Nervous Tissue & System
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ojames03 Plus on October 10, 2011
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134 terms
Terms | Definitions |
|---|---|
 Nervous System | -->Dekivers rapid & precise communication btwn. parts of the body via NEURONS |
| Anatomical Division of CNS | 1) CNS (Brain & Spinal Cord) 2)PNS (Nerves outside the CNS AND Ganglia (Nerve Relay Stations) |
| "Functional" Division of Nervous System | 1) Sensory Nerve Fibers -->Transmit impulses to CNS 2) Motor Nerve Fibers (Two Parts) -->Transmit impulses from CNS to various structures of the body |
| 2 Divisions of Motor Nerve Fibers | 1) Somatic Nerves 2) Visceral Nerves |
| "Histological" Division of Nervous System | 1) Nerve Cells (=neurons) -->Conduct electrical impulses 2)Glial Cells ("Neuroglia Cells") -->Supporting Cells that support, nurture, & protect the neurons |
| Fundamental Properties of Neurons | 1) Excitability -->Wave of depolarization & repolarization; "Action Potential" 2) Transmission to other neurons or effector groups, via synapses |
| Embrylogical Development of the nervous system | 1)Neural Tube -->Help develop the BRAIN & SPINAL CORD 2)Neural Crest Cells -->Develops Sensory nerve fibers & sensory neurons (DRG) --> " Autonomic Ganglia --> " Schwann Cells (Produce myelin in the PNS) |
| Pathway in the development of the nervous system | Neuroectoderm --> neuroepithelium --> differentiates to form the neural plate --> neural groove --> neural tube |
| Other important structures that arise from the neural crest cells (from edges of neural groove) | 1)Sensory neurons of cranial and spinal ganglia. 2)Enteric and autonomic ganglia and their postganglionic neurons and associated glia. 3)Most sensory neurons and Schwann cells of the PNS. 3)Most of the mesenchymal cells of the head and anterior portion of the neck. 4)Melanocytes of the skin ***Failure of the neural crest cells to migrate results in a LACK OF MELANIN PIGMENT 5)Odontoblasts (responsible for producing dentin) 5)Cells of the arachnoid and pia matters. 6)**Chromaffin cells of adrenal medulla.** |
| Components of the structue of the Neurons | 1) Cell Body (Parkaryon; Soma) 2)Processes (2 Types --> Dendrites & Axons) |
| Cell body of neuron | -->Large nucleus with nucleus & cytoplam |
| Dendrites | -->Highly Branched & tapering process -->Function to TRANSMIT the signals TOWARD the cell body |
| Axon | -->Arise from the AXON HILLOCK (cone shaped part of the cell body) -->Terminates on neuron OR effector organs through TERMINAL BOUTONS (presynaptic knob) |
| **What is an axon considered** | **A NERVE FIBER** (i.e. A nerve fiber is only the axon part of the neuron) |
| 3 Types of Morphologies of Neurons | 1)Multipolar Neuron (***Most common type 2)Bipolar " 3)Pseudo-Unipolar |
| Multipolar Neuron | -->1 axon & a number of dendrites -->Ex. Motor Neurons |
| Bipolar Neuron | -->1 axon & 1 dendrite; Each arise from OPPOSITE POLES -->MAJOR EXAMPLE: **Retina of the eye** (Receives multiple inputs to the dendrites) 1)Anything related to vision, hearing, or smell; olfactory epithelium of the nose or the ear |
| Pseudo-Unipolar Neuron | -->Similar to bipolar neurons, but the first part of the neuron FUSE during embryological development 1) Appears as 1 process, which then BRANCHES into 1 axon & 1 dendrite -->MAJOR EXAMPLE: Spinal & Cranial Ganglia |
| 3 Types of Neurons | -->Sensory, Interneurons, & Motor Neurons **SEE KEY NOTES FOR DETAILS** |
| Details of Neuron (Microscopic) | 1)Nuclei: Big, spherical, and commonly centrally located 2) Chromatin: Dispered/Vesicular Chromatin 3) Nucleolus: Very prominent; **OWL-EYE APPEARENCE** due to high metabolic activity 4)Cytoplasm: Abundant, stained basophilia due to extensive ribosomal RNA -->Contains **NISSEL BODIES** composed of polysomes & aggregations of rER |
