CNS 2

Question 1

Neuroglia in CNS

Answer 1

1. astrocytes
2. oligodendroglia
3. microglia (latent phagocytes)
4. ependymal cells (line ventricles/CSF production)

Question 2

Neuroglia in PNS

Answer 2

1. Schwann cells (cover/myelenate the axon)
2. satellite cells (cover the cell body)

Question 3

pyramidal cells

Answer 3

• a type of multipolar neuron of cerebral cortex classified by dendrites
• makes up about 75% of neurons
• Primary excitation unit of frontal cortex
• Excited by: glutamate and aspartate
• Inhibited by: GABA_A

Question 4

Stellate or granule cells

Answer 4

• neuron type in cerebral cortex
• makes up about 25%
• excitatory amino
  
  • acid (glutamate or aspartate)
• most are inhibitory
  
  • y-aminobutyric acid (GABA) transmitter

Question 5

Myelination

Answer 5

• allows for faster conduction
  
  • increases the effective membrane resistance (by decreasing the amt of Na that leaks out)
  • decreases the capacitance
  • restricts action potential generation to only the nodes of Ranvier

Question 6

capacitance

Answer 6

the ability of a system to store an electric charge

Question 7

functional benefits of myelination

Answer 7

1. efficiency
2. fast reflexes
3. complex mental processing
4. lower metabolic requirements

Question 8

Synaptic Signaling

Answer 8

• classic neuron-neuron junction
  
  • electrical (gap junctions)
  • chemical (neurotransmitter)
• Neuron- Glial
  
  • Ligands to G protein receptors in glial cells
• Extra-synaptic
  
  • Neurotransmitters sneak out and hit other axons

Question 9

electrical synapses/ gap junctions

Answer 9

1. low resistance pathway that allows current to flow from one cell to another
2. allows exchange of small molecules between cells
3. bidirectional
4. Gap junctions regulated by:
   
   1. voltage, intracellular pH, Ca, and G protein coupled receptors

Question 10

SNARE

Answer 10

• the protein that mediates vessicle fusion
• brings the vessicle to the terminal edge of the axon

Question 11

astrocytes

Answer 11

• BBB
• K+ uptake
• SVR of small vessels
• ACh recycling
• communication

Question 12

oligodendroglia

Answer 12

myelination of the CNS

(multiple different axons)

Question 13

microglia

Answer 13

• phagocytic cells of the CNS
  
  • since Ab don’t cross BBB

Question 14

Ependymal

Answer 14

• CSF production
  
  • line the ventricles

Question 15

bipolar neurons

Answer 15

• type of neuron classified by number of neurites
• two processes
  
  • axon and dendrite
  • retina/olfactory epithelium only–not common

Question 16

pseudo unipolar neurons

Answer 16

• type of neuron classified by number of neurites
  
  • sensory only
  • One axon, two branches
    
    • branches serve the function of both axon and dendrite
    • one branch in CNS, one in PNS
  • cell body in the dorsal root ganglion

Question 17

multipolar neurons

Answer 17

• Type of neuron classified by number of neurites
  
  • by far most common
  • one axon and multiple dendrite

Question 18

stellate cells

Answer 18

• type of neuron classified by dendrites
  
  • star shaped
  • 25% of CNS
  • Ex: inhibitory, GABA or some excitatory, aspartate or glutamate

Question 19

v-SNARES

Answer 19

are incorporated into the membrane of the transport vesicles

Question 20

t-SNARES

Answer 20

associated with the nerve terminal membrane

Question 21

types of SNARE proteins

Answer 21

synaptobrevin

syntaxin

SNAP-25

Question 22

synaptotagmin

Answer 22

• binds to the Ca++ and SNARE complex and allows for exocytosis to occur

Question 23

4 mechanisms of Ca++ entry and exit

Answer 23

1. Ca++ pump
2. Ligand gated Ca++ channel
3. Voltage gated Ca++ channel
4. Na+/Ca++ exchanger

***remember Ca++ concentration gradients are HUGE!!

Question 24

criteria for a neurotransmitter

Answer 24

1. must be present in presynaptic terminal
2. cell must be able to synthesize the substance
3. must be released upon depolarization of presynaptic membrane
4. there must be a specific receptor on the postsynaptic membrane (some go to extrasynaptic locations)

***over 100 neurotransmitters currently identified

Question 25

Class 1 Neurotransmitter

Answer 25

Acetylcholine

Question 26

Class II Neurotransmitters Biogenic Amines

Answer 26

1. Norepinephrine 2. Epinephrine 3. Dopamine 4. Serotonin 5. Histamine

Question 27

Class III Neuro transmitters Amino Acids

Answer 27

1. Gamma-aminobutyric acid (GABA) 2. Glycine 3. Glutamate 4. Aspartate

Question 28

Class IV Neurotransmitters

Answer 28

1. Neuropeptides/Peptide transmitters 1. i.e. hormones, Angiotensin II, Insulin, Oxytosin

Question 29

Gaseous Neurotransmitters

Answer 29

* Are not released from "vesicles" * able to diffuse out at any point and may travel far before encountering receptor * Ex: NO, CO

Question 30

Glutamine-Glutimate cycle aka Glutamate Recycling

Answer 30

1. Axon terminal is depolarized and glutamate is released by vesical out of axon terminal 2. Glutamate hits receptors on other side of synaptic cleft. Once it is released or if it never bound, glutamate gets taken up by glial cells and converted back into glutamine. 3. Glutamine gets released by the glial cells and it goes back into the axon. 4. Glutaminase turns the glutamine into glutamate and it gets repackaged into vesicle and ready for next release.

Question 31

Acetylcholine Recycling

Answer 31

1. Acetylcholine is made from choline and Acetyl CoA 2. after being released from Axon terminal, acetylcholine is quickly broken down by acetylcholinesterase. 3. Choline is transported back into the axon terminal and is used to make more ACh.

Question 32

Ion current equation

Answer 32

I_x = g_x\*(V_m-E_x) I_x = total current g_x = conductance of individual ion channel V_m = resting membrane potential E_x = Nerst potential for that ion \*\*Ion current flow direction depends on electrochemical gradients of permeant ions

Question 33

MEPP

Answer 33

* Miniature end plate and potential * small \<0.5 mV depolarizations of postsynaptic membrane * reflect spontaneous release of a single synaptic vesicle * too small to reach threshold so no action potential occurs

Question 34

EPSP

Answer 34

* Excitatory response * increased Na+ influx * decreased Cl- influx or K+ efflux * change in receptor expression or enzymatic/metabolic activity * lasts about 15 milliseconds, must have multiple within this time for an AP to occur

Question 35

IPSP

Answer 35

* Inhibitory response * Increased Cl- influx or K+ efflux * pre synaptic * post synaptic * change in receptor expression or enzymatic metabolic activity

Question 36

changes in pH affect on synaptic transmission

Answer 36

* alkalosis- greatly increases neuronal excitability * acidosis- greatly depresses neuronal activity * hypoxia- severely decreases neuronal excitability

Question 37

A alpha sensory

Answer 37

* large, myelinated, fast * primary golgi