-subunit (stimulatory)

Answer 39

activates alpha stimulatory subunits to increase adenylyl cyclase > increase cAMP

Question 40

SA node: Beta receptors with HCN channels are activated by?

Answer 40

increase cAMP > increase Na and Ca influx to the pacer cells in phase 4

Question 41

SA node: increase in cAMP, you get an increase in pKA that activates (phosphorylates)....

Answer 41

- L-type Ca channels - Troponin I > increases contractile sensitivity to Ca++ - Phospholamban > inhibits SERCA > reset faster > increase hr

Question 42

If you have too much Beta adrenergic receptors causing > increase cAMP > increase pKA > L type Ca channel influx > MI

Answer 42

Ex. Grandpa shoveling snow > EAD (early after depolarizations) / DAD (delayed after depolarizations) > arrhythmia

Question 43

cAMP can fall apart on its own. But our body has PDE that leads to?

Answer 43

increase cAMP conversion to AMP > reduce pKA > reduce L type Ca influx > reduce hr PDE inhibitor > pKA

Question 44

Second beta receptor attached to HCN channel has unknown reason but it does per Schmidt!