neurontransmission and psychopharmacology Flashcards
lecture 4
synapse
- junction between the terminal button of a neuron and the membrane of another neuron
- conduit of info from one neuron to another
structure of synapses
-presynaptic axon: contains neurotransmitters, mitochondira and other organelles
- postsynaptic ending: receives neurotransmitters
- synaptic cleft: the tiny gap where neurotransmitters diffuse across
synaptic transmission 1.
action potential arrives at axon terminal, triggering Ca+ ions to move into cell
synaptic transmission 2.
Ca+ ions cause the migration of vesicles to the pre-synaptic membrane
synaptic transmission 3.
neurotransmitters diffuse across the synaptic cleft towards the post-synaptic membrane
synaptic transmission
neurotransmitters bind to receptor sites on the post-synaptic membrane with ‘lock and key’ specificity
synaptic transmission 5.
this binding opens NT dependent ion channels which change the excitability of the post-synaptic cleft
postsynaptic receptors
direct receptor (ionotropic)
- binding site for a neutrotransmitter
- ion channel opens when neutotransmitter molecule binds
postsynaptic receptors
indirect receptor (metabotropic)
- only a binding site for a NT
- activates enzyme
- ion channel opens elsewhere
postsynaptic potential
- this refers to ions moving acorss post synaptic membrane and after the membrane potential
- depolarising (excitatory) = increased likelihood of AP
- hyperpolarising (inhibitory = decreases likelihood of AP
- depolarisation > threshold (-55mV triggers AP
depolarisation vs hyperpolarisation
- depends on which type of ion channel is opened by the neurotransmitter
- Na+, K+, Cl-
Na+ channels
- produces excitatory postsynaptic potentials
K+ channels
- produces inhibotry postsynaptic potentials
Cl- channels
- either stabilisation or rest
neurotransmitters
- acetylcholine
- serotonin
- dopamine
- nor/epinephrine
- GABA
- glutmate
acetylcholine
- excitatory
- released in ANS, regulating heart rate, blood pressure, and gut mobility
- imbalances linked with Alzheimer’s disease, seizures and muscle spasms
serotonin
monoamines
- excitatory or inhibitory
- produced in neurons in midbrain, pons, medulla
- regulates mood, sleep patterns, anxiety, pain
- imbalance include SAD, anxiety, depression
dopamine
monoamines
- excitatory or inhibitory
- produced in neurons in mid brain
- faciliates focus, concentration, memory, sleep
- reward system
- imbalance include parkinson’s disease, schizophreina, bipolar disorder, ADHD
epinephrine and norepinephrine
monoamines
- realsed into blood stream
- responsible for “fight or flight response”
- stimulates body’s response
- excess epinephrine can lead to high blood pressure, diabetes, heart disease
endorphins
peptides
- pain relievers
- released by hypothalamus and pituitary gland
- inhibitors
glutamine
amino acids
- excitatory
- most common
- key role in cognitive functions like thinking, learning and memory
- imbalances associates with alzheimer’s disease, dementia, parkinson’s
GABA (gamma-aminobutyric acid)
amino acids
- most common inhibitory NT
- regulates brain acitivity to prevent anxiety, irritability, concentration, sleep, depression
- contributes to motor control, vision
NT removal from synapse
- reuptake: NT pumped back into glia or the axon terminal that released it
- deactivation: NT destroyed by enzymes near receptors
- removal: diffuses into surrounding area
psychopharmacology
- study of the effects of drugs on the nervous system and behaviour
