Module 3: Nervous system cells and resting membrane potential Flashcards
What is the function of the NS?
- sensory input
- integration
- motor output
what are the 3 components to resting membrane potential?
- neurons
- glia
- nerves
What is a cell body?
integrates all inputs it receives
what is are dendrites?
receives input from other neurons
what is an axon?
- sends output signals to the next neuron
- generates and propagates action potentials
what are some examples of neurons?
- multipolar: 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
where do neurons get their energy from?
membrane potential
what is the resting membrane potential of neurons?
-70mV
how many and where are the glial cells?
- 4 in CNS
- 2 in PNS
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 do astrocytes do?
- form blood-brain barrier
- regulate ion and neurotransmitter levels
- structural support
What do oligodendrocytes do?
myelinate axons
What do microglia do?
immune cells of the CNS
What do ependymal cells do?
line ventricles
what are the 2 glial cells in the PNS?
- satellite cells
- Schwann cells
what does a satellite cell do?
- surround cell bodies in ganglia
- regulate nutrient, gas and neurotransmitter levels around neurons
what does a Schwann cell do?
myelinate axons
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
is membrane potential a general or local charge?
local
what is the resting membrane potential of neurons?
-70mV
How is membrane potential generated?
- differences in ionic composition of intracellular fluid and extracellular fluid
- differences in membrane permeability to ions
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
