Nervous System Flashcards
Central Nervous System
brain and spinal cord.
What is the CNS derived from?
neuroectoderm
Peripheral Nervous System
nerves and ganglia
What is the PNS derived from?
neural crest cells
Nerves
carry signals from the CNS to the target tissues.
Ganglia
collection of neurons that relay signals to target signals
Parts of Neuron
cell body (soma), nucleus, dendrites, axon, axon terminals
Dendrites
receive signals from other tissues or nerves and relay them to the nucleus for processing
Axon
signals head away from the nucleus on their way to other nerves or effector tissues
Axon Terminals
signal passed to another neuron at a synapse or transferred to effecter tissues at neuromuscular junctions
Neuroglia
cells that support and surround neurons. Provide half the mass of the cells. Provide mechanical and metabolic support
Gray Matter
parts of the brain with a high density of neuronal cell bodies. Unevenly sized neurons
White Matter
where there are clusters of neurons’ axons
Astrocytes
the most numerous neuroglial cells in the gray matter. Protect and nurture neurons, fill much of the space between neurons. Surround blood vessels to form blood-brain barrier
Microglia
mesenchymal cells. Have immune function and are considered part of the macrophage-monocyte defense system
Ependymal Cells
cuboidal cells that line the ventricles of the brain and spinal canal. May have cilia or micorvilli
Oligodendrocytes
most numerous neuroglial cells in white matter. Surround axons and form the myelin.
Schwann Cell
neuroglial cells in white matter of PNS
Nodes of Ranvier
gaps between Schwann Cells
Histologic appearance of myelin
myelin is fatty and lost in processing so all you see are clear spaces surrounded by the pink of the Schwann cytoplasm
Cross Section
tiny pink circles = axons
Surrounded by clear space = myelin
Scattered nuclei
Longitudinal Section
pink lines (axons) surrounded by bubbly clear spaces (myelin) and some pink stuff (Schwann cytoplasm). Scattered nuclei
Choroid Plexus
makes the cerebrospinal fluid that bathes and nurtures CNS.
What reabsorbs cerebrospinal fluid?
arachnoid villi
Hydrocephalus
failure of cerebrospinal fluid to be reabsorbed; results in accumulation of fluid and dilation of the ventricles
Meninges
connective tissue layers that surround the CNS.
Provides support for the blood vessels that feed the brain and spinal cord
Keep the cerebrospinal fluid close to the brain and spinal cord
Tether the brain and spinal cord to the overlying bone
Layers of Meninges
Pia Mater, Arachnoid Mater, Dura Mater
Cerebrum
cranial 2/3 of brain. gray matter on outside and white matter inside. Neurons arranged in layers called laminar cortex.
Cerebellum
caudal 1/3 of brain. Has Purkinje cell layer between gray and white matter
Nuclei
collections of neurons in CNS
Spinal Cord
white matter outside, gray matter inside. Central canal runs through the middle. Surrounded by meninges
Ganglia
collections of neurons in the peripheral nervous system. located near the spinal cord and scattered throughout the body. Supportive neuroglial cells called satellite cells
Nerves
collections of neurons in the PNS. carry signals from the CNS to target tissues. supportive neuroglial cells called Schwann cells
What is a collection of axons in the CNS?
tract
What is a collection of axons in the PNS?
nerve
