Module 3: Nervous system cells and resting membrane potential

Question 1

what are the 3 components to resting membrane potential?

Answer 1

1. neurons
2. glia
3. nerves

Question 2

what is the function of a neuron cell body?

Answer 2

to integrate all information

Question 3

about how many neurons are in the brain?

Answer 3

100 billion, they’re all connected

Question 4

what is the function of a dendrite?

Answer 4

1. to receive input from other cells
2. connect to other cells

Question 5

what is the function of the axon?

Answer 5

sends signals to the next neuron

Question 6

what are some examples of neurons?

Answer 6

1. multipolar: like most of body, has multiple poles: dendrites and axons.
2. bipolar: found in eyes, has 2 poles: 1 axon and 1 dendrite
3. unipolar: found in sensory organs like touch has 1 pole off body, then the axon and dendrite come off of that

Question 7

what are nerves?

Answer 7

a bunch of axons bundled together in layers of connective tissue

Question 8

do nerves go in 1 direction?

Answer 8

no, they carry efferent and afferent signals around the body

Question 9

what is the name of the nerve if it’s from the brain?

Answer 9

cranial nerve

Question 10

what is the name of the nerve if it’s from the spine?

Answer 10

spinal nerve

Question 11

what are the 6 types of glial cells?

SEASOM

Answer 11

1. Schwamm cells
2. ependymal cells
3. astrocyte
4. satellite cell
5. oligodendrocyte
6. microglia

Question 12

how many types of glial cells are in the PNS?

Answer 12

2

Question 13

how many types of glial cells are in the CNS?

Answer 13

4

Question 14

what are glial cells?

Answer 14

non electrical cells in the CNS and PNS, holding them together and maintaining the structure

Question 15

what are the 4 glial cells in the CNS?

Answer 15

1. astrocyte
2. oligodendrocyte
3. microglia
4. ependymal cells

Question 16

what are the 2 glial cells in the PNS?

Answer 16

1. satellite cells
2. Schwann cells

Question 17

what do astrocytes do?

Answer 17

1. form the blood brain barrier by wrapping the blood vessels in foot processes and blocking off holes for infection to get into the brain
2. regulate chemical levels around neurons: ions and neurotransmittors, cleaning up after AP.
3. structural

Question 18

what do oligodendrocytes do?

Answer 18

myelinate axons (same as Schwann cell in PNS)

Question 19

what do microglia do?

Answer 19

act as an immune defence to the brain, as the astrocyte stops WBC getting into the brain, as well as everything else, the brain needs it’s own immunity defence

Question 20

what do ependymal cells do?

Answer 20

1. line the ventricles holding the CSF and help move it around
2. involved in the process of CSF production in the choroid plexus

Question 21

what does a satellite cell do?

Answer 21

1. controls the levels of chemical around neurons: nutrients/gases/neutrotransmitter levels (like astrocyte)
2. sits around the soma of a neuron

Question 22

what do Schwann cells do?

Answer 22

myelinate axons, like the oligodendrites in the CNS

Question 23

what is voltage?

Answer 23

a measurement of the difference in electrical potential between 2 points in space (V)

Question 24

where are membrane potentials found?

Answer 24

in all cells of the body

Question 25

how is a membrane potential caused?

Answer 25

by a difference of ions on either side of a membrane, which creates a voltage as the opposite ions are attracted to each other through the membrane, creating a voltage

Question 26

where do neurons get their energy from?

Answer 26

membrane potential

Question 27

is membrane potential a general or local charge?

Answer 27

local

Question 28

does the membrane potential change?

Answer 28

yes, it depends how many ions are gathered at the wall, depends how strong the charge will be

Question 29

what is the resting membrane potential of neurons?

Answer 29

-70mV

Question 30

why is the resting membrane potential of neurons -70mV?

Answer 30

1. difference in ionic composition: more Na+,K+, Cl- and -ve proteins on either side of the ECF and ICF end up at -70mV 2. difference in membrane permeability to ions: lots of K+ leakage channels, a few Na+ leakage channels allow for passive transport down the gradient, ending in -70mV

Question 31

after an action potential, how does a neuron get back to the resting membrane potential of -70mV?

Answer 31

through the use of the Na+K+ATPase pump pushing Na+and K+ up their chemical gradient to equalise the composition between the ECF and ICF again 3Na+ out, 2K+in

Question 32

what does excitable mean in regards to neurons and muscles?

Answer 32

there can be a rapid change in response to stimuli, which triggers electrical responses. This relys on volted gated channels