Peripheral Nervous System and

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Peripheral Nervous System and

• Autonomic Nervous System

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When is the nervous system formed?

• During the first month of fetal development

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Some situations during pregnancy that could cause
nervous system malformations

• Measles deafness
• Drugs, alcohol, crack babies
• Radiation
• Lack of oxygen death of neurons, retardation

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Due to a gradual lack of oxygen, the aging
process will lead to what disease?

• Senility

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Why does brain shrinking seem to be accelerated
in professional boxers

• Brain damage and atrophy occur at each fight

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Two types of neurons in the PNS

• Afferent or sensory
• Efferent or motor

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12 pair of cranial nerves

• Their names indicate their anatomical or
  functional features

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Structure and distribution of spinal nerves

• At each segment of spinal cord, a pair of nerves
  exits the H shaped gray matter
• One goes to the left side of the body and one
  goes to the right side of the body

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Spinal nerves

• Are named and numbered according to the region
  and level of the spinal cord area from which they
  emerge
• 31 pair

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Branches of spinal nerves

• The ventral rami of spinal nerves are arranged to
  form plexuses
• Cervical C1 through C4
• Brachial C5 to C8 sand T1
• Lumbar L1 to L4
• Sacral L4, L5 and S1 through S3
• Coccygeal S4 and S5

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What are the plexuses?

• A network of nerves which serve the motor and
  sensory needs of the limbs
• Brachial
• Lumbar
• Sacral

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Degeneration and regeneration of peripheral nerves

• Neurons
• Development begins at birth
• Completes during infancy
• Deteriorates for the rest of your life

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The Autonomic Nervous System

• Main function is to promote homeostasis
• Regulates
• Heart contractions and rate
• Smooth muscles
• Glands
• Breathing rate
• Stomach secretions
• Pupil dilations

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• Most actions are NOT under conscious control
• Hypothalamus is the regulatory center of the ANS
• Is divided into two sections
• Sympathetic and parasympathetic

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Structure of the ANS

• Two divisions sympathetic and parasympathetic
• Each division sends efferent nerve fibers to that
  which it innervates
• They have opposite effects

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Sympathetic division

• Helps the body adjust to stressful situations.
  Mobilizes the body during extreme situations such
  as fear, exercise, and rage (fight or flight)
• Releases norepinephrine

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Parasympathetic division

• Operates when body is under normal circumstances,
  day to day activities
• Allows us to unwind and conserve energy
• Releases neurotransmitter acetylcholine

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Autonomic control centers in the Central Nervous
system

• Brainstem and spinal cord
• Hypothalamus
• Limbic system