Lecture 8- Intro to neurons of the nervous system and electrical activity

Question 1

what are the 7 cells of the nervous system?

Answer 1

neural stem cells
common progenitors
neuronal progenitors –> neurons
glial progenitors –> astrocytes, oligodendrocytes

Question 2

what do neurons do?

Answer 2

specialized to carry electrical signals and communicate with other cells and distant targets

Question 3

what are unique features of neurons? (3)

Answer 3

1. high density of ion channels (bc communicating with distant targets occurs electrically… need high density)
2. special transport mechanisms to move materials from one end to the other using the cytoskeleton
3. secrete signaling molecules

Question 4

what are the 9 parts of a neuron?

Answer 4

dendrites
cell body & nucleus
axon hillock
axon
myelin sheath
node of ranvier
synaptic terminals
synaptic cleft
postsynaptic cell

Question 5

what do the dendrites of a neuron do?

Answer 5

receive and process signals from the axons of other neurons

Question 6

what does the cell body and nucleus of a neuron do?

Answer 6

contain genetic information, maintains neurons structure, provides energy to drive activities

Question 7

what does the axon hillock of a neuron do?

Answer 7

site of transition between the cell body and the start of the axon

Question 8

what does the axon of a neuron do?

Answer 8

joins cell body and is normally insulated with myelin sheath

Question 9

what does the myelin sheath of a neuron do?

Answer 9

most neurons have them, the ones that do create faster action potentials and are insulated

Question 10

what is the node of ranvier of a neuron?

Answer 10

gap between myelin sheath covered axon
allow fast impulse along the axon

Question 11

what do the synaptic terminals of a neuron do?

Answer 11

convert electrical signals to chemical signals, synaptic vesicles aide in uptake and storage

Question 12

what does the synaptic cleft of a neuron do?

Answer 12

provide space for chemical transmission of messages from the nervous system

Question 13

what are the 4 types of neurons?

Answer 13

pseudounipolar
bipolar
interneurons of CNS
efferent neurons

Question 14

what are the two types of sensory neurons?

Answer 14

pseudounipolar
bipolar

Question 15

what is a pseudounipolar neuron?

Answer 15

variation of bipolar
carry information about touch, vibration, proprioception, pain and temperature.

Question 16

what is a bipolar neuron?

Answer 16

transmission of sense

Question 17

what do interneurons of CNS do?

Answer 17

carry sensory information and regulate motor activity

Question 18

what do efferent neurons do?

Answer 18

carry signals from the brain to the PNS to initiate an action

Question 19

what types of glia are in CNS?

Answer 19

oligodendrocytes
ependymal cells
microglia
astrocytes

Question 20

what do oligodendrocytes do?

Answer 20

myelinate axons

Question 21

what do ependymal cells do?

Answer 21

line ventricles of the nervous system and make neural stem cells

Question 22

what do microglia do?

Answer 22

immune cells of the CNS

Question 23

what do astrocytes do? (5)

Answer 23

1. blood brain barrier
2. trophic factors (produce molecules to help neurons change when they have to)
3. take up excess water and K+
4. neural stem cells
5. pass lactate to neurons (astrocytes break down sugar into lactate so that neurons can consume glucose)

Question 24

what types of glia are in the PNS?

Answer 24

satellite cells
schwann cells

Question 25

what are satellite cells?

Answer 25

trophic factors

Question 26

what do schwann cells do?

Answer 26

myelinate axons

Question 27

what two things lead to the RMP? (recall: goldman equation)

Answer 27

ion gradients
differences in relative permeability of Na+, K+, Cl-

Question 28

why does the membrane potential change if ion channels open?

Answer 28

because it allows ions to move into or out of the cell making the cell more positive or negative (because ions are charged!)

Question 29

neurons contain a high density of ion channels, what are the 3 classes of ion channels? why do we call them what we do?

Answer 29

ions they carry (ex. Na+ channels)
where on the cell they are located (ex. cell is between pre- synaptic and post synaptic = post synaptic channel)
gating mechanisms

Question 30

what are the 5 ion channel gating mechanisms?

Answer 30

1. voltage gated ion channel
2. receptor channels
3. phosphorylation gated
4. stretch gated
5. temperature gated

Question 31

what is a voltage gated ion channel, how does it work?

Answer 31

changes in membrane potential open the channel if passed the threshold

Question 32

what is a receptor channel? how does it work?

Answer 32

gate when they bind a ligand

Question 33

what is a phosphorylation gated channel? how does it work?

Answer 33

causes some channels to open or close when a phosphate is added

Question 34

what is a stretch gated channel? how does it work?

Answer 34

poke cell membrane and stretch it, channel will open

Question 35

what is a temperature gated channel? how does it work?

Answer 35

changes in temperature could produce a ligand that binds to a receptor and affects the channel
can be gated by certain chemicals for ex. the spice in peppers causes temperature gated channels to open

Question 36

what does the opening and closing of ion channels cause?

Answer 36

rapid changes in membrane potential (basis of electrical signaling)

Question 37

what is an action potential?

Answer 37

wave of depolarization that actively propagates across neuronal membrane