P1: Histology of the nervous system Flashcards
What is a multipolar neuron?
A neuron with a single axon and multiple dendrites
Name the important structures of a neuron
- Dendrites
- Soma/body
- Axon
- Synaptic terminal
- Myelin sheath associated with neuron
Where would you find a multipolar neuron?
alpha motor neuron located in ventral horn
Where would you find a bipolar neuron?
Sensory neuron in the retina
Where would you find a pseudounipolar neuron?
Cell body located in the DRG - sensory neurons
What is the ratio of neurons:glial cells in the human nervous system?
1:10
What is grey matter?
Grey matter is the tissue in the CNS which contains neuronal cell bodies, neutropil, and glial cells (astrocytes and oligodendrocytes.
What is white matter?
Tissue in CNS which contains mainly myelinated axons and glial cells.
How do you tell the ventral from dorsal surface of the spinal cord?
Ventral surface has a much wider median tissue.
Where do upper motor neurons reside?
Primary motor cortex (pre-central gyrus)
Where do lower motor neurons (alpha motor neurons) reside?
Ventral horn of spinal cord
What do lower motor neurons innervate?
Skeletal muscles
What is a Nissl body?
Granular accumulation of RER in the soma of a neuron
What is the term used to describe a collection of neuron cell bodies in the CNS?
Nucleus
What is a ganglia?
Collection of cell bodies in the PNS
What structural type of neuron is found in the DRG?
Pseudounipolar
What is the node of Ranvier and what is the functional significance?
Small ‘gaps’ or ‘joints’ between myelin sheath segments which cause the action potential to ‘jump’ from node to node for faster transmission of the AP to the target.
What are the four types of neurons as described by their connections?
- Motor neurons
- Sensory Neurons
- Interneurons
- Projection neurons
What structure are most motor neurons?
Multipolar
What structure is the common sensory neuron, and what structure are some special sensory neurons (e.g. optic)
Common = pseudo unipolar
Special sensory = bipolar
What are projection neurons - structurally and functionally
Structurally usually multipolar. They connect distant parts of the CNS with each other e.g. neuron to neuron from one hemisphere to the other
What are interneurons - structurally and functionally?
Generally multipolar, but follow the structure of the communication in they are in. They connect different local areas of CNS e.g. in reflex arcs within the spine between motor & sensory, as well as between 1st 2nd order neurons etc.
What are the four types of glial cells found in the CNS?
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocyte
What are the two types of glial cell found in the PNS?
- Schwann cell
2. Satellite cell (modified Schwann cell)