| Nissel Bodies | -->Aggregations of polysomes & aggregations of rER -->Most abundant in LARGE MOTOR NEURONS --> ***Seen in the dendrites, but NOT IN THE AXON!!!!! |
| Other organelles of the cell body | -->Golgi Apparatus (near nucleus) -->Mitochondria -->Cytoskeletal components (Neurofilaments & Microtubules) -->Some melanin granules -->Lipofuchsin Granules (Incr. with age) -->Lipid Droplets |
| Neurotransmitters & Axonal Transport | -->Neurotransmitters produced in the PERIKARYON are transported in vesicles through MICROTUBULES along axon to the synapse |
| Neurofilaments | ***INTERMEDIATE FILAMENTS ; help maintain shape of neuron |
| Microtubles | -->Found throughout cell body, dendrite, & axon -->Serve as networks for materials anterorade via kinesin & retrograde to perikaryon using dynein ("DKNY") |
| Microscopic Details of Dendrites | -->Numerous; allows receipt of multiple inputs -->**DOES NOT CONTAIN GOLGI APPARATUS (vs. cell body of neuron)** -->Abundant amount of mitochondria -->Contains DENDRITIC SPINE |
| Dendritic Spine | -->A small membranous protrusion from the dendrite that RECEIVES input from axon -->1 dendrite contains hundreds to thousands of spines -->Major Function: 1)Increase the number of possible contacts betwn. neurons 2)Anatomical substate for memory storage/synaptic transmission -->***DECREASE WITH AGE & POOR NUTRITION --->***HAVE ALTERED CONFIFURATIONS IN TRISOMY 13 & 21 |
| Microscopic Details of Axons | -->>Vary in length & diameter -->Originates from part of the cell body called AXON HILLOCK 1) Contains NO rER, ribosomes, Golgi, & Nissl bodies 2) Contains many ***MICROTUBULES & NEUROFILAMENTS -->Contains **AXOPLASM**(Axon cytoblasm) 1)Contains sER, rER, & mitochondria 2)***HAS NO GOLGI COMPLEX -->Terminates into small branches known as Axon Terminals or TERMINAL BOUTONS (Presynaptic Knob) |
| Terminal Buotons | -->Transmit impulses through synapses to other neurons or effector cells |
| Neuroglial Cells | ***NOT NEURONAL CELLS -->Highly branched; fill space btwn. neurons -->Major Function: Support & protect the neurons WITHOUT transmitting impulses or forming synapses with other cells |
| 5 Types of Neuroglia cells | 1) Astrocytes 2) Olgodendrocytes 3) Microglia 4) Ependymal Cells ("Epithelium of ventricles") 5) Schwann Cells (PNS) |
| Astrocytes | -->***LARGEST NEUROGLIAL CELLS -->Contain PERIVASCULAR FEET (as part of the blood brain barrier (BBB) 1)Extends around surrounding blood vessels -->Found in the GLIA LIMITANS (basement membrane betwn CNS & pia mater) -->Major Functions: 1)Provide sealed barrier as part of BBB 2)Provide structural support for nervous tissue 3)Supply energy 4)Scavenger for ions & debris from neuron metabolism ***Proliferates into SCAR TISSUE after injury to the CNS |
| 2 Types of Astrocytes | 1)Protoplasmic Astrocytes 2)Fibrous Astrocytes |
| Protoplamic Astrocytes | ***LOCATED IN GREY MATTER -->Contain BRANCHED PROCESSES that surround blood vessels, neurons, & synaptic areas -->Contain some intermediate filaments composed of glial fibrillar acidic protein (GFAP) |
| Fibrous Astrocytes | ***LOCATED IN WHITE MATTER -->Long, slender processes with FEW BRANCHES -->Contain many intermediate filaments composed of GFAP |
| **Major Difference Between Grey & White Matter** | NO CELL BODIES IN THE WHITE MATTER OF THE CNS |
| Oligodendrocytes ("Fried Egg Appearence") | ***Located in BOTH grey & white matter -->Nucleus: Small, round, & condensed -->Processes: SHORT -->***PRODUCES MYELIN that insulates & protects **MULTIPLE axons in CNS -->Abundant in grey matter; PREDOMINANT in WHITE MATTER (no cell bodies) |
| Schwann Cells | -->Flat cells with only a FEW mitochondria & a small Golgi apparatus -->Produce myelin to insulate & protect the axons in the **PNS* -->Cover myelinated & unmylinated axons ***ONLY the mylinated axon is covered by multiple layers of plasmalemmae by wrapping around a single axon |
