1/64
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
neuron
a specialized cell of the nervous system that communicates information through electrical and chemical signals
86B in the human brain
~50% of brain cells
4 morphologically defined regions:
cell body
dendrites
axon
axon terminals
dendrites
extensions of the neuron that receive information from other cells
myelin sheath
increases speed of neural signals
axon hillock
generates neural impulse
axon
transfers neural signals
axon terminal
forms junctions with other cells; contains neurotransmitters
cell body (soma)
most prominent part of the neuron
filled with cytoplasm
salt water + ions, proteins, molecules
contains numerous organelles
nucleus: DNA-containing structure
endoplasmic reticulum, Golgi apparatus, ribosomes: protein synthesis
mitochondria: ATP production
cell membrane
cytoplasm
in cell body; salt water + ions, proteins, molecules
nucleus
in cell body; DNA-containing structure
location of protein synthesis
in cell body; endoplasmic reticulum, Golgi apparatus, ribosomes
mitochondria
in cell body; responsible for ATP production
cell membrane
bilipid layer with proteins āfloatingā within
lipid molecules = hydrophilic heads + hydrophobic tails
allows membrane to hold its shape
heads orient toward liquid
tail orients away from liquid
double-layer membrane
some small molecules can pass through; larger molecules only pass through protein channels
motor neurons
carry commands to the muscles and other organs
brain ā body
found mainly within CNS
multipolar
sensory neurons
carry information from the body and external world
body ā brain
found mainly within PNS
unipolar, bipolar
interneurons
connect one neuron to another within CNS
multipolar
short or no axon
communicates locally
selective permeability
some small molecules can pass through the cell membrane, larger molecules only pass through protein channels
ā polarization
positive electrical charge on one side and a negative charge on another side
difference in electrical charge between the inside and outside of the neuron = voltage
voltage
the difference in electrical charge between the inside and outside of the neuron
resting potential
the difference in charge between inside and outside of a neuron at rest (usually -70 mV)
as a result of unequal distribution of electrical charges on extracellular (outside cell) and intracellular (inside) fluid
the cell is āpolarizedā
maintained by passive transport (short-term) and active transport (long-term)
ions outside the cell
lots of sodium (Na+) and chloride (Cl-), more positive ions
ions inside the cell
lots of potassium (K+) and anions (A-), more negative ions (negative resting potential)
ion channels
proteins in cell wall; pore in the center allows ions to enter and leave the cell
passive transport
short-term way of maintaining resting potential; can move ions when the voltage-gated channels are not active
concentration gradient (force of diffusion): high concentration to low
electrostatic pressure: ions repelled from the side with similar charges; want to move toward the opposite charge
active transport
long-term way of maintaining resting potential
sodium-potassium pump: uses ATP, pumps 3 Na+ out and 2 K+ in, uses 40% of the cellās energy to keep the cell negatively charged at rest
concentration gradient (force of diffusion)
passive transport; high concentration to low
electrostatic pressure
passive transport; ions repelled from the side with similar charges; want to move toward the opposite charge
sodium-potassium pump
active transport; uses ATP, pumps 3 Na+ out and 2 K+ in, uses 40% of the cellās energy to keep the cell negatively charged at rest
action potential
abrupt depolarization of the membrane that allows the neuron to communicate over long distances
if local threshold (by a stimulus) can reach a certain threshold, it is initiated (all-or-none)
then, electrical signal travels along axon
synapses on another neuron or the target
glial cells
nonneural cells that provide a number of supportive functions to neurons
myelin-producing
oligodendrocytes (CNS)
Schwann cells (PNS)
astrocytes
microglia
myelin-producing glia
myelin: fatty tissue that wraps around axon to insulate it
oligodendrocytes (CNS): 1 cell can wrap multiple internodes
Schwann cells (PNS): 1 cell wraps single internode
Nodes of Ranvier: gaps in myelin sheath
saltatory conduction: a form of transmission in which action potentials appear to jump from node to node
myelin
myelin-producing glia, fatty tissue that wraps around axon to insulate it
oligodendrocytes
myelin-producing glia, found in CNS, 1 cell can wrap multiple internodes
Schwann cells
myelin-producing glia, found in PNS, 1 cell wraps single internode
Nodes of Ranvier
myelin-producing glia, gaps in the myelin sheath
saltatory conduction
myelin-producing glia, a form of transmission in which action potentials appear to jump from node to node
astrocytes
type of glial cells
support/form blood-brain barrier, insulate neurons, structural support etc.
