Final Exam Chapter 8 review

Question 1

Where does the interneuron fit in, in the CNS?

Answer 1

It is in between the sensory neurons and the motor neurons. The interneuron takes the information from the sensory input (afferent neurons) to the motor output (efferent neurons). IN THE CNS NOT PNS

Question 2

What roles do astrocytes (5 things) play in supporting neurons of the CNS?

Answer 2

Astrocytes: Maintains the blood brain barrier
- framework for the CNS
- repairs damaged neural tissue
- helps with embryonic neural development
- controls the interstitial fluid environment (ion regulation, Rapid transport between capillaries/neurons and glucose, controlling capillary blood volume, recycling neurotransmitters, and enhance/suppress synapse communication)

Question 3

Describe the function of of oligodendrocytes of the CNS

Answer 3

They are neuroglial cells that form the myelin sheath in the CNS and wrap around the axon of the neuron and form layer of plasma membrane. They are pad shaped

Question 4

How are oligodendrocytes and Schwann cells similar and how are they different?

Answer 4

Similar: They are both neuroglial cells that form a myelin sheath around the axons of the neurons

Differences
oligodendrocytes: Wrap around the axon of a neuron and extend into a pad shape and form layers of the plasma membrane. IN THE CNS NEURONS

Schwann Cells: They coil (make a swirly) around the axon of the nerves. They also incorporate their cell bodies in LAST LAYER of the myelin sheath. The nucleus and cytoplasm are on the OUTSIDE layer of the schwann cell and help in cell regeneration. IN THE PNS NERVES

Question 5

Do oligodendrocytes and schwann cells belong to the PNS OR CNS?

Answer 5

oligodendrocytes - CNS
schwann- PNS

Question 6

Describe the function of Schwann cells of the PNS

Answer 6

They are neuroglial cells that form the myelin sheath in the PNS. They coil their plasma membrane around the axon of the nerves. They incorporate their cell bodies in the myelin sheath. Protect against extracellular fluid

Question 7

What is the function of schwann cells and where are they found (PNS or CNS)?

Answer 7

Forms myelin sheath (PNS)

Question 8

What is the purpose of ACh (acetylcholine) in a neuron?

Answer 8

It binds to the neurotransmitter and opens up the Na+ voltage gated channels and start the action potential

Question 9

What is the purpose of AChE in a neuron?

Answer 9

To breakdown ACh (acetylcholine) into acetate and choline to get it off the neurotransmitter and close the violated gated Na+ channels

Question 10

What is the function of voltage gated Ca2+ channels in a synapse?

Answer 10

To let calcium in and bind to the vesicles to draw them closer to the plasma membrane in the presynaptic synapse

Question 11

What are the 6 steps of the action potential?

Answer 11

1. Resting potential ( sodium and potassium gated channels closed and got -70mV)
2. Graded potential reaches threshold (stimulus initiates depolarization and passes the threshold and opens the voltage gated sodium channels)
3. Depolarization (Sodium channels activate and rush into the cell and inner membrane becomes more positive)
4. Repolarization (The inner membrane reaches +30mV which closes the voltage gated sodium channels to close and activates potassium channels to open and inner membrane reaches -70mV)
5. Hyperpolarization (K+ channel remain open and the inside of the cell becomes -90mV)
6. Resting potential (voltage gated K+ close and it turns back to its -70mV the resting membrane potential by the sodium potassium pump

Question 12

What do the potassium voltage gated channels help with?

Answer 12

Repolarization

Question 13

How does myelin effects continuous and saltatory propagation?

Answer 13

continuous: It makes the process go slower because it has no myelin so the sodium leaks out.

saltatory: It affects by resisting the flow of the ions. So it causes the ions to jump from node to node.

Question 14

What is the difference between continuous and saltatory propagation?

Answer 14

Continuous: It is where the action potential in the first segment spreads the information/sodium to the segment next to it. Then that segment sends it to the segment next to it. So, in short it sends the information to one segment at a time. And it flows in one direction. SLOWER BECAUSE IT LEAKS OUT

Saltatory: The myelinated axons resist the flow of the ions in the axon. So, this causes the ions to jump from node to node in the axon in one direction. FASTER

Question 15

Is myelin gray or white matter?

Answer 15

White matter

Question 16

What is the refractory period?

Answer 16

Where each section of the membrane will not respond to additional stimulus during the action potential as it is going (nothing happens like nap time)

Question 17

Why doesn’t an action potential travel both directions?

Answer 17

• Due to the refractory period. Which is where each section of the membrane which will not respond to more stimuli while the action potential is going until it reaches its resting potential.