Histology of CNS Flashcards
A typical neuron has a cell body with a large nucleus with a well-developed nucleolus and _______ _______.
Nissl bodies
***These contain RER and free ribosomes
In a typical neuron, numerous dendrites extend from the perikaryon (cell body with nucleus). There is extensive branching and numerous _______ _______ that increase the receptive area.
Dendritic Spines
Dendritic spines are _________.
Plastic
Long axons emerge from an…
Axon hillock
This is a dense network of nerve fibers and their branches and synapses, together with glial filaments.
Neuropil
What are the 4 structural classifications of neurons?
Multipolar
Unipolar
Bipolar
Anaxonic
This type of directional transport carries material from the nerve cell body to the axon.
Anterograde Transport
Anterograde Transport utilizes ________, a microtubule-associated motor protein.
Kinesin
This type of directional transport carries material from the axon terminal to the cell body, or from the dendrites to the cell body.
Retrograde Transport
Retrograde Transport utilizes ________, a microtubule-associated motor protein.
Dynein
Anterograde movement of substances is (FAST/SLOW) transport, with a speed of 0.2-4 mm/day. Typically cytoskeletal elements.
Slow
Retrograde movement is (FAST/SLOW) transport because it involves bidirectional movement of organelles. Speed is 20-400 mm/day and may include endocytose toxins and viruses.
Fast
Nerve impulses are transmitted from one neuron to ________ cells.
Effector
Synaptic transmission is (UNIDIRECTIONAL/BIDIRECTIONAL).
Unidirectional
Synaptic communication converts a (CHEMICAL/ELECTRICAL) signal (nerve impulse) from a presynaptic cell to a (CHEMICAL/ELECTRICAL) signal that affects the postsynaptic cell.
Electrical
Chemical
What is the chemical signal usually caused by?
Neurotransmitters
This part of the chemical synapse contains mitochondria and synaptic vesicles. It releases neurotransmitters via exocytosis.
Presynaptic terminal bouton
A 20- to 30-nm wide intercellular space, called the ________ ________, separates the pre- and postsynaptic membranes.
Synaptic cleft
What does the postsynaptic membrane contain?
- Receptors for neurotransmitters
- - Ion channels to initiate a new impulse
An electrical synapse is a direct, passive flow of electrical current between neurons via _______ _______. These contain ________ that link pre- and postsynaptic membranes.
Gap Junctions
Connexons
These cells have a large number of long, branching processes. Proximal regions are reinforced with intermediate filaments made of glial fibrillary acid protein (GFAP).
Astrocytes
These cells form a vast network of delicate terminals contacting synapses and other structures. The terminal processes of a single cell typically associates with over 1 million synaptic sites.
Astrocytes
These cells extend processes that enwrap nearby axons in myelin, only in CNS. Enwrap axons from multiple neurons, and a single axon may be enwrapped by many of these cells.
Oligodendrocytes
Oligodendrocytes usually appear as small cells with rounded, condensed nuclei and unstained _________.
Cytoplasm
These cells are columnar or cuboidal and line the brain ventricles and the central canal of the spinal cord. Apical end may have cilia and long microvilli to facilitate movement of CSF and for absorption.
Ependymal cells
Ependymal cells are joined apically by apical junction complexes and they have no…
Basal lamina
This is found in the roofs of the 3rd and 4th ventricles and parts of the lateral ventricular walls. It removes water form the blood and releases it as CSF.
Choroid Plexus
The Choroid Plexus is a thin, elaborated folded layer of well-vascularized ______ ______ covered by cuboidal _______ cells.
Pia Mater
Ependymal
What ions does CSF contain?
Na+
K+
Cl-
CSF has very little protein and only cells include sparse _________.
Lymphocytes
This is what is responsible for the absorption pathway of CSF back into the venous circulation.
Arachnoid Villi
This structure is a branching system of blood vessels which run in fronds composed of a fibrous core covered by cuboidal/columnar epithelium.
Villous structure
In a villous structure, capillaries and vessels are large, thin-walled and epithelial cells rest on a basal lamina. Long bulbous _________ project from the epithelial cells.
Microvilli
These lie between epithelial cells, contributing to a blood-CSF barrier.
Tight junctions (zonula occludens)
These cells are less numerous than oligodendrocytes or astrocytes. They are migratory and will remove damaged or inactive synapses or other fibrous components.
Microglia
Microglia are a major mechanism of immune defense in the CNS, removing any microbial invaders. They originate from _________.
Monocytes
This is a fibrous intercellular network of cellular processes emerging from neurons and glial cells.
Neuropil
In the Spinal Cord, the central mass of _______ matter has the shape of a butterfly. This is made up of ventral, dorsal, and lateral horns.
