Brain Bee Chapter 2 - Jacey Flashcards
What is something all neurons have in common?
their activity is electrical and chemical.
true or false? neurons cooperate and compete with each other in regulating the overall state of the nervous system
true
neurons consist of which four things?
dendrites, cell body, axon and synaptic terminals.
what is a neuron’s outer membrane made out of?
fatty substances
inside neurons are many different layers of _______, and they consist of ______.
compartments, proteins
true or false? Tiny
protuberances that stick out from the dendrites called
dendritic spines. These are where incoming calls make
most of their connections.
false
true or false? Proteins transported to the
spines are important for creating and maintaining neuronal
connectivity.
true
The end-points of the ____ also respond to molecules called growth factors.
axons
true or false? These factors are taken up inside and then
transported to the cell body where they influence the
expression of neuronal genes and hence the manufacture of new proteins
true
On the receiving side of the cell, the dendrites have __________ with incoming axons of other cells
close contacts
These junction spots are
named ____, from classical Greek words that mean “to
clasp together”
synapses
What are communication between nerve cells at these contact points is referred to as?
synaptic transmission
When the dendrite receives one of the chemical messengers
that has been fired across the gap separating it from the
sending axon, miniature _____ are set up inside the receiving dendritic spine
electrical currents
define ‘excitation’
miniature electrical currents that come into the cell
define ‘inhibition’
currents that move out of the cell
True or false?
All these positive and negative waves of current are accumulated in the dendrites and they spread down to the cell body.
true
If they don’t add up to very much activity, the currents soon die down and nothing further happens. However, if the currents add up to a value that crosses a threshold, the neuron will
________________.
send a message to the other neurons
To communicate from one neuron to another, the neuronal
signal has first to travel along the _______.
The axons of neurons transmit electrical pulses called action potentials
name two channels and their ions.
potassium (K) and sodium (Na)
these channels are kept in balance by an ____
ion pump
what is an ion pump’s job?
to bale out excess sodium ions.
the action potential is an ______ event
electrical
what do nerve fibres behave like?
electrical conductors
what is an analogy that can help think about action potentials?
the movement of energy along a
firework sparkler after it is lit at one end.
what do you call “the marvellous feature of nerve fibres is that after a very brief period of silence”
the refractory period
True or false?
In many axons, action-potentials move along reasonably well,
but not very fast
true
Define myelin sheath
a fatty, insulating blanket,
made out of the stretched out glial cell membranes
which two people won the Nobel Prize for discovering the mechanism of transmission
of the nerve impulse?
Alan Hodgkin and Andrew Huxley
the mylin sheath prevents the ____ ____ from leaking out in the wrong place
ionic currents
Every so often, glial cells leave a little gap - the axon concentrates its ___ and ___ ion channels.
Sodium (Na) and Potassium (K)
what do these ion channels do?
They function as amplifiers that boost and maintain the action potential as it skips along the nerve.
Fun fact: In myelinated neurons, action-potentials can race along at ____!!
100m/s
what is the distinctive characteristic of the action potential?
all or nothing
(they don’t vary in size, only in how often they
occur.)
true or false?
the only way that the strength or duration of a stimulus can be encoded in a single cell is by variation of the frequency of action potentials.
true
