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Neural Communication

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... allows sodium ions to enter. Step 2 Calcium ions enter the cytoplasm of the synaptic knob ACh release occurs through exocytosis of nuerotransmitter. – PowerPoint PPT presentation

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Title: Neural Communication


1
Neural Communication
This is anything that deals with the synapse and
the neurons communication with each other
  • By Ryan Gov
  • Sera Choi
  • Iris Gonzalez

2
Movement of information
  • Information in the nervous system moves to other
    locations through action potentials
  • These electrical movements are nerve impulses
  • Chemicals known as neurotransmitters transfer the
    information when released.
  • In neuron communication, the synapse may be at
    the dendrite, cell body, or the axon.
  • Neuroeffector junctions are synapses between a
    neuron and other types of cells
  • Neuronglandular junctions are where a neuron
    controls the activity of a secretory cell.

3
Structure of a synapse
  • Communication between neurons occur in only one
    direction across a synapse.
  • An impulse can travel from the synaptic knob of
    the presynaptic neuron to the postsynaptic
    neuron.
  • The opposing cell membranes are separated by
    narrow spaces called a synaptic cleft.
  • The synaptic terminals have mitochondria,
    synaptic vesicles, and endoplasmic reticulum.
  • Synaptic vesicles have thousands of molecules of
    specific neurotransmitters.
  • When the vesicles release these neurotransmitters
    they diffuse across the synaptic cleft, then they
    bind to the receptors

4
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5
Functions and neurontransmitters
  • There are many different neurotransmitters, an
    example being acetylcholine or ACh.
  • The cholinergic synapses is where the ACh is
    released, and these are numerous in and out of
    the Central Nervous system.
  • Another common neurotransmitter is norepinephrine
    (NE), or nonadrenaline.
  • NE is important to the brain and the autonomic
    nervous system.
  • Dopamine is another important neurotransmitter in
    the central nervous system
  • Serotonin is a neurotransmitter important to the
    mood of humans, it is known as the happy
    hormone even though its not a hormone.

6
The sequence of events for a cholinergic synapse
  • Step 1
  • An action potential arrives and depolirizes the
    synaptic knob.
  • The binding of ACh to sodium channels causes them
    to pen and allows sodium ions to enter.
  • Step 2
  • Calcium ions enter the cytoplasm of the synaptic
    knob
  • ACh release occurs through exocytosis of
    nuerotransmitter.
  • The release ends quickly because the calcium ions
    are removed from the cytoplasm by active
    transport

7
  • Step 3
  • ACh binds to receptors and depolarizes the
    postsynaptic membrane
  • The binding of ACh to sodium channels causes them
    to open and allows sodium ions to enter
  • If the depolarization of the postsynaptic
    membrane reaches threshold, an action potential
    is produced.
  • Step 4
  • Then the removal of ACh by AChE occurs
  • The effects on the postsynaptic membrane is
    temporary because of AChE
  • The AChE removes ACh by breaking it into acetate
    and choline

8
  • In the central nervous system, there are 50 other
    neurotransmitters that are not well understood
  • There are also gases that are important to
    neurotransmitters nitric oxide and carbon
    monoxide
  • Neurotransmitters released from the synapse can
    have either excitatory or inhibitory effects
  • Excitatory effects means the nerve cells have a
    higher probably of producing an action potential
  • Inhibitory effects is when the intensity of the
    action potential is suppressed
  • ACh and NE have an excitatory effect
  • Dopamine and serotonin are usually inhibitory

9
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10
  • The action potential depends on the balance of
    depolarization and hyperpolarizing stimuli
    arriving.
  • The activity of a neuron depends on the balance
    between excitation and inhibition.
  • These interactions between neurons are very
    complex and somewhat confusing
  • The synapses at the cell body and dendrites may
    involve tens of thousands of other neurons.
  • Some neurons will be releasing excitatory
    neurotransmitters while others inhibitory.

11
Neuron pools
  • A human has about 10 million sensory neurons, 20
    billion interneurons, and one-half million motor
    neurons
  • This is the simplest form of organization in the
    CNS
  • A neuronal pool is a group of interconnected
    interneurons with specific functions.
  • Neuronal pools have limited numbers of input
    sources and output destinations
  • Thus the output of one pool may stimulate or
    depress the activity of other pools
  • The neuronal pool may also exert direct control
    over motor neurons or peripheral effectors.

12
  • Neurons and neuronal pools communicate in
    different patterns called neural circuits
  • The two simple circuit patterns are divergence
    and convergence.
  • This is how information spreads from one neuron
    or neuronal pool to other neurons or neuronal
    pools
  • Divergence occurs when sensory neurons bring
    sensory information to the CNS
  • This is due to the distribution of the sensory
    information through the brain and the spinal
    column
  • Ex The information from your eyes reaches your
    conscious awareness at the same time its carried
    to the areas of the brain that control posture
    and balance at the subconscious level.

13
  • Divergence can also be involved with other
    responses
  • Ex when you step on a sharp object
  • The action stimulates sensory neurons that
    distribute information to neuronal pools
  • There will be several possible reactions
    withdrawing your foot, shifting your weight,
    moving your arms, feeling the pain, or saying
    ouch
  • This all may even happen at the same time
  •  When the neuron fires, the signal is sent to
    many other neurons, resulting in a divergence of
    output.

14
Convergence
  • Convergence is when several neurons synapse on a
    single postsynaptic neuron.
  • This makes both voluntary and involuntary control
    of some body processes
  • Ex the movement of your diaphragm now.
  • The movement is being involuntarily controlled by
    the brain
  • These movements can be controlled voluntarily too
  • When you take a deep breathe and hold it.
  • Two neuron pools are involved, and both synapse
    on the same motor neuron.

15
Quiz time!!!!
  • 1. What are the electrical movements that help
    disperse information between neurons?
  • 2. Name at least two neurotransmitters and what
    their functions are.
  • 3. How is an action potential produced?
  • 4. Describe the two effects a neuron can have.
  • 5. Describe the two simple circuits of a neuron.

16
  • 1. Nerve impulses
  • 2. Serotonin (mood regulator) and Dopamine
    (important in the CNS)
  • 3. If the depolarization of the postsynaptic
    membrane reaches threshold, an action potential
    is produced.
  • 4. excitatory and inhibitory
  • 5. divergence or convergence
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