Cells & Communication Flashcards
Outline the cell types in the nervous system
Neurones: principal cells and interneurones
Glia: astrocytes, ependymal cells, microglia, oligodendrocytes, schwann cells
Outline the structure of a neurone
Dendrites - receptive field
Soma (cell body) - metabolic and integrating centre (nucleus)
Axon - rapid unidirectional communication between cell body and terminals
Synaptic terminals - release NTs
Outline the roles of 5 different types of glia
Astrocytes - maintain BBB
Ependymal cells - line ventricles (CSF producing)
Microglia - activated by trauma (WBC equivalent)
Oligodendrocytes - myelin production in CNS
Schwann cells - myelin production in PNS
What type of conduction does myelin allow and what’s its role?
Saltatory - fast communication
Provides insulation - not complete at birth
What are 2 demyelinating disorders?
MS - CNS
GBS - PNS
How do the 2 types of synapses (chemical and electrical) differ?
Chemical: faster transmission, NT release from vesicle dependent which act on postsynaptic receptors
Electrical: slower transmission, gap junctions allowing small molecules and current to pass through “low-pass filter”
Outline the NMJ
APs trigger release of ACh which acts on nAChR on motor end plate to initiate muscle contraction as impulse carried through T-tubules and SR
What disorder affects the NMJ?
Myasthenia Gravis - autoimmune disease whereby circulating antibodies block ACh receptors to slow muscle activity and reduce tone
What are the major excitatory and inhibitory NTs in the NS?
Glutamate and Aspartate
GABA and Glycine
Why is GABA so important in message transmission throughout the NS?
Inhibitory role responsible for coding information: direct inhibition, lateral inhibition, disinhibition
Outline the 3 types of GABA inhibition
Direct inhibition: excitatory neurones continuously firing - require inhibitory inputs to shape firing pattern
Lateral inhibition: activation of excitatory cells activates associated inhibitory cells to reduce activity of neighbouring cells but strengthen response of cell directly activated
Disinhibition: activation of inhibitory circuit leading to excitation
What’s the difference between neurotransmitters and neuromodulators?
NTs stored in vesicles for communication
Neuromodulators often co-localised with NTs to indirectly alter neuronal activity eg change sensitivity
Activation of these classes of neurone have effects on what other pathways?.. NA 5HT DA ACh
NA - 5HT
5HT - DA
DA - ACh
ACh - GABA
What broad mechanisms are involved in pathogenesis of neuronal and psychological disorders?
Altered neuronal activity Altered synchrony Cellular changes Subcellular changes Genetic/Epigenetic changes
What’re 3 functions of the nervous system?
Sensation - receptors in skin and organs respond to changes in the environment
Integration - input from external and internal environment is processed by CNS
Activation - appropriate response to stimuli to appropriate muscles/glands
What are 3 different types of neurone?
Multipolar = one axon and multiple dendrites
Bipolar = cell body with 2 principal processes
Pseudounipolar = one process to cell body
Inhibition is responsible for coding neuronal activity - what are the 3 types?
Direct inhibition = excitatory neurones have regular firing in absence of inhibition, so the sequence of inhibitory cell firing will produce the pattern of activity
Lateral inhibition = excitatory cell activation activates associated inhibitory cells, which can inhibit neighbouring cells to control strength of activity
Disinhibition = activation of inhibitory circuits actually excites the circuit
Which systems use lateral inhibition to code neuronal activity?
Vision
Touch
Olfactory
What do synchrony and plasticity do to neuronal transmission?
Synchrony coordinates activity
Plasticity coordinates strength of activity
How can plasticity alter neuronal strength?
Up or down regulates synaptic strength
LTP or LTD
Alters synaptic morphology, metabolic changes, subunit changes
What are the 4 main types of cutaneous receptor?
Nociceptor
Mechanoreceptor
Thermoreceptors
Prioprioceptors