| Embryologica Origin of Schwann Cells | -->NEURAL CREST CELLS (b/c the migrate to the PNS |
| Microglia | -->Small cell with a condensed elongated nucleus, little cytoplasm, & HIGHLY BRANCHED PROCESS -->***PHAGOCYTIC GLIAL CELLS derived from the mononuclear phagocytic cell population -->Become antigen presenting cells **(APC's)** & secrete cytokines |
| Embyrological Development of Microglia | **Meschychmal in origin** |
| Embryological Development of Ependymal Cells | -->Neuroepithelium |
| Ependymal Cells | -->***LINE THE VENTRICLES & NERUAL TUBE OF THE BRAIN -->Contain cilia in some regions of the brain to help move the CSF |
| Choroid Plexus | -->Are ***Modified ependymal cells that function to ABSORB CSF |
| Synapses | -->Specialized cell jnx. that allows DIRECT COMMUNICATION btwn. cells -->Siganls are transmitted: 1)Neuron to Neuron 2)Neuron to effector cells (eg muscle cell) |
| Neuromuscular Junctions or Motor End Plate | -->Synapeses that link a NEURON with a skeletal muscle |
| 4 Types of synapeses | 1)Axodendritic (Axon -->Cell body) 2)Axoaxonic (Axon-->Axon) 3)Dendrodendritic Synapses (Dendrite-to-dendrite) 4)Cell Body to Cell body synapses |
| 2 Major Methods of Signal Transduction | 1)Chemical Synapse 2)Electrical Synapse |
| Transmission of an action potential through a chemical synapse | ***See Key Notes for Details |
| Features of electrical synapses | -->***Involves GAP JUCTIONS 1) Ions from one neuron DIRECTLY to another neuron; which generates action potentials in the postsynaptic neuron -->Less common than chemical synapses -->RAPID signal transmission through these synapses |
| General pathway of impusle from cell body | Axon --> terminal bouton --> synaptic cleft --> postsynaptic membrane |
| Structures around the synapse | 1)Terminal Boutons -->Boulbous expansions at the terminal end of the AXON 2)Boutons in Passage -->Swellings along the axon terminal; synapses may occur at each swelling 3)Presynaptic membrane -->Thickened axolemma at the terminal end of an axon 4)Postsynaptic Membrane -->Thickended plasma membrane of the subsequent neuron OR other target cells; receive the impulse 5)Synaptic Celft -->Narrow space btwn. pre- & postsynaptic membranes; neurotransmitter diffuses across this synaptic cleft 6)Synaptic Vesicles -->Small, membrane boud structures in presynaptic knob containing the neurotransmitter |
| Features of Terminal Boutons | 1) ***NON-MYLINATED 2)Contain MITOCHONDRIA and SYNAPTIC VESICLES (containing neurotransmitter) |
| General Pathway of Neurotransmitter Substance | 1)Neurotransmitter docks with membrane 2)***EXOCYTOSIS 3)Diffuses through the synaptic cleft 4)Binds to receptors on the POST-SYNAPTIC MEMBRANE |
| Features of the Presynaptic Membrane | -->Contains **Voltage-gated Ca2+ channels** which regulate the entry of Ca2+ ions into the axon terminal -->Synaptic vesicles FUSE with & become incorporated into this membrane prior to the release of their neurotransmitter into the synaptic cleft |
| 2 supporting cells that envelop individual axons | 1)Schwann cells in **PNS** 2)Oligodendroctyes in **CNS** |
| Non-mylinated vs. myelinated axon coverings | 1) Myelinated: Concentric Layers; Large in Diameter 2)Non-Mylinated: Non-concentric layers; Small in Diameter |
| Mesaxon | --> Lips of the paired membrane spiral around the axon |
| Myelin | -->The plasmalemma of the oligodendrocyte or Schwann cell organized into a sheath that is wrapped several times around the axon |
| Features of the Myelin Sheath | -->NOT CONTINOUS along the length of the axon, but is inturrupted by small gaps knowna as the NODE OF RANVIER -->Bigger axons by diameter have THICKER myelin sheaths (BUT is constant in thickness along total length of axon) -->Regular staining dissolves the lipid component of the myelin sheath, leaving EMPTY SPACES 1)Can be preserved via OSMIUM TETROXIDE |
