Neurons Flashcards
(14 cards)
What direction can information pass through a neuron?
Unidirectionally
What are the three coverings of the peripheral nervous system?
Endoneurium - covers the axon and is involved with Schwann cells
Perineurium - surrounds groups of axons known as fascicles
Epineurium - robust connective tissue that surrounds fascicles and contains blood vessels
What is chromatolysis?
When Nissl bodies (for protein synthesis) of the neuron begin to die therefore staining does not effectively occur
What are the functional groups of neurons?
Sensor (afferent) - AP towards CNS
Motor (efferent) - AP away from CNS
Interneurons - connect one neuron to the other
What are the structural group of neurons?
Unipolar - neurons with single process that often divide into two branches to CNS and peiphery
Bipolar - sensory neurons in retina of eye and olfactory system
Multipolar - most neurons in CNS eg motor neuron
What does an axo-dendritic synapse do?
Converts an electrical signal to a chemical one and then back to an electrical signal
What is convergence?
When pre-synaptic nerves converge onto one post synaptic neuron
What is divergence?
Most pre-synaptic nerve axons divide into branches and end on many post-synaptic neurons
What are the main types of neuroglia?
CNS: Astrocytes, oligodendrocytes, ependymal cells microglia
PNS: Schwann cells
What is an astrocyte and what does it do?
Star-shaped cell that fills spaces between neurons and forms glial limitans
Regulates water, neurotransmitter and K+ levels
inhibits axon regeneration
What is the job of a oligodendrocyte?
‘many branched cell’ - it myelinates glia in CNS and inhibits axon regeneration
What does an ependymal cell do?
Line brain ventricles and spinal cord, specialised versions create the choroid plexus that secretes cerebrospinal fluid within the brain ventricles
What are microglia?
Specialised macrophages that respond to inflammation and remove necrotic tissue or foreign bodies in CNS
What are Schwann cells?
They wrap around one part of an axon in PNS to create myelin sheath, they can be phagocytic and promote axon regeneration
Myelin allows for rapid propagation of an action potential
