Neurons Flashcards
Neurotransmitter is stored and released from? A.axon terminals only B.axon varicosities only C.dendritic spines only D.cell bodies only E.axon terminals and axon varicosities
E Axon terminals are at synapses
varicosities are the circular terminals that release neurotransmitter to veins to dilate and contract uniformly
What signal propagates across the cell body and in unmyelinated axons
Graded potential - Propagates across the cell to the axon hillock that determines the actuation potential (if any for myelinated cells)
soma or somata means
cell body
The multiple thin, branched structures on a neuron whose
main function is to receive incoming signals are the
A.cell bodies
B.axons
C.dendrites
D.somata
E.nerve
C Dendrites accept the signal from another cell
The total amount of neurotransmitter released at the axon terminal is directly related to? A.amplitude of the action potential B.length of the axon C.amplitude of the graded potential D.diameter of the axon E.total number of action potentials
E More action potentials means more firing, more firing means more neurotransmitter
The amplitude of an action potential can vary? T or F
F
The amplitude of a graded potential can vary? T or F
T
Length of a myelinated axon determines the signal strength? T or F
F
The smaller the diameter of an axon the faster the conduction T or F
F
Conduction is restricted by what forms of resistance
non myelination and small diameters (cause resistance)
Reduce resistance: Mylination, and larger axons
Which of the following is the most common location where action potentials originate? A.axon hillock B.dendrites C.cell body D.synaptic cleft E.presynaptic terminal
A
The rising phase (Depolarization) of the action potential is primarily due to?
A.Na flow into the cell only
B.Na flow out of the cell only
C.K flow out of the cell only
D.K flow into the cell only
E.Na flow out of the cell and K+ flow into the cell
A rising phase has Na flowing into the cell via a positive feedback loop
The falling phase (repolarization) of the action potential is due to?
the closing of the Na gates and the opening of the K gates to allow for K to repolarise
Saltatory conduction is what
due to myelination, causing faster conduction
Multiple sclerosis and Guillain-Barre syndrome are caused by
degredation of myelination
relative refractive period is what
the period after an axon has actuated, proceeding the absolute refractory period. A high enough graded potential can set it off
Absolute refractive period is what
1-2ms period after the threshold has been reached where no other action potential may procceed
Gated channels (such as Na and K) are excitatory or inhibitory
excitatory
definition of suprathreshold
Graded potential is higher than the threshold
Definition of subthreshold
Graded potential is lower than the thresthold
glial cells serve what purpose
to aid CNS and PNS neurons
Name of Glial Cells found within the PNS
Schwann cells: Myelinate periphery neurons
What cell myelinates CNS neurons
Oligodendrocytes
Astrocytes are responsible for what?
Shuttling nutrients through the blood brain barrier
