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117 Cards in this Set

  • Front
  • Back
What's another name for spinal ganglia?
Dorsal root ganglia.
Where are spinal ganglia found?
The dorsal roots of spinal nerves.
What kind of impulses do spinal ganglia carry?
Afferent sensory impulses.
What do dorsal root ganglia look like in a microscope?
Little fried eggs.
Where is the gray matter in the spinal cord?
Located most interiorly.
Where is the white matter in the spinal cord?
Located to the outside of the gray matter.
Does the ventral root of a spinal nerve contain ganglia?
No.
Which side of the spinal cord is the dorsal root on? The ventral root?
Dorsal is posterior; ventral is anterior.
What do the dorsal horns of spinal nerves do?
They innervate sensory nerves.
What do the ventral horns of spinal nerves do?
They innervate muscles.
What's a perikaryon?
A soma or neuron cell body.
Are cell bodies of dorsal root ganglia involved in nerve transmission?
No.
In the dorsal root, a group of several ____ surrounds each perikaryon. What functions do these serve?
Glial cells. They are satellite cells that provide support services.
How are the cell bodies distributed in the dorsal root?
They're unevenly distributed--found in groups fairly close to the periphery.
What is Nissl substance?
RER found in neurons. It usually stains a dark purple and makes up the "white" of the "fried egg" look.
What is a ganglion?
A collection of cell bodies found in the PNS.
What's the function of autonomic ganglia? Where are they located?
They are clusters of motor neuron cell bodies in the PNS. They serve as a junction between autonomic nerves originating from the CNS and autonomic nerves innervating their target organs in the periphery. They include the synapses between pre- and post-ganglionic autonomic nerves.
What are the two types of autonomic ganglia?
Sympathetic and Parasympathetic.
What's the cerebral cortex?
The thin outer layer (4mm) of gray matter that covers the external surfaces of the cerebral hemispheres and is superficial to the white matter.
What are gyri and sulci?
Folds in the cerebral cortex. More than 2/3 of the cortical surface area is "buried" in the sulci.
In the brain, what is contained in gray matter?
Neuronal cell bodies, their dendrites, and glial cells.
In the brain, what is contained in the white matter?
The outgoing axons of cortical neurons, incoming axons, and glial cells.
How many layers are in the cerebral cortex?
6.
Name the layers of the cerebral cortex, from surface to interior.
Molecular Layer, External granular layer, External pyramidal layer, Internal granular layer, Internal pyramidal layer, Polymorphic/Multiform layer.
How many neurons are in the brain?
10-14 billion.
What characterizes the molecular layer of the cerebral cortex?
Few scattered neurons; consists mainly of extensions of apical dendritic tufts of pyramidal neurons and horizontally-oriented axons, as well as glial cells.
What characterizes the external granular layer of the cerebral cortex?
Contains small pyramidal neurons and numerous stellate neurons.
What characterizes the external pyramidal layer of the cerebral cortex?
Has predominantly small and medium sized pyramidal neurons as well as non-pyramidal neurons with vertically-oriented intracortical axons.
What characterizes the internal granular layer of the cerebral cortex?
Contains different types of stellate and pyramidal neurons.
What characterizes the internal pyramidal layer of the cerebral cortex?
Contains large pyramidal neurons.
What is the meninges?
The system of membranes which envelops the CNS. Consists of dura mater, arachnoid layer, and pia mater.
The axon of a pyramidal cell extends into the ____.
White matter.
What are the efferent cells of the cerebral cortex?
Pyramidal cells.
The ____ of a pyramidal cell points toward the cortical surface.
Apex.
Pyramidal neurons comprise about __% of the cells in the cerebral cortex.
80%
What neurotransmitter do pyramidal cells use?
Glutamate; this makes them the major excitatory component of the cortex.
Are pyramidal cells input neurons or output neurons?
Output neurons; they transmit signals to other parts of the CNS.
T/F: Both the cerebrum and the cerebellum contain gyri and sulci.
True.
What four important functions is the cerebellum responsible for?
Coordination of voluntary motor movement, balance, equilibrium, and muscle tone.
How many layers are in the cerebellar cortex? What are they?
3. Molecular layer (outer), Purkinje cell layer, and Granular layer (inner).
In the brain, where would you find basket cells and stellate cells?
The molecular layer of the cerebellar cortex.
