Lecture 1: Cellular Components Flashcards
What are the different types of glia?
oligodendrocytes, microglias, astrocytes, ependymal cells and radial glias
How are neurones classified?
based on morphology / structure, location, function, chemical
What type of cells are neurones?
excitable cells which have specialised membrane properties
What does the functional phenotype of a neurone describe?
what the cell does e.g. motor neurone which excites skeletal muscle cells for motor function
What are different types of functional phenotype?
motor neurone, excitatory neurone
How can the functional phenotype of a neurone be identified?
electrophysiologically (measuring and directly recording the activity) -> observing the effect of exciting the neurone
What does the chemical phenotype of a neurone describe?
which neurotransmitter is produced by the neurone e.g. acetylcholine (cholinergic neurone)
How can the chemical phenotype of a neurone be identified?
direct labelling (immunohistochemistry), mRNA (in situ hybridisation) and genetic markers
What are the most important regions of a neurone?
dendrites, cell body / soma, axon hillock, axon and synapse
How does information flow occur in neurones?
information flow is generated by graded potentials produced by the axon of a presynaptic neuron and passes through the neurone in the form of action potentials to reach the axons where this information is passed on to the dendrites of a postsynaptic neuron
dendrites -> cell body -> axon
What is the role of the cell body of a neurone?
information is integrated and sent out through the axon
What are synaptic processes?
communication between neurones, can be axo-dendritic and axo-somatic
What is myelin characterised by?
specialised properties for electrical conduction
Are there more neurones or glia in the nervous system?
there are more glia in the nervous system
What is the role of satellite cells?
supports cell bodies
What is the role of Schwann cells (PNS) and oligodendrocytes (CNS)?
forms myelin sheaths
What is the role of microglia?
modified immune cells which act as scavengers
What is the role of ependymal cells?
create barriers between compartments and are a source of neural stem cells
What is the role of astrocytes?
involved in NT uptake as they have glutamate transporters
possess an array of ion transporters to clean up extracellular spaces between neurones (EC homeostasis)
regulate local micro-vasculature and blood flow
important for the BBB
Why do astrocytes depolarise after neurones?
levels of extracellular potassium increases dramatically following the depolarisation of neurones and is taken up by astrocytes which become activated
Why don’t astrocytes suffer from potassium toxicity?
because they are connected to other astrocytes by gap junctions which allows for potassium to move down its concentration gradient into cells which do not contain as much potassium
Why do arterioles dilate as neural activity increases?
activation of neurones results in increased metabolic demand, production of metabolic waste and dilation of the arterioles
What is the role of astrocytic end-feet?
surround arterioles and capillaries
What are tripartite synapses?
astrocytic foot processes contact both pre- and post-synaptic areas
What are gliotransmitters?
chemical transmitters released by astrocytes -> not only are they passive cleaners but astrocytes actively participate in cellular communication in the brain
What stimulates the release of gliotransmitters?
increased activity in adjacent neurones and astrocytes -> increased [Ca2+] in astrocyte -> release gliotransmitters (e.g. glutamate, ATP)
What are characteristics of a neural circuit?
essential for complex functions, output varies depending on constituent components
What is the functional phenotype of a neurone usually determined by?
the NT released -> effect on post-synaptic receptor (however exact effect of NT can depend on the post-synaptic receptor esp. GPCRs)
What is a convergent circuit?
when multiple neurones send axons to a single neurone
What is a divergent circuit?
when a neurone sends axons to multiple neurones
What are different types of circuits?
convergent, divergent, feedback, lateral excitation, feedforward inhibition, feedback inhibition and disinhibition
