Neurobiology- Neurophysiology Flashcards
What is chemical signaling in neurons and where is it utilized?
Is signaling between cells (neuron to neuron or neuron to myocyte)
Occurs at synapse
What is electrical signaling in neurons and where is it utilized?
Is signaling within neurons themselves
Occurs in neurons
What is the resting membrane potential?
concentration of ions creates a charge differential across the membrane
More negative inside the cell and more positive on the outside of the cell
How is the resting membrane potential maintained?
Maintained by a Na/K pump and K+ leak channels
What factors contribute to the ion gradients across the cell membrane?
The charge of the ion
The size of the ion
the concentration of the ion across the membrane
What factors contribute to the opening of sodium, chloride and potassium channels?
the binding of signaling molecules such as neurotransmitters (ligand-gated ion channels), or on the voltage across the membrane (voltage-gated ion channels).
What is an action potential?
Depends on the charge differential across the membrane
Where are Action potentials formed?
At the synapse between 2 neurons or a neuron and a myocyte
What is an Post-synaptic potential?
- Open when they bind to a ligand (neurotransmitter)
Where each are Post-synaptic potentials formed?
at the axon terminal where neurotransmitters is stored and released
Describe the role of voltage gated ion channels in action potential transmission along an axon.
Resting membrane potential depolarization that activates the Na+ channel allowing Na+ into the cell that causes further depolarization down the axon.
- This brings the membrane potential to be more positive on the inside and negative on the outside
Na+ channels close
K+ channels will open (slower than Na+ channels) allowing K+ into the cell.
- This brings the membrane potential back to more negative inside the cell and positive outside the cells.
Resting membrane potential is reached
How does axon diameter affect the speed of action potential propagation.
The speed of action potential increases as the axon diameter increases
How does myelination affect the speed of action potential propagation.
It increases the speed of the action potentials by decreasing leakage of ions. Electrical signals jump across the myelinated parts of the axon and only the voltage gated channels in the gaps between myelination (Nodes of Ranvier) have to open.
What is myelin?
an insulating sheath
How does excitatory postsynaptic potentials determine whether or not a neuron will fire an action potential.
Release of excitatory neurotransmitters binds and opens Na+ channels allowing Na+ to flow into the cell making the inside of the cell more positive and the outside of the cell more negative
How does inhibitory postsynaptic potentials determine whether or not a neuron will fire an action potential.
Release of inhibitory neurotransmitters binds and opens Cl- channels allowing Cl- to flow into the cell making the inside of the cell more negative and the outside of the cell more positive
What does Excitatory postsynaptic potentials do to the membrane & why?
Depolarizes the membrane
Usually due to sodium channel opening
What does inhibitory postsynaptic potentials do to the membrane & why?
Hyperpolarizes membrane
Usually due to calcium channel opening
What occurs at the axon hillock that determines whether or not a neuron will fire an action potential?
all of the changes are going to be added up either resulting in a big depolarization or big hyperpolarization, resulting in either the firing of an action potential or not.
What are ionotropic neurotransmitter receptor characteristics?
Produce and electrical signal
Binding of a transmitter directly opens or closes ion channel
Usually made of protein subunits forming a pore
Fast
Short-lived effect
Local effect
What are metabotropic neurotransmitter receptor characteristics?
Produce s a chemical signal with a potential secondary electrical signal
Binding of transmitter activates second messengers
Protein with 7 transmembrane regions
May indirectly open or close ion channels
Slower
Longer lasting
Can have effects throughout the cell
Where is Acetylcholine made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?
in nerve terminals from acetyl coenzyme A (acetyl CoA, which is synthesized from glucose) and choline, in a reaction catalyzed by choline acetyltransferase
Excitatory & inhibitory
CNS and PNS in the neuromuscular junctions
Ionotropic & Metabotropic
Where is Glutamate made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?
is recycled and made by glial cells in your brain. Glial cells convert “used” glutamate to glutamine, which is converted back again into glutamate when delivered back to the terminal area of nerve cells
Excitatory, responsible for excitatory postsynaptic potentials
acts on postsynaptic glutamate receptors
Ionotropic & Metabotropic
Where is GABA made & how?
What is its function?
Where is its site of action?
What type of receptors does it have?
synthesized in the cytoplasm of the presynaptic neuron from the precursor glutamate by the enzyme glutamate decarboxylase
Inhibit postsynaptic potentials
brain
Ionotropic & Metabotropic
