Lecture 4- Synaptic communication Flashcards
What are the two proteins that set up the resting membrane potential:
1) Sodium potassium transporter
2) Leak potassium channels
What are the 3 voltage gated ion channel proteins involved in the action potential:
3) Voltage gated SODIUM channel
4) Voltage gated POTASSIUM channel
5) Voltage gated CALCIUM channel
Why is it that an ion channel can be permeable to K+ but not Na+?
Because K+ is bigger (more protons, neutrons, electrons) and they have the same charge when dissolved in water
How do potassium ion channels only let in the bigger element? (K+)
In genetics, a promoter is a region of DNA that initiates transcription of a particular GENE, what does it indicate regarding cells?
They indicate what kind of cells should read the gene and when.
—-Promoter———–|gene for potassium ion channel
How many distinct genes does the human genome contain for the voltage gated potassium channel?
40, each cell can express any combination to optimize cell function.
What is a Neuroglia (or Glial cells)? where are they found?
Name the 3 types of glial cells:
Glial are found all over neurons. They help traffic nutrients and maintain molecular stability. Glials outnumber neurons in the brain.
There are astrocytes, microglia, oligodendrocytes.
What is an Astrocyte?
It is a glial cell that provides physical support and cleans up debris in the brain through PHAGOCYTOSIS.
They control chemical composition of the surrounding environment and help nourish neurons.
What is microglia?
It is the smallest of the glial cells. Thye provide an immune system for the brain and protect the brain from invading microorganisms
What are oligodendrocytes?
Oligodendrocytes produce myelin sheath, which encapsulates axons. The sheath is not continuous, it is a series of segments, The Exposed axon is called the NODE of RANVIER.
What is saltatory conduction?
The conduction of actions potentials by myelinated axons.
Action potential jumps from one node of Ranvier to next, the strength of the signal is regenerated with additional voltage gated Na+ channels.
What is is synapse? How is synaptic communication achieved?
It is a junctions between axon terminals of the sending neuron and the cell membrane of the receiving neuron.
The communication is achieved by the release of a molecule from an axon terminal called a neurotransmitter, it can have excitatory or inhibitory effect.
What are synaptic vesicles? What doe they do?
They contain molecules of neurotransmitters. They attach to the presynaptic membrane and release a neurotransmitter into the synaptic cleft.
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What is a synaptic cleft?
It is the the space between the pre and post synaptic membranes.
What is the PRE-synaptic membrane?
The membrane of the terminal button, this is where the neurotransmitter is released from.
What is the POST-synaptic membrane?
It is the membrane of a receiving cell that is opposite the axon terminal.
What is an electron microscopy?
This allows us to see small anatomical structures using a special electron microscope
What are signalling molecules that bind to protein receptors called?
Ligands, neurotransmitters are ligands.
What are the two categories of neurotransmitter receptors:
-Ionotropic, which are ion channels
-Metabotropic receptors, Which are g proteins coupled receptors that can open ion channels through an intercellular signaling cascade.
Neurotransmitter receptors that can be found on the cell membrane or inside the cell are called: (2)
-POST-synaptic receptors: located on postsynaptic membrane
-PRE-synaptic receptors: located on presynaptic membrane
What is a Binding site?
The location on a receptor protein to which a ligand binds.
What is a ligand-gated ion channel?
A receptor that is an ion channel, also known as an ionotropic receptor, the ion channel opens when the ligands binds to it.
What is Enzymatic deactivation?
The destruction of a neurotransmitter by enzyme after its release
What is the action of reuptake?
Reentry of a neurotransmitter just liberated by a terminal button back through its membrane, thus terminating postsynaptic potential.
What is postsynaptic potential?
Alterations in the membrane potential of a postsynaptic neuron, produced by neurotransmitter release into the synapse and receptor activation.
Postsynaptic potentials can either be (2):
EXCITATORY: positive sodium ions depolarize the cell
or
INHIBITORY: negative chloride ions hyperpolarize the cell.
What is hyperpolarization? Give an example:
When the membrane potential of a cell becomes more negative than it normally is at rest.
Ex. Acute influx of negative ions Cl- hyperpolarize a neuron from -60 to -70 mV.
What is depolarization? Give an example:
When the membrane potential of a cell becomes less negative than it normally is at rest.
Ex, Acute influx of positive ions Na+ depolarize an ion channel from -60 to -50mV.
What is excitatory postsynaptic potential (EPSP)? What will it be more permeable to?
Excitatory depolarization of postsynaptic membrane caused by neutransmitter binding to a postsynapstic receptor protein.
EPSP are mediated by receptor prtoeins that open ions channels permeable to sodium (+) = depolarize cell.
What is Inhibitory postsynaptic potential (IPSP)?
What will it be more permeable to?
Inhibitory hyperpolarization of postsynaptic membrane caused by neurotransmitter binding to a postsynaptic receptor protein.
IPSP are mediated by receptor proteins that open ions channels permeable to chloride(-).
= hyperbolize the cell.
The interaction of the excitatory and inhibitory synapses on a particular neuron is called :
Neural integration
