Podcast Beta
Questions and Answers
What is the primary purpose of voltage gated ion channels in synaptic transmission?
What type of receptors are activated by GABA, resulting in an inhibitory postsynaptic potential?
What is the primary function of synaptic vesicles in synaptic transmission?
What is the primary mechanism by which ionotropic receptors regulate the flow of ions across the membrane?
Signup and view all the answers
What type of potential is generated when glutamate binds to ionotropic glutamate receptors?
Signup and view all the answers
What is the primary function of calcium ions in synaptic transmission?
Signup and view all the answers
Which of the following receptors has a single polypeptide subunit with 7 transmembrane alpha helices?
Signup and view all the answers
What is the primary function of mGluRs of group II and III in the hippocampus?
Signup and view all the answers
What is required as a co-transmitter for the activation of uncharacterized presynaptic mGluR?
Signup and view all the answers
Which of the following is NOT a characteristic of GABAB1?
Signup and view all the answers
What is the effect of GABABR activation on Ca2+ channels?
Signup and view all the answers
What is the primary location of mGluRs of group I in the hippocampus?
Signup and view all the answers
What type of ions do NMDA receptors require for activation?
Signup and view all the answers
What is the function of Mg2+ in NMDA receptors?
Signup and view all the answers
What is the significance of the post-synaptic calcium permeability of NMDA receptors?
Signup and view all the answers
What is the difference between AMPA and NMDA receptors?
Signup and view all the answers
What is the role of glycine in NMDA receptors?
Signup and view all the answers
What is the structure of GABA(A) receptors?
Signup and view all the answers
What is the effect of propofol on GABA(A) receptors?
Signup and view all the answers
What is the difference between ionotropic and metabotropic receptors?
Signup and view all the answers
What is the function of G-proteins in metabotropic receptors?
Signup and view all the answers
What is the significance of long-term potentiation in synaptic plasticity?
Signup and view all the answers
Study Notes
Neuron to Neuron Communication
- Action potential reaches the synaptic terminal, leading to local voltage changes across the membrane
- Voltage changes activate voltage-gated ion channels, resulting in an influx of calcium ions
- Calcium ions trigger the mobilization and fusion of synaptic vesicles with the cell membrane, releasing neurotransmitters into the synaptic cleft
Excitatory and Inhibitory Neurotransmission
- Glutamate activates postsynaptic ionotropic glutamate receptors, causing an excitatory postsynaptic potential (EPSP)
- GABA activates postsynaptic ionotropic GABA receptors, causing an inhibitory postsynaptic potential (IPSP)
Ionotropic Receptors
- Ionotropic receptors are ligand-gated ion channels, also known as neurotransmitter receptors
- Neurotransmitter binding causes a conformational change, opening the ion channel
- Examples: ionotropic glutamate receptors and ionotropic GABA receptors
Metabotropic Receptors
- Metabotropic receptors have one subunit with 7 transmembrane alpha helices (TM 1-7)
- The cytoplasmic loops interact with G proteins
- Examples: muscarinic acetylcholine receptors, adrenergic receptors, and metabotropic glutamate receptors
Metabotropic Glutamate Receptors (mGluRs)
- mGluRs of groups II and III are predominantly expressed on the presynaptic side, negatively linked to transmitter release
- mGluRs of group I are found postsynaptically
- Activation of presynaptic mGluRs increases transmitter release, requiring arachidonic acid as a co-transmitter
Ionotropic Glutamate Receptors
- Glutamate is the primary excitatory neurotransmitter in the mammalian brain
- AMPA and NMDA-type glutamate receptors are the main receptors involved
- NMDA receptors have a Mg2+ block, and their Ca2+ permeability is important for synaptic plasticity
Ionotropic Glutamate Receptor Structure
- Four transmembrane alpha helices (M1-M4)
- The Glu binding domain is encoded on the N-terminal
- The channel is formed by four subunits, surrounding the pore of the channel
- When open, the ion channel is permeable to Na+, K+, and in some cases, Ca2+
AMPA and NMDA Receptors
- AMPA receptors: fast sodium entry, fast EPSP, fast inactivation
- NMDA receptors: slow activation, Ca2+ permeability, stay open for a long time
- NMDA receptors require co-activators: glycine and D-serine
NMDA Receptor Kinetics
- Glycine (together with glutamate) is required for the activation of NMDA receptors
- NMDA receptors are readily blocked by magnesium (Mg2+)
- Ketamine selectively blocks NMDA channels
Molecular Integrators
- NMDA receptors act as molecular integrators, opening only when the membrane is already depolarized by AMPA receptors
- This allows Ca2+ to enter the cell, leading to synaptic plasticity, memory, long-term potentiation, and neuronal death
GABA Receptors
- GABA is the main inhibitory neurotransmitter in the vertebrate brain
- GABA binds to GABAA receptors with high affinity
- GABAA receptors have a pentameric structure with 5 subunits, an allosteric binding site for GABA, and a benzodiazepine binding site between alpha and gamma subunits
GABA Functions
- GABA(A) receptors contribute to several components of the anaesthetic state, including amnesia, sedation, hypnosis, and immobility
- GABA(A) receptors are substrates for some general anaesthetics
Propofol
- Propofol is frequently used for the induction of anaesthesia
- Propofol works by increasing GABA-mediated inhibition, decreasing the rate of dissociation of GABA from the GABAA receptor, leading to longer-lasting hyperpolarization of cell membranes
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the process of synaptic transmission, including the action potential, ion channels, and neurotransmitter release. It also explores the role of excitatory neurotransmitters like glutamate. Test your knowledge of neuron communication!