CNS+ PNS Flashcards
Spinal cord
NS composed of CNS- brain+ spinal cord
spinal cord is divided in two segments white+ gray. its neurons are large+ multipolar
PNS nerve fibres+ganglia
white
peripheral in spinal cord: outer part of the spinal cord but inner part of brain
contains ASC and DESC MYELINATED (myelin coats axons) nerve fibers
fibrous astrocytes + glial cells+ oligodendeocytes+ microglia+
divided into 3 parts; ant, lat and post funiculi
NO CELL BODIES of neurons
gray:
-inner part of the spinal cord and brain cortex
- CELL BODIES of the neurons (PERIKARYA)+ their DENDRITIES, glial cells; protoplasmic astrocytes, microglia and oligodendrocytes
- vascularized
- divided into ant (motor neurons whose axons make up vnetral roots of spinal cord), lat, post columns/horns (receive sensory axons from neurons in spinal ganglia)
- central gray commissure with a central canal (lumen of neural tube) lined with EPENDYMAL cells (neuroepithelial MULTICILIATED cells (columnar) that line the spinal cord and the cerebral ventricles; derived form the RADIAL glial cells)
Staining
Nissl’s (nissl’s bodies-rer, polyribo, nuclei, nucleoli) - basic dyes: TOLUIDINE BLUE, METHYLENE BLUE+ THIONINE
LUXOL BLUE- myelin sheath
Weigert’s method (myelin sheath)/ mordant= chromium salts
Ag IMPREGNANTION - neurons, neurofilaments+ tubules, glial cells
IMMUNOHISTOCHEM - specific antigens of neurons: neurotubules, neuroglia (intermediate filaments of the astrocytes composed by the GFAP)
Meningi
Membranes of CT between bone+ nervous tissue.
periosteum
epidural space (at vertebral column)
dura mater (dense CT):
fibroblast, continous w periosteum but separated from it EPIDURAL SPACE (thin walled veins+ AREOLAR tissue)
subdural space separate arachnoid layer from dura mater.
arachnoid (CT w squamous cells)
2 parts: CT in contact w dura mater and protrude blood venus sinus+ system of loosely arranged trabecular w fibroblast+ collagen continous w pia mater (often called pia-arachnoid)
arachnoid filled protrusion= ARACHNOID VILLI (transport CSF from subarachnoid to venous sinus)
subarachnoid space (CT trabeculae, vessels)
spongy like cavity w CSF- form HYDRAULIC cushion to protect CNS
pia mater(loose CT + vessels)
LIMITING LAYER OF ASTROCYTIC PROCESSES
pia mater+glial layer= PHYSICAL BARRIER (separate CNS tissue form CSF in subarachnoid)
blood vessels penetrate CNS through PERIVASC SPACES- covered by pia mater form ant+post root of spinal n.
posterior root ganglia (cell bodies of sensory n)
cerebral cortex
formed by GREY MATTER, cells F: integration of sensory info-> initiation of voluntary response.
pyramidal cells are arranged vertically+ interspersed w glial cells in eosinophilic neuropil
CYTOarchitecture - describes the appearance of the NEURONS in diff parts of the cortex MYELOarchitecture - shows the arrangement of the nerve fibers in the cortex
-CYTOarchitecture
1. MOLECULAR layer - pia mater overlies molecular layer. nerve fiber, glial cells, neurons + GLIAL CELLS HORIZONTAL CAJAL mainly.
