The Nervous System

THE NERVOUS SYSTEM 1




1

,THE NERVOUS SYSTEM 2
The Nervous System


Functions of the Nervous System
1. Sensory input—gathering information
o Sensory receptors monitor
changes, called stimuli,
occurring inside and outside
the body; input
2. Integration
o The nervous system processes
and interprets sensory input
and decides whether an action
is needed
3. Motor output
o A response, or effect, activates
muscles or glands

Organization of the Nervous System
 Nervous system classifications are based on:
o Structures (structural classification)
o Activities (functional classification)


A. Structural Classification
 The central nervous system (CNS)




2

, THE NERVOUS SYSTEM 3
o Organs
 Brain
 Spinal cord
o Function
 Integration; command center
 Interprets incoming sensory
information
 Issues outgoing instructions
 The peripheral nervous system (PNS)=NERVES
o Nