**L3 - Synaptic Transmission Flashcards
what do NEURONS do?
NEURONS TRANSMIT ELECTRICAL IMPULSES, known as ACTION POTENTIALS, between the PRE SYNAPTIC NEURON (the neuron transferring the action potential) and the POST SYNAPTIC NEURON (the neuron receiving the action potential)
what happens when the ACTION POTENTIAL reaches the PRE SYNAPTIC TERMINAL?
When the ACTION POTENTIAL reaches the PRE SYNAPTIC TERMINAL it TRIGGERS the RELEASE OF NEUROTRANSMITTERS (CHEMICAL MESSENGERS) FROM SACS on the PRE SYNAPTIC MEMBRANE known as VESICLES in a process called EXOCYTOSIS.
The released NEUROTRANSMITTER will DIFFUSE ACROSS THE SYNAPTIC CLEFT (gap between the pre synaptic membrane and the post synaptic membrane) where it BINDS to SPECIALISED POST SYNAPTIC RECEPTOR SITES
SYNAPTIC TRANSMISSION FURTHER
SYNAPTIC TRANSMISSION takes only a FRACTION OF A SECOND, with the EFFECTS TERMINATED by a process called RE-UPTAKE
The NEUROTRANSMITTER is TAKEN BACK by the VESICLES on the PRE SYNAPTIC NEURON where they are STORED FOR LATER RELEASE.
The QUICKER THE NEUROTRANSMITTER is TAKEN BACK the SHORTER THE EFFECTS
what are the two types of NEUROTRANSMITTERS?
1) EXCITATORY NEUROTRANSMITTERS
2) INHIBITORY NEUROTRANSMITTERS
what are EXCITATORY NEUROTRANSMITTERS?
EXCITATORY NEUROTRANSMITTERS cause an ELECTRICAL CHARGE in the POST SYNAPTIC MEMBRANE resulting in an EXCITATORY POST SYNAPTIC POTENTIAL (EPSP), meaning that the POST SYNAPTIC NEURON is MORE LIKELY TO FIRE AN IMPULSE
what are INHIBITORY NEUROTRANSMITTERS?
INHIBITORY NEUROTRANSMITTERS cause an INHIBITORY POST SYNAPTIC POTENTIAL (IPSP), making it LESS LIKELY that the neuron will fire an impulse
what decides whether or not a NEURON WILL or WILL NOT FIRE AN IMPULSE?
A neuron CAN RECEIVE BOTH EPSPs and IPSPs AT THE SAME TIME
The likelihood that the neuron will fire is DETERMINED by ADDING UP THE EXCITATORY and the INHIBITORY SYNAPTIC INPUT.
The NET RESULT of this CALCULATION, known as SUMMATION, determines whether or not the neuron will fire an impulse
If the NET EFFECT is INHIBITORY the NEURON WILL NOT FIRE, if the NET EFFECT is EXCITATORY, the NEURON WILL FIRE
what is the DIRECTION of SYNAPTIC TRANSMISSION? - PT 1
Information can ONLY TRAVEL IN ONE DIRECTION AT A SYNAPSE.
The VESICLES containing NEUROTRANSMITTERS are ONLY PRESENT on the PRE SYNAPTIC MEMBRANE
The RECEPTORS for the NEUROTRANSMITTERS are ONLY PRESENT on the POST SYNAPTIC MEMBRANE.
what is the DIRECTION of SYNAPTIC TRANSMISSION? - PT 2
It is the BINDING of the NEUROTRANSMITTER to the RECEPTOR which enables the information to be TRANSMITTED TO THE NEXT NEURON.
DIFFUSION of the NEUROTRANSMITTERS mean they can only go from HIGH TO LOW CONCENTRATION, so can only travel from the PRE SYNAPTIC NEURON TO THE POST SYNAPTIC NEURON
what are PSYCHOACTIVE DRUGS?
PSYCHOACTIVE DRUGS (medication that AFFECTS BRAIN FUNCTION to ALTER PERCEPTION, MOOD or BEHAVIOUR), such as SSRIs, work by AFFECTING (increasing or inhibiting) the TRANSMISSION OF NEUROTRANSMITTERS ACROSS THE SYNAPSE
how do PSYCHOACTIVE DRUGS ACTUALLY WORK? - PT 1
Some pain medications MIMIC THE EFFECTS of INHIBITORY NEUROTRANSMITTERS. STIMULATION of POSTSYNAPTIC RECEPTORS by an INHIBITORY NEUROTRANSMITTER RESULTS IN INHIBITION of the POSTSYNAPTIC MEMBRANE
When an INHIBITORY NEUROTRANSMITTER binds to the POST SYNAPTIC RECEPTORS it makes the POST SYNAPTIC NEURON LESS LIKELY TO FIRE
how do PSYCHOACTIVE DRUGS ACTUALLY WORK? - PT 2
Due to SUMMATION, if INHIBITORY NEUROTRANSMITTERS are HIGHER THAN EXCITATORY NEUROTRANSMITTERS they can INHIBIT AN ACTION POTENTIAL FROM OCCURRING.
Therefore, pain medications would DECREASE OVERALL ACTIVITY and REDUCING BRAIN ACTIVITY may lead to LESS PAIN
