The Nervous System and the Brain

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The Nervous System and the Brain

• Information in this presentation is taken from
  UCCP content

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The Nervous System

• Our nervous system has three primary functions
• 1. to gather and process information
• 2. produce responses to stimuli
• 3. coordinate the working of different cells
• It is divided into two parts central nervous
  system (brain and spinal cord) and the peripheral
  nervous system.

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Peripheral Nervous System

• The peripheral nervous system consists of neurons
  that transmit messages to and from the central
  nervous system.
• There are two types of neurons in this system
  sensory neurons and motor neurons.
• Sensory, or afferent, neurons receive the
  information from muscles and glands and transmit
  the message to the brain and spinal cord.
• Motor, or efferent, neurons receive messages from
  the brain and spinal cord and transmit the
  information to muscles and glands.
• An easy way to remember what afferent and
  efferent neurons do is to remember the mnemonic,
  SAME. Sensory neurons (S) are Afferent neurons
  (A) Motor neurons are Efferent neurons (E).

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Peripheral Nervous System

• There are two divisions of the peripheral nervous
  system the somatic nervous system and the
  autonomic nervous system.
• The somatic nervous system connects the CNS to
  sensory receptors and muscles. Neurons in the
  somatic nervous system transmit messages about
  sights, sounds, smell, temperature, and body
  position to the CNS. It also transmits
  information from the brain to produce purposeful
  motor movements.
• The autonomic nervous system is automatic. It
  controls and regulates the glands and muscle of
  internal organs. For example, it controls
  activities such as heart rate, respiration
  (breathing), digestion, and pupil dilation.
  These activities occur automatically.

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Autonomic Nervous System

• There are two branches of the autonomic nervous
  system sympathetic and parasympathetic.
• The sympathetic nervous system is most active
  during processes that involve spending the bodys
  energy from stored reserves. It prepares the
  body to respond in times of danger or high
  emotion. Basically, it is arousing the body to
  take action. (example if you see a mean dog
  running towards you, your body will prepare you
  to expend your energy and RUN!)
• The parasympathetic nervous system is most active
  during processes that replenish reserves of
  energy. It quiets the body and lowers its level
  of arousal. It is most active after high
  emotional states. It works to keep your heart
  rate and breathing at moderate levels.

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The Nervous System

• The somatic and autonomic nervous systems work
  together to coordinate the inner world of the
  body with what is going on in the outside world.
  For example, if a large dog growls and lunges at
  you, your autonomic nervous system (sympathetic)
  increases your blood pressure and heart rate and
  prepares you to react. At the same time, the
  somatic nervous system is sending messages to
  your leg muscles allowing you to run.
• Sometimes peoples sympathetic nervous system
  overreacts. In the absence of external threats,
  their bodies still respond as if they were faced
  with danger, such as in anxiety or panic attacks.
  

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The Central Nervous System

• The central nervous system consists of the brain
  and spinal cord.
• Its primary functions are to
• 1) receive, process, interpret and store
  sensory input and
• 2) initiate motor outputs

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The Central Nervous System

• The spinal cord is like an information highway.
  It is a column of nerves that transmits messages
  (1) from sensory receptors to the brain and (2)
  from the brain to muscles and glands. The most
  basic pattern of neural responses, however, does
  not even include the brain.
• Spinal reflexes are unlearned, automatic
  responses to stimuli that typically include only
  two neurons, a sensory neuron and a motor neuron.
  Sometimes interneurons will transmit the neural
  impulse from the sensory neuron through the
  spinal cord to the motor neuron.

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The Central Nervous System

• The pain reflex illustrates this neural pathway.
  Imagine if your right hand touches the burner on
  the stove. The sensory neurons in your hand
  detects the pain and instantly fires off a
  message to your spinal cord. When the message
  reaches your spinal cord it connects with an
  interneuron that in turn activates a motor
  neuron. The motor neuron sends a message to
  cells in your arm muscles that are capable of
  muscle movement. Muscle cells in your right arm
  contract, causing you to lift your right hand off
  the stove. If this happened, would it require
  any brain activity or thinking on your part?
• However, the spinal cord will also send a message
  to the brain notifying it about what you have
  done. After you withdraw your hand, you will
  most likely feel the pain and shout, Ouch!

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The Brain

• The brain consists of three major regions
• The hindbrain
• The midbrain
• The forebrain
• Our forebrain is most important in those aspects
  of life that are most relevant to psychology
  (e.g. perception, memory, thinking and social
  behavior).

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The Hindbrain

• The hindbrain controls some basic functions such
  as breathing and heart rate. It is also
  important in attention, sleep, alertness, body
  movement, and balance. The primary structures of
  the hindbrain are the following
• The cerebellum coordinates motor behavior, muscle
  coordination, and balance.
• The medulla regulates unconscious functions such
  as breathing and circulation.
• The pons connects the brain stem to the
  cerebellum and is involved in sleep and arousal
  as well as transmits information about body
  movement.
• The reticular formation controls arousal and
  attention.

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The Midbrain

• The midbrain plays a role in vision, hearing,
  motor movements, attention, and sleep. For our
  purposes, the midbrain is a conduction and switch
  center that serves as a link between the
  hindbrain and the forebrain.

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The Forebrain

• The primary structures of the forebrain are
• Thalamus relay station that receives and relays
  sensory information to the appropriate area of
  the cerebral cortex (e.g. sensory info. from the
  eyes)
• Hypothalamus regulates autonomic nervous
  system, motivation and emotion. It also
  controls eating, drinking, sexual behaviors and
  aggression.
• Limbic System includes the amygdala,
  hippocampus and parts of the hypothalamus. The
  amygdala is involved in aggression and fear
  responses. The hippocampus is important in
  learning and memory.