Nervous System And Drugs

Question 1

What is the function of the nervous system ?

Answer 1

It is a communication net work, receiving information and initiating actions

Question 2

What is the language of the nervous system?

Answer 2

Electrical signals; action potential‘s ,neural networks giving a degree of connectivity

Question 3

What are the two types of specialized cells within the nervous system?

Answer 3

Neurons and Glia cells

Question 4

What makes up the peripheral nervous system?

Answer 4

Autonomic nervous system: make up of the sympathetic nervous system (fight or flight) and the parasympathetic nervous system (rest and digest).
The somatic nervous system.

Question 5

What makes up the central nervous system?

Answer 5

The brain and the spinal cord

Question 6

What are the features of the autonomic nervous system?

Answer 6

1) It is involuntary

2) It stimulates smooth muscle cardiac muscle and glands

Question 7

What is a nerve fiber?

Answer 7

I know fiber is a bundle of art sons of men in your rooms surrounded by a protective covering.

Question 8

Membrane ionic permeability: how do ions cross the cell membrane?

Answer 8

Ions cross through ion channel proteins which cross lipid bilayer and they have a hydrophilic environment for the safe pass of ions

Question 9

ATPase Pump

Answer 9

The ATPase pump creates a concentration gradient across the membrane, it actively pumps to potassium ions into the cell and simultaneously pumps three sodium ions out of the cell.

Question 10

What is the membrane potential of a normal cell

Answer 10

-70mV

Question 11

How is this membrane potential established

Answer 11

A) The ATPase pump creates concentration gradient across the membrane
B)  potassium diffuser out of the cell down the potassium concentration gradient making the outside of the membrane positive in the inside negative creating a potential difference
C) The potential difference will pull potassium back into the cell
D) note that they are organic onions within the cell which are negatively charged such as amino acids and proteins and these are the main source of negative charge inside the axon as they are too large and cannot cross the membrane
E) at -70 mV the two gradients counteract each other and there is no net movement of potassium I.e The potassium concentration gradient in the electrical gradient is that equilibrium

Question 12

Equation for Equilibrium potential (k+)

(Same goes for sodium)

Answer 12

Ek= (RT/zF)x ln ([ko]/[ki])

Question 13

How does depolarization occur

Answer 13

Voltage dependent sodium channels open I.e there is a confirmational change, sodium flows into the axon depolarizing the membrane ,more gates will open once a threshold potential difference is met, action potential is pinnacle at 30 mV

The channel activation gate and inactivation gate is open

Question 14

Describe repolarization

Answer 14

Although the channel activation gate of the sodium voltage dependent channel is still open the inactivation gate is now closing and therefore sodium can no longer pass through the voltage-dependent sodium channel however the voltage-dependent potassium gate opens in potassium leaves the axon repolarizing the membrane
Note at this point ATPase starts to pump sodium out of the axon here potassium moves down there concentration gradient from inside to outside also moving down there electrochemical gradient attracted by the negative charges outside of the membrane

Question 15

Describe hyper polarization

Answer 15

A lot of potassium has been moved out of the axon as well as sodium from the pump in so there is an overshoot and the axon is now more negative than originally. The voltage dependent potassium channels now close allowing potassium to diffuse back into the axon to re-create/reestablish the resting potential and concentrations of both ions

Question 16

What does the refractory period state

Answer 16

An action potential cannot be generated in the same section of membrane for around 5 ms this lasts until all the voltage-dependent channels have returned to their normal resting state ensuring impulses travel in one direction if the action is myelinated.

Question 17

Can action potential‘s move in both directions in an unmyelinated axon 

Answer 17

so action potential can move in both directions from point of stimulation

Question 18

If you stimulate an action potential along the length (not stimulated at axon hillock) of a myelinated axon can the action potential travel in both directions

Answer 18

Yes but when we get to the end of the dendrite the action potential stop because there is no way to transmit it

Question 19

What is the cause of the disease multiple sclerosis

Answer 19

Multiple sclerosis is an autoimmune disease of the central nervous system characterized by chronic inflammation, demyelination,plaques ,scarring and neural loss.

Question 20

What happened to transmission in multiple sclerosis

Answer 20

When an action potential reaches a plaque transmission will stop here causing all sorts of symptoms such as bad eyesight body posture lack of talking

Question 21

How can we modify this action potential to help jump from one node, across a plaque, to another

Answer 21

We have to try prolong the the action potential we could then have a realistic chance of jumping the plaque

Question 22

How can we prolong an action potential how best to achieve that

Answer 22

A) slow down the closing of the sodium inactivation gate Prolonging repolarization
B) blocking potassium channels-this gives us a chance for us to jump the gap allowing sodium to enter a few channels that are open and to spread to the next node and polarizing the membrane at the node making the action potential jump

Question 23

Which method of prolonging an action potential is preferred

Answer 23

By blocking the K+ channels this is more realistic than preventing the inactivation gate from closing because It is difficult to find drugs that can work from within a nerve cell and get them in the nerve cell

Question 24

What are the drugs given to prolong action potential’s in multiple sclerosis

Answer 24

A) 4-aminopyridine

B) tetraethylammonium

Question 25

Are there more or less channels in myelinated neurons

Answer 25

Less