| Physical Features of Myelin Sheath on EM | 1) MAJOR DENSE LINES -->Lines formed by the fusion of TWO plasma membranes; Separated by a THIN CYTOPLASM in btwn 2)INTRAPERIOD LINES -->Lines caused by the close contact (NOT FUSION!!!!) btwn. 2 plasma membranes; originally separtated by extacellular space 3)***SCHMIDT-LANTERMAN CLEFTS -->Cone shaped, oblique DISCONTINITIES of the myelin sheath -->Seen due the prescence of the remaining cytoplasm of Schwann/Oligodendrocytes Cells within the myelin -->Seen as a narrow channel of cytoplam that connects PERIPHERAL Schwann/Oligodendrocytes cell cytoplasm to narrow Schwann/Oligodendrocytes cell cytoplasm ADJACENT to the axon |
| Neurorequilin | -->Assists in the rolling of the myelin sheath |
| Node of Ranvier | -->Interruptions that occur in the myelin sheath along the length of the axon -->Represent discontinuities btwn respective oligiodendrocyte or Schwann Cell |
| Physical Characteristics of nodes of ranvier | -->In PNS: Nodes of Ranvier covered by interdigitated cytoplasmic processes of adj. Schwann cells (**NO MYELIN SHEATH**) -->In CNS: Nodes of Ranvier is covered by foot plates of ASTROCYTES -->Axolemma at the nodes contains many sodium pumps -->Contains characteristic electron density on EM -->External lamina of Schwann cells continues ACROSS nodes of Ranvier |
| Internodes | -->Segments of nerve fiber btwn. adjacent nodes of Ranvier -->Size varies depending on size of Schwann/Oligiodendrocytes |
| Peripheral Nerve | -->Each Peripheranl Nerve consists of fascicles (bundles) of nerver fibers grouped together -->Contain combination of afferent or efferent nerve fibers that are SOMATIC or AUTONOMIC in function -->Presence of myelin gives it a WHITTISH appearance |
| 3 connective tissue sheaths of peripheral nerves | 1)Epineurium 2)Perineurium 3)Endoneurium |
| Epineurium | -->An external fibrous coat of dense CT that covers the ENTIRE NERVE & can also fill the space BETWEEN a nerve |
| Perineurium | -->A sleeve of dense CT that covers EACH BUNDLE of nerve fibers -->Formed by layers of flattened cells joined by **ZONA OCCLUDENS* 1)Prevents the passage of most macromoleucules (**Forms a perneurium barrier**) |
| Endoneurium | -->A thin layer of reticular fibers produced by Schwann cells -->Surrounds each INDIVIDUAL nerve fiber |
| Sensory Receptors | -->Represent either nerve endings OR specialized cells that can convert (transduce) stimuli into AFFERENT NERVE IMPULSES -->3 Major Types of sensory receptors: 1)Exteroceptors 2)Proprioceptors 3)Interoreceptors |
| Exteroreceptors | -->Respond to stimule from OUTSIDE of the body (Ex.PTT } Pain, Touch, & Temperature) |
| Proprioceptors | -->Located within skeletal muscle -->Provide conscious & unconscious info. about orientation, skeletal position, tension, & movement -->Ex. Vestibular Apparatus of the ear, Tendon Stretch Receptors, & Neuromuscular Spindles |
| Example of Neuromuscular Spindles | -->Are STRETCH RECEPTOR ORGANS located within skeletal muscle -->Function: 1)Regulation of muscle tone via the "Spindle stretch reflex" -->Lie parallel to muscle fibers; surrounded by endomysium or perimysium -->Each spindle contains: 1)Intrafusal fibers (2-10 modified skeletal muscle fibers; SMALLER than extrafusal fibers) 2)Arranged nuclei (***NUCLEAR BAG & NUCLEAR CHAIN) |
| Nuclear chain nuclei of intrafusal fibers | -->Contains NO DIALATIONS; nuclei arranged as a SINGLE ROW |
| Nulear bag nuclei of intrafusal fibers | -->Contains DIALATED central nuclear area |
| 2 Major types of sensory receptor endings | 1)Annulospiral endings -->Branched, NON-MYLINATED endings of large myelinated sensory fibers 2)Flower Spray Endings -->Smaller, MYELINATED sensory fibers located on STRIATED PORTIONS of intrafusal fibers |
| Interoceptors | -->Respond to stimuli from the VISCERA Ex. Baroreceptors, Chemoreceptors, Receptors for visceral pain/hunger/thirst/well-bein/malaise |
| Two major groups of sensory receptors | 1)Simple Receptors 2)Compound Receptors |
