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Patho Phys Exam 2 > Action Potential > Flashcards

Flashcards in Action Potential Deck (52)
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1
Q

of cell types in the CNS

A

80-100 billion neurons in the adult brain

2
Q

Each neuron connects to about how many others

A

1000-thus 100 trillion connections

3
Q

Neurons function

A

Transmission, storage, and processing of info; communicate mainly via chemical synapses

4
Q

Glia

A

supporting cells, now known to be involved in processing and signaling

5
Q

Astrocytes

A

Supply nutrients, buffer substances (pH), communicate, insulation, form CNS scarring

6
Q

Damage repair of brain

A

Astrocytes

7
Q

Oligodendrocytes

A

Form myelin sheaths around axons in the CNS

8
Q

Microglia

A

Macrophage system of CNS

9
Q

Ependymal cells

A

line ventricles (fluid filled)

10
Q

Gray matter

A

neuron and glial cell bodies

11
Q

White matter

A

myelinated axons

12
Q

Soma

A

Cell body

13
Q

Dendrites

A

Receive signals to the body

14
Q

dendritic spine

A

Form synapses/connections-mushroom shaped

15
Q

Axon hillock

A

important in signaling

16
Q

Axon lenght

A

very long-can be myelinated too

17
Q

Axon terminal

A

Vesicles filled with NTs to be sent to the next neuron in the chain

18
Q

Impulse conduction main two categores

A

graded

19
Q

graded potentials

A

local changes-change in Amplitude based on distance from the signal

Nearby –> strong effect
Far –> weaker effect (smaller Amplitude)

20
Q

Max distance graded potentials and go and how they move

A

transduction of these is passive, and can go a max of 5mm

21
Q

Variable Amplitude

A

Of passive conduction-goes down with distance

22
Q

Action potentials

A

a way to send a signal very long distances (30ft in a whale :P) without having it decline

ALL OR NOTHING PHENOMONUM`

23
Q

Which cells do APs happen in

A

Cells which are excitable (neurons, muscles, heart)

24
Q

Threshold potential

A

Membrane potential at which you would fire an action potential. happens when the sodium conductance is greater than the potassium conduction.

25
Q

Active propagation-

A

Energy to keep the action potential going is stored along the axon. -Like rows of dominoes.

Potential energy energy stored in dominoes and you are tipping them over and they will keep going.

Energy far from the site is the same as the energy close to the site. AMPLITUDE IS CONSTANT OVER THE DISTANCE!

26
Q

How is action potential energy stored

A

as resting membrane potential

27
Q

Na+ channel opens when

A

if the threshold is reached they open –> membrane highly depolarizes

28
Q

Inactivation of Na+ channel? How long?

A

Seperate from channel opening.

It is like a
flap at the end of the channel and prevents sodium from moving even if channel is open.

Have to reset
it so that it can be activated again. aka REPOLARIZE TO OPEN Open rapidly.

29
Q

K+ delated rectifier-what does that mean

A

They open slow and close slow (stay open longer)

30
Q

Rate at which Na and K channels open

A

Na open fast and close fast

31
Q

Resting membrane level is at

A

-60mV

32
Q

Threshold of AP

A

All or nothing-Starts here! Sodium is greater than K conductance here

33
Q

Rising phase

A

Na Channels opening and depolarized up to zero

34
Q

Overshoot

A

After 0 the potential becomes hyperpolarized to near +25mV

35
Q

Period of Repolarization

A

K channels open and Na channels inactivate

36
Q

Peak

A

Na channels maximally opened (not all are open but the most than can be at once are)

37
Q

After hyperpolarization

A

K conductance returns to the point of normal leak rate

38
Q

Gk vs Gk at rest

A

gK > Gk at rest

39
Q

What happens to stop depolarization

A

inactivation flap closes

40
Q

Refractory period

A

Axon is resistant to firing another action potential, right after one has been fired. Need time to rest

41
Q

Absolute Refractory period

A

Cannot fire another action potential-system has to reset first and the Na channel is inactive

42
Q

Relative refractory period

A

Threshold here is higher than at rest-still high levels of K conductance –> threshold you need to reach is more +++ and the amplitude will be less

43
Q

A wave of what follows the action potential (behind it)

A

in unmyelinated axons—passive depolarization which is very fast and said to be in refractory- this keeps the action potential propagating in one direction.

44
Q

Passive depolarization happens in which kind of neurons

A

myelinated

45
Q

How AP is propagated in a myelinated axon

A

oligodendrocytes will insulate more of the cell membrane (CNS)

46
Q

what myelinates axons in the PNS

A

Schwann cells

47
Q

Nodes of Ranvier

A

interruptions of myelin on the myelinated axon which the AP jumps across (Saltatory conduction)–high Na channel concentration here

48
Q

Concentration of Na channels at nodes of ranvier

A

high concentration Na channels here

49
Q

At the nodes what kind of conduction happens?

A

Passive, thus passive is very fast

50
Q

Myelinated axons conduction V

A

225mph

51
Q

Unmyelinated axons conduction V

A

225mph

52
Q

Effect of axon size on speed of conduction

A

larger the axon the faster it is—–want large myelinated axons