Cells + communication in the nervous system Flashcards
What are the key functions of the nervous system?
Sensation
Integration
Activation
How can dysfunctions of the nervous system manifest?
Loss (of sensation or function)
Gain (appearance of new features e.g. twitch/ tremor)
Change (in behaviour/ personality)
Which glial cells produce myelin?
Oligodendroglia (CNS) Schwann Cells (PNS)
What are the different types of neurons?
Principal cells
Interneurons
What are the key features of neurons?
Dendrites (receptive field)
Soma (metabolic and integrating centre)
Axon (one way communication)
Synaptic terminals (release of transmitters, communication with other cells)
What is the role of astrocytes?
Form bridge between neuron and blood vessels
What is the role of ependymal cells?
Simple, ciliated, cuboidal cells that form the lining of the ventricular system
What are microglia cells?
Small glial cells activated by trauma as part of an immune response
What is the clinical relevance of glia cells?
Tumours in the CNS more commonly originate in glia cells rather than neurons.
What are the 3 main groups of neurons?
Multipolar
Bipolar
(Pseudo) unipolar
[Refers to amount of input into cell body]
What are the functions of myelination?
Insulation Saltatory conduction (faster transmission)
What are the 2 key myelination disorders?
Multiple Sclerosis (CNS) Guillain Barre (PNS)
What are chemical synapses?
Most common synapses
Fast transmission
Vesicles released from presynaptic terminal and act on receptors on postsynaptic terminal
What are electrical synapses?
Slower transmission
Gap junctions
Two channels join to form single junction to allow small molecules and current to pass through
‘Low-pass filter’
Which type of synapse is the current major drug target?
Chemical synapses
What is Myaesthenia Gravis?
An autoimmune disease affecting the neuromuscular junction where Ach receptors are not responsive to Ach
Causes slowing of muscle activity and reducing tone
How would neuromuscular communication effectiveness be tested?
Nerve conduction tests
Electromyography
What are the 2 main chemical transmitters in the CNS?
Glutamate (excitatory)
GABA (inhibitory)
What is the importance of inhibitory transmitters in the CNS?
Responsible for coding of activity (stops firing of neurotransmitters)
Direct and lateral inhibition
Disinhibition
Synchrony (coordinates activity)
Plasticity (changes strength of activity)
What is the difference between direct and lateral inhibition?
Direct inhibition acts on target cell to reduce activity
Lateral inhibition acts on neighbouring cells to reduce activity
What is disinhibition?
Activation of inhibitory circuit to cause excitation of cells (by inhibiting an inhibitory cell to prevent it from inhibiting excitatory cell)
Plays a key role in Basal Ganglia circuitry to shape motor function
What are the 2 types of transmitters found in the CNS?
Neurotransmitters (rapid cell communication)
Neuromodulators (indirect activity)
What are the key excitatory neurotransmitters in the CNS?
Glutamate
Aspartate
What are the key neuromodulators in the CNS?
Neuropeptide Y Substance P Vasopressin Somatostatin Anandamide
What are some common interactions betwen neuronal pathways?
NA levels can directly alter 5-HT activity
5HT levels can directly alter DA activity
DA levels can directly alter ACh activity
ACh levels can directly alter GABA activity
Where does communication between neurons and muscles take place?
Neuromuscular junction
How does communication at the neuromuscular junction take place?
1) action potentials trigger exocytosis of ACh from synaptic terminal
2) ACh crosses cleft
3) Acts on Cholinergic receptors in motor end plate
4) Muscle contraction initiated
5) Impulse carried through muscle via T-tubules and sarcoplasmic reticulum
What are the key inhibitory neurotransmitters in the CNS?
GABA
Glycine
What neurotransmitter acts at the neuromuscular junction?
Acetylcholine
What neurotransmitters are involved in stress/ arousal?
Adrenaline
Noradrenaline
Histamine (arousal)
What neurotransmitter plays a key role in motivation and motor function?
Dopamine
What neurotransmitter plays a key role in homeostasis?
Serotonin (5-HT)
What are ionotropic receptors?
Receptors linked to ion channels
What are the 4 main types of cutaneous receptors?
Mechanoceptors
Thermoceptors
Nociceptors
Proprioceptors
What do mechanoceptors detect?
Tactile sensation (touch, pressure)
What do thermoceptors detect?
Temperature changes
What do nociceptors detect?
Painful stimuli
What do proprioceptors detect?
Changes in head and body position
What mechanisms are involved in pathogenesis of neuronal and psychological disorders?
Altered neuronal activity Altered synchrony Cellular changes Subcellular change Genetic/epigenetic changes
