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7 - Nervous Tissue

7 - Nervous Tissue - Chapter 12 Nervous Tissue Pages 415...

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Chapter 12 Nervous Tissue Pages 415 – 454 Overview Of The Nervous System Master controlling/communicating system of the body o Every action/motion/thought controlled by nervous system o Communicate by chemicals (neurotrasmitters) and electrical impulses (generates action potential/affect on effector) Weighs about 5 pounds (2 kg) Organized into networks Made up of billions of neurons Times 10 more neuroglia Hard to study the brain Structures of the Nervous System: Fig 12.1 Central Nervous System Brain Spinal Cord Peripheral Nervous System Everything else Brain (CNS) Enclosed by the skull 100 billion neurons (10 x neuroglia) Cranial Nerves (PNS) Arise from base @ brain (brain stem) Still enclosed by the skull 12 pairs of cranial nerves supply special senses (eye, smell, hearing, facial nerves) Nerve “Getting on my nerves” getting on my axons Nerve = bundles of axons enclosed by connective tissue, have blood vessels CNS uses nerves to communicate with various parts of the body o Nerve carries it from brain to big toe or hand to brain (when pick up a pen) Follow distinct pathway, supply specific regions of the body Spinal Cord 100 million neurons (not as many as brain) x 10 neuroglia Spinal Nerves 35 pairs of spinal nerves & arise from spinal cord supply the rest of the body (arms, legs, torso) Ganglia Most neuronal cell bodies located in brain/spinal cord protected by skull & vertebral column (axons going out & forming nerves) Ganglia = part of the PNS, cell body lies in the ganglia Sensory Receptors Dendrites (enclosed in a capsule) / sensory neurons (pick up info/sense) / special cells Baroreceptors have these special neurons (know body temp) Enteric plexuses 1
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Special neurons, reside in GI tract ~100 million neurons Functions of the Nervous System Complicate Thoughts, actions, emotions, reasoning make us who we are Mind (know body) is separate from brain (consciousness, know me!) o Koch = theory Communicate with each other at high wavelengths Special neurons o Green = theory No special neurons Neuron gathers then breaks, move on Sensory Pick up info and carry it to CNS Touch pen (immediately tells brain you’ve touched pen) Integrative Function Info has come in and been interpreted by brain Figure out what to do with pen Brain decides action Motor Control muscles to carry out action (hold pen) Histology of Nervous Tissue Fig 12.2 Neuron Most interesting cell of the body (delicate) Have unique function Crying/thinking controlled by neurons Electrically excitable Touch something neurons excited, convey electrical impulse to CNS & away from CNS Can convert touch into an electrical signal (muscle cells can’t do this) Parts of a neuron Nucleus Nissel Bodies – rough endoplasmic reticulum Neurofibrils – intermediate filaments, give shape to neurons and play an active part in some sort of transport Microtubules
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7 - Nervous Tissue - Chapter 12 Nervous Tissue Pages 415...

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