Axonal Neurotransmission CM Flashcards
4 different neuron types
Multipolar neuron
Bipolar neuron
Pseudo-unipolar neuron
Unipolar neuron
What is a synaptic transmission
Integration/processing of input at a single neuron
What is an axonal transmission
Transmission of information from location A to location B
What is the most common disease of the nervous system among young adults
Multiple Sclerosis
Symptoms of Multiple Slerosis
Uncontrolled eye movement Slurred speech Partial/complete paralysis Tremor Loss of Co-ordination Weakness Sensory numbness. prickling, pain
What is the prognosis of MS?
Initial symptoms with slight remission, becomes more numerous, severe and frequent
Why is MS difficult to diagnose?
- person doesnt go to doctor
- other diseases have similar symptoms
- no current laboratory test
Who can get MS?
young adults 20-40
more women than men
temperate zones
Areas of high standards of sanitation
What is a nerve impulse?
the signal used ny neurones to transmit information between different spatial locations
give two substances that are electrically charged +ve and -ve that cross readily
potassium (K+) and chloride (Cl-)
Name a substance that crosses the neuron with difficulty
Sodium (Na+)
Name a substance that does not cross the neuron at all
large organic proteins (-ve charge)
Define diffusion
the force driving molecules to move to areas of lower concentration
Electrostatic pressure
ions move according to charge,- like ions repel and unlike attract
A protein ion is called?
anion (A-)
How does the sodium-potassium pump work?
it is an active process to transport Na+ ions out of neuron and K+ ions in
Three Na+ ions for every two K+ ions
It requires energy supplied by ATP
ATP
Adenosine Triphosphate
ADP
Adenosine Diphosphate
- (starting an action potential)
Neurotransmitters activate receptors on ____/_____
dendrites
soma
- (Starting an action potential)
Receptors open ____ channels
ion
- (Starting an action potential)
Ions cross ______, changing the ________
- plasma membrane
2. membrane potential
- (starting an action potential)
The potential changes spread though the _____
cell
- (starting an action potential)
if the potential changes felt at the ________ are _______ (+mV), and ______ enough, an action potential is triggered.
- axon hillock
- positive
- large
Excitatory neurotransmitters ______ the cell membrane
depolarise
depolarising the cell membrane increases what?
the probability of an action potential being elicited
depolarising a cell membrane increases probability of an action potential which causes what?
Excitatory Post Synaptic Potential (EPSP)
EPSP=
Excitatory Post Synaptic Potential
what type of neurotransmitters depolarise the cell membrane?
Excitatory
Inhibitory neurotransmitters ______ the cell membrane
hyperpolarise
hyperpolarising the cell membrane decreases what?
the probability of an action potential being elicited
hyperpolarising a cell membrane decreases probability of an action potential which causes what?
Inhibitory Post Synaptic Potential (IPSP)
IPSP=
Inhibitory Post Synaptic Potential (IPSP)
what type of neurotransmitters hyperpolarise the cell membrane?
Inhibitory
An action potential will be elicited if the membrane potential is depolarised beyond the ________
threshold of excitation
What is passive conduction in relation to postsynaptic potentials?
Voltage changes spread away decrementally from point of origin.
Why is Ouabain used in poison arrows?
it selectively blocks the sodium/potassium pump
How is Ouabain used in neuroscience today?
treatment of heart failure in small doses
How are voltage changes caused?
by the opening and closing of ion chambers
why is action potential self perpetuating?
because the voltage changes control the ion channels which control the voltage changes
Where is Lidocaine widely used?
in local anaesthetics
What does Lidocaine do?
Blocks voltage gated sodium ion channels
Stops APs immediately
(It is on WHO list of worlds essential medicines)
What does Myelination do?
greatly speeds up axonal conduction
What is Saltatory conduction?
decremental conduction between nodes, re-boosted each time, very fast along axon, occurs in most CNS neurons.
Why does the breakdown of myelin affect the transmission of messages?
Degeneration of myelin and development of scar tissue disrupts and eventually blocks neurotransmission along myelinated axons.
When the action potential reaches the terminal button, what does the AP cause?
The voltage gated ion channels to open
when the AP reaches the terminal button, and the ion channels open, what do the influx of calcium ions cause?
exocytosis
What do a few vesicles undergo for each single action potential ?
exocytosis
When a neurotransmitter is released into the synaptic cleft, what does it do?
it diffuses
what do the receptors on the dendrites of the postsynaptic neuron do?
it binds the neurotransmitter
What is transmitter re-uptake of neurotransmitters in the synaptic cleft?
Some neurotransmitters are transported back into the pre or postsynaptic terminal for reuse.
name two neurotransmitters that are reuptaken in the pre or postsynaptic terminal
serotonin
noradrenaline
What is Enzymatic Degradation?
when some neurotransmitters are broken down in the cleft by enzymes
What is ACh broken down by? and what does this cause?
acetylcholinesterase
it becomes inactive
The neurotransmitter would remain in the synapse if it wasn’t for…
- simple re-uptake
- enzymatic degradation
- diffusion out of cleft
