Cell Types in the Nervous System Flashcards
How many neurons are there in the human brain?
10^10 - 10^12
How many non-neuronal cells are there in the human brain?
> 10^11
What are other names for glia?
Glial cell
Neuroglia
What are glia?
Non-excitable support cells
What types of neurons are there?
Unipolar Bipolar Multipolar Long axons (Golgi type 1) Short axons (Golgi type 2) No axons
What is an example of a unipolar neuron?
Dorsal root ganglion
What is an example of a bipolar neuron?
Retinal bipolar cells
What is an example of a multipolar neuron?
Motor neuron
Purkinje cell
Cerebellar granule cell
Pyramidal cells
What is the general structure of a neuron?
Dendrite Cell body Axon Node of Ranvier Synaptic terminal Growth cone
What is special about a olefactory granule cell?
Anaxonic (no axons)
Dendrodendritic synapses
What are the main types of glial cell?
Macroglia
Microglia
Ependyma
Examples of macroglia
Astrocytes
Oligodendrocytes
Schwann cells
What is an astrocyte?
Star shaped
Multiple, long processes
Forms the glia limitans
What do astrocytes enwrap?
Blood vessels
Processes
Synapses
What are the types of astrocytes?
Fibrous
Protoplasmic
What is a fibrous astrocyte?
White matter
Many intermediate filaments
What is a protoplasmic astrocyte?
Grey matter
Shorter, stouter processes
Fewer intermediate filaments
Examples of specialised astrocytes
Retinal Muller cells
Radial glia
What is a retinal Muller cell?
Span the width of the retina
Columnar cell
What is a radial glial cell?
Span from pia to Purkinje cell layer
Stem cells adult/developing brain
Astrocytes role in spatial buffering
Active neurons release K+
Astrocytes are very K+ permeable and are a functional syncytium
Astrocytes span from synapse to blood vessel
Spatial buffering regulates [K+]o
Muller cells in the retina?
Photoreceptors release K+
Muller cells take up K+
K+ reduced near the photoreceptors
Astrocyte role in transmitter uptake
Uptake is an important inactivation mechanism
Glutamate into astrocytes, GABA
Glutamate converted into glutamine
Recycling to neurons
Astrocyte role in glucose metabolism
Glucose = main energy substrate
Neurons prefer 3-carbon
Astrocytes store most glycogen
Astrocytes span blood
What are the processes on microglia like?
Short and spiky
Where are microglia derived from?
Circulating monocytes
Where are ependyma found?
In the epithelial lining of ventricles and spinal canal
What are the types of ependyma?
Ependymocytes
Tanycytes
Choroid epithelial cells