week 4: neurophysiology Flashcards
neurons
basic functional units of the nervous system
glial cells
nourish, protect and physically support neurons
what are the glial cells critical for
brain development
oligodendrocyte glial cell
covers the axons of neurons with myelin
parts of the neuron
dendrites soma (cell body) axon terminal buttons myelin
dendrites function
receives messages from other neurons
transmit the information they received to the soma
the soma function
controls the cells metabolism and maintenance
collates/collects messages from other neurons
the axons function
carries messages away from the soma towards other neurons
these messages are called action potentials
terminal buttons function
secrete neurotransmitters which affect the activity of other cells with which the neuron communicates
myelin function
insulates some axons to promote efficient transmissions of action potentials
aids in increasing speed of the axon potential along the axon
cell membrane structure
lipid bilayer
embedded with protein molecules which form pores/channels that control movement of material in and out of the cell
cell membranes role
separates the intracellular and extracellular fluid
molecules are exchanged via the protein channels
are the protein channels of a cell open or closed at rest?
a cell at rest protein channels are closed
resting membrane potential
-70mV
derives from the difference in chemical composition inside and outside the cell at rest
chemicals that result a RMP
concentrations of potassium ions (K+) chloride ions (CI-) negatively charged protein ions and sodium ions (Na+)
what is an action potential?
a brief reversal in the resting charge of the neuron
what causes an action potential?
triggered by an exchange of ions across the neuron membrane
when does an action potential happen?
when the neuron membrane is depolarised and once it reaches the depolarisation threshold (-55mV) the neuron will fire an action potential. if the neuron doesn’t reach -55mV the action potential wont fire
what is depolarisation?
when the RMP moves towards 0mV
how does sodium and potassium ions move during the action potential?
sodium channels open and the sodium enters the cell which reverses the membrane potential. Potassium channels then open potassium leaves the cell restoring the membrane potential. Ion transporters pump sodium and potassium ions back to their locations.
where is sodium and potassium ion located?
potassium ions is located within the cell
sodium ions is located outside the cell
how is the speed of propagation of the action potential determined?
diameter of axon
presence/absence of myelin sheath
myelin sheath
electric insulator
current can only flow across the membrane at the myelin breaks (nodes of ranvier)
synaptic transmission
when an action potential reaches the terminal buttons it causes the release of specialised chemicals (neurotransmitters) that travel across the synaptic cleft and are received by other neurons dendrites
what is the space that separates neurons called?
synaptic cleft
types of neurotransmitters?
dopamine
serotonin
endorphins
what is reuptake?
when the whole neurotransmitter molecule is taken back into the axon terminal of the neuron that released it
what is diffusion?
when the neurotransmitter drifts away out of the synaptic cleft where it can no longer act on a receptor
what is deactivation/degradation?
a specific enzyme changes the structure of the neurotransmitter so it is not recognised by the receptor
