brain chemistry Flashcards
what is the most common type of synapses in the mammalian central nervous system?
axo-dendritic (axon to dendrite) or axo-somatic (axon to cell body)
what are presynaptic boutons?
they contain tiny vesicles of neurotransmitters
what different substances does the brain use as neurotransmitters? give some examples
glutamate, GABA, glycine, acetylcholine, serotonin (also called 5HT), dopamine, noradrenaline, enkephaline
how many transmitter will one neuron normally produce and release?
only one type of neuron
what causes exocytosis of neurotransmitter?
when action potential arrive at presyp. bouton, voltage-gated Ca++ channel let Ca++ in
what is exocytosis of neurotransmitter?
few of neurotrans vesicles fuses with other membranes and shed its content in the synaptic cleft
how do neurotransmitters travel from one neuron to another to transmit messages?
neurotransmitters diffuse across the cleft and bind to receptor proteins on the postsynaptic cell membrane
what are two types of receptors
- metabolic receptor
- ionotropic receptor
what is ionotropic receptor
chem gated ion channels that open when they bind neurotransmitter
what is metabolic receptor
interact with other proteins to work indirectly via a 2nd messenger cascade
what receptor depolarize cell
recp that opens channels permeable to Na+ or Ca++
what receptor hyperpolarize cell
recp that opens CI- or K+ channels
how are chemical signals in synapses terminated?
by removal of neurotrans from synaptic cleft either by reuptake pumps or ezymes that destroy trans
why are synaptic inputs received by a neuron every few ms combined / integrated?
to make the neuron more or less likely to fire action potentials itself
why are chemical synapses used by motor neurons to communicate with muscles particularly vulnerable to poisoning?
they are not protected by the BBB