Where do Purkinje cells send their axons? Their dendrites?
Axons into white matter, dendrites into the molecular layer.
What's the most cellular layer in the cerebellar cortex?
The granular layer.
What are granule cells?
Very small neurons with nuclei about the same size and shape as lymphocytes.
Where do the axons of the granule cells project?
Into the molecular layer of the cerebellar cortex.
These are some of the largest neurons in the brain.
Purkinje cells.
What's characteristic of Purkinje cell dendrites?
They look like a tree with all their branching.
The meninges are membranes covering the ____ and ____.
Brain; spinal cord.
What is the main function of the meninges and the CSF?
To protect the brain and the spinal cord.
This layer of the meninges is outermost and is made up of dense, fibrous cx tissue that is impermeable and tough.
Dura mater.
What can neural tube defects result in?
Spina bifida.
Describe the steps of early NS development.
1) Neural plate begins to thicken.
2) Somites appear on either side of now folding neural groove.
3) Folding complete; now there is a neural tube. Neural crest cells appear.
4) Spinal cord develops from neural tube.
Which part of the NS issues commands?
CNS.
What does the somatic nervous sytem do?
Relay motor impulses (from CNS) and sensory impulses (to CNS).
What does the autonomic NS do?
Maintains body's homeostasis--regulates heart beat, blood vessels, digestive, respiratory, and urinary tracts; stimulates glands to secrete mucous, tears, and digestive enzymes.
Describe the general structure of the spinal cord.
Gray matter is deep to white matter. Butterfly shape, ventral horns wider than dorsal. White matter is cortical and has tracts. Spinal nerves are attached to spinal cord via ventral and dorsal roots.
What are groups of nerve cell bodies in the CNS called?
Gray matter.
What are groups of nerve cell bodies in the PNS called?
Ganglia.
What are groups of nerve cell processes in the CNS called?
White matter.
What are groups of nerve cell processes in the PNS called?
Nerve fibers or bundles.
In the spinal cord, where does communication between neurons via synapses occur?
In the gray matter.
How many spinal nerves are there?
31.
In the spinal cord, what does white matter mostly consist of?
Myelinated nerve fiber bundles.
Describe the arachnoid layer.
A layer of very loose cx tissue lying between the dura and the pia. CSF occupies the arachnoid space. Fluid-filled spaces are sometimes called "sub-arachnoid," but are actually in the arachnoid layer.
Describe pia mater.
Innermost layer of the meninges. It's a delicate layer of collagen and fibroblast-like cells.
What are the two layers of the dura mater?
The periosteal layer and the meningeal layer.
What are ependymal cells?
Located in certain regions of the brain, they create the structure (choroid plexus) that is responsible for the creation of CSF.
Where do you find ependymal cells?
In the whole path from the lateral ventricles to the third ventricle, to the aqueduct to the fourth ventricle to the central canal within the spinal cord. In some places the ependymal tissue forms the choroid plexus, which makes/secretes CSF.
Histologically, what are ependymal cells?
Simple cuboidal epithelium. And they have cilia.
Where is the choroid plexus?
Within the brain ventricles.
What are the two broad cell types in the NS?
Neurons and Supporting (Glial/Neuroglia) cells.
What's the main functional unit of the NS?
The neuron.
What are other words for neuron cell bodies?
Perikaryon or soma.
What's the RER in soma called?
Nissl.
What is a unipolar neuron?
One with no dendrites.
What is a multipolar neuron?
One with multiple dendrites.
What are the two chief purposes of the axon hillock?
1) Connect the cell body to the axon.
2) Sum up EPSPs and IPSPs.
What cytoskeletal structure do axons contain and what do they do?
MTs and MT-associated proteins. They provide tracks for transport along the axon.
What protein is involved in anterograde transport along an axon?
Kinesin.
What protein is involved in retrograde transport along an axon?
Dynein.
What are the 3 major types of neurons?
Sensory neurons, motor neurons, and interneurons (aka association neurons).
Nissl substance is not found in this cell process.
The axon.
Size-wise, how do glial cells compare to neurons?
They're smaller.
Relative to other tissues, how much connective tissue does nervous tissue contain?
Not a lot.
What cells in nervous tissue provide support and protection for neurons?
Glial cells.
What cells in nervous tissue modulate the transmission of nerve impulses?