| Simple Receptors | -->Represent branched or Unbranched free nerve endings found in the supporting tissues throughout the body -->May be myelinated or non-mylinated Ex. Receptorf for ***Pain & Temperature in dermo-epidermal jxn of the skin |
| Compound receptors | -->Organization of associated non-neural tissues to complement the fnx. of the neural receptors -->Has a spectrum of arrangements from simple encapsulation to more sophisticated -->4 major groups 1)Messiners Corpuscles 2)Pacicnian Courpuscles 3)Neuromuscular Spindle 4)Organs of special sense (eye, ear, & receptors for the sense of smell & taste |
| Messiner's Corpuscles | -->SMALL, encapsulated sensory receptor located in: 1)Dermis of the skin (fingertips, soles of the feet, nipples, eyelids, lips, & genitalia) -->Used for light discriminatory touchP 2)Just underneath DERMAL PAPILLAE beneath epidermis -->Function: For reception of **light discriminatory touch** |
| Pacinian Corpuscles | -->LARGE, encapsulated sensory receptors -->Function: For reception of **pressure/coarse touch, vibration, & tension** -->Location: 1)DEEPER layers of the skin, ligaments, & joint capsules -->Shape: Delicate collagenous capsule surrounding a mass of large oval cells arranged transversely ("Onion Appearance") |
| Ruffinini Corpuscles | -->Spindle-Shaped structures found primarily in the Soles ("Ruff"; Pressure Receptors) |
| Krause End bundles | -->DELICATE receptors found in the oropharynx & conjuctiva |
| Death of Neurons | -->A result of injury of injury or disease, neurons may degenerate & permanently have a loss of nervous tissue -->Response of body to neuronal injury depends on LOCATION (CNS & PNS) |
| Response of neurons to injury in the CNS | -->**NEURONS CANNOT REGENERATE** -->Dead neuronal cells are removed by macrophages -->The damaged area is then reparired by the proliferation of neuroglial cells to fill the defect (forming a scar (gliosis) |
| Response of neurons to injury in the PNS (Overview) | -->Degeneration of the axon DISTAL to the site of injury undergoes ANTEROGRADE (WALLERIAN) DEGENERATION 1)Degenerated axon becomes beaded & fragmented, which will be removed by macrophages 2)The damaged area is repaired by the proliferation of astrocytes, which fill the defect AND form an astrocytic scar called GLIOSIS -->Schwann Cells then proliferate within remaining connective tissue (intact basal lamina) 1)Give rise to solid cellular COLUMNS; which serve as guides to sprouting axons formed from the PROXIMAL SEGMENTS -->Only fibers that PENETRATE Schwann cell columns will continue to grow & reach an effector organ |
| Specifics of Anterograde (Wallerian) Degeneration | -->Due to interrupted axonal transport: 1) Axon SWELLS & then disintegrates 2)Microtubules & neurofilaments will be DISASSEMBLED ("granular disintegration") 3)Schwann cells starts to de-differentiate & breakdown the myelin sheath 4)Resisdent Macrophages Clear up the myelin debris in ~ 2 weeks |
| Traumatic Degeneration | -->Occurs PROXIMAL to the site of injury when a sprout cannot penetrate into a BAND OF BUNGER distally (see below) -->Can be a form of spontaneous pain |
| Chromatolysis | -->The process of disappearance of Nissel bodies from the center of cell; become periperally displaced -->**DUE TO UPREGULATION OF C-JUN TRANSCRIPTION FACTOR** -->Cell Body: 1)Swells 2)Loses its COLOR |
| Specifics of Regeneration of nerve fibers after injury (after the 2nd Week) | -->Schwann cells divide & arrange themselves to form longitudinal cylinders known as ENDONEURIAL TUBES -->With the debris cleared by the macrophages, Schwann cells form cellular bands know as BANDS OF BUNGER -->SPROUTS ("Neurites") develop from the proximal area of the injury -->IF one the sprouts penetrate the band of bunger, the sprout grows along the band and is able to re-establish connection with the neuron/effector organ |
