CNS Introduction Flashcards
What are the extensions from neurones called?
Dendrites.
What is an action potential?
A short-lived depolarisation that moves down the axon and results in a chemical transmitter being released.
What are neurotransmitters contained in?
Small pockets called vesicles.
What is the movement of potassium and sodium across a normal membrane?
Potassium goes out of the cell and sodium goes into the cell.
What is an excitatory synapse?
A synapse where depolarisation occurs - excitatory post synaptic potential (EPSP)
What is the most important excitatory transmitter the brain uses?
Glutamate.
What excitatory neurotransmitter is used in some areas of the brain?
Aspartate.
What is an inhibitory synapse?
The transmitter hyperpolarizes and causes an inward negative current. An inhibitory post synaptic potential is created (IPSP).
What is a common inhibitory neurotransmitter?
GABA.
What is an alternative inhibitory neurotransmitter?
Glycine.
What are the two types of synaptic summation?
Temporal summation and spatial summation.
What are the differences between the two types of summation?
Temporal summation is when two EPSPs occur in a short time frame and add up to generate a large signal, whereas spatial summation is when two different potentials from different neurones combine to create an action potential.
What is EPSP-IPSP cancellation?
When an excitatory and inhibitory potential cancel out each others effect to result in no change in membrane potential.
Why is the CNS so complex?
Neurones are highly complex structures, there are multiple synapses on each neurone, there are several types of synapse, multiple transmitters, multiple receptors, multiple messenger systems and the neurones are interconnected in complex networks.
How does a motor neurone compare to a pyramidal neurone?
A motor neurone has a relatively larger cell body in comparison to dendrites.
Where are pyramidal neurones found?
In the cortex.
Where are purkinje neurones found?
In the cerebellum.
What is the defining feature of purkinje neurones?
They have lots of dendrites.
What are the four different types of synapses?
Axo-somatic, axo-axonic, axo-dendritic and dendro-dendritic.
What are the different types of CNA neurotransmitters?
Amines, amino acids, peptides and purines.
What are G-protein Coupled receptors?
They are receptors that are linked to ion channels. When a transmitter binds, a g protein opens/closes an ion channel. They can also be linked to enzymes to release second messengers.
What is the implication of having the CNS so complex?
There are multiple sites for dysfunction, resulting in subtle variations in the phenotype of disorders resulting in diagnosis problems.
What is the implication of the CNS being so complex on drug action?
The drugs are rarely selective, but there are multiple possible drug targets even for a single neurotransmitter.
