The Nervous System Neural Anatomy

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The Nervous SystemNeural Anatomy
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Neurons The Building Blocks of the Nervous
System

• Module 7 Neural and Hormonal Systems

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Nervous System

• The electrochemical communication system of the
  body
• Brings information to the brain from the senses
• Sends messages from the brain to the body to
  enact behavior

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Neuron

• The basic building block of the nervous system --
  a nerve cell
• Neurons perform three basic tasks
• Receive information
• Carry the information
• Pass the information on to the next neuron

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Types of Neurons

• Afferents, or sensory neurons, carry
  information from the body to the brain

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Types of Neurons

• Interneurons, found in the spinal cord and the
  brain, interpret the incoming information and
  determine the next course of action

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Types of Neurons

• Efferents, or motor neurons, carry information
  from the spinal cord or the brain to the rest of
  the body in order to initiate behavior

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Parts of the Neuron
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Parts of the Neuron - Dendrites
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Parts of the Neuron - Soma
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Parts of the Neuron - Axon
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Parts of the Neuron Myelin Sheath
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Parts of the Neuron - Terminals
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Neuron
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Neuron
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The Neural Network

• How does the whole system fit together?

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• A neuron is considered at resting potential
  when there is no sensory input and it is awaiting
  stimulus.

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A Neural Chain
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• Special receptors in each of the five senses
  detect stimuli from the outside world.

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• When a neuron receives enough information to pass
  on, it has reached its action potential and
  fires off the message to the next neuron in the
  link

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• Once a neuron fires, it must re-set momentarily
  in order to receive another message. This re-set
  period is called refraction. It cannot fire
  during this period.

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A Neural Chain
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• Sensory neurons carry all of the input to the
  spinal cord.

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A Neural Chain
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• Interneurons in the spinal cord and the brain
  process the information and decide the best
  course of behavior.

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A Neural Chain
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• Motor neurons from the brain travel back down the
  spinal cord and out to the appropriate parts of
  the body with the appropriate behavior
  instructions.

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A Neural Chain
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Neural Communication The Neural Impulse
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A neuron firing is like a toilet flushing

1. Like a Neuron, a toilet has a resting potential.
   The toilet is charged when there is water in
   the tank and it is capable of being flushed.

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Neuron firing like a Toilet

• 2. Like a Neuron, a toilet has an action
  potential. When you flush, an impulse is sent
  down the sewer pipe.

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Neuron firing like a Toilet

1. Like a neuron, a toilet has a refractory period.
   There is a short delay after flushing when the
   toilet cannot be flushed again because the tank
   is being refilled
2. Like a Neuron, a toilet operates on the
   all-or-nothing principle it always flushes with
   the same intensity, no matter how much force you
   apply to the handle

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Communication Between Neurons

• Module 7 Neural and Hormonal Systems

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Synapse

• The electrical message from the dendrite travels
  down the axon to the terminal buttons. Here, it
  changes into a chemical message to be transferred
  to the next neuron.
• The tiny, fluid filled gap between the axon
  terminal of one neuron and the dendrite of
  another neuron is called the synapse.

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Neurotransmitters

• A chemical messenger that travels across the
  synapse from one neuron to the next

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Neurotransmitters
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Acetylcholine (ACh)

• Enables muscle action, learning, and memory
• Undersupply, as ACh-producing neurons
  deteriorate, marks Alzheimers disease

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Dopamine

• Influences movement, learning, attention, and
  emotion
• Excessive dopamine receptor activity is linked to
  schizophrenia a lack of dopamine produces the
  tremors and lack of mobility of Parkinsons
  disease

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Serotonin

• Affects mood, hunger, sleep, and arousal
• Undersupply is linked to depression Prozac and
  other anti-depressants raise serotonin levels

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Norepinephrine

• Helps to control alertness and arousal
• Undersupply can depress mood

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Endorphins

• Natural opiates that are released in response to
  pain and vigorous exercise
• Endorphins

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The Structure of the Nervous System
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The Nervous System
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Central Nervous System (CNS)

• The brain and spinal cord
• The brain is the location of most information
  processing.
• The spinal cord is the main pathway to and from
  the brain.

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Spinal Cord
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Divisions of the Nervous System
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Peripheral Nervous System (PNS)

• The sensory and motor nerves that connect the
  central nervous system to the rest of the body
• Peripheral means outer region
• The system is subdivided into the somatic and
  autonomic nervous systems.

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Divisions of the Nervous System
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Somatic Nervous System

• The division of the peripheral nervous system
  that controls the bodys skeletal muscles
• Contains the motor nerves needed for the
  voluntary muscles

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Divisions of the Nervous System
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Autonomic Nervous System

• The division of the peripheral nervous system
  that controls the glands and muscles of the
  internal organs
• Monitors the autonomic functions
• Controls breathing, blood pressure, and digestive
  processes
• Divided into the sympathetic and parasympathetic
  nervous systems

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Divisions of the Nervous System
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Sympathetic Nervous System

• The part of the autonomic nervous system that
  arouses the body to deal with perceived threats
  and stress

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Divisions of the Nervous System
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Parasympathetic Nervous System

• The part of the autonomic nervous system that
  calms the body
• Brings the body back down to a relaxed state

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Divisions of the Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Divisions of
the Autonomic Nervous System
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The Sympathetic and Parasympathetic Nervous
Systems

• Physical Responses