Neurohistology Flashcards
What defines the CNS anatomically?
Brain and spinal cord
Brings sensory information from the periphery to the CNS (type of nerve)
Afferent
Takes motor information from CNS to periphery (type of nerve)
Efferent
Location of neuronal cell bodies in the CNS (2)
Grey matter and deep nuclei
Location of neuronal cell bodies in the PNS
ganglia
Location of axons in the CNS
white matter
Location of axons in the PNS
nerves
Types of supporting cells (glia) present in the CNS (4)
1) astrocytes
2) oligodendrocytes
3) microglia
4) ependymal cells
Types of supporting cells (glia) present in the PNS (2)
Schwann cells and satellite cells
Another name for neuronal soma
perikaryon
Nissl body composition (2)
Rough endoplasmic reticulum and polyribosomes
Residue of lysosomal breakdown. Contain lipids and pigments. Accumulates with age.
Lipofuscin
Motor protein involved in anterograde transport
kinesin
Motor protein involved in retrograde transport
dynein
Which is slower, anterograde or retrograde transport in axons?
anterograde
[Morphological classification] Multiple dendritic processes. Characteristic of motor neurons and interneurons.
multipolar neuron
[Morphological classification] One main dendrite and one axon. Characteristic of special sensory neurons (vision, olfaction, hearing)
bipolar neuron
[Morphological classification] Single bidirectional axon-peripheral process (transmitting from the periphery) and a central process (transmitting information to the CNS). Characteristic of sensory neurons in the dorsal root ganglia.
unipolar neuron
Most numerous glial cell type in the brain
astrocytes
Two types of astrocytes
1) Fibrous Astrocytes (present in white matter)
2) Protoplasmic Astrocytes (present in gray matter)
Supportive functions of astrocytes (4)
1) forming the blood-brain barrier
2) nutritional support
3) uptake of neurotransmitters
4) regulate extracellular ionic concentrations
These glia line the ventricles of the brain and central canal of the spinal cord. Apical ends have cilia and microvilli
Ependymal cells
Cells responsible for producing cerebrospinal fluid
Ependymal cells
Microglia are derived from what type of cell
Monocytes
Small glial cells with mobile processes that sense the environment – important for immune surveillance
Microglia
Smaller cell with several cytoplasmic extensions (can myelinate multiple internodes of multiple neurons), responsible for myelinating axons in the CNS
Oligodendrocytes
Protective insulation from the cell membranes of supporting cells that concentrically wrap around a section of the axon
myelin sheath
What’s different about Schwann cells as opposed to oligodendrocytes in terms of how it wraps neurons?
One Schwann cell wraps one internode of one neuron
True or false: Small diameter axons which are unmyelinated are still enveloped by Schwann cells
True!
Multiple axons are enveloped by a Schwann cell but they’re not individually wrapped like with myelination. It’s not layered
Three levels of macroorganization of the brain
1) cerebrum
2) cerebellum
3) brainstem
In the spinal cord, is the white matter deep or superficial?
superficial
In the brain, is the white matter deep or superficial?
deep
Connective tissue membranes that wrap the brain and spinal cord
meninges
Outermost and toughest connective tissue membrane in the CNS
dura mater
Two layers of the dura mater
1) periosteal layer - attached to the bone of the skull
2) meningeal layer - closer to the brain itself.
The meningeal layer will separate to form _____ and rejoins to form a _____ (formed from two meningeal layers of dura in between hemispheres of the brain)
Dural sinus; dural fold
Bleeding between the skull and dura
Epidural hematoma
Layer between dura mater and pia mater. Contains spider web-like extensions
Arachnoid matter
Located between the arachnoid and pia mater and contains CSF
Subarachnoid space
Delicate, highly vascularized layer that is intimately applied to the surface of the brain and spinal cord
pia mater
Dural fold that separates the right and left cerebral hemispheres
falx cerebri
Gray matter in the cerebrum is found in the ____ ____ layer. Organized into 7 layers
cerebral cortex
Three layers of the cerebellar cortex
1) molecular layer
2) purkinje cell layer
3) granular layer
Connective tissue layers covering nerves in the PNS (from superficial to deep)
1) epineurium - surrounds entire nerve
2) perineurium - surrounds nerve fibers bundled in fascicles
3) endoneurium - surrounds individual axon
The sensory pathway goes through the posterior root ganglion or the anterior root?
posterior root ganglion
The motor pathway goes through the posterior root ganglion or the anterior root?
anterior root
Discrete organization of CT capsules. Clusters of neuronal soma and myelinated fiber tracts
Sensory Ganglia (Spinal/Dorsal Root Ganglia)
Two types of Autonomic (Visceromotor) Ganglia
Sympathetic and parasympathetic ganglia
Thin CT capsule. Diffuse arrangement of neuronal soma and thin, indistinct, unmyelinated fiber tracts. Multipolar neurons with satellite and capsule cells. More than 100 neurons usually.
Sympathetic ganglia
Indistinct CT capsule. Found in the wall of a target organ. Diffuse arrangement of soma and unmyelinated fiber tracts. Less than 100 neurons usually
Parasympathetic ganglia
Responsible for light touch and texture sensation. Found n the dermal papillae of thick skin
Meissner’s Corpuscles (Tactile Corpuscles)
Responsible for deep pressure, vibration and stretch sensations deep in the dermis.
Pacinian Corpuscles (Lamellar corpuscles)
Responsible for proprioception in skeletal muscles
Muscle spindles
Responsible for proprioception in tendons
tendon organ
Responsible for pain, heat, and cold sensations. Found all over basically lmao
Free nerve endings
Responsible for light touch and movement sensation surrounding the hair follicle
Hair receptors
What do free nerve endings and hair receptors have in common?
they’re unencapsulated
Specialized mucosa found on the dorsum of the tongue
lingual papillae
Smallest and most numerous papillae. Have keratinized tips and are important in sensing the texture of food. NOT associated with taste buds
filiform papillae
Four types of lingual papillae
1) filiform papillae
2) fungiform papillae
3) circumvallate papillae
4) foliate papillae
Mushroom shaped papillae that are less abundant than filiform and are scattered widely over the tongue. Taste buds associated.
fungiform papillae
Papillae directly anterior to the sulcus terminalis. Taste buds are embedded on the lateral aspects of these papillae.
circumvallate papillae
Located on posterolateral aspect of the tongue. They are associated with taste buds but not well developed in humans.
Foliate papillae
Barrel-shaped epithelial organs housing taste receptor cells
taste bus
Components of taste buds (3)
1) epithelial-derive taste receptors cells
2) supporting cells (sustenacular cells)
3) basal cells (at the bottom of the taste bud)
Located in the upper 1/3 of the nasal cavity. Has bipolar neurons specialized for transmission of odor molecules
olfactory epithelium
