Chapter 45: Nuerons and Nervous System Flashcards
dendrites
receive information from other neurons
cell body
contains the nucleus and most of the cell organelles
axon
conducts action potentials away from the cell body
axon terminals
synapse with a target cell
synapse
axon terminal comes extremely close to the membrane of the target cell
neurotransmitter
chemical messengers
oligodendrocytes
wrap around axons of neurons of brain and spinal cord, covering them with concentric layers of insulating plasma membrane
schwann cells
outside brain and spinal cord, wrap axons
myelin
covering produced by the oligodendrocytes and schwann cells. Give glistening white appearance
Astrocytes
contribute to the blood-brain barrier
blood-brain barrier
protects the brain from toxic chemicals in the blood
tripartite synapse
idea that a synapse includes not only the pre- and postsynaptic neurons but also connections from astrocytes
microglia
provide the nervous system with immune defenses
membrane potential
is a charge difference across the membrane. with the inside of cell negative relevant to outside
resting potential
steady state membrane potential
voltage
force that causes electrically charged particles to move from one point to another
sodium potassium pump
keeps the concentration of K+ greater on the outside. requires ATP to do work
patch clamping
record in real time the tiny electric currents caused by the opening and closings of single ion channels
depolarized
inside of neuron becomes less negative (or more positive) in comparison to its resting condition
hyperpolarized
membrane potential become even more negative
graded membrane potential
change from the resting potential
axon hillock
region of the cell body at the base of the axon
refractory period
about 1-2 milliseconds during which, voltage-gated sodium pumps cannot open again
after-hyperpolarization
dip in the membrane potential following an action potential
nodes of Ranvier
regularly spaced gaps, where axon is not covered with myelin
saltatory conduction
action potentials “jump” from node to node in myelinated axons, allowing faster transmissions
electrical synapses
action potential spreads directly from presynaptic cell to postsynaptic cell
chemical synapses
neurotransmitters released from presynaptic cell induces change is postsynaptic cell
neuromuscular junctions
synapses between neurons and skeletal muscle cells
acetylcholine
neurotransmitter used by all vertebrate neuromuscular synapses
motor end plate
postsynaptic membrane of the neuromuscular junction is modified part of the muscle cell plasma membrane
synaptic cleft
space between the pre synaptic membrane and the postsynaptic membrane
spatial summations
adds up the simultaneous influences of synapses at different sites on the postsynaptic cell
temporal summation
adds up the postsynaptic potentials generated at the same site in a rapid sequence
ionotropic receptors
ion channels or directly influence ion channels. generally fast
metabotropic receptors
influence the postsynaptic cell through various signal transduction pathways an can result in the opening or closing of ions. slower than inotropic receptors
agonist
drugs that mimic or potentiate the effect of a neurotransmitter
antagonists
block the actions of neurotransmitter
afferent neuron
carry sensory information into the nervous system.
efferent neuron
carry commands to physiological and behavioral effectors such as muscles and glands
interneuron
integrate and store information and communicate between afferent and efferent neuron
gray matter
rich in neural cell bodies
whiter matter
contains myelinated axons
spinal reflex
conversion of afferent to efferent information in the spinal cord without the participation of the brain
