Flashcards in SDL-2 Neurotcytology & CSF Deck (87):
Neurons are said to be __________, based upon their ability to respond to the environment and activity with morphological changes.
The neuronal _______ is the metabolic (trophic) center for the neuron.
Soma (cell body)
(T/F) The size of neuronal somas are uniform throughout all neurons.
False. The size of the soma depends upon the function of the neuron, and to a large extent, the length of its processes, the axon in particular.
What effect does axon length have upon the soma?
The longer the axons a neuron possesses, the larger the diameter of the soma.
In general, the dorsal horn contains ________ neurons.
In general, the ventral horn contains ________ neurons.
The three shapes of neurons are __________, __________, and ___________.
Pseudounipolar; bipolar; multipolar
(Pseudounipolar/Bipolar/Multipolar) neurons have a single process that extends from the soma and then bifurcates.
(Multipolar/Pseudounipolar/Bipolar) neurons have two processes that extend from the soma, one of which is an axon, and the other a dendrite.
(Bipolar/Multipolar/Pseudounipolar) neurons have one axon and two or more dendrites extending from the soma.
The most common type of neuron is a (pseudounipolar/multipolar/bipolar) neuron.
(Bipolar/Multipolar/Pseudounipolar) are restricted to the sensory system and are found almost exclusively within the peripheral nervous system.
(Pseudounipolar/Bipolar/Multipolar) neurons are the most rare shape and are found predominately in the peripheral nervous system.
Rough endoplasmic reticulum that has been organized into parallel cisternae with numerous polyribosomes (polysomes) between them is termed ___________.
Nissl substance or bodies
Nissl bodies and ribosomes are found throughout every part of the neuron except for the __________.
Transport away from the soma is termed ________.
Transport toward the soma is termed _________.
Microtubules involved in transport are more numerous in (axons/dendrites).
Intermediate filaments used for cytoskeleton structure and found in neurons are known as ____________.
A granule found in neurons that consists of material undigested by lysosomes is known as a(n) __________.
(T/F) Lipofuscin granules are greater in young nervous systems due to underdeveloped lysosomes. These lipofuscin granules dissipate as lysosomes mature.
False. Lipofuscin granules are greater in older nervous systems as material undigested by lysosomes increases with age.
Peripheral dorsal root ganglion (DRG) processes (sometimes referred to as dendrites) involved in pain and temperature are (unmyelinated or lightly myelinated/heavily myelinated).
Unmyelinated or lightly myelinated
Peripheral DRG processes (sometimes referred to as dendrites) involved in touch, vibration, and joint position sense are (unmyelinated or lightly myelinated/heavily myelinated).
Neuronal dendrites are generally highly branched, also referred to as being _________.
The region of the soma that the axon originates from is called the __________.
The axon hillock may be distinguished from other cytoplasmic extensions by ________________.
The absence of Nissl bodies
(Neurofilaments/Microtubules) predominate over (neurofilaments/microtubules) in the cytoplasm of the axon (axoplasm).
Neurofilaments predominate over microtubules.
(Neurofilaments/Microtubules) predominate over (neurofilaments/microtubules) in the cytoplasm of the dendrite.
Microtubules predominate over neurofilaments.
(T/F) Unlike dendrites, an axon may leave the CNS and enter the periphery.
Slow axoplasmic transport occurs at a rate of ___________ per day.
Fast axoplasmic transport occurs at a rate of ____________ per day.
The types of macroglia are ____________ and ___________.
Astrocytes that contain an abundance of ___________ are classified as fibrous astrocytes.
Glial fibrillary acidic protein (GFAP)
Astrocytes whose processes do not contain much GFAP are termed ___________.
Protoplasmic astrocytes are found in (gray matter/white matter/both gray and white matter) of the CNS.
Fibrous astrocytes are found in (gray matter/white matter/both gray and white matter) of the CNS.
Both gray and white matter
Astrocytes may affect axon regeneration in what way?
Following an injury to the CNS, astrocytes will proliferate and may wall off the injured area, a process that interferes with axonal regeneration.
The nucleus of an astrocyte is (round/ovoid) in shape, while the nucleus of an oligodendrocyte is (round/ovoid).
Astrocyte = ovoid
Oligodendrocyte = round
Oligodendrocyte nuclei tend to stain (lighter/darker) than astrocyte nuclei.
A(n) _______________'s primary function is myelination of CNS axons, analogous to Schwann cells in the peripheral nervous system.
(T/F) The soma of neurons are sometimes myelinated based upon their function within the nervous system.
False. The soma of a neuron is NEVER myelinated.
In contrast to the rest of the CNS, microglia are of (endodermal/mesodermal/ectodermal) origin.
A microglia's primary function is to participate in ______________.
Inflammatory responses and phagocytic activities
Ependymal cells originated from the proliferative layer of the ____________ and may be found lining the __________.
Neural tube; interior of the CNS
Ependymal cells' primary function is to ______________________.
Regulate transfer of substances between the neuropil and CSF
(T/F) Zonula adherens and zonula occludens are both present laterally between all ependymal cells.
