The Nervous System

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The Nervous System
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The Nervous System

• Functions of the nervous system include
• coordination of the physical movements of the
  body
• corresponding to the action of the senses
  (hearing, tasting, smelling, touching, and sight)

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The Nervous System

• The Nervous System is composed of two major
  parts
• the Central Nervous System
• the Peripheral Nervous System

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The Nervous System

• The Central Nervous System includes the brain and
  spinal cord.
• This system controls most of the voluntary
  responses of the animal.

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The Nervous System

• The brain controls the central nervous system.
• Parts of the brain include the
• cerebrum
• cerebellum
• pons
• medulla oblongata

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Regions of the Brain
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The Nervous System

• The largest part of the brain is the cerebrum,
  which is usually large in relation to the body
  size in more intelligent animals.
• The cerebrum is responsible for the
  decision-making or thinking process that controls
  the voluntary muscles and reacts to the stimuli
  of the senses.

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The Nervous System

• The cerebellum serves as the coordinator of the
  messages from the other parts of the brain to the
  body.
• Reflex actions, like blinking, breathing, and
  swallowing are controlled by the pons and medulla
  oblongata.

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The Nervous System

• The spinal cord is the main organ used for
  impulse transferal between the brain and other
  parts of the body.
• The spinal cord is divided into segments, and
  from each segment a pair of spinal nerves extends
  to the body.

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The Nervous System

• The spinal cord receives messages from sensory
  nerve fibers from various parts of the body and
  transmits them to the brain.
• Efferent neurons (motor nerve fibers) in the
  spinal cord then transmit the responses from the
  brain back to the body.

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The Nervous System

• The peripheral nervous system controls the
  functions of body tissues and organs.
• Somatic nerves transmit signals from the outer
  parts of the body to the brain.
• Autonomic nerves help to control the functions of
  internal organs, like the heart and stomach.

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The Nervous System

• Nerve cells, called neurons, consist of a single,
  long fiber, called an axon, and several branched
  threads called dendrites.
• Sensory organs, like the skin, stimulate the
  dendrites through which a nerve impulse passes to
  the axon.

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The Nervous System

• The impulse may be conducted to an effector
  organ, like a muscle cell.
• The point where the dendrite is connected to the
  axon is called a synapse.
• Some impulses are not sent to the brain, but go
  directly to the effector organ.

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The Nervous System

• Nerves occur in single neurons or in bundles,
  called nerve trunks.
• Nerve cells that are found outside the brain and
  spinal cord are called ganglions.

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The Nervous System

• Nerve cells that receive stimuli and carry the
  impulses to the central nervous system are called
  sensory or afferent neurons.
• Nerve cells which carry messages from the brain
  to muscles or glands are called motor or efferent
  neurons.