Chapter 12 - Neuron & Glia

Question 1

Excitibality

Answer 1

• Neurons & Muscle cells are excitable
• Ions move and changes in membrane potential conduct

Question 2

Central Nervous System

Answer 2

Brain and Spinal Cord

Question 3

Peripheral Nervous System

Answer 3

Nerves and Ganglia

Question 4

Efference

Answer 4

Motor

Question 5

Afference

Answer 5

Sensory

Question 6

Tract

Answer 6

Bundle of axons
(CNS)

Question 7

nucleus

Answer 7

group of cell bodies
(CNS)

Question 8

nerve

Answer 8

bundle of axons (PNS)

Question 9

ganglion

Answer 9

group of cell bodes (PNS)

Question 10

Which glial cell type does the most different kinds of activities to support neurons?

Answer 10

Astrocytes

Question 11

Schwann cells

Answer 11

wrap unmyelinated axons, but not multiple spiral wraps.

Question 12

Ependymal cell

Answer 12

• Produce CSF
• Line the ventricles of the brain and central canal of the spinal cord and
• Tufts of ependymal cell tissue = choroid plexus.
• Creates barrier between these CSF filled spaces and the neural tissue.
• Source of neural stem cells

Question 13

Choroid plexus

Answer 13

transport ions and nutrients from the blood into the cerebrospinal fluid.

Question 14

Astrocyte

Answer 14

Regulate the ECF of neurons in the CNS:
Take up excess K+ to help neurons maintain their resting potential, “K+ sponges”
Take up excess neurotransmitter, prevent excess synaptic signalling, “NT sponges”.
Produce growth factors for neurons “nourish” and provide nutrition (fuel to make ATP).
Structural support:
Spatial support, “hold neurons in place” so they can maintain synapses
Guide migrating neurons during devel of brain
Cover brain surface
Cover nonsynaptic regions of neurons
Induce blood-brain-barrier to form.
Communicate electrically with neurons/influence synapses.
Form scar tissue after damage to the CNS.
Source of neural stem cells.

Question 15

Microglia

Answer 15

Phagocytes
Scavengers of dead tissue (after injury to CNS)
Immune function against pathogens
Derived from Monocyte (white blood cell made in bone marrow)

Question 16

oligodendrocytes

Answer 16

Myelinating cells of the CNS.

Question 17

Resting Membrane potential

Answer 17

At Rest (unstimulated),A Neuron has a voltage

Question 18

Initial Stimulation

Answer 18

the act of disturbing a neuron that was at rest
- Can be accomplished 3 ways: electrically, chemically or physically

Question 19

Chemical Stimulation

Answer 19

Chemical (neurotransmitter, NT) binds to a receptor (ligand-gated channel shown) which allows for opening of an ion gate
and that changes the voltage

Question 20

Resting membrane potential

Answer 20

-70, potassium would need to leave the cell and take its positive charge outside the cell so it becomes more negative.

Question 21

threshold

Answer 21

-55, mV value at which the voltage gates will open

Question 22

+35

Answer 22

peak of action potential

Question 23

+62, ENa+

Answer 23

equilibrium potential for sodium
- sodium wants to bring as much positive charge as possible
- Sodium would want to bring in as many sodium ions as possible, to get the -70 mV all the way up to +62 mV

Question 24

-90, Ek+

Answer 24

• Potassium balance is at -90

Question 25

Depolarization

Answer 25

• brings cell closer to threshold later, EPSP
• Moving in the positive direction of our resting potential
• When sodium channels open

Question 26

Hyperpolarization

Answer 26

• Brings cell away, more negative
• this is inhibitory, brings cell away from threshold later, IPSP
• When potassium channels open

Question 27

At threshold

Answer 27

Voltage gated channels open

Question 28

Repolarization

Answer 28

going back to its resting membrance potential

Question 29

Absolute refactory period

Answer 29

wouldn’t get another action potential at all

Question 30

Relative action potential

Answer 30

if we have a big enough stimulus we can stimulate another action potential with that voltage gated sodium channel

Question 31

what is undirectional conducation

Answer 31

one way, can’t back up

Question 32

Why does conduction occur

Answer 32

because of the refactory period

Question 33

Saltatory conduction

Answer 33

jumps

Question 34

Electrical synapses

Answer 34

rare in CNS but common in muscle. They make use ofGap Junction Proteins

Question 35

Chemical Synapses

Answer 35

MUCH more prevalent – Adjustable!
When Action Potential reaches Axon Terminal it stimulates Voltage-gated Ca++ channels
The influx of Ca++ causes exocytosis of vesicles that contain Neurotransmitter (NT)
Transmitter binds to a receptor on the mb of the next neuron (or muscle cell, etc.)
There are 2 Different types of Receptors: Receptors associated w/ Ion Channels vs Receptors associated w/ 2nd Messenger Systems
There are over 100 different types of transmitters. The text gives three examples: Acetylcholine, GABA, & Norepinephrine

Question 36

Acetylcholine

Answer 36

will bind to a receptor that is connected to a Na+ channel.
It lets Na+ enter to stimulate
the postsynaptic neuron… an
Excitatory Postsynaptic Potential (EPSP) which is a form of initial stimulation.

Question 37

Neuromodulators

Answer 37

peptides released like small simple amino acid derived neurotransmitters, but they alter synapses.

Question 38

Memory

Answer 38

due to “strengthened” synapses, when you form memorys its due to new synaptic connections

Question 39

Temporal summation

Answer 39

Done in a timing kind of manner

Question 40

Spatial summation

Answer 40

over space and area we’re looking at we see three separate inputs to one post - synaptic neuron.

Question 41

anasthesia

Answer 41

makes it impossible for pain stimulus to transmit afferently, don’t sense pain because voltage gate channels are inhibited