Glial cells.
What type of cells in the nervous system are typically responsible for becoming tumors?
Glial cells.
List the types of glial cells, from largest to smallest.
Astrocytes, Oligodendrocytes, Microglia.
What are "oligodendrocytes" of the PNS called?
Schwann cells.
What is the analogue of Schwann cells called? What part of the nervous system are those cells in?
Oligodendrocytes, and they are in the CNS.
In a slide, what will microglia look like?
Rectangular.
In a slide, what will oligodendrycytes look like?
Dark, round, often with a halo.
In a slide, what do astrocytes look like?
Round to oval, not as dark as oligodendrocytes, and nuclei can be a bit larger.
What are there more of--neurons or glial cells? By how much?
Glial cells 10:1
What are the most abundant glial cells?
Astrocytes.
What are the major functions of astrocytes?
1) Provide structural support to neurons.
2) Help regulate external chemical environment of neurons, thus modulating neuronal activity, by removing excess ions and recycling neurotransmitters.
3) Regulating capillary blood flow via production of arachidonic acid metabolites.
4) Supplying glucose needed in the brain.
5) Maintaining the blood-brain barrier.
How are astrocytes connected with each other?
Gap junctions.
What do microglia derive from?
From blood-borne monocytes. Mesodermal origin.
What's the point of microglia?
Phagocytic cells that act as the first line of defense against foreign invaders in the brain.
What do microglia look like?
Small cells with elongated bodies, elongated nuclei, dense chromatin and relatively few processes.
What cells are found in all regions of the brain and spinal cord and comprise about 15% of the cells in the CNS?
Microglia.
What are ependymal cells?
Cuboidal or low-columnar cells that form a single layer lining the internal cavities (ventricles) of the brain and the central canal of the spinal cord. Their apical surfaces have cilia, which helps circulate CSF around the CNS and to the subarachnoid space.
Within the brain's ventricles, modified ependymal cells, loose connective tissue, and capillaries together form the ____, which produces CSF.
Choroid plexus.
What do oligodendrycytes and Schwann cells do?
Wrap around axons and form the myelin sheath.
Where are oligodendrocytes found?
Both the gray and white matter of the CNS.
What forms the myelin sheaths around peripheral nerves?
Schwann cells.
What purpose do Schwann cells serve aside form forming myelin sheaths?
They have phagocytic activity and they clear cellular debris that allows for regrowth of PNS neurons.
Describe the structure/function of a myelin sheath.
Made of concentric wrappings of Schwanns or oligodendrocytes. The wrappings unite to form a lipoprotein complex that appears fatty and whitish and serves as insulation/protection and serves to increase the speed of AP propagation. Interrupted at intervals by nodes of Ranvier.
Besides their location, what's an important difference between Schwann cells and oligodendrocytes?
A single oligodendrocyte can provide sheaths for several axons. Also, there is no endoneurial connective tissue sheath, and the nodes of Ranvier are larger and exposed to the extracellular space in oligodendrocytes.
Discuss non-myelinated nerve fibers.
Axons of small diameter are usually non-myelinated fibers. They're found in both the CNS and PNS. Postganglionic fibers of the autonomic nervous system are non-myelinated. The axons are enclosed in simple clefts of oligodendrocytes or Schwann cells. Each Schwann cell or oligodendrocyte may enclose several non-myelinated axons.
Are post-ganglionic fibers of the autonomic nervous system myelinated?
No.
When we say "nerve," what are we actually referring to?
Bundles of nerve fibers (neurons) that are all traveling in the same direction and are bound together, though different fibers may have different functions. There are no cell bodies in nerves!
Where are nerve cell bodies located?
Either in the CNS or in ganglia in the PNS.
In the NS, what's a fascicle?
A grouping of axons surrounded by a Cx tissue called endoneurium and packed in another Cx tissue called perineurium.
What is the composition of a nerve bundle?
A whole nerve bundle is composed of several fascicles surrounded by the epineurium and a layer of fat surrounding everything, plus the associated blood vessels.
In a cross section of a peripheral nerve, if nuclei are visible what cells do they belong to?
NOT neurons. They belong to Schwann cells or fibroblasts.
In an H&E slide, how would you distinguish a peripheral nerve from smooth muscle or collagen?
Nerves are surrounded by an epineurium and tend to appear somewhat paler in color.