Lecture 5 8/30/23 Flashcards
What are the two parts of the central nervous system?
-brain
-spinal cord
What are the two parts of the peripheral nervous system?
-nerves
-ganglia
What does the central nervous system arise from?
neuroectoderm
What does the peripheral nervous system arise from?
neural crest cells
What are the characteristics of neurons?
-main part of cell
-contains the nucleus
-found in the grey matter
What is the role of dendrites?
receive signals and relay them to the neuron nucleus
What is the role of axons?
convey signals away from neuron nucleus and to cells/target tissues
What is the role of axon terminals?
transfer signals to next neuron or target tissue (synapse)
What are astrocytes?
-most common neuroglia cell in gray matter
-support and nurture the neuronal cell bodies
-fill the space between neuronal cell bodies
-form blood-brain barrier
How do neuron cells arrange between gray and white matter?
-gray matter contains neuronal cell bodies
-white matter contains axons
What is neuropil?
the “pink stuff” between nuclei that contains the axons, dendrites, etc.
What are microglia?
-mesenchymal cells
-macrophages of the brain
What are ependymal cells?
cells that line the ventricles of the brain and central canal of the spinal cord
What are oligodendroglia?
-most numerous cells in white matter
-wrap around axons to myelinate them
What is the equivalent of oligodendroglia in the peripheral nervous system?
Schwann cells
How do oligodendroglia myelinate the axons?
branches of the oligodendroglia cell will wrap around multiple axons and arrange down the entirety of each axon
What are the gaps between oligodendroglia cells?
nodes of Ranvier
What is the importance of myelination and nodes of Ranvier?
-action potentials move node to node rather than down entire axon
-makes the process faster
What is different about how oligodendroglia cells and Schwann cells myelinate axons?
-one oligodendroglia cell myelinates multiple axons
-one Schwann cell myelinates only one axon
What are non-myelinated axons?
-provide pain sensation
-less myelination, but still myelinated
-slower conduction
-multiple axons “embedded” in a single Schwann cell
What is the function of the choroid plexus?
makes the cerebrospinal fluid
What are the characteristics of the cerebral spinal fluid?
-bathes/nurtures central nervous system
-gets re-absorbed into blood
-constant turnover
What is hydrocephalus?
when too much water is in the ventricles, leading to them becoming enlarged
What are the characteristics of the meninges?
-connective tissue layers
-support blood vessels
-contain CSF
-tether brain to bone
What are the three layers of the meninges, from outermost to inner most?
-dura mater
-arachnoid mater
-pia mater
What is meningitis?
inflammation of the meninges
What are the sections of the brain?
-cerebrum
-cerebellum
-brainstem
How are grey matter and white matter arranged in the cerebrum and cerebellum?
-gray matter outside
-white matter inside
What are gyri?
raised portions of the cerebrum
What are sulci?
the grooves on the cerebrum
What is laminar cortical necrosis?
death of neural cell bodies in the laminar cortex
What is the laminar cortex?
various layers of tissue that make up the cerebrum
How can you determine whether the brain matter you are looking at microscopically is grey or white matter?
-linearity = axons =white matter
-more uniformity = oligodendroglia only = white matter
Why is the cerebellum also known as the tree of life?
the arrangement of white matter within the gray matter looks like a tree
How is the cerebellum microscopically arranged?
gray matter:
-outer molecular layer
-row of Purkinje cells
- inner granular cell layer
white matter
What are the characteristics of the brainstem organization?
-gray matter and white matter mixed
-“nuclei” of gray matter dispersed within white matter
How are gray matter and white matter arranged in the spinal cord?
-gray matter on the inside (butterfly shape)
-white matter outside
What is the central canal?
a canal through the spinal cord containing CSF
What are sensory nerves?
nerves that bring impulses to the spinal cord from the body
What are interneurons?
nerves that transmit signals between the sensory and motor nerves
What are motor nerves?
nerves that send impulses from the spinal cord to the target tissue
What are ganglia?
collections of neurons in the peripheral nervous system
What is the role of ganglia?
to relay signals from target tissues
What are satellite cells?
the supportive cells of the peripheral nervous system
How do nerves travel?
to the target tissues
What is a collection of axons called in the CNS?
tract
What is a collection of axons called in the PNS?
nerve