| Major reasons why injured axons in CNS CANNOT regenerate | 1)Inability of oligodendrocytes/microglia to clear debris of myelin quickly (myelin has inhibitory actions for axonal regeneration 2)Blood Brain Barrier --> Restricts entry of incoming macrophages 3)Scar formation of astrocytes restricts nerve regeneration |
| Ganglia | -->Aggregations of cell bodies located OUTSIDE the CNS -->2 Types: 1)Sensory & Cranial Ganglia 2)Autonomic Ganglia |
| Sensory & Cranial Ganglia | -->***SENSORY GANGLIA associated with some cranial nerves & DRG -->Contain NO SYNAPSES -->Cell bodies in the ganglion are ***PSEUDOUNIPOLAR TYPE (transmit signals from receptors TO CNS) |
| Autonomic Ganglia | -->***MOTOR GANGLIA whose axons of preganglionic neurons SYNAPSE on the postganglionic neruons ***MULTIPOLAR TYPE in most cases, surrounded by SATELLITE CELLS |
| Major Difference btwn. somatic & autonomic nervous system | -->Somatic: May contain sensory fibers & motor fibers -->Autonomic nervous system: Contains **only motor fibers** ***See Key notes for details |
| Divisions of Autonomic NS | -->Into Sympathetic System (thoracolumbar outflow) & Autonomic System (craniosacral outflow) ***See key notes for details |
| Components of the CNS | 1)Grey & White Matter 2)Meninges 3)Cerebrospinal Fluid |
| White Matter | **THINK AXONS** -->Contains mostly myelinated nerve fibers (some unmyelinated fibers) |
| Grey Matter | ***THINK CELL BODIES -->Contains neuronal cell bodies, mostly unmyelinated cell bodies (some myelinated fibers), & **neuroglial cells** |
| Grey Matter of the Brain | -->Is the CORTEX of the cerebrum & cerebellum |
| Meninges | -->Membranous covering of the brain & spinal cord -->3 Layers: 1)Dura Mater (Outermost) 2)Arachnoid Mater 3)Pia Mater (Innermost) |
| Pia Mater | -->Delicate layer of collagen & elastin fibers attached to the SURFACE OF THE BRAIN -->Continues into the sulci around penetrating vessels |
| Arachnoid Mater | -->Thick fibrous layer -->Region that is continuous with the pia mater is known as LEPTOMENINGES |
| Subarachnoid Space | -->Region btwn arachnoid & pia mater -->Region where CSF is produced; arteries/veins enter & exit at this region |
| Dura Mater | -->A dense fibroelastic layer closely opposed BUT NOT attached to the arachnoid layer -->Merges with the periosteum of the skull via DENTICULATE LIGAMENTS ***Location of the venous sinuses |
| Subdural Space | -->A potential space; becomes a REAL space only in PATHOLOGY (Ex. subdural hemotoma) |
| Epidural Space | -->Filled with loose fibrofatty tissue & a venous plexus (A real space under normal conditions) |
| Cerebrospinal Fluid | -->A clear fluid produced MOSTLY from the choroid plexus in the ventricles of the brain -->Composed of fold of pia mater & capillaries; surrounded by CUBOIDAL EPENDYMAL CELLS -->Function: 1) Circulates through ventricles, subarachnoid space, & central canal to provide nourishment to the brain & spinal cord 2)A ***shock absorber to protect brain & spi |
| Archnoid Granulations | ***Produce & reabsorb CSF -->Transports CSF to the superior sagital sinus -->If circulation of CSF is blocked in brain --> **HYDROCEPHALUS** 1)Any condition in which an excess quantity of CSF is present in the CNS; increases the intracranial pressure |
| Choroid Plexus | -->***ARE MODIFIED EPENDYMAL CELLS located in the wall of the 4 ventricles -->***Produce CSF |
| Meningeal Vessels | ***Lie in the subarchnoid space |
| Types of Meningeal Diseases | 1)Bacterial Meningitis 2)Subarachnoid Haemorrhage 3)Subdural Haemorrhage 4)Extradural Haemorrhage |
| Bacterial Meningitis | -->Penetration of infective organisms into the CSF, initiating an inflammatory response -->Clinical Markers 1)Incr. amounts of WBC's in the CSF 2)Low CSF glucose 3)Turbid appearance |
| Subarachnoid haemorrhage | -->Ruptures blood vessels (due to a weakness in blood vessel) ***BLOOD ENTERS CSF |
| Subdural haemorrhage | -->**Mainly Veins (Venous Plexus) in this region** |
