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NERVE CELLS

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NERVE CELLS by Grace Minter OVERVIEW Definition Structure Function BASIC DEFINITION Nerve Cell (Neuron) the structural and functional unit of the nervous system ... – PowerPoint PPT presentation

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Title: NERVE CELLS


1
NERVE CELLS
  • by Grace Minter

2
OVERVIEW
  • Definition
  • Structure
  • Function

3
BASIC DEFINITION
  • Nerve Cell (Neuron)
  • the structural and functional unit of the nervous
    system

4
NEURON STRUCTURE
  • All nerve cells contain 4 distinct regions
  • 1. Cell body
  • 2. Dendrites
  • 3. Axon
  • 4. Axon terminals

5
STRUCTURE CONTINUED
  • CELL BODY
  • houses nucleus is site of protein synthesis and
    degradation of all neuron proteins and membranes
  • AXON
  • specialized for the conduction of an electric
    impulse or action potential away from the
    neuronal cell body to axon terminals
  • AXON TERMINALS
  • Send chemical signals to dendrites of other
    neurons
  • DENDRITES
  • receive chemical signals from the axon termini of
    other neurons convert the signals into electric
    impulses for delivery to cell body

6
FUNCTIONAL MECHANISM
  • Neurons function through both electric chemical
    signaling
  • An electric potential exist across the plasma
    membrane of neurons
  • the potential is due to the selective
    permeability of the membrane to differing ions
  • resting membrane potential ? 60 mV, negative on
    inside because cell pushes large number of K
    ions out
  • An electrical impulse results from the sequential
    opening closing of ion channels and is
    converted into a chemical signal for message
    transmission

7
A CLOSER LOOK
  • Transmission of an electrical signal (performed
    by axons)
  • 1. Na channels open influx of Na into cell
    causes depolarization of neuronal membrane
  • 2. Na channels close K channels open
    release K ions into extracellular space,
    causing hyperpolarization of the membrane
  • 3. K channels close membrane returns to
    resting potential ( 60 mV)
  • 4. This process spreads across the axon,
    generating an electric signal to the axon
    terminals

8
A CLOSER LOOK PART II
  • Transmission of a chemical signal through
    synapses (performed by axon terminal
    dendrites)
  • synapses ? sites where neurons send receive
    information from other cells
  • 1. electrical impulse generated reaches axon
    terminals causes the exocytosis of a chemical
    neurotransmitter contained within a synaptic
    vesicle from the presynaptic cell
  • 2. Neurotransmitter travels through synaptic
    cleft binds to specific receptors on the
    dendrites of postsynaptic cell, causing a
    change in its permeability to ions

9
BRINGING IT TOGETHER
10
SUMMARY
  • NEURON ? functional structural unit of the
    nervous system
  • All neurons are composed of a cell body, axon,
    axon terminals, dendrites
  • Neurons function through both electrical and
    chemical signals in order to transmit messages
    throughout the body

11
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12
QUESTIONS
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