(3) Nervous tissue .pdf

nervous tissue dr.abdullah elagali  Overview 10 billion neurons TITI Divided anatomically into:- cell havenerve A) Central Nervous Sy...

nervous tissue dr.abdullah elagali  Overview 10 billion neurons TITI Divided anatomically into:- cell havenerve A) Central Nervous System (CNS) – Brain and spinal cord B) Peripheral Nervous System (PNS) cell havenerve don't – Cranial, spinal nerves and ganglia havenervecell – Nerve cells are present Only in nerve ganglia but NOT present in peripheral nerves. _________ t But they divided histologically into:- A) Neurons – main cell of the nervous tissue; stellate shaped, with long processes f ES B) Neuroglial or Glial Cells – support, protect neurons. Isincreaseitwilldeterminethat after10years youwillhaveGheimers The nervous system is divided anatomically into  Neuron Theendofaxonis synapses Soma Dendrites Axon Structural and functional unit of the nervous tissue e Most neurons have 3 parts 1. Dendrites; multiple elongated processes that receive impulses. They have the same tstructure of soma containing the usual feree organelles except Golgi apparatus. tainnk ifitnaveprobemitw.ineadto paralysis 2. Soma or cell body; it contains single central active nucleus , basophilic cytoplasm with prominent polyribosomes (Nissle bodies), and neurofilamints but it doesn’t have centrioles. se sons 3. Axon; single elongated processes that transmit the nerve impulses, it begins by axon hillock and ends by axon terminals. It is surrounded by axolemma and its cytoplasm (axoplasm) tree 2 contains neurofilamints and mitochondria.  If Classification of neurons according to its processes see Pseudounipolar – contains a common stem that divides into 2 branches central and peripheral),the central one acts as axon and Is I the peripheral branches to form dendrites. Found in sensory ganglia (dorsal root ganglia) Bipolar – contains 2 processes, consisting of an axon and a dendrite. Found in the retina and olfactory cells of olfactory epithelium. see Multipolar – contains more than 2 processes. Most common type. Motor neurons  there Multipolar neurons Divided according shape of cell body into: f Pyramidal: as pyramidal cells in cerebral cortex. Pyriform: purkinje cells of cerebellum. Stellate: AHCs of spinal cord and Autonomic ganglia cells. GolgiNo7 longaxon GolgiNo2 shortaxon  Classification of neurons according to its function e 1- Sensory neurons; reception of stimuli f tffe from the environment and conduct them to CNS. i 2- Motor neurons; originate in CNS and e conduct impulses to effecter organs as muscle and glands. 3- Associated neurons (interneurons); connects the sensory with the motor neurons. to  Nerve Fibers Made up of the axons of neurons Most axons are enveloped by sheaths called myelin sheaths They are formed by the oligodendrocytes in the CNS and Schwann cells for the PNS a Myelin Sheath increase nerve impulse conduction through salutatory conduction Also there are connective tissue coats around the nerve fibers in the form of CT sheath. deer CT coat (sheath) 1-Epineurium ; connective tissues that surrounds the nerve trunk. 2-Perineurium ; connective tissues that surrounds the nerve bundles 3-Endoneurium ; Connective tissue that surrounds the individual nerve fibers  Neuroglial cells (Nerve glue) bodyguard e Neuroglia of PNS IT (Schwan andcellsatellite cells) barrier nerve vesselsand betweenblood brain blood Neuroglia of CNS tff (Astrocytes, Oligodendroglia, Microglia, and Ependymal cells). incerebrospinalfluid  Ganglia Ganglia are ovoid structures containing neuronal cell bodies 0 and glial cells (satellite cells) supported by connective tissue. 0 0 Sympathetic ganglia Craniospinal (sensory) ganglia 1- Sensory (Spinal) Ganglia: Theyereceive peripheral afferent impulses that go to the central f Iter nervous system. The neurons of these ganglia are pseudounipolar. 2- Autonomic ganglia: They receive efferent too impulses to the effectore organs (motor). Autonomic ganglia usually non capsulated and have multipolar neurons. seedier  c Diseases Central nervous system a Alzheimer's Disease (AD) is a brain disease that slowly destroys brain cells. Bell's palsy is temporary weakness or lack of movement affecting 1 side of the face. Saturday nigh palsy radialnerve. Sciatica refers to pain that radiates along the path of the sciatic nerve, which branches from your lower back through your hips and down each leg.