Exam 2: Lecture 2

Front 1

The heart is innervated by the sympathetic and parasympathetic systems, they increase the heart rate and decrease the heart rate according to what neurotransmitter is released, if those two systems are cut off will the heart still beat? Why or why not?

Back 1

Yes because of the pace makers cells. They set the pace of the heart beats

Front 2

Explain what the conduction pathway is.

Back 2

The path that conducts electricity through the heart
Muscle cells are modified to conduct electrical information (myogenic pacemaker)

Front 3

How do autorhythimcal cells communicate to one another?

Back 3

Gap Junctions

Front 4

Explain an autorythmical Cell.

Back 4

They initiate or propagate the APs that initiate muscle contraction, however they do not actually contract.

Front 5

Do autorhythmical cells contract?

Back 5

No, they carry the Action Potentials

Front 6

What are the five autorhythmical cells?

Back 6

SA Node
AV Node
Bundle of His
Bundle Branches
Purkinje Fibers

Front 7

What can the SA Node and AV Node do that the other cells can't do? What are the two names for that?

Back 7

They can initiate the Action Potential, they can generate the actual current
Pace makers cells OR Myogenic cells (muscle-beginning)

Front 8

What's the actual name for the SA node?

Back 8

Sinoatrial Node

Front 9

After the signal is generated in the SA node, where does the signal go next?

Back 9

The interatrial pathway and the AV node

Front 10

Does the SA node depolarize the interatrial pathway first or the AV node?

Back 10

Does the SA node depolarize the interatrial pathway first or the AV node?

Front 11

What is the Interatrial pathway?

Back 11

Conduction Pathway between the two atriums

Front 12

What is the actual name for the AV node?

Back 12

Atrial Ventricular Nerve

Front 13

Where will the AV node send the signal next?

Back 13

The AV Bundle (Bundle of HIS)

Front 14

After the Bundle of His depolarizes, what happens next?

Back 14

The Bundle of His splits into two branches (the left and the right) which both get depolarized

Front 15

After the Bundle branches get depolarize, where does the electrical signal travel to?

Back 15

The Purkinje Fibers

Front 16

Where does the signal ultimately stop?

Back 16

The Purkinje Fibers

Front 17

In the big picture of the heart, what contracts first and what second?

Back 17

The atria contracts first then the ventricles

Front 18

The SA node starts the Action Potential and goes to the interatrial pathway along with the hitting the AV node, but what does the interatrial pathway contract and what is first and second?

Back 18

Will contract both atria
Both atria will contract at the exact same time

Front 19

Since the heart has a steady rhythm that it follows by itself, can the heart fluctuate out of that rhythm? Why or Why not?

Back 19

Yes it will definitely fluctuate because of the neurotransmitters in the sympathetic and para-sympathetic nervous systems

Front 20

What nerve allows the sympathetic nervous system to act on the heart? Where does the nerve start? Where is it attached to?

Back 20

The sympathetic cardiac nerve
Starts near para vertebral ganglia
Attached to the SA node and the AV node

Front 21

Does the SA node or the AV node depolarize faster?

Back 21

The SA node

Front 22

What pace maker cells are the backup to the SA node? If something would happen to the SA node what would be the result? Why?

Back 22

The backup is the AV node
If something happened to the SA node, the AV node would take over and generate action potentials but at a much slower rate because it does not depolarize as fast

Front 23

What would happen if norepinephrine was released? Where would it bind to and what would be the cause?

Back 23

It would be released from the sympathetic cardiac nerve and would bind to beta receptors
It would up regulate the SA node to depolarize faster

Front 24

When you increase norepinephrine, what ion/ions will INFLUX?

Back 24

Sodium and Calcium
Will cross into the SA node faster

Front 25

What nerve allows the parasympathetic nervous system to act on the heart? Where does the nerve start?

Back 25

Vagus Nerve
Starts from cranial nerves

Front 26

Once acetylcholine is released from the vagus nerve, what will happen to the heart, why?

Back 26

The heart will down regulate because parasympathetic only releases acetylcholine and since parasympathetic will down regulate the heart, the heart beat will decrease

Front 27

What ion/ions will EFFLUX out of the heart when you want to down regulate?

Back 27

Potassium (K+)

Front 28

What do you have to do to repolarize a cell?

