Neurons Flashcards
dominant theory
states that nervous system composed of a continuous structures
*stated that it was composed of continuous network of nerves
structure of neurons
100 billion neurons in human brain
dendrites
extends away from cell body (main input)
soma
cell body: contains nucleus & genetic information
axon
extends off of soma, connects to other neurons (main output)
nucleus
contains genetic info, directs protein synthesis and supplies energy & resources
synapse
place where axon & dendrite connect
myelin sheath
surrounds axon for insulation
- allows signal of one neuron to the next rapidly
terminal button
end of axon, forms synapses with spines (protrusions) of dendrites
synaptic gap/cleft
space between presynaptic terminal button, and postsynaptic dendritic spine
synaptic vesicles
in terminal button; packages of neurotransmitters
neurotransmitters
chemical substance released by terminal button and act on post synaptic cell
sensory neuron
receive info about world around us
motor neurons
initiate movement and behaviour
interneurons
process the sensory input from our environments into meaningful representations, plan appropriate behavioural response and connect to motor neurone to execute those behavioural plans
3 main categories of neurons
- unipolar neurons
- bipolar neurons
- multipolar neurons
unipolar neurons
structured in a way that is ideal for relaying info forward
- 1 axon & no dendrites
- communicating body temperatures through spinal cord to brain
bipolar neurons
sensory perception
- structured to have one axon + one dendrite
- to acquire and pass sensory info to brain
multiple neurons
one axon, many dendrites
- most common
- communicating sensory & motor info in brain
glia cells
oligodendroglia (forms myelin sheath), microglia(biggest debris of dead neurons)
2 stages of electrochemical action
- chemical conduction & dendritic input to the initiation of an action potential within a neuron
- chemical transmission across the synaptic gap between the presynaptic neuron & the post synaptic neuron
resting membrane potential
fluid of neurons composed of combination of ions
(Na+, K+, Cl-, anions)
Separated by cell membrane (lipid bilayer)
Ion Channel in Membrane - ions pass through and go from high to low concentration
Components of Resting Membrane Potential
voltage inside cell relative to outside
* (-70mV) while at rest.
Anions - High conc. outside cell, contribute to negative charge of RMP
Potassium - stays inside cell bc attract to anions
Chloride - stays outside of cell
Sodium - cannot pass through membrane, stays outside cell…. if inside, pushed out by sodium-potassium pump
action potential
an all-or-nothing response that occurs w a change in charge from it’s resting membrane potential (-7omV) in a more positive direction
- depolarization
ex: either 1 or 0, nothing in between
