Lecture 3 NS - Cells of the Nervous System Flashcards
What is a neuron and what is it supported by?
Basic structural and functional unit of the NS, information processing unit Supported by neuroglia, comprising several different cell types
How is diversity in cellular structure of neurons achieved?
All neurons have similar structures - diversity is achieved by differences in number and shape of their processes and where they project to in the brain
What is the structure of neurons?
Very large nucleus, prominent nucleolus, abundant RER, well developed GA, abundant mitochondria, highly organised cytoskeleton, highly organised metabolically active cell
What are dendrites and what is their function?
Spread from cell body and branch frequently - function: major area of reception of incoming information, as they greatly increase SA of neuron
What is the structure of dendrites?
Often covered in dendritic spines, which receive majority of synapses
What are axons and their function?
Emerge at axon hillock, ONE per cell - conduct impulses away from cell body, may branch after leaving cell body and at target
What is the structure of axons?
Prominent in microtubules and neurofilaments (intermediate filaments), can be myelinated/unmyelinated, cable properties, Nodes of Ranvier when exposed
How do paranodes help with transmission of AP?
Keeps ion channels separate to allow AP to propagate
What is the structure of axon terminals?
Either boutons or varicosities - axons often branch extensively close to target, forming synaptic terminals with target
What is the structure of a synapse?
There are synaptic densities where the vesicles fuse and release NT, and synaptic vesicles which hold the NT are packaged in GA and shipped by fast anterograde transport, w/specialised mechanisms for association to the plasma membrane MANY MITOCHONDRIA - so sensitive to O2 deprivation
How are the synapses organised?
Neurons receive multiple synaptic inputs, neurons use a diversity of chemical transmitters (excitatory and inhibitory), w/competing inputs integrating in the postsynaptic neuron (Neuronal integration)
What are the 3 types of synapse and are they often excitatory or inhibitory?
Axo-dendritic (often excitatory) Axo-somatic (often inhibitory) Axo-axonic (often modulatory)
What type of synapse is an axo-dendritic synapse?
Axon to dendritic spine
What type of synapse is an axo-somatic synapse?
Axon to cell body
What type of synapse is an axo-axonic synapse?
Axon to node of ranvier
How is the neuronal cytoskeleton arranged?
Highly organised as axons can be really long - inc. microfilaments, intermediate filaments and microtubules
What do neurofilaments do in the neuronal cytoskeleton?
They play a critical role in determining axon caliber
How does fast axonal transport occur?
It’s the transport of membrane associated materials, where vesicles with associated motors are moved down the axon Different membrane structures targeted to different compartments Retrograde moving organelles are morphologically and biochemically distinct from anterograde vesicles
What are the 4 different morphological subtypes of neurons?
Pseudounipolar, bipolar, golgi type I multipolar, Golgi type II multipolar