Back 28

Make the inside more negative (less positive)

Front 29

If the cell is more negative then the resting membrane potential, what is that called?

Back 29

Hyper-polarization

Front 30

What does the long refractory period in the ventricular muscle ensure?

Back 30

A regular heart beat

Since the muscle is so big, it needs time for the signal to get to the whole muscle, therefore it needs to stay depolarized longer, ultimately having a longer refractory period.
With a longer refractory period, the ventricles can't beat again unless the first one is fully complete (which is longer than the atrias) therefore ensuring a regular heart beat.

Front 31

What is a refractory period?

Back 31

The time it takes for another action potential to cause a reaction

Front 32

Why would the purkinje fibers want to stay depolarized longer?

Back 32

They stay depolarized longer because then they have a longer refraction period

Front 33

Is the conductive pathway the same or different between the atrias and the ventricles?

Back 33

Very different

The purkinje fibers stay depolarized MUCH longer

Front 34

We know that the pathway is longer to ventricular muscle compared to the atria but which physically CONTRACTS slower?

Back 34

The ventricles

There is more muscle so it will take longer to contract

It is slow to start (longer pathway) and slow to stop (physically contracts slower)

Front 35

Why does the ventricular muscle take so long to contract?

Back 35

There is a longer pathway, going from the SA node to the AV node and then to the ventricular muscle

Front 36

What happens to the permeabilities of the ions when we want to repolarize?

Back 36

Ca+ decrease

Na+ decrease

(we are making the cell less positive so we don't want to bring any of these ions in)

K+ Increase

(we don't want any more positive so we wil let some K+ out until we get down to -60 mV

Front 37

What do we have to do inside the cell to repolarize?

Back 37

Make more negative or less positive

Front 38

What is the value that we will get to after done depolarizing and the signal to start repolarizing?

Back 38

+5 mV

Front 39

Once we hit the -40 mV, what will happen?

Back 39

An action potential that will now go to all the cells

Front 40

If we are depolarizing the cell, what do we do to the permeability of Na+? Why?

Back 40

We are going to INCREASE the permeability of Na+.

Na+ is high outside so we want all the positive inside the cell so we will increase the permeability so the ions can come in

Front 41

If we are depolarizing the cell, what do we do to the permeability of Ca+? Why?

Back 41

We are going to INCREASE the permeability of Ca+.

Ca+ is high outside so we want all the positive inside the cell so we will increase the permeability so the ions can come in

Front 42

If we are depolarizing the cell, what do we do to the permeablity of K+? Why?

Back 42

We DECREASE the permeablity of K+

If we are depolarizing the cell then we need to make the inside more positive so we need to keep all the positive we have and gain more. K+ has a high concentration inside the cell so we are going to lower the permeability to keep all positive inside the cell.

Front 43

If we are going to depolarize a pace maker cell, what is the threshold potential to get the action potential?

Back 43

-40 mV

Front 44

If we want to depolarize the cell, what do we need to do?

Back 44

Make the inside of the cell less negative or more positive

Front 45

What is the charge normally inside the pace maker cells?

Back 45

-60 mV

Front 46

Explain permeability. If you have a high permeability, can ions get in easy or hard, what about low?

Back 46

Permeability: how easy ions can cross the membrane

High permeability: the ions can cross the membrane easy

Low permeability : it is hard for the ions to cross the membrane

Each ion has an individual permeability to a membrane due to certain proteins on the membranes that either allow that ion to come in or not

Front 47

What ion/ions have a low concentratino inside the cell and a high concentration outside of the cell? If diffusion took place, what would happen?

Back 47

Ca+ calcium

Na+ sodium

Ions would INFLUX into the cell

Front 48

What ion/ions naturally have high concentratino inside the cell and a low concentration outside of the cell? If diffusion took place, what would happen?

Back 48

K+ potassium

Ions would efflux (go out of the cell)

Front 49

What are the 3 ions that are involved in the contractino of the heart?

Back 49

Ca+, Na+, and K+

Front 50

So what are the only two signals that the heart recieves in terms of cells?

Back 50

Depolarization and Repolarization

Front 51

Do you have a resting membrane potential in the heart? why?

Back 51

No because the heart is always beating you would not want the heart to have a resting membrane potential because it should either be depolarizing or repolarizing

Front 52

How do cells send one signal from one to another?

Back 52

Lateral connection between cells Gap Junctinos