compose 20-50% of the brain volume
arise from radial glia
microglia
mediate immune responses in the nervous system
engulf damaged tissue and invading organisms
vesicles
membrane-enclosed bubbles at axon terminals which store neurotransmitters
chemical transmission at the synapse
action potential arrives at axon terminals
opening of Ca2+ channels
Ca2+ enters
vesicles move to presynaptic membrane
fusion of vesicles
neurotransmitter release
effect on cellular processes:
EPSP and IPSP
neurotransmitter effects on presynaptic and postsynaptic neuron
excitatory postsynaptic potential (EPSP)
postsynaptic cellular process; when receptors open sodium channels to produce a partial depolarization of the dendrites and cell body
partial depolarization - more likely to produce action potential
inhibitory postsynaptic potential (IPSP)
postsynaptic cellular process; when receptors open potassium channels, chloride channels, or both to produce a hyperpolarization of the dendrites and cell body
hyperpolarization - less likely to produce action potential
spatial summation
postsynaptic cellular process; combines potentials occurring simultaneously at different locations on the dendrites and cell body
temporal summation
postsynaptic cellular process; combines potentials arriving a short time apart, from either the same or separate inputs
neurotransmitter binding
postsynaptic cellular process
ionotropic receptors
ligand-gated ion channels
binding of neurotransmitter to receptor directly opens or closes an ion channel
local, fast, short
metabotropic receptors
ligand-activated proteins and enzymes āsecond messengersā
binding to receptors activates g-protein
distant, slow, long
ionotropic receptors
neurotransmitter binding process, postsynaptic cellular process
ligand-gated ion channels
binding of neurotransmitter to receptor directly opens or closes an ion channel
local, fast, short
metabotropic receptors
postsynaptic cellular process
ligand-activated proteins and enzymes āsecond messengersā
binding to receptors activates g-protein
distant, slow, long
reuptake
presynaptic cellular process; process in which transmitters are taken back into the terminals
controlling this process is used extensively in psychopharmacology (e.g., antidepressants)
autoreceptors
control the amount of transmitter
neurotransmitter release
reuptake
excess neurotransmitters:
broken down by enzymes
absorbed by glial cells
diffuse away
neurotransmitters
chemicals the neuron releases to communicate with a muscle, an organ, or the next neuron in a chain
acetylcholine
between nerves and muscles (movement)
nerves communicate with muscles by releasing it
release ā muscle contraction
inhibition ā muscle relaxation
involved in learning
memory - death of these neurons in Alzheimerās disease
GABA
amino acid; main inhibitory neurotransmitter
anti-anxiety drugs and alcohol act to enhance it
deficiency can cause epilepsy
glutamate
amino acid; main excitatory neurotransmitter
involved in learning and memory - lots in cerebral cortex
serotonin
monoamine; involved in mood, sleep and arousal, aggression, depression, OCD, and alcoholism
dopamine
monoamine
movement (death of these neurons impairs movement, Parkinsonās disease)
promotes reinforcing effects of food, sex, and abused drugs
motivation
schizophrenia (blocking its receptors improves psychological disturbance)
norepinephrine
monoamine
released during stress
increase arousal and promote sleep/waking cycle
related to depression
epinephrine (adrenaline)
monoamine
stress hormone from adrenal glands e.g., making heart beat faster
minor role in brain
endorphins/enkephalins
neuropeptide
block pain, produce pleasure (heroin, morphine)
placebo, acupuncture effects
placebo can cause increase in its release/transmission
Substance P
neuropeptide; transmission of pain info
Neuropeptide Y
neuropeptide; initiates eating and produces metabolic shifts
ligand
binds to receptor (has affinity)
affinity
similarity, resemblance in structure
direct agonist
binds and mimics effect of transmitter (has affinity and efficacy)
number of target chemicals increase
efficacy
ability to produce a desired or intended result
indirect agonist
increases neurotransmitters via a mechanism other than receptor interaction - changes could be in synthesis, storage, release, reuptake, or degradation stage as listed above (has efficacy)
number of target chemicals increase
antagonist
binds and does not have an effect, preventing transmitter action (has affinity)
blocker