Gray
The lies in the central commissure of gray matter. It is lined by ependymal cells and contains CSF.
Central Canal
White matter consists of ascending tracts of (MOTOR/SENSORY) fibers and descending tracts of (MOTOR/SENSORY) fibers.
Sensory
Motor
What are the three layers of the Cerebellar Cortex?
1) Molecular layer
2) Purkinje cells
3) Granular layer
This layer of the cerebellar cortex has much neuropil and scattered neuronal cell bodies.
Molecular layer
This layer of the cerebellar cortex extends dendrites throughout the molecular layer as a branching basket of nerve fibers. Conspicuous in H&E stained sections.
Purkinje cells
This layer of the cerebellar cortex contains various very small, densely packed neurons (i.e., granule cells) and little neuropil.
Granular layer
The cerebellar cortex is organized into ________ with the cerebellar medulla located deep.
Folia
Biologically older parts of the Cerebral Cortex are arranged into three layers, called the…
Archicortex
Most of the Cerebral Cortex is called _________ and consists of six layers. It has a variety of cells and is divided into five different morphological types.
Neocortex
The Neocortex has a variety of cells, divided into five different morphological types which are…
Pyramidal cells Granule (stellate) cells Cells of Martinotti Fusiform cells Horizontal cells of Cajal
This cell in the Neocortex has a pyramid-shaped cell body with the apex directed toward the cortical surface.
Pyramidal cells
Huge upper motor neurons of the motor cortex, called ______ cells, are the largest pyramidal cells.
Betz
This cell in the Neocortex has small neurons with a cell body the shape of a star (look like granules in micrographs).
Granule (stellate) cells
This cell in the Neocortex has small polygonal cells with a few short dendrites.
Cells of Martinotti
This cell in the Neocortex has spindle-shaped cells oriented at right angles to the surface of the cerebral cortex.
Fusiform cells
This cell in the Neocortex has small and spindle-shaped but oriented parallel to the surface (least common).
Horizontal cells of Cajal
The cerebral cortex also contains supporting glia, which are…
Astrocytes
Oligodendrocytes
Microglia
There are five layers of the cerebral cortex, which are what from superficial to deep?
I - Molecular layer II - External granular layer III - External pyramidal layer IV - Inner granular layer V - Ganglionic layer VI - Multiform (polymorphic) layer
This layer of the cerebral cortex consists largely of fibers, most of which travel parallel to the surface, and mostly neuroglia cells and horizontal cells of Cajal.
I - Molecular layer
This layer of the cerebral cortex consists mainly of small pyramidal cells and granule cells.
II - External granular layer
This layer of the cerebral cortex has pyramidal cells that are somewhat larger and possess a typical pyramidal shape. Not sharply demarcated from the layer above it.
III - External pyramidal layer
This layer of the cerebral cortex is characterized by the presence of many small granule cells.
IV - Inner granular layer
This layer of the cerebral cortex has internal pyramidal cells that are extremely large, called Betz cells. These are in motor areas.
V - Ganglionic layer
This layer of the cerebral cortex contains cells with diverse shapes, many are fusiform cells.
VI - Multiform (polymorphic) layer
This is the most common neurodegenerative disease, and incidence increases with age. Typical presentation is 70+ years. Symptoms include memory failure, progressing steadily to involve motor skills, speech, and sensation.
Alzheimer’s disease
In Alzheimer’s disease, the etiology is unknown and there is a small proportions of cases that have a genetic association. There is a striking thinning of _______, particularly those of the frontal and temporal lobes.
Gyri
In Alzheimer’s disease - plaques, neurofibrillary tangles, and neuronal loss are identified on sections. ________ _______ are amorphous, pink masses in the cortex and ________ ________ are flame-shaped skeins formed by abnormal accumulation of Tau.
Amyloid Plaques (Amyloid Beta) Neurofibrillary Tangles
This is a large mass of gray matter containing multipolar neurons with dark pigment. It has connections with the cortex, spinal cord, corpus striatum, and reticular formation. Has important role in fine control of motor function.
Substantia Nigra
In the Substantia Nigra, neurons contain numerous membrane-bound granules of neuromelanin pigments. Neuromelanin contains _________, which causes inhibitory effects in brain areas dedicated to movement.
Dopamine
This disease presents with clinical features of tremor, slow movement, and rigidity resulting from degeneration of neurons in the Substantia Nigra. This results in loss of dopamine.
Parkinson’s Disease
In Parkinson’s Disease, there are distinctive inclusions seen in the remaining neurons of the Substantia Nigra. These inclusions are called…
Lewy bodies
Lewy bodies are pink-staining inclusions with a pale halo. They are composed of aggregates of the protein __________ and other proteins.
Alpha-synuclein
