Cells of the Nervous System

Question 1

What are the four primary regions of a neuron?
1. (center)
2. (branches)
3. (tail)
4. (fingertips)

Answer 1

1. Cell body (Soma)
2. Dendrites
3. Axon
4. Buttons (tips of the axon branches)

Question 2

Walk yourself through the process of how a neuron receives a signal from another neuron.

Answer 2

1. Another neuron’s buttons transmit a signal to the neuron’s dendrites.
2. The signal is conducted through the soma and axon to the buttons.
3. The buttons of our neuron then send the signal to other neuron’s dendrites.

Question 3

What is the Rough Endoplasmic Reticulum and what is its purpose?

Answer 3

The Endoplasmic Reticulum is a collection of plate-shaped membranes.
(It is the surface on which most ribosomes dwell.)

Question 4

What do Ribosomes do?

Answer 4

They synthesize (make) proteins.

Question 5

What does the Golgi Apparatus do?

Answer 5

The Golgi packages proteins in membrane sacks.
(checks protein sequences then ships them out of the cell)

Question 6

What do Microtubules do?
What do Neurofilaments do?

Answer 6

Microtubules-> Provide a route for the transport of molecules

Neurofilaments-> Provide support for the cell membrane & maintain the shape of the cell

Question 7

What are Neurotransmitter Molecules?
Where can they be found?

Answer 7

1. These are molecules released from the buttons of a neuron that influence the function of the receiving cells.
   (ex. Sleep, muscle function)
2. They are found in Synaptic Vesicles.

Question 8

What are Synaptic Vesicles?
Which organelle manufactures Synaptic Vesicles?

Answer 8

1. Synaptic Vesicles are membrane sacs that store neurotransmitter molecules until they are released.
2. The Golgi Apparatus manufactures Synaptic Vesicles.

Question 9

What is the Receptive Area of a neuron? Why is it named this?

Answer 9

1. The Receptive Area of a neuron refers to the dendrites and cell body (soma).
2. This is the area of a neuron that receives the most synaptic input (signal from other neurons).

Question 10

What is the Synapse?

Answer 10

The Synapse is a narrow gap between a button and the receptive membrane of another neuron.

Question 11

What is a Postsynaptic Neuron?

Answer 11

(This refers to the neuron receiving a signal.)
The neurotransmitter molecules must pass from a button ACROSS a synaptic gap to reach the receptive area.

Question 12

What is a EPSP & IPSP?

Answer 12

EPSP-> Excitatory Postsynaptic Potentials
(encourages action, making the neuron more likely to fire)
IPSP-> Inhibitory Postsynaptic Potentials
(prevents/inhibits action, making the neuron less likely to fire)

Question 13

What does it mean that EPSPs and IPSPs are Decremental?

Answer 13

Decremental signals fade in strength as they pass through the neuron.
(dendrite->soma-> axon hillock-> axon branches-> buttons)

Question 14

What is the Axon Hillock?

Answer 14

This is the cone-shaped structure between the tube-shaped bit of the axon and the soma.

Question 15

What is a neuron’s Threshold of Excitement?

Answer 15

The amount of excitation necessary for said neuron to send out a neurotransmitter/ action potential signal.

Question 16

Under what conditions is an Action Potential produced?

Answer 16

All the EPSPs & IPSPs that reach the axon are continuously summated over space and time. When the total level of excitation exceeds the threshold of excitation, an Action Potential is produced.

Question 17

What does it mean that “EPSPs & IPSPs are continuously summated over space and time.”?

Answer 17

Space Summation-> Similar signals from differing sources add up.
(think four different buttons all releasing the same neurotransmitter at the same time)

Time Summation-> Similar signals that appear in rapid succession add up.
(think one button just rapid firing its neurotransmitter)

Question 18

Where are Action Potentials generated?

Answer 18

Action Potentials are generated at the Axon Hillock.

Question 19

Action Potentials are ____. Meaning they don’t fade and area full-send situation.

Answer 19

Nondecremental
(stay strong throughout)

Question 20

Differentiate between the Presynaptic Membrane and the Postsynaptic Membrane.

Answer 20

Presynaptic-> This refers to a section of the presynaptic membrane that releases neurotransmitters into the synaptic gap.

Postsynaptic-> This refers to a section of the dendrite/neuron that contains postsynaptic receptors that receive the neurotransmitters.

