Lecture 2 Test 4 Flashcards by Eric Barretto

How many vagus nerve do we have?

Left and Right vagus nerve

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Where does the tip of the right vagus nerve attach?

Where does the Left vagus nerve attach?

SA node

AV node

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Where does the majority of the PNS innervation occur?

Pace maker of the heart.

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Does the branches of the vagus nerve pass the nodal are?

Yes, some.

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Main emphasis of the PNS innervation is…

suppression of activity of pacemaker cell in the nodal area of the heart

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Sympathetic innervation

innervation to nodal areas, thick connections with atrial and ventricle muscle tissues.

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Primary catecholamines of the heart released by sympathetic nerves?

Norepinephrine working on B receptors

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Acetylcholine

primarily affect m-ACh-R of the heart

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Which autonomic stimulus is stronger in regards to the nodal tissue (pacemaker) of the heart?

Parasympathetic system

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Which autonomic stimulus is stronger in regards to the ventricles of the heart?

Sympathetic system

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Fast action potential phase

phase 0

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Ventricular myocite

ventricular muscle cell

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heart resting Vrm

Peak AP

Normal amount of heart depolarization (heart stimulus)

-80 mV

+20 mV

100 mV

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sum of all the current (APs) flowing in the heart at the same time is measured by

EKG

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What is the magnitude of QRS deflection?

1.5 mV

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Are fibroblasts growth hormones?

Yes

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Vegetative endothelial growth factor is

growth hormone
(ex) fibroblasts

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Decrease wound healing with ACE inhibitors?

No, there’s enough growth factor

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The closest to the surface of the heart leads to ______ ischemia

least

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Can you have MI in the superficial part of the heart?

Yes

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Most likely to have an ischemia at the ____

Subendocardium

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T/F: In a normal cell, K channels open up at the end of depolarization. In the heart, K channels close at the end of phase 0.

True

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What prolongs the action potentials of the heart?

Slow calcium channels open, K channels closing

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T/F: Can the depolarization close the K channels of the heart?

True

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Each big box of an EKG strip is how much voltage?

+0.5 mV

Does fatty tissue conduct electricity?

Why do Pts with COPD have low QRS while there's nothing else wrong with them?

Air doesn't conduct electricity very well

(depolarization) If there's no charge difference in the electrodes, voltage meter should read...

Where do electrons wanna go?

Into an area that is positively charged.

(depolarization) Slight depolarization would show on the voltage meter as

Slightly positive

(depolarization) When you're half depolarized and half resting?

The voltage meter would be reading a really positive number(perpendicular line to the right (+)).

(depolarization) When there's a little bit of tissue that needs depolarizing

Slightly positive deflection on the meter.

(depolarization) When you're 100% depolarized, the voltage meter will show

0, because now the electrons have nowhere to go to.

What is the voltage meter set up similarly to?

Lead I

(Repolarization L>R) slightly negative, voltage meter would be

Slightly to the left (-)

(Repolarization L>R) Half repolarized, half positive

Voltage meter: pointed all the way to the left (-)

(Repolarization L>R) 90% repolarized

Voltage meter: slightly left

100% repolarized L>R

Voltage meter: pointed to 0

(Repolarization, R>L) Slightly repolarized

voltage meter: slightly right

(Repolarization, R>L) half repolarized

Voltage meter: all the way to the right (+)

(Repolarization, R>L) 90% repolarized

Voltage meter: slightly right (+)

100% repolarized R>L

Voltage meter: 0 current

Heart Repolarization conduction

Depolarizes the outer layers of the heart first and then the inside of the heart muscles second.

Depolarization of the heart conduction process.

Starts off from deep muscle to the outside of the superficial surface. (inside of the ventricles depolarizes first. Outer layers of ventricle depolarizes second)

How does the repolarization of the ventricles show on the EKG?

Positive deflection due to the reversal of the depolarization order starting from outside of the heart to the inside of the heart.

What is P wave?

Atrial depolarization

What is QRS wave?

Ventricle depolarization

What is the T wave?

Ventricular repolarization

If current is moving towards the + electrode

It would show a positive deflection

If current is moving away from the + electrode

It would show as a negative deflection

T/F: Depolarization occurs from inside of the heart to the outside of the heart where the muscles are still at rest.

True

What does an ischemic heart muscle mean?

That part of the muscle is constantly depolarized

What would an injured part of the heart tissue look during action potentials?

There would be a chronic depolarization occurring at a certain spot.

How can you find where the abnormal current is happening?

If you have enough leads, you can eventually find the area where the abnormal current of the heart is occurring,

How do you know if there's an abnormal current?

Typically there would be a current when there shouldn't be a current occurring.

Main pacemaker of the heart and why?

SA node, depolarizes faster than any other part of the heart.

Normal beats per minute of a healthy normal heart (ideal patient)

*72 bpm*

increase in membrane potential (phase 4) is due to

(permeable) leaky calcium and sodium channels

What is a HCN channel? -Hyperpolarization and cyclic nucleotide

Some opens during repolarization, and then more and more open. Non specific for any positive ions but mainly (1st) sodium and (2nd) calcium,

Beta agonist on AP

- shuts down K channels - increased cAMP > increased HCN ch opening in phase 4 > less time in phase 4 (slope increases) > earlier AP > increased HR

B blockers on AP

reduced phase 4 slope > longer AP > decreased hr

m-ACh-R and APs

more ACh > increased K efflux > lower Vrm (-55 > -60) > phase 4 prolonged > decrease hr decrease adenylyl cyclase > decrease cAMP

Vrm is mainly affected by?

How many K channels we have open

Hyperkalemia and hr

increased hr

less potassium gradient

less k movement > Vrm more positive

Slight increase in blood Ca++

increase threshold potential > slow hr

Calcium deficiency in the blood

low threshold potential > more negative > more AP > increased hr *reason unknown*

Lecture 2 Test 4 Flashcards

(67 cards)