Neurophysiology Flashcards
What type of neuronal structures exhibit true action potential?
Axons
What is a major excitatory transmitter in the brain?
Glutamate
What is the major inhibitory neurotransmitter in the brain?
GABA
What happens to sodium ions (Na+) during cellular excitation?
In an excited cell, sodium ions predominantly flow into the cell. This influx of sodium ions is a key event in the depolarization phase of the action potential, where the membrane potential becomes less negative, leading to the generation and propagation of the action potential along the neuron.
What happens to K+
moves out of the cell when in depolorasation
Axonal Transport - Slow:
Speed: 1-5 mm/day
Content: Involves the transport of complex products such as axoplasm to terminals.
Function: Part of neuronal growth and mature neuron function.
Axonal Transport - Fast
Speed: 200-400 mm/day
Content: Facilitates the transport of neurotransmitters, growth factors, as well as toxins and pathogens such as tetanus toxin, viruses (e.g., rabies, herpes simplex, polio).
Function: Essential for the rapid delivery of crucial substances and for the spread of harmful agents within the nervous system.
Name the synaptic types:
- Axodendritic
- Axosomatic
- Axoaxonic
What are ionotropic receptors?
Ionotropic receptors are receptors that directly regulate ion channels upon binding of a neurotransmitter. This rapid activation or inhibition of ion channels leads to changes in membrane potential and cellular excitability.
Give an example of an ionotropic receptor and explain its function.
An example of an ionotropic receptor is the nicotinic acetylcholine receptor (nAChR). Upon binding acetylcholine, nAChRs open cation channels, leading to depolarization of the postsynaptic membrane.
What are metabotropic receptors?
Metabotropic receptors are receptors that are indirectly linked to ion channels via intracellular signaling pathways. Upon binding of a neurotransmitter, these receptors activate G-proteins, which then modulate ion channels or initiate intracellular signaling cascades.
Provide an example of a metabotropic receptor and describe its mechanism of action.
An example of a metabotropic receptor is the GABA-B receptor. Upon activation by gamma-aminobutyric acid (GABA), GABA-B receptors activate G-proteins, leading to the modulation of ion channels and downstream cellular responses.
How are excitatory neurotransmitters defined?
Enhance probability of action potential
What defines inhibitory neurotransmitters?
reduce probability of action potential
Where is the distinction between excitatory and inhibitory neurotransmitters most meaningful?
on a single neuron or receptor level
Why is the classification of neurotransmitters as excitatory or inhibitory less meaningful on a higher level?
The classification of neurotransmitters as excitatory or inhibitory is less meaningful on a higher level without specifying the receptor or circuit involved in the neurotransmitter’s action.
What is Glutamates function
cognition, memory, learning
What central role in excitotoxicity is Glutamate linked to?
Neurodegenrative conditions
Describe the relationship between GABA and Glutamate metabolism.
There is a complex interrelationship between GABA and Glutamate metabolism. GABA is taken up into astrocytes and converted into glutamate and glutamine. Glutamine is released from astrocytes and taken up by neurons where it is converted to glutamate and then GABA.
What is the Physiology behind stimulants?
Reward-driven learning = Stimulants (e.g. cocaine, methamphetamine) increase synaptic DA by acting on DA transporter
In which pathologies is dopamine involved
- schizophrenia (decreased)
- ADHD (decreased)
- restless leg syndrome
- Parkinsons (deficiency)
What is the physilogy behind Noradrenalin
Attention and focus
In which pathologies is noradrenalin involved in?
ADHD, depression, schizophrenia
What is the physiology behind serotonin
- well-being
- happiness
- mood
- appetite
- sleep
What pathologies is serotonin involved in?
Depression, Anxiety disorder, Eating disorder
What is the physiology behind histamine?
regulates sleep, appetite, body temperature
What pathophysiologies is histamine involved in?
- schizophrenia
