Chapter 3 Flashcards
Neurotransmission
EXPLAIN
What is an Electrical Neurotransmission?
The nerve impulse is transmitted via channel proteins
think of little bridges between the neurons
EXPLAIN
What is a Chemical Neurotransmission
The nerve impulse is transmitted via neurotransmitters
DEFINE
Electrical Potential
The local difference between the electrical charge across the membrane
DEFINE
Depolarization
Decrease on the electrical potential
Opposite of hyperpolarization
DEFINE
Hyperpolarization
Increase in electrical potential
Opposite of Depolarization
DEFINE
Resting Potential
The electrical potential when a neuron is not firing (-70mV)
DEFINE
What is an Na/K Pump?
A neuronal membrane mechanism that maintains the resting potential
DEFINE
What is an Ion Channel?
The pores in a neuronal membrane that allows the passage of ions
LIST
What are the 3 types of Ion Channels?
- Ligand Gated
- Voltage Gated
- Mechanically Gated
EXPLAIN
How does a Ligand-gated ion channel work?
They open when a chemical ligand such as a neurotransmitter binds to the protein
EXPLAIN
How does a voltage-gated ion channel work?
They open and close in response to changes in the membrane potential
EXPLAIN
How does a Mechanically-gated ion channel work?
open in response to physical deformation of the receptor
DEFINE
Postsynaptic Potentials
Changes in membrane potential in dendrites in response to neurotransmitters
EXPLAIN
What is the difference between an electrical gradient and a chemical/concentration gradient?
A chemical/gradient is the difference in the amount of a substance across a space, causing it to move from high to low concentration. An electrical gradient is the difference in charge across a membrane, causing ions to move toward opposite charges.
THINK Chemical: Diffusion Electrical: Magnets
DEFINE
Action Potential
The rapid depolarization of an axon
EXPLAIN
What happens during action potential?
- Voltage gated Na channels open
- Na rapidly enters cell
- Cell reverses polarity
- Na channel closes, and K exits
DEFINE
What is the refractoy period?
The time in which the resting potential is being restored
EXPLAIN
Why is the refractory period needed?
After action potential, there is:
* too much Na in cell
* too much K outside the cell
DEFINE
What is the All-or-None Law?
The magnitude of an Action Potential is independent of the magnitude of the potential change elicted
ie. It either fires fully or it doesnt at all
EXPLAIN
What is the firing rate dependant on?
Dependant on the amount of stimulation by other neurons
EXPLAIN
What is the function of Enzymes in neurotransmitter synthesis?
Makes neurotransmitters from precursor molecules
EXPLAIN
What is the function of Synapatic Vesicles?
Store and protect neurotransmitters after synthesis
Packaged by vesicular transporters
DEFINE
Receptors
Specialized proteins that are embedded in neuronal membranes to which neurotransmitters bind and activate
LIST
What are the 2 types of Presynaptic Receptors?
- Autoreceptors
- Heteroreceptor
DEFINE
Autoreceptor
Activiated by neurotransmitters released from the same axon terminal
DEFINE
Heteroreceptor
Activiation by neurotransmitters different from those released by the axon terminal
DEFINE
Ionotropic
A receptor that is coupled to an ion channel
* NT binds to the receptor to open the ion channel
* Wears off when the NT is no longer bound
DEFINE
Metabotropic
A receptor that is far away from where its effects are seen
* NT binds to receptor and the G protein is activated, causing intracellular signalling
* Takes time for effects to wear off, even after NT is no longer bound
DEFINE
Which receptor has these traits:
* Attached to ion channel
* Opens the ion channel
* Effect ends when neurotransmitter unbinds
* Changes the local potential
Iontropic Receptor
DEFINE
Which receptor has these traits:
* Seperate from its ion channel and enzymes
* Uses G proteins to activate ion channel, effector enzymes and second messengers
* Effect persists after unbinding
* Can affect local potential, enzyme regulation, gene activiation and protein synthesis
Metabotropic Receptor
DEFINE
What are the 3 subunits of G proteins?
α, β, γ
DEFINE
Glutamate
The most abundant excitatory neurotransmitter
EXPLAIN
When is glutamate inhibitory?
In mGlu group II and III which is only expressed in utero
DEFINE
GABA (y-aminobutyric Acid)
Most abundant inhibitory neurotransmitter
DEFINE
Rate-Limiting Step
The slowest conversion rate in the synthesis process, limiting how much of the drug can be made without artifical bypassing
EXPLAIN
What drug can be used to bypass the rate-limiting step in the production of dopamine?
Levodopa
DEFINE
Mesolimbic Pathway
The pathway from the midbrain (VTA) to the limbic areas
such as the nucleus accumbens, Amygdala and hippocampus
DEFINE
Mesocortical
Pathway from the midbrain (VTA) to the neocortex, including the pre-frontal cortex
DEFINE
Nigrostriatal Pathway
From substantia nigra to the basal ganglia
DEFINE
Tuberoinfundibular Pathway
From the hypothalamus to the posterior pituitary
