lockkey and modulators and transmitters Flashcards
How Do Neurons Communicate?
Neural communication is described as an electrochemical process
Electrical messages known as action potentials travel within a neuron (along the axon)
Chemical messengers known as neurotransmitters are sent between neurons to allow messages to continue
Action potentials (electrical) and neurotransmitters (chemical) form the electrochemical process of neural communication
Lock-and-Key Process
Each type of neurotransmitter has a chemically distinct shape
When released by the presynaptic neuron, neurotransmitter searches for the correctly shaped receptor site on the dendrites of the postsynaptic neuron
Lock-and-Key Process pt 2
A neurotransmitter’s shape must precisely match the distinct shape of the receptor site on the postsynaptic neuron’s dendrites in order to bind (‘attach’) to its receptors
The binding ‘unlocks’ the postsynaptic neuron’s response so that the neurotransmitter causes changes to the neuron, resulting in an excitatory or inhibitory effect
A postsynaptic neuron can have many different shaped receptor sites on its dendrites and may therefore be able to receive several different neurotransmitters
Excitatory vs. Inhibitory
Generally, a specific neurotransmitter will have either two effects – excitatory or inhibitory
Neurotransmitters with an excitatory effect will stimulate or activate the postsynaptic neurons to perform their functions
Neurotransmitters with an inhibitory effect will block or prevent postsynaptic neurons from firing
Glutamate
The primary excitatory neurotransmitter in the CNS
It enhances information transmission by making postsynaptic neurons more likely to fire
Most abundant neurotransmitter in the brain and involved in most aspects of normal brain function, including perception, learning, memory, thinking and movement
Glutamate pt 2
Release of glutamate is associated with enhanced learning and memory – this is due to excitation of neural pathways, increasing their strength
Too much or too little can be harmful to neurons and brain functioning
Example: abnormally high glutamate can result in over-excitation or receiving neurons > this can lead to effects such as neuronal damage and/or death
Gamma-amino butyric acid (GABA) pt 2
The primary inhibitory neurotransmitter in the CNS
Works throughout the brain to make postsynaptic (receiving) neurons less likely to fire
One of its roles is to fine-tune neurotransmission in the brain and maintain neurotransmission at an optimal, or ‘best possible’, level
Gamma-amino butyric acid (GABA) pt2
Without the inhibitory effect of GABA, activation of postsynaptic neurons might get out of control –> uncontrolled activation spreading to brain and causing seizures
Anxiety sufferers have been linked to a low level of GABA in the brain – impacting neuronal transmission in the brain
The inhibitory action of GABA counterbalances the excitatory activity of glutamate and vice versa
What is a neuromodulator?
A neuromodulator is a chemical messenger that affects a diverse population of neurons.
What do neuromodulators do?
neuromodulators can affect a large number of neurons at the same time these neurons could be distant from the release site
Neuromodulators can influence the effects of other chemical effects
Neuromodulators are slow-acting but bring about lasting change
Dopamine as a neuromodulator
Dopamine is a neuromodulator that has an impact on a range of functions.
It is heavily involved in our motivation to seek rewards.
Serotonin as a neuromodulator
Serotonin is a neuromodulator that plays a role in ‘moderating’ our mood.
Neurotransmitters and Neuromodulators - Similarities
Both neurotransmitters and neuromodulators are chemical substances
Both neurotransmitters and neuromodulators are released from the axon terminals of neurons
Both neurotransmitters and neuromodulators have an impact on our behaviour/functioning
Neurotransmitters and Neuromodulators - Differences
Neurotransmitters- Affects directly on their post-synaptic target, produces a rapid effect that lasts for a short period
Neuromodulators- Indirectly affect their post-synaptic targets via second messages, produces a slow but long-lasting effect