Question 21

What are Receptors? Where can they be found?

Answer 21

1. Neurotransmitters mind to receptors, thus inducing signals to the receiving neuron.
2. Receptors are found on a neuron’s cell membrane.

Question 22

What are Dendritic Spines?

Answer 22

Tiny little bumps found on dendrites that oftentimes receive neurotransmitters.

Question 23

Walk yourself through the process of one neuron sharing neurotransmitters with another.

Answer 23

• Neurotransmitters are kept in storage within synaptic vesicles until the neuron fires. (buttons)
• The vesicles will bind to the presynaptic membrane, releasing the neurotransmitters into the synapse.
• The neurotransmitters cross the synapse and are received by receptors found in the postsynaptic membrane (dendrite).

Question 24

What are Nodes of Ranvier?

Answer 24

The gaps between myelination of an axon.

Question 25

Differentiate between: -Oligodendrocytes -Schwann Cells

Answer 25

THEY ARE BOTH GLIAL CELLS Oligodendrocytes-> These glial cells myelinate the CNS Schwann Cells-> These glial cells myelinate the PNS

Question 26

What is a major difference between Schwann Cells & Oligodendrocytes other than the part of the NS they support?

Answer 26

Schwann Cells promote axonal regeneration (regrowth of an axon after damage), while Oligodendrocytes don't.

Question 27

What are the benefits of myelination?

Answer 27

Signals are conducted faster when axons are myelinated. (referring to: saltatory conduction)

Question 28

What is Saltatory Conduction?

Answer 28

This refers to when the action potential jumps from the myelinated portion of the axon to the next myelinated portion and so on. (saltatory=skipping)

Question 29

What color is Myelin? Why does this matter?

Answer 29

1. Myelin is white. 2. White Matter-> Parts of the NS that contain myelinated axons. Gray Matter-> Part of the NS that does not contain myelinated axons.

Question 30

What are the two primary structures found in a Neural Cell Membrane?

Answer 30

1. Ion Channels 2. Signal Proteins

Question 31

What are Ion Channels? What are two types of Ion Channels?

Answer 31

1. Ion Channels are specialized pores through which an ion (neurotransmitter) can pass. 2. Chemically-Gated, Voltage-Gated

Question 32

Differentiate Between: - Chemical-Gated Ion Channels - Voltage-Gated Ion Channels

Answer 32

Chemical -> open/close in response to neurotransmitters Voltage- > open/close in response to overall voltage changes

Question 33

What are Signal Proteins? What do they do?

Answer 33

1. These are long tube-like proteins that fold over themselves. 2. When a neurotransmitter/hormone binds to the protein, it sends a message deeper within the cell to the G-protein. (aka. doorbell)

Question 34

What are G-Proteins? What do they do?

Answer 34

1. A protein molecule found inside a neuron. G-proteins are activated by Signal Proteins. 2. The g-protein initiates a change in the internal environment/chemistry of the neuron.

Question 35

Differentiate between: - Ionotropic Receptors - Metabotropic Receptors

Answer 35

Ionotropic Receptors-> induce rapid/brief signals (associated with ion channels) Metabotropic Receptors-> induce slow/ long lasting signals (associated with signaling & G proteins)

Question 36

What are the two types of receptor molecules found in a neuron's cell membrane? (or in general)

Answer 36

1. Ionotropic Receptors 2. Metabotropic Receptors

Question 37

What are Microglia? What is their primary function?

Answer 37

1. Microglia are tiny glial cells. 2. Their primary function is to phagocytose dead cells and cell waste.

Question 38

What are the three types of Macroglia?

Answer 38

1. Oligodendrocytes 2. Schwann Cells 3. Astrocytes

Question 39

What are Astrocytes? What are their primary functions?

Answer 39

A type of macroglia, easily distinguished by its star-like shape. - regulate chemicals thus forming the blood-brain barrier - control the ionic env. of neurons (the soup)

Question 40

The process of neurotransmitter release is called ________.

Answer 40

Exocytosis (to exit)

Question 41

Unlike APs, EPSPs and IPSPs are conducted instantly and ___________.

Answer 41

Decrementally

Question 42

Conduction in myelinated axons is called _________.

Answer 42

Saltatory Conduction

Question 43

In the terminal buttons, the ________________ manufactures synaptic vesicles from fragments of button membrane.

Answer 43

Golgi Apparatus (makes synaptic vesicles)