Transcript The Nervous System

The Nervous System
The Nervous System
• Gathers information both externally and
internally
• Transmits this information for processing
• Processes the information to determine the
best response
• Sends information to the muscles, glands
and organs so they can respond
appropriately
The Nervous System
Central Nervous System
(CNS)
Peripheral Nervous
System (PNS)
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• Nerves that extend
throughout the body
• Gathers and delivers
information
• Works with the Central
Nervous System
Brain and Spinal Cord
Main Control Center
Processes information
Sends instructions to other
parts of the body
The Nervous System
Structure of the Neuron
• Cell body
• Dendrites receive and carry information toward the
cell body
• Axon carries nerve impulses away from the cell
body
• Glial cells protect, support and assist neurons
• In the PNS, the glial cells are Schwann cells
– Schwann cells are wrapped by a myelin sheath
Neuron
The Central Nervous System
• Brain
Brain Stem: Joins brain to spinal
cord
Cerebellum: Center of coordination
Cerebrum: Largest part of brain,
conscious thought
Cerebral Cortex: Sensory, motor
and association areas
• Spinal Cord
Relays nerve impulses to and from
the brain
Controls spinal reflexes
Parts of the Brain
• 2 cerebral hemispheres
– Further divided into lobes
• Parietal Lobe – somatic sensory area, impulses
traveling from the body’s sensory receptors are
localized & interpreted here
– Ex. pain, cold, touch
• Occipital Lobe – visual area
• Temporal Lobe – auditory area and olfactory area
• Frontal Lobe – primary motor area – skeletal muscles,
also specialized area for fine motor control such as
speech
Cerebral Cortex – sensory and
motor areas
Cerebellum
• 2 hemispheres
– Under occipital lobe of cerebrum
• Balance
• Coordinates body movements (makes
movements smooth)
Cerebellum (colored purple)
Brain Stem
• 3 inches long, diameter of thumb, base of
brain
• 3 parts:
– Midbrain – reflex centers for hearing and vision
– Pons – (means bridge), center for breathing
– Medulla oblongata – merges into spinal cord
• Automatic, homeostatic functions
• Such as: heart rate, blood pressure, breathing,
swallowing, vomiting and digestion
Spinal Cord
• Continuation of brain stem
• 2-way conduction pathway to and from the
brain and a major reflex center
• Cushioned and protected by meninges
– Meninges = connective tissue membranes
• 31 pairs of spinal nerves arise from the spinal
cord
The Peripheral Nervous System
Somatic Nervous System
Autonomic Nervous System
• Controls voluntary responses of
skeletal muscles
• May involve some reflex
reactions
• Controls the activities of smooth
muscles, organs, and glands
• Divided into:
Sympathetic Nervous System
which controls the response of the
body to stress
Parasympathetic Nervous
System which controls the
functions of the body related to
rest and digestion