2. OUTER GRANULE layer - small neurons (10um) and star-shaped)
3. OUTER PYRAMIDAL layer- pyramidal neurons (40um) - apical DENDRITES (branch to molecular layer) and BASAL axons (MULTIPOLAR, spherical EUCHROMATIC nucleus W nucleolus)
4. INNER GRANULE- small granule cell, neurons and star-shaped
5. INNER PYRAMIDAL layer - large pyramidal cells = Pyramidal cells of BETZ 100um(precentral gyrus)
6. multiformis/POLYMORPHIC cells - diverse shapes; FUSIFORM, ANGULAR and MARTINOTTI cells (multipolar cells)
-MYELOarchitecture
nerve fibers radial+ horizontal (Exners band, Bechterv’s band, outer Baillargers band+ inner, Meynert’s band)
cerebellum
cerebellar cortex
grey matter - cortex (Coordinate m activity) forms folia, separated by sulci have cerebellar nuclei
white matter - medulla forms arbor vitae
3 Layer in cotex
1. molecular layer;
- BASKET and STELLATE cells
- DENDRITES ramification of the PURKINJE cells
- AXONS of small GRANULE cells (T fibres), dendrites of large granules
- CLIMBING FIBERS (olivocerebellar tract in medulla ob)
- stratum gangliosum
- BODIES of the PURKINJE cells
- BASKETS axosomatic synapses (axon of basket and bodies of Purkinje) - stratum granulosum
- small GRANULE cells (5-6um) + dendrites
- large GRANULE cells (8-10um) + axons
- MOSSY fibers (all terminal fibres from cerebellar afferent tract) BERGMANN glial cells (unipolar)
- cerebellar GLOMERULI (synaptic connections between the granule cells + mossy fibers)
*CLIMBING fibers - axons of the inferior olivary nucleus
medulla
- white matter, UNMYELINATED n fibers, GLIAL cells+ small blood vessels
choroid plexus
highly specialised tissue (SIMPLE CUBOIDAL EPENDYMAL CELLS) w folds =VILLOUS processes form the pia mater to the brain ventricles.
convex apical surface with MICROVILLI, round nuclei
basal plasmalemma infolding like BASAL LABYRINTH
LPM - LOOSE CT and highly VASC
F: (remove water from blood and use to for) CSF by SELECTIVE ULTRAFILTRATION. fill ventricles, central canal, subarachnoid space, perivasc space.
CSF
- clear/yellowish
- slightly ALKALINE
- adult 135 ml
- daily production = 500 ml
*similar contents as the blood plasma
PNS
develops from the NEURAL CREST cells
composed of nerve ganglia (cell bodies of the neurons) and peripheral nerves (nerve fiber»space;nerve fascicles»space; nerves)
*its supporting glial cells are the SATELLITE and SCHWANN cells
satellite cells - envelope the neuronal bodies to provide electric INSULATION and metabolic path exchange
schwann cells - MYELIN sheath surrounding the axon - insulation form the rapid conduction of IMPULSE (through nodes of ranvier)
- ENDONEURIUM - nerve fiber envelope
- Axon with the schwann sheath (MYELIN)
- composed of LOOSE CT
- PERINEURIUM - fascicle envelope
- specialized flatten tissue cells
- contributes to the BLOOD-NERVE barrier (works w endothelium w tight junctions
- EPINEURIUM - nerve envelope
- DENSE IRREG CT
nerve ganglia
Contain;
- BODIES of the neurons by the SATELLITE cells
- bundles of nerve fibers
- enveloped by a DENSE CT CAPSULE
*no synaptic connection in the ganglion
SENSORY
at the post root of the peripheral nerve/cranial+spinal
PSEUDOUNIPOLAR neurons (ganglion cells); grouped
a CONTINOUS layer of the SATELLITE cells surrounding the neurons
AUTONOMIC (peripheral motor ganglia)
parasympathetic and sympathetic NS
MULTIPOLAR neurons; SOLITARY (smaller than the spinal ggl)
DISCONTINOUS layer of SATELLITE cells around the neurons
*pale-staining nucleus and prominent nucleolus
contain LIPOFUCHSIN
Muscle spindle
ENCAPSULATED AFFERENT N ENDING: sending signal to the brain
CAPSULE (inner capsule- periaxial space w fluid - external capsule of CT), intrafusal muscle fiber (8-10), stretch receptors - about 6mm long
*(INTRAFUSAL have the nuclei centrally and myofibrils at the periphery); EXTRAFUSAL muscle contracts and so does the intrafusal and is detected by the muscle spindle
signal to the SENSORY AFFERENT N FIBER for AP
to the alpha and beta motoneurons at the spinal cord
gamma motoneurons are connected to intrafusal muscle for the sensitivity