| Extradural haemorrhage | -->Seen in a skull fracture -->Blood can accumulate in the tissue plane outside the dura |
| Epidural vs. Subdural Hematoma | -->Lens-Shaped hematoma vs Moon-shaped hematoma |
| Blood Brain Barrier (BBB) | -->Contributed by the ENDOTHELIAL CELLS OF THE CAPILLARIES & THEIR TIGHT JUCTIONS 1)The pia mater is completely separated from the underlying neural tissue by NEUOGLIAL CELLS 2)The **end feet of astrocytes** cover the capillaries in the brain, creating a CONTINOUS LAYER **See slides for details** |
| Regions of body that DO NOT have a blood brain barrier (due to specialized functions) | 1)Choroid Plexus 2)Pineal Gland 3)Pituitary Gland |
| Components of the CNS | 1)Spinal Cord 2)Cerebellum 3)Medulla 4)Pons 5)Midbrain 6)Basal Ganglia & Thalmus 7)Diencephalon 8)Cerebral Hemispheres ***See images for details |
| Physical Characteristis of Cerebellum | -->Contains FOLIA in the outer grey matter 1)Deeply convouluted folds with a branching central medulla of WHITE MATTER |
| 3 Layers of the Cortex of the Cerebullum | 1)Molecular Layer (Outer) 2)Purkinje Cell Layer (Middle) 3)Granular Layer (Inner) |
| Molecular Layer | -->Less dense appearance due to 1)Sparse amount of neuronal cell bodies 2)Large number of UNMYLINATED nerve fibers |
| Purkinje Cell Layer | -->Located btwn. molecular & granular layer; Contain LARGE NEURONAL CELLS -->Contains axons that branch into the granular layer -->Its DENDRITES branch out into the OUTER molecular layer |
| Granular Cell Layer | -->HIGHLY CELLULAR LAYER |
| Other Cell Types in the molecular layer of the cerebullum | 1)Basket Cells 2)Stellate Cells (Located more superficially) 2)Stellate Cells |
| Substantia Nigra | -->A large mass of grey matter extending throughout the midbrain -->Neurons contain DARK PIGMENT ("Neuromelanin") known as DOPAMINE 1)Dopamine has INHIBITORY effects; esp. on membrane -->Major Fxn:Plays important role in fine control of MOTOR FUNCTION |
| Thalmus | -->See pictures |
| Physical characteristics of the cortex of the Cerebellum | -->Composed of GREY MATTER subdivided into six layers, with each layer containing a particular morphology -->Major neuronal cell types: pyramidal, stellate (granule), horizontal, & inverted ("Martinotti") cells -->Subdivisions refer to the NEOCORTEX from superficial to deep -->First Layer: **DEEP TO PIA MATER** -->Sixth Layer: ***DEPPEST CORTICAL LAYER; borders the central white matter |
| 6 Layers of Neocortex (From External to Internal; "Mol-G--P-G-P-Pol") | 1)Molecular Layer -->Composed of Horizontal cell of Cajal 2)External Granular Layer -->Contains mostly granule (stellage cells); tightly packed 3)External Pyrimidal Layer -->Contains Large Pyrimidal Cells (& some stellate cells) 4)Internal Granular Layer -->Closely packed granule (stellate); most of which are SMALL 5)Internal Pyrimidal Layer -->Medium to LARGE pyrim 6)Polymorphic Layer -->Consists of various cell shapes; many of which are "fusiform" -->Houses Martinotti cells ***See key notes for more specifics about cell types |
| Betz Cells | ***The largest of the pyrimidal cells -->Located deeper layers of neocortex |
| Clinical Correlations (***See Key Notes & Slides for explanations) | 1)Spina bifida (Cystica vs.Occulta) 2)Anecephaly 3)Hirschprung Disease (Congenital Megacolon) (loss of ***Aurbach's plexus from the distal segment of colon) 4)Neuroglial Tumors & Peripheral Nerve Disease (Demylinating vs Axonal; Ex. Guillain-Barre Syndrome, Mutiple Scelrosis; Giant Axonal Neurpathy) (slide #60) 5)Meningitis (Diagnosis: Lumbar puncture & culture of CSF) 6)Multiple Scelrosis 7)Parkinson's Disease 8)Huntingtons Disease (Cholera)(Due to loss of neurons that produce GABA neurotransmitter) 9)Alzheirmiers Disease (Loss of memory due to accumulation of amyloid plaques & neurofibrillary tangles) |
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