Lecture Week 3 Flashcards
How many Australians are estimated to be living with MS?
Around 25, 600
On average, how many Australians are diagnosed with MS every week?
More than 10
What is damaged in MS?
the myelin
What are some symptoms in MS?
thoughts, visions, taste, feelings, muscles, smell, hearing, touch
What do nerve cells generate to transmit information?
electrical signals
What are neurons general resting potential?
Generally more negative, around -70mv.
What are neurons separated by?
extracellular fluid, composed of mainly water and salts.
What are the two parts of SALTS molecules?
One part carry a postitive charge and the other a negative charge.
Describe the head and tail of the cell membrane.
The head has a polar region and do is hydrophilic, while the tail has no polar regions and so is hydrophobic.
What are the three factors which influence movement of ions into and out of cells?
- concentration gradient
- voltage gradient
- structure permeability of the membrane
Describe the concentration gradient
Is ink is dropped into water, it will flow away from the initial point of contact until it is equally distributed
Describe an electrostatic gradient
If a salty solutions is poured into the water, the positive and negative ions will flow down their electrostatic gradients until the positive and negative charges are everywhere equal.
Describe the selective permeability of the membrane
salt placed in one side of a glass of water that is divided by a barrier dissolves. positive and negative ions distribute themselves in half the container but cannot cross the barrier.
What are four major ions in a neuronal membrane
- potassium
- sodium ions
- chloride ions
and - large protein anions
What is a ligand gated channel?
ion transporters and ion channels are responsible for ionic movements across neuronal membranes
What are mechanically gated channels?
opened when a force requires them to open
what are voltage gated channels?
“ball and chain” when ball is open, allows ions to flow through.
What are leakage channels?
a channel which randomly open, allowing ions to flow through
What is a sodium and potassium pump?
The processor moving sodium and potassium ions across the cels membrane.
What how do we calculate the equilibrium potential?
For a given ion, the electrical potential generated across the membrane can be predicted by the nearnst equation.
What is the equilibrium potential?
The voltage at which that ion no longer wants to flow across the membrane.
What is the postsynaptic potential?
A gadded potential in the dendrites of a neutron that receives synapses from other cells
What is an excitatory postsynaptic potential?
Is depolarising (+) because it causes the membrane potential to move toward threshold
What is the inhibitory postsynaptic potential?
It is hyper polarising (-) because it causes the membrane potential to move away from the threshold
What is an action potential?
A brief (about 1 ms) change from negative to positive in the trans-membrane potential. It is all or none.
What is produces in an action potential?
A brief, large influx of Na+ ions and a brief, large efflux of K+ ions.
What is the movement of an action potential along an axon called?
A nerve impulse
How is a nerve impulse produces?
Each AP propagates another AP or an adjacent part of the axon membrane.
Before the action potential, where are the neurotransmitter stored?
in vesicles within the terminal buttons
What happens after the neurotransmitters diffuse across the synaptic cleft?
Some will attach to receptor molecules in the postsynaptic membrane and activate them
Who discovered the first neurotransmitter?
Otto Loewi in the 1920’s.
What are neuromodulators?
other neuroactive substances which have been described that modulate the effects of neurotransmitters, but do not meet all the requirements to be a neurotransmitter
For a substance to be a neurotransmitter, it must have what properties? (4)
- be synthesised and stored in the presynaptic neutron
- be released into the synapse when the neuron fires
- cause a post synaptic effect after it interacts with a receptor
- have some mechanisms for degradation or repuptake
What do agonistic drugs effects do?
increase the synthesis of neurotransmitter molecules
What do antagonist drug effects do?
blocks the synthesis of neurotransmitter molecules
What are amino acid transmitter?
Provide the majority of excitatory and inhibitory neurotransmission in the nervous system
What is acetycholine (ACh). ?
The first neurotransmitter ever discovered
What does acetylcholine do in terms of function?
Controls heart rate, plays a role in motor movement, plays a role in memory (Alzheimer’s disease involves a degeneration of ACh in the basal forebrain)
Describe the treatment of mild moderate dementia:
Acetylcholinesterate inhibitor + activates presynaptic nicotine receptors to facilitate ACh release
What are the biogenic amines?
- norepinephrine
- epinephrine
- dopamine
- histamine
- serotonin
What is norepinephrine?
distributed throughout the central and peripheral nervous system. maintains cortical arousal.
What is norepinephrine involved in?
attention, eating and emotion. play a role in there PNS. Deficits linked to depression and to ADD.
Where is dopamine located?
in two main forebrain pathways which originate in the brainstem.
- nigrostriatal pathway
- central tegmental area
Where is serotonin distributed?
Throughout the brain and spinal chord.
What is serotonin involved in?
In the control of the sleep/wake cycle, mood, impulsive behaviour and appetite.
What is serotonin used for?
numerous behavioural problems including sleep disorder, aggression, obesity, anorexia and depression
