Soma (cell body) produces proteins and
Intro to biopsychology chemicals
Divisions of the brain Axons send signals away from the soma
(one per neuron)
Forebrain – limbic system, hippocampus
Dendrites carry signals towards soma
Midbrain – hypothalamus (many dendrites per neuron)
Hindbrain – cerebellum, brain stem
Electrical transmission – voltage difference between intra & extra cellular fluid
Cellular fluid – movement of cations (+ atoms) & anions (- atoms) produce voltage
Resting membrane potential = -70mV difference between intra & extra charge = ion channels
maintain the polerised cell
Resting membrane potentail = passively lets Na+ influx & K+ efflux (unwanted) so active goal of
encouraging Na+ efflux & K+ influx instead as a counter (desired)
Exocytosis – secretion of neurotransmitters into extracellular fluid – voltage gates open so vesicles
cross cleft to post synaptic ion gates where it can either:
EPSP increases likelihood of firing IPSP decreases likelihood of firing
Action potential – excitation threshold = -65mV = if triggered by a strong enough EPSP the action
poteltial causes the charge to change from resting -70mV to +50mV in 1ms
APs are not graded = all or nothing response = slower than E/IPSPs but do not reduce in intensity
Neurons can add up EPSP + IPSP into one signal to be strong enough to trigger an AP (integration)
Neurons could also add up EPSP + IPSP that occur near each other (spatial summation) or that occur
at the same time (temporal summation) = the charges could cancel each other out of create a net +
or – effect
If triggered = vesicles release neurotransmitter into cleft
Myelination – axon insulation increases speed of conduction
, 08/10/2020 PY1PAB – lecture 2 neurotransmitters
Neurotransmitter = ligand = binds to a receptor (specific receptor for a specific neurotransmitter)
Ionotropic receptors = fast ligand gated ion channels (controls ion influx/efflux)
Metabotropic receptors = G proteins that can bind to a ligand gated ion channel (slower but
more prevalent)
Criteria to be a classic neurotransmitter Glutamate – prevalent excitatory neurotransmitter
1) Has a specific receptor GABA – prevalent inhibitory neurotransmitter
2) Exist at terminal button
3) Can be synthesised by enzymes
4) AP triggers a significant release
5) Changes cause postsynaptic cell changes
6) Blocking the release prevents activity
Dopamine receptors = metabotropic pathway projects to limbic system
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