* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Learning Objectives
Psychoneuroimmunology wikipedia , lookup
Neural modeling fields wikipedia , lookup
Types of artificial neural networks wikipedia , lookup
End-plate potential wikipedia , lookup
Apical dendrite wikipedia , lookup
Neural engineering wikipedia , lookup
Central pattern generator wikipedia , lookup
Neural coding wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Mirror neuron wikipedia , lookup
Optogenetics wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Microneurography wikipedia , lookup
Multielectrode array wikipedia , lookup
Neurotransmitter wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Circumventricular organs wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Single-unit recording wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Axon guidance wikipedia , lookup
Neuroanatomy wikipedia , lookup
Development of the nervous system wikipedia , lookup
Synaptogenesis wikipedia , lookup
Biological neuron model wikipedia , lookup
Nervous system network models wikipedia , lookup
Neuroregeneration wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Synaptic gating wikipedia , lookup
Learning Objectives At the end, a student should be able to define Nervous Tissue (NT) Types of NT: Neurons & Neuroglia Definition Structure & Function Comparison Classification Myelin Structure Nerve Structure Lecture outline: Nervous Tissue (NT) Definitions NT Comprises of Neurons, Neuroglia, and blood vessels Neuron is the basic structural and functional unit of nervous tissue Neuroglia is the supporting or glial tissue that is 10-times more abundant in mammalian brain than neurons Neuron: Structure & Function Parts of Neuron Body: Soma/Perikaryon Processes: Axon and Dendrites Neuron: Structure & Function Body Contains Nucleus: Cytoplasmic organelles: Inclusions Cytoskeletal components Neuron: Structure & Function Nucleus: Centrally located Large Pale-staining Spherical (Owl-eye appearance, large nucleolus) Euchromatin (shows intense activity of cells) Bi-nuclear neurons in sensory and symp-ganglia Neuron: Structure & Function Cytoplasmic Organelles Nissel bodies Polysomes and RER More abundant in motor neurons Golgi complex (located near nucleus) Mitochondria (scattered diffusely cytoplasm) No centriole (non-capable of division) Neuron: Structure & Function Inclusions Melanin containing granule in CNS neuron and dorsal root sympathetic ganglia Lipofuscin granules in some neurons increase with age Lipid droplet present occasionally Neuron: Structure & Function Cytoskeletal Components Neurofilaments Microtubules Microfilaments Neuron: Structure & function Processes: Dendrites Input receiving process Conveys afferents signals to Soma Usually multiple and small in length Thickness decreases near terminals Arborized terminals Cytoplasmic organelles similar with Soma except bi-polar neuron only lack golgi complex Organelles reduces near terminals except mitochondria Neuron: Structure & Function Processes: Axons Output receiving process Conduct impulse away from soma … to axon terminals – efferent signals Different lengths, golgi type-I & type-II Single and usually long Diameter remains uniform through length Originates from axon hillock Specialized region of soma lacks RER, ribosomes shows many microtubules & neurofilaments Neuron: Structure & Function Processes: Axons … Axolemma surrounds the axons Terminates at many small branches May have collateral branching … called Axon terminals at right angle from main trunk axon Axon terminal passes impulses to another neuron or other type of cell, ie, muscle or gland Neuron: Classification Morphological Classification Unipolar Bipolar Multipolar Pseudounipolar Neuron: Classification Morphological Classification Unipolar Bipolar single process, eg … neurons of mesencephleic nucleus of 5th CN single axon & single dendrite, eg … Special sensory organs, retina, taste, … Multipolar … Pseudounipolar … Neuron: Classification Morphological Classification … Unipolar … Bipolar Multipolar Single axon & multiple dendrites Most common type in men, eg Motor cortex, interneuron, … Pseudounipolar Single process arises from body Branches into an axon and dendrite, eg Present in spinal and cranial ganglia Neuron: Classification Functional Classification Sensory or Afferent Motor or Efferent Interneurons Neuron: Classification Functional Classification Sensory/Afferent: 3-types of receptions Exteroceptors (external: touch, temp) Proprioceptors (position: muscle & joints) Interoceptors (internal: GIT, UGT, RT) Motor/Efferent: 2-types of commands Somatic motor (PNS-skeletal muscles) Visceral motor (ANS-gut) Pre-ganglionic fiber & Post-ganglionic fiber Interneurons Runs b/n sensory & motor neurons Most numerous type – only in CNS Coordinates b/n sensory inputs & motor outputs Neuron: Supporting Tissue … or Glial Tissue or Neuroglia In CNS (dividing tissues) Astrocytes (macroglia) protoplasmic & fibrous Helps establish & maintain blood-brain barrier Oligodendrocytes (macroglia) Produce myelin Microglia (phagocytic cells) a sheath that wraps axons of several cells Several cells with multiple branching processes Ependyma (epithelial cells with cilia) Contributes for choroids plexus formation Neuron: Supporting Tissue … or Glial Tissue or Neuroglia In PNS (dividing tissues) Satellite Cells Found in ganglia, around nerve cell body Functions as exchange of nutrients and waste Schwann Cells (neurolemmocytes) Flattened cell produce myelin sheath in PNS … that surround axons … only associated with a single axon Forms myelinated or unmyelinated coverings over neurons Myelin: the sheath Produced by oligodendrocytes in CNS and Schwann cells in PNS Several spiral layers of plasma membrane Not continues along the length of axon Interrupted by gaps (nodes of ranvier) of oligodendrocytes or … Schwann cells wrapping around axons Nodes of ranvier lack myelin Internodes: segments of nerve fiber b/n adjacent nodes of ranvier Nerves: cord like bundles Cord like bundles of nerve fibers Surrounded by connective tissue sheath Appears whitish due to myelin Connective tissue coverings include Epineurium Perineurium Fibrous DCT forms external coats of nerve trunks Surrounds each bundle of nerve fibers (fasicle) Endoneurium Thin layer of reticular fibers surrounds individual nerve fibers … produced mainly by Schwann cells