EXAM 2 - Nervous System: Intro

Question 1

Glial cells

Answer 1

1. Supporting cells
2. Support survival, function & structure of neurons & nervous tissue.
3. 6 x total (4 in CNS, 2 in PNS)

Question 2

Astrocytes

Answer 2

Most abundant
1. Support
2. Guide
3. Supply nutrients
4. Release neurotransmitters
5. Control chemical environment

Question 3

Microglial

Answer 3

1. Phagocytise bacteria &
   Neuronal debris

Question 4

Ependymal cells

Answer 4

1. Lines cavities of brain and spinal cord
2. Permeable barrier between CSF & nervous tissue

Question 5

Oligodendrocytes

Answer 5

Form myeline sheath (insulate neurons)

Question 6

Satellite cells

Answer 6

1. Form around cell body
2. Similar to astrocytes

Question 7

Schwann cells

Answer 7

1. Similar to Oligodendrocytes
2. Form myelin sheath

Question 8

Dendrites

Answer 8

1) Receives information
2) Conveys toward cell body

Question 9

Axon

Answer 9

Generates & transmits Action Potential (AP)

Question 10

Axon terminal

Answer 10

Releases neurotransmitter from presynaptic cell TO postsynaptic cell

Question 11

Cell body

Answer 11

1) Contains nucleus
2) Produces Neurotransmitters
3) Receives info from other neurons

Question 12

Chemical Synapse Steps

Answer 12

1. AP reaches presynaptic terminal
2. Depolarization of presynaptic terminal opens ion channels, allows Ca2+ into cell.
3. Ca2+ triggers release of neurotransmitters from vesicles.
4. Neurotransmitters bind to receptor sites on postsynaptic membrane.
5. Opening & closing of channels causes change in postsynaptic membrane potential
6. AP propagates through next cell.
7. Neurotransmitters are inactivated OR transported back to presynaptic terminal

Question 13

Action Potential Steps

Answer 13

1. Resting membrane potential
2. Depolarisation
3. Repolarisation
4. Hyperpolarisation
5. (step 1): Return to RMP

Question 14

Action Potential Step 1

Answer 14

1. Resting Membrane Potential
   - membrane potential -70mV
   - all voltage ion gates closed
   - neuron considered to be at rest
   - RMP maintained via NA+ & K+ passive (leak) channels)

Question 15

How is RMP / Electrochemical gradient maintained?

Answer 15

Sodium-potassium exchange pumps (powered by ATP) - 3 x NA+ out, 2 x K+ in
- transports substances against chemical gradient

Question 16

Action Potential Step 2

Answer 16

2. Depolarisation
   - Na+ (sodium ion) Voltage-gated channel opens, and Na+ rushes into cell.
   - Rush of Na+ into cell causes rapid depolarisation, and inner membrane surface changes from negative to positives (+30mV)

Question 17

Action Potential Step 3

Answer 17

3. Repolarization
   - Sodium ion voltage gated channel closes
   - Potassium ion voltage-gated channel opens
   - K+ rushes out of cell

Question 18

Action Potential Step 4:

Answer 18

4. Hyperpolarization
   - K+ Voltage-gated channel remains open and K+ continues to leave cell (not as quick to close as Na+ voltage gated channel was)
   - Na+ voltage-gated channel still closed

Question 19

Neurotransmitter: Acetycholine (Ach)

Answer 19

• CNS & PNS (vertebrate neuromuscular junction)
• to vertebrae skeletal muscles
• Excitatory or Inhibitory at other sites (i.e. cardiac muscle)

Question 20

Neurotransmitter: Norepinephrine (NE)

Answer 20

• CNS & PNS
• Excitatory or inhibitory

Question 21

Neurotransmitter: Dopamine

Answer 21

• CNS & PNS
• Generally Excitatory (may be inhibitory at some sites)

Question 22

Neurotransmitter: GABA (gamma aminobutyric acid)

Answer 22

• CNS & Invertebrate neuromuscular junction
• Inhibitory

Question 23

Neurotransmitter: Glutamate

Answer 23

• CNS & Invertebrate neuromuscular junction
• Excitatory