Lecture 2 Test 4 Flashcards
How many vagus nerve do we have?
- Left and Right vagus nerve
Where does the tip of the right vagus nerve attach?
Where does the Left vagus nerve attach?
SA node
AV node
Where does the majority of the PNS innervation occur?
Pace maker of the heart.
Does the branches of the vagus nerve pass the nodal are?
Yes, some.
Main emphasis of the PNS innervation is…
suppression of activity of pacemaker cell in the nodal area of the heart
Sympathetic innervation
innervation to nodal areas, thick connections with atrial and ventricle muscle tissues.
Primary catecholamines of the heart released by sympathetic nerves?
Norepinephrine working on B receptors
Acetylcholine
primarily affect m-ACh-R of the heart
Which autonomic stimulus is stronger in regards to the nodal tissue (pacemaker) of the heart?
Parasympathetic system
Which autonomic stimulus is stronger in regards to the ventricles of the heart?
Sympathetic system
Fast action potential phase
phase 0
Ventricular myocite
ventricular muscle cell
heart resting Vrm
Peak AP
Normal amount of heart depolarization (heart stimulus)
-80 mV
+20 mV
100 mV
sum of all the current (APs) flowing in the heart at the same time is measured by
EKG
What is the magnitude of QRS deflection?
1.5 mV
Are fibroblasts growth hormones?
Yes
Vegetative endothelial growth factor is
growth hormone
(ex) fibroblasts
Decrease wound healing with ACE inhibitors?
No, there’s enough growth factor
The closest to the surface of the heart leads to ______ ischemia
least
Can you have MI in the superficial part of the heart?
Yes
Most likely to have an ischemia at the ____
Subendocardium
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
What prolongs the action potentials of the heart?
Slow calcium channels open, K channels closing
T/F: Can the depolarization close the K channels of the heart?
True
Each big box of an EKG strip is how much voltage?
+0.5 mV
Does fatty tissue conduct electricity?
No
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…
0
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
