cellular structure of the nervous system Flashcards
How do electrical synapses work
gap junctions, current carried via ion transfer directly through channels. Minimal delay and bideirectional
How do chemical synapses work
presynaptic neurontransmitter+postsynaptic receptors, slight delay, unidirectional. Depolarisation, hyperpolarisation and second messengers
What types of neurotransmitters are there
Biogenic (ACh, noradrenaline, adrenaline, dopamine, serotonin), AA (glutamate, aspartate, GABA, glycine), peptides (somatostatin, endorrphin, bradykinin), ATP, NO
What types of synapses are there
axoddendritic, axoaxonic, axosomatic, dendrodendritc, somatosomatic, somatodendritic
How do synapses and dendrites display plasticity and integration
synapses=efficiency of transfer can be modulated=learning
dendrites=integrate inputs from multiple synapsses
What can you find on dendritic spine and what are its properties
synapses
spines are dynamic
spine ‘neck’ adjusts the amplitude of the synapse
Why does dendrite complexity matter
- shape constrains processing
- more distant, more electrically isolated
- simplified circuit building
- coincidence detectors
- directional filters
What do demyelinating diseases do
slow down or prevent conduction
Why are there layers in the grey matter
spatially distributed info maps, modularity, within modules: types of connections compartmentalised into different layers
Give examples of diseases of layering of the grey matter
double cortex syndrome lissencephaly, heterotopias
Why do nuclei exist in grey matter
group together neurones with similar function, facilitates local circuit control, maximises the efficiency of connections between nuclei
what types of neurones are there
prrojection neurones, local interneurons, motor neurones, peripheral sensory neuron
where are autonomic ganglions located in sympathetic and parasympathetic
sympathetic=thoracic
parasympathetic=cranial&sacral
Origins of CNS and PNS neurones
neural tube formed by dorsal closure. Neural crest (exits dorsal tube) populates PNS
How are different types of CNS neurones born
Dependent on dorsoventral position. 2 sets of chemicals released from dorsal midline and ventral midline, they diffuse to neural tube and form gradient of information. Depending on how much dorsal and chemical distribution the embryo gets at different points, diff types of neurones born. Motor born ventrally, sensory born dorsally. Interneurons in between motor and sensory neurons. All born on inner surface of neural tube
What does proliferation and migration of neurons allow
structure and diversity (morphogenesis)
What kind of migrations is the brain formed by
radial and tangenital
what kind of glial cells are there and what do they do
radial-structure and development
oligodendrocyte (CNS), schwann cells (PNS)-deposit myelin
Microglia (CNS)-clear damaged tissues, phagocytic
Astrocytes-physiological homeostasis blood vessel/brain interface astrocyte
What do radial glia do in adult, development and the injured brain
Adult=structural scaffold
development= guide for migrating neurons
injured brain=source of astrocytes
What do astrocytes do
homeostatic function: Blood vessels/brain interface linking
refining signalling: remove excess K+ at nodes, removing synaptic neurotransmitter, insultating synapse
What can brain injury do to astrocytes
K+ and water absorption->brain swelling->reactive astrocytes form gilial scars (potential epilepsy trigger)
