Module 3: Nervous system cells and resting membrane potential Flashcards
what are the 3 components to resting membrane potential?
- neurons
- glia
- nerves
what is the function of a neuron cell body?
to integrate all information
about how many neurons are in the brain?
100 billion, they’re all connected
what is the function of a dendrite?
- to receive input from other cells
- connect to other cells
what is the function of the axon?
sends signals to the next neuron
what are some examples of neurons?
- multipolar: like most of body, has multiple poles: dendrites and axons.
- bipolar: found in eyes, has 2 poles: 1 axon and 1 dendrite
- unipolar: found in sensory organs like touch has 1 pole off body, then the axon and dendrite come off of that
what are nerves?
a bunch of axons bundled together in layers of connective tissue
do nerves go in 1 direction?
no, they carry efferent and afferent signals around the body
what is the name of the nerve if it’s from the brain?
cranial nerve
what is the name of the nerve if it’s from the spine?
spinal nerve
what are the 6 types of glial cells?
SEASOM
- Schwamm cells
- ependymal cells
- astrocyte
- satellite cell
- oligodendrocyte
- microglia
how many types of glial cells are in the PNS?
2
how many types of glial cells are in the CNS?
4
what are glial cells?
non electrical cells in the CNS and PNS, holding them together and maintaining the structure
what are the 4 glial cells in the CNS?
- astrocyte
- oligodendrocyte
- microglia
- ependymal cells
what are the 2 glial cells in the PNS?
- satellite cells
- Schwann cells
what do astrocytes do?
- form the blood brain barrier by wrapping the blood vessels in foot processes and blocking off holes for infection to get into the brain
- regulate chemical levels around neurons: ions and neurotransmittors, cleaning up after AP.
- structural
what do oligodendrocytes do?
myelinate axons (same as Schwann cell in PNS)
what do microglia do?
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
what do ependymal cells do?
- line the ventricles holding the CSF and help move it around
- involved in the process of CSF production in the choroid plexus
what does a satellite cell do?
- controls the levels of chemical around neurons: nutrients/gases/neutrotransmitter levels (like astrocyte)
- sits around the soma of a neuron
what do Schwann cells do?
myelinate axons, like the oligodendrites in the CNS
what is voltage?
a measurement of the difference in electrical potential between 2 points in space (V)
where are membrane potentials found?
in all cells of the body
how is a membrane potential caused?
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
where do neurons get their energy from?
membrane potential
is membrane potential a general or local charge?
local
does the membrane potential change?
yes, it depends how many ions are gathered at the wall, depends how strong the charge will be
what is the resting membrane potential of neurons?
-70mV
why is the resting membrane potential of neurons -70mV?
- difference in ionic composition: more Na+,K+, Cl- and -ve proteins on either side of the ECF and ICF end up at -70mV
- 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
after an action potential, how does a neuron get back to the resting membrane potential of -70mV?
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
what does excitable mean in regards to neurons and muscles?
there can be a rapid change in response to stimuli, which triggers electrical responses. This relys on volted gated channels
