Nerve Tissue 2 Flashcards
What is the CNS protected by?
By skull and vertebral column
Directly surrounded by connective tissue (meninges)
Contrast gray and white matter
Grey matter- contains cell bodies, axons, dendrites, and glial cells, synapses
White matter- myelinated axons of nerve cells, glial cells, vessels
What are the meninges?
- dura mater
- arachnoid mater
- pia mater
Describe the dura mater
- outer covering
- dense connective tissue
- vascular
- in the cranium forms the rural venous sinuses
- innervated
Describe the arachnoid mater
- loose connective tissue
- lined back to back by simple squamous epithelium
- projects into the sinus to drain CSF into the bloodstream
Describe the Pia mater
- Vascular loose connective tissue
- Lies directly on brain and spinal cord
- Interact with ependymal cells to form choroid plexus
What are the features of the spinal cord?
- butterfly-shaped inner gray matter
- Anterior/Ventral Grey Horn- contains alpha motor neurons cell bodies
- Posterior/Dorsal grey horn-contains central segments of sensory neurons and cell bodies of interneurons
- Lateral Grey Horn-contains cell bodies of visceral neurons
- Grey commisure- contains grey matter around the central canal
- Central canal - contains CSF
Contrast the white and grey matter of TG’s spinal cord
Grey matter- inner core
- cell bodies of motor neuron, dendritic and axonal processes and glial cells
- neuropil
White matter
-peripheral tissue surrounding grey matter
-Unmyelinated and myelinated fibers forming tracts
What is the alpha motor/ Golgi type 1 neurons?
- Large cells with pale staining large nuclei
- Abundant Nissan bodies
- Embedded in neuropil
What is a neuropil?
- Meshwork of tissue in grey matter excluding the cell bodies
- Comprised of dendritic and axonal processes, and central glial cells
Describe the white matter kf the spinal cord
- Outer layer of the spinal cord
- Axons travel to other parts of the CNS/PNS
- Axons are called tracts-grouped axons in CNS carrying out a specific function
Describe the white matter of the brain
- Inner core of brain tissue
- Axons (tracts) travel to other parts of the CNS
Describe the gray matter of the brain
- Outer layer
- Cell bodies arranged in layers
- Nuclei-islands of grey matter that project into white matter tissue
Explain the cerebrum
Cerebral cortex- grey matter has 6 layers
-contains both afferent and efferent fibers
- Main cell type- Pyramidal Cells (integrative neurons) of cerebral cortex:
- found in layers III, V (large pyramidal cells)
Describe Grey matter in the cerebelli cortex
- outer portion
- Cell bodies arranged in layers
Describe white matter in the cerebellum cortex
- Inner core
- Axons travel to other parts of the CNS
- Axons forms tracts
Describe the cerebellum cortex
Molecular (outer layer)
-Stella the cells
-basket cells
Purkinje cell layer (middle layer)
-single layer of motor neurons
Granular layer (inner layer) -granule cells
-type II Golgi cells
Describe what are Purkinje cells
- Located between outer molecular layer and inner granular layer
- has an Apical dendrite that arborizes in molecular layer
- Has a single axon that extends into granular layer and represents the beginning of neuronal outflow from cerebellum
Describe what are granule cells
- Located in inner most layer of cerebellum
- They project into molecular layer connect (synapse) with dendrites of Purkinje cell via parallel fibers in the molecular layer.
Purkinje cell via parallel fibers in the molecular layer
-Granule cells carry excitatory signals to the cerebrum
What is the choroid plexus?
Invagination folds of pia mater containing tufts of fenestrated capillaries and covered by simple cuboidal ependymal cell found in ventricles of the brain
What is the function of the CNS Blood brain barrier?
Protests the CNS from imbalances in surrounding environment, as well as electrolytes, hormones, metabolites disturbances
What are the parts of the CNS that have no blood brain barrier?
- Circumventricular organs (windows of the brain)
- Important in regulating homeostasis
What is the blood brain barrier composed of?
- Continuous capillaries with:
- complex tight junctions between endothelial cells
- continuous basal lamina
- no fenestrations in basement membrane - Foot processes of astrocytes
- Surround the capillaries and neurons
- Characteristic of the cerebral cortex
The blood brain barrier can lose effectiveness in certain brain d8seases due to loss of tight junctions or altered astrocyte integrity
Describe a peripheral nerve
A nerve is a collection of axons (nerve fibers) in the peripheral nervous system, whereas s tract is a collection of axons in the CNS
-Perioheral nerves carry impulses from/to the CNS or PNS. They are covered by connective tissue layers forming epineurium, perineureum and endoneurium
What is the epineureum ?
-Outermost tissue of peripheral nerve
- Typically made of dense connective tissue
- binds fascicles together. Adipose tissue often seen in larger nerve sheaths
- Carry blood vessels supplying nerves
- vessels branch and penetrate the perinerium
Describe the perineurium
- Surrounds bundles of nerve fibers
- Sheath of unique connective tissue cells- epithloid myofibroblasts that have contractile property- numerous actin microfilaments
- Cells joined by tight junctions
- Restrict passage of most macromolecules
- forms the blood nerve barrier
Describe the endoneurium
Associated with individual nerve fiber/axon
Consists of thin layer of reticular fibers produced by Schwann cells
