Biological Foundations of Behaviour Flashcards
action potential
an electrochemical impulse that consists of localized areas of depolarization of the plasma membrane that travels in a wave-like manner along an axon
synaptic transmission
when an action potential reaches the end of an axon at a synapse, the signal is transformed into a chemical signal with the release of neurotransmitter into the synaptic cleft
bipolar
neurons with one dendrite
multipolar
multipolar
how many axons do all neurons have?
only one
synaptic knobs
the terminal end of the axons that form connections with target cells
synaptic cleft
the small gap between the synaptic knob and the target cell
what is a neuron’s resting membrane potential?
-70mV
what are the two primary membrane proteins that determine the resting membrane potential?
sodium potassium pump and potassium leak channels
how does the sodium potassium pump work?
for every ATP, three sodium ions are pumped out of the cell and two potassium ions pumped into the cell
in which direction does potassium flow through potassium leak channels?
out of the cell
polarized
difference in charge across membrane of neuron, negative on the inside and positive on the outside
depolarization
change in membrane potential from resting -70mV to +35mV
repolarization
returns the membrane potential to normal
what causes the change in membrane potential during the passage of an action potential?
movement of ions in and out of neurons through ion channels
voltage-gated sodium channels
opens at -50mV and close at +35mV, allows sodium ions to flow into cell
threshold potential
-50mV, must reach this potential for voltage-gated sodium channels to open
what allows for repolarization
1) voltage-gated sodium channels inactivate at +35mV
2) voltage-gated potassium channels open at +35mV and stay open until -90mV
3) potassium leak channels contribute to repolarization
myelin
an insulating sheath wrapped around some neurons, no ions can exit or enter axonal membranes covered in myelin
what cells create the myelin sheath?
Schwann cells
nodes of Ranvier
gaps in the myelin sheath where voltage-gated sodium and potassium channels and concentrated
saltatory conduction
the rapid jumping conduction in myelinated axons at Nodes of Ranvier
glial cells
specialized non-neuronal cells that typically provide structural and metabolic support to neurons, do not generate action potentials
what are the five types of glial cells?
Schwann cells, oligodendrocytes, astrocytes, microglia, ependymal cells
Schwann cells
PNS glial cell, forms myelin to increase speed of conduction of action potentials along axon
oligodendrocytes
CNS glial cell, forms myelin to increase speed of conduction of action potentials along axon
astrocytes
CNS glial cell, guides neuronal development, regulates synaptic communication via regulation of neurotransmitter levels
microglia
CNS glial cell, remove dead cells and debris
ependymal cells
CNS glial cell, produce and circulate cerebrospinal fluid
equilibrium potential
the membrane potential at which the gradient does not exist and there is no net movement of ions across the membrane, specific to each particular ion
what is the equilibrium potential for Na+?
+50mV
what is the equilibrium potential for K+?
-90mV
refractory
the state of a neuron after passage of an action potential in which it is unresponsive to membrane depolarization and unable to transmit another action potential
absolute refractory period
a neuron will not fire action action potential no matter how strong a membrane depolarization is induced: VOLTAGE-GATED SODIUM CHANNELS HAVE BEEN INACTIVATED (+35mV to -70mV)