Key Points Flashcards
Charges on the two layered membrane
Outer has lots of positive ions (like Na and K)
Inner has negatively charged proteins
When a signal is received the membrane is….
depolarised.
Both sides become positive
Efferent Neurons
Take information from the receptors to the brain
Sensory
Signal transmission
- Resting potential
- Stimulus activation
- Depolarization
- Repolarisation
- Hyperpolarisation
Presynaptic membrane or element
Action potential
Activates Ca2+ ion channel
Neurotransmitters
Post synaptic membrane
Exert Action
_ receptors seem to increase sympathetic traits and _ receptors tend to decrease them
1 and 2
Glutamate is the main _ transmitter in the CNS
Excitatory
NMDA receptor
Dual gated Na+/Ca2+ channel
Na+ out, K+ out, Ca2+ in
Voltage and ligand gated, depolarisation required to relieve Mg block
Much slower time course than AMPA
AMPAr receptor
Ligand gated Na+ channel
Permeable to Na+ in and K+ out
Ca2+ permeable if there is no GluA2 subunit
Fast excitatory transmission
The principle … transmitter in the CNS
Inhibitory
GABA A
- Ligand gated ion channels
- Permeable to Cl- ions
- Hyperpolarises membrane
- Primarily postsynaptic
- Mediate fast inhibition
GABA B
- G-protein-coupled receptors (GPCR)
- Coupled to Ca2+ and K+ ion channels
- Pre and postsynaptic
- Mediate slow inhibition (seconds-minutes)
- Also inhibit transmitter release
Main treatment for anxiety
Benzodiazepines
Method of Action of Benzodiazepines
Binds with specific modulatory site on GABA A receptor
Enhances GABA activity
Opening of Cl- channels
Hyperpolarisation of cells
Depression of CNS
Nociception
The physical process of detection and transmission of damaging or potentially damaging (noxious) stimuli
Sequence of nociception
- Noxious stimulus
- Primary transduction
- Secondary transduction
- Depolarisation and action potential generation
- Transmitter release
- Second order neuron response
Opiates
Act on the opioid receptors
Mimic endogenous opioids
Examples: morphine, heroine and fentanyl
What is a stroke?
A stroke is a transient or permanent interruption in the cerebral blood supply.
This has a cardiovascular cause and leads to ischaemia, which is a lack of O2 and glucose.
Ischaemic stroke
Everything downstream of the blockage becomes ischaemic.
Incidence is 85%
Lower mortality than haemorrhagic
Excitotoxicity
- Excessive release of glutamate
- The neurones are “excited to death”
- Ca2+ overload within neurons.
Neurodegeneration
Progressive loss (death) of neurons beyond that of the normal aging process.
It is a problem because neurons cannot be replaced.
Possible causes of ND
Aggregates - toxicity
Inflammation - microglia going wrong
Oxidative stress - tau
Mitochondrial damage
What does Motor Neuron Disease refer to?
A group of conditions characterised by a degeneration of lower motor neurons and/or upper motor neurons
Progression of ALS
Gradually muscles under voluntary control are affected
Individuals lose strength, ability to sleep, eat, move and breath.
Most people with ALS die of respiratory failure within 3 to 5 years of onset
What happens to upper and lower MN in ALS?
They degenerate and die
Unable to function, the muscles degenerate
Etiology
The cause, set of causes, or manner of causation of a disease or condition.
K+ channels
Allows K+ out of the cell
Repolarisation
Cl- channel
Allow Cl- into the cell
Repolarisation