False. Zonula adherens and gap junctions are present but zonula occludens are only present in specialized regions.
Zonula adherens and zonula occludens are both present laterally between all (ependymal/choroidal epithelial) cells.
The function of the choroidal epithelium is _______________________.
The secretion of CSF
The H- or butterfly-shaped portion of the spinal cord consists of (white/gray) matter.
The term _________ refers to the areas of gray matter that consist of intermingled processes such as dendrites and axonal endings.
Constituents of gray matter include:
I. Somata (neuronal cell bodies)
II. Dendritic arbors (trees)
III. Axons arising from somata
IV. Terminal portions of axons that participate in synapses
V. Protoplasmic astrocytes
VI. Non-myelinating oligodendrocytes
VIII. Rich vasculature
Neuronal cell bodies are organized in what two ways within the CNS?
I. Nuclear organization
II. Laminar organization
A cluster of neuronal cell bodies each possessing a similar function is referred to as a(n) _____________.
Neuronal somata (cell bodies) organized into a layer of similar types is known as a(n) ____________.
(Gray/White) matter surrounds the H- or butterfly-shaped section of the spinal cord.
White matter is found (superficial/deep) to the cerebral cortex and cerebellum.
Constituents of white matter include:
I. Myelinated axons
II. Myelinating oligodendrocytes
III. Fibrous astrocytes
V. Poor vasculature
A(n) _____________ is the site of contact between the axon of one neuron and a portion of another neuron; an interface between the two neurons that usually occurs on the dendritic arbor or tree.
A synapse between an axon and a dendrite is referred to as ___________.
A synapse between the soma of two neurons is referred to as ____________.
(T/F) The most common synapse is a somosomatic synapse, which is a synapse between the soma of two neurons.
False. The most common synapse is an axodendritic synapse, which is a synapse between an axon and a dendrite.
The small space observed between two neurons at the EM level when attempting to view a synapse is the _____________.
The (presynaptic/postsynaptic) cell contains the neurotransmitters to be released across the synaptic cleft.
The expanded portion of an axon that forms the presynaptic portion of a synapse is referred to as the ___________.
Bulb or bouton
The markedly thickened cytoplasmic membrane and the cytoplasm immediately deep to this membrane that receive the neurotransmitters is termed the ______________.
(Neurosecretory/Electrical/Chemical) synapses involve the release of neurotransmitters from vesicles into the cleft where they affect the postsynaptic membrane.
(Electrical/Neuromuscular/Secretomotor) synapses form when plasma membranes from two neurons come into close proximity to form gap junctions with a 2nm distance between the cells.
The typical distance between neurons in a chemical synapse is _________.
(Electrical/Secretomotor/Neuromuscular) synapses occur between an axon and muscle cells.
If a neuromuscular synapse ends upon skeletal muscle, the terminal is referred to as a(n) ___________.
How does a neuromuscular synapse that ends upon cardiac or smooth muscle differ from one that ends upon skeletal muscle?
The axon that ends on cardiac or smooth muscle terminates in a number of small boutons which release their neurotransmitters over a widespread area.
The axon that ends on skeletal muscle releases its neurotransmitters at a small, specialized site on a skeletal fiber.
(Neuromuscular/Chemical/Secretomotor) synapses refer to synapses between a neuron and a glandular cell.
(Neuromuscular/Neurosecretory/Secretomotor) synapses refer to axons that terminate freely near fenestrated (possessing small holes or windows) capillaries and release large vesicles of neurotransmitters or hormones that are distributed by the vascular system, such as between the neurons of the hypothalamus and the pars nervosa of the hypophysis.
The most common synapse is a(n) __________ synapse.
(T/F) Astrocytes seem to determine the nodes of Ranvier.
Cerebrospinal fluid is an ultrafiltrate of plasma that is produced by selective transmission of blood-borne components through the _______________.
CSF circulates throughout the ventricular system and subarachnoid spaces and is resorbed by _____________ back into the venous system.
__% of CSF is produced in the choroid plexus in the lateral and fourth ventricles.
Choroidal epithelium secretes ____ and _____ in the formation of CSF.
Na+ and HCO3-
The remaining 20% of CSF is formed by the small amount of choroid plexus found in the roof of the __________.
CSF comprises about __-__% of intracranial volume.
The blood brain barrier (BBB) excludes ___________ and limits the entry of __________ soluble molecules.
Macromolecules; non-lipid soluble
On average, ____ ml of CSF is produced daily by the lateral ventricles.
Pathology of CSF physiology can usually be attributed to what three causes?
I. Over/underproduction of CSF
II. Impediments to CSF circulation
III. Over/under absorption of CSF
Overproduction of CSF is usually attributed to ______________, which can produce up to four times the normal amount of CSF.
Choroid plexus papillomas
Congenital or acquired stenosis of the cerebral aqueducts that prevent normal CSF egress and results in dilated lateral ventricles, dilated third ventricles, and a small fourth ventricle is termed _____________________.
Non-communicating or obstructive hydrocephalus