Neurons

Front 1

corpus callosum

Back 1

(area around the lateral ventricle)

facilitates much of the communication between the 2 hemispheres; main function is to allow communication between the brain's left and right hemispheres

Front 2

severed corpus callosum

Back 2

'split brain'

when the corpus callosum connecting the 2 hemispheres is split to some degree

Front 3

neuron

Back 3

an electrically excitable cell that processes and transmits information through electrical and chemical signals

100 billion in human brain; longest neuron is ~3 feet, info can travel through a neuron at top speed of ~250mph

Front 4

parts of neuron

Back 4

input zone: cell body, dendrites

conduction zone: axon

output zone: axon terminals

Front 5

types of glial cells (4)

Back 5

astrocyte, microglia, oligodendrocyte, Schwann cell

Front 6

astrocyte (3)

Back 6

most common glial cells

metabolic exchange between neurons and blood

support BBB

Front 7

microglia (3)

Back 7

type of glial cell

immune defense / sense pathology

clean up debris

Front 8

oligodendrocyte (2)

Back 8

type of glial cell

myelinate axons in CNS / supplies myelin sheath

Front 9

Schwann cell (2)

Back 9

type of glial cell

myelinate axons in PNS / supplies myelin sheath

Front 10

multiple sclerosis

Back 10

demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged

this damage disrupts the ability of parts of the nervous system to communicate

Front 11

what makes up gray matter and white matter?

Back 11

gray matter: cell bodies of neurons

white matter: bundles of axons

Front 12

How do signals travel through neurons? (5 steps)

Back 12

1. neuron at rest

2. input stimulates neuron

3. if large enough stimulus at axon hillock, an action potential is created

4. action potential propagates down axon

5. sends signal through synapse to other neurons

Front 13

difference between electrical and chemical neuron signaling

Back 13

electrical: within neuron

chemical: between neurons

Front 14

potential

resting potential

Back 14

difference or separation of charge

neuron is prepared for action; resting potential is always negative (-40mV to -90mV0

Front 15

define: ion, cations, anions

give examples of cations and anions

Back 15

ion: atom or molecule that has electrical charge

cations: positively charged (Potassium K+, Sodium: Na+, Calcium, Ca2+)

anions: negatively charged: (Chloride: Cl-, Protein: anion-)

Front 16

membrane potential

Back 16

the difference in electric potential between the interior and the exterior of a biological cell

Front 17

what generates membrane potentials?

Back 17

ion channels: passive, but open or closed based on voltage or chemical activity; when open, let specific ions in and out

active/ion transporters (pumps): e.g., sodium potassium pump; they're active--require energy; bring ions in + take ions out

Front 18

Are there many ions inside or outside of the cell for the following: Na+, K+, Cl-, Ca2+, anion proteins

Back 18

Na+: many outside

K+: many inside

Cl-: many outside

Ca2+: many outside

anion proteins: many inside

Front 19

charge outside and inside of cell

Back 19

outside: +

inside: -

Front 20

what are the two forces acting on ions? describe them

Back 20

Diffusion: ions move from areas of high concentration to areas of low concentration

electrostatic: like charges repel, opposites attract

Front 21

What is the neuron membrane like when the neuron is at rest?

Back 21

Neuron shows selective permeability to potassium: K+ can enter and leave the cell freely

Some channels are open all the time and allow only potassium ions to cross

Front 22

Where does K+ want to go due to electrostatic forces and diffusion?

Back 22

electrostatic forces: inside

diffusion: outside

Front 23

Where does Na+ want to go due to electrostatic forces and diffusion

Back 23

electrostatic forces: inside

diffusion: inside

But neuron at rest is not nearly as permeable to sodium as it is to potassium, so only some sodium can pass through

Front 24

What does the Na+/K+ pump (an active transporter) do?

Back 24

Pumps 3 Na+ out of cell and 2 K+ into the cell

Front 25

What 4 factors does resting potential rely on?

Back 25

diffusion

electrostatic forces

selective permeability

sodium-potassium pumps

Front 26

receptor potential

Back 26

sensory neurons receive info from sensory receptors

Front 27

post-synaptic potential

Back 27

neurons receive info from other neurons

Front 28

What happens when Na+ comes into the cell?

Back 28

depolarization (reduction of membrane potential -- inside of cell becomes less negative)

Front 29

depolarization

Back 29

reduction in membrane potential, making inside of cell less negative relative to outside, i.e., getting closer to 0

Front 30

Are action potentials graded?

Back 30

No, they are ALL or NONE, will propagate as is down an axon without decay

depolarization across a threshold causes an action potential

Front 31

action potential process (5)

Back 31

1. stimulus crosses threshold value

2. depolarization (Na+ enters)

3. repolarization (K+ leaves)

4. after-hyperpolarization (undershoot)

5. resting potential

Front 32

in step 1 of action potential process, does it matter whether the stimulus is a little over threshold or a lot?

Back 32

No, as long as it is over threshold, it will generate the same action potential

Front 33

what happens during step 2 of action potential process, "large depolarization"?

Back 33

voltage-gated Na+ channels open

membrane potential passes 0, becomes more positive inside the neuron because of the huge influx of Na+

(Na+ enters, membrane potential becomes more positive)

Front 34

what happens during step 3 of action potential process, "repolarization"?

Back 34

K+ channels open, K+ leaves the cell (because diffusion and electrostatic forces want it out of the cell)

(K+ exits, membrane potential becomes more negative)

Front 35

what happens during step 4 of action potential process, " after-hyperpolarization"?

Back 35

K+ channels take a little longer to close so more K+ rushes out bringing membrane potential briefly even more negative than resting potential

(K+ keeps exiting a little too much, membrane potential briefly becomes even more negative than resting potential)

Front 36

What happens to a sub-threshold stimulation as it propagates down an axon? What happens to a stimulation that produces an action potential as it propagates down the axon?

Back 36

when a sub-threshold stimulation propagates down an axon, the signal decays over time

but otherwise, the signal remains as strong as it propagates down the axon because of channels and myelin

Front 37

2 characteristics of action potential

Back 37

self-perpetuating: once it starts, it keeps going

self-limiting: repolarizes, signal doesn't travel "backwards"

Front 38

what part of the neuron receives the action potential signal? what part conducts? What part transmits?

Back 38

receives: dendrites, cell body

conducts: axon

transmits: synaptic terminals

Front 39

Why doesn't the signal travel "backwards"? (2 reasons)

Back 39

absolute refractory period: second action potential cannot be initiated, no matter how large a stimulus is applied

relative refractory period: initiation of second action potential is inhibited, though not impossible

Front 40

How does myelination affect speed of propagation?

Back 40

myelin allows for faster conduction and greater energy efficiency

Front 41

saltatory conduction

Back 41

saltare means jump or hop -- idea that the action potential gets boosted at these Nodes of Ranvier (areas without myelin that have ion channels)