CHAPTER 6: NERVOUS TISSUE
The nervous system is an organized network of billions of neurons & neuroglia. It includes the brain, spinal cord, nerves, ganglia & receptors. It operates through high speed nerve impulses, coordinating all other systems and initiates all voluntary & involuntary movements.
Structural Divisions of the Nervous System
1. Central Nervous System –
2. Peripheral Nervous System –
Functional Divisions of the Nervous System 1. Autonomic Nervous System – Involuntary
a. Sensory neurons that convey info from the automatic sensory receptors located in viscera to the CNS b. Motor neurons from the CNS that conduct impulses to smooth muscle, cardiac muscle, glands & adipose tissue c. Motor portion has 2 parts Sympathetic & parasympathetic 2. Somatic Nervous System – Voluntary a. Sensory neurons convey sensory info from somatic & special sensory receptors primarily in head, body wall & limbs to CNS. b. Motor neurons from the CNS that conduct impulses to skeletal muscle
3. Enteric Nervous System – involuntary
a. plexus that extends the length of the gastrointestinal tract b. sensory receptors monitor chemical & mechanical changes c. motor impulses govern the contraction of GIT smooth muscle, secretions of GIT organs and the activity of GIT endocrine cells
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