Neuron
electrically excitable cells that process and send information via electrochemical message
synapse
site of communication between a neuron and a target cell
other neuron componets
dendritesaxons
What are the 3 glial cells
astrocytes, oligodendrocytes, microglia
blood-brain barrier
protective functional barrier between the blood and the extracellular fluid of the CNS
what is the BBB made of?
tightly joined capillary endothelial cells and tightly joined surrounding layer of astrocyte feet
voltage gated channels respond to
changes in membrane potential
'voltage sensitive'
slower- some even slow an action potentialex. potassium and calcium channels
neurotransmitters can exert their effect on neurons through
binding to ionotropic receptors or metabotropic receptors
ligand-gated channels (ionotropic receptors)
-multiple subunits-neurotransmitter ligand directly opens the channel-activation results in brief opening of the channels
metabotropic receptors
-g-protein coupled receptors-ligand engages a G protein --> produces 2nd messengers --> cellular effect-often results on modulation of voltage gated channels
inhibitory pathway
post-synpatic is hyperpolarized due to incoming of chloride or exit of potassium due to opening of channels
neuronal systems two groups
hierarchical systems diffuse systems
hierchical systems
-pathways for sensory or motor-large myelinated fibers for fast conduction-projection & circuit neurons
projection neurons
-long axons that relay info over longer distances-usually activating -release glutamate-always excitatory
circuit neurons
-smaller neurons that remain in immediate vicinity-release GABA or glycine-always inhibitory
diffuse neuronal systems
-neuronal cell bodies in a limited number of places in the brain-branches from a single diffuse neuron may innervate different areas-fine and unmyelinated for slower conduction
neurotransmitters of the diffuse system
monoamines (such as norepinephrine) and acetylcholine
diffuse systems involved in
global functions (sleeping, waking, attention, emotional status)-longer lasting effects
Neurotranmitters
chemical substances that is released at the end of nerve fiber by the transmission of a nerve impulse and causes an effect
Glutamate: excitatory or inhibitory?
excitatory
ionotropic receptors
-AMPA-KA-NDMA
NDMA
-on almost all neurons in the CNS-highly permeable to K+, Na+, and Ca2+-more difficult to activate the nerve
inhibitory neurotransmitters
GABA and glycine
how do glycine and GABA receptors mediate effect
-hyperpolarize by influx of chloride ions-or block Na+/Ca2+ influx with K+ efflux
GABAa receptor
· Fast inhibitory response· Ionotropic receptors that open chloride channels
GABAb receptor
-slow and long-lasting inhibitory response-inhibits Ca2+ influx or opens K+ channels to allow efflux
M1 receptors facilitate
a slow excitatory response by decreasing permeability of K+ channels
M2 receptors facilitate
an inhibitory response by opening K+ channels
most CNS responses to acetylcholine are mediated by
muscarinic
dopamine receptors are
metabotropic
alpha 2 receptors
-In the locus coeruleus cause hyperpolarization in response to norepinephrine
alpha-1 and beta receptors
-in the brain facilitate and enhanced excitatory effect
norepinephrine is associated with
attention and arousal
all 5-HT3 subtypes are
metabotropic
5-HT3 receptors are
-ionotropic and have a rapid excitatory effect in limited areas in the brain
5-HT1A receptors are
often associated with strong inhibitory response by opening K+ channels for efflux
5-HT involved in
perception, mood, anxiety, pain, sleep, appetite, temperature, aggression and neuroendocrine control
histamine receptors are
metabotropic
histamine receptors modulate
arousal, attention and memory
Substance P excitatory or inhibitory?
excitatory
substance P associated with
pain and nausea
orexin
-excitatory effect-associated with wakefulness
endocannabinoids can travel
backward in the synaptic cleft and results of inhibition of neurotransmitter release
CB1
-high levels in brain-may produce short or long lasting inhibition-activated by THC
pre-synaptic effects
o Drugs that affect synthesis, storage, metabolism, and release of neurotransmitters
post synaptic effects
o Drugs that affect post-synaptic receptors as agonists or antagonists to augment neurotransmitter responses