Chapter 2 part 3 Flashcards
nerve cells and their messages
how is the neuron different from other cells in the body?
it is specialized for communication
what is a neuron?
a specialized cell of the nervous system
what is a neuron used for?
detecting information, transmitting information, and affecting muscles and glands
what is the soma of the neuron?
the round part that contains everything a regular human cell would (nucleus, mitochondria, etc.)
what is the name for the cell body of the neuron?
the soma
what do dendrites look like?
tree branches at the beginning of the neuron
what does the axon look like?
the long tube in the middle of the neuron
what do terminal buttons look like?
the little balls at the end of the neuron
what do dendrites do?
receive messages from neighboring neurons or the outside world
if a dendrite receives a message from a neuron, what does it usually consist of?
neurotransmitters (chemicals)
in what situation is there more dendrites than normal?
in a part of the brain where no chemical messages can be missed
in what situation is there less dendrites than normal?
in a part of the brain that doesn’t receive many messages
what happens to the neurons in a part of the brain that is being used more often
they can grow new spines
use it or lose it
use the pathway and grow neurons or don’t and the brain gets rid of the pathway and sometimes the neurons (like pruning trees, we need to prune the smaller branches so the big healthy ones can keep growing)
axon
conducts nerve impulse from the cell body to distant location -> carries the electrical impulse
myelin sheath
increases speed and efficiency of nerve impulse
how do axons look?
they can be short or as long as your body, some are wide tubes and others are skinny
what does myelin sheath look like?
pellet covering that wraps around sections of axon, looks white
what is myelin sheath made out of?
lipids (fat)
how does myelin sheath increase speed and efficiency?
it wraps around sections of the axon to insulate it and protect the axon from interference (like the plastic covering on a wire)
terminal buttons
release chemical messages (neurotransmitters) onto neighboring dendrites
when are neurons active?
all the time
electrochemical transmission
communication from nerve cell to nerve cell
how does a neuron generate electricity?
using charged particles called ions
what is cerebral spinal fluid?
the liquid our brains float it, it has ions and tastes salty
where do electrical signals ALWAYS start?
the cell body
where do electrical signals ALWAYS end?
terminal buttons
the inside of a neuron is more _________ than cerebral spinal fluid
negatively charged
the cerebral spinal fluid is more ________ than the inside of a neuron
positively charged
iNside
negative
outside
positive
what happens when the axon membrane won’t let sodium (Na) in?
Na lines up on the outside of the membrane
why does Na want in the axon?
because the inside of the neuron is more negatively charged than the cerebral spinal fluid, and Na is a positive ion
what is already inside the axon when it is at rest?
potassium (K)
what are the holes in the membrane for?
they sometimes allow ions to go in and out of the axon
when are the channels closed?
when the neuron is at rest and the inside is more negative than the outside
membrane potential
difference in charge (voltage) across a cell membrane
resting membrane potential
-70 millivolts (more negative than outside the membrane)
threshold
minimum amount of stimulation necessary to open channels and trigger the neural impulse
after stimulation and a channel opens ->
sodium (Na) rushes in the cell and potassium (K) is also positive so it rushes out, this is enough stimulation to open the next channel (and so on for all the other channels in the membrane)
what really is the electrical signal?
the exchange of Na and K along the axon
action potential
brief wave of positive electrical charge that sweeps down the axon
action potential is defined by what?
sodium
during the refractory period, the inside of the cell is __________
more negative than when it is at rest for a short period of time (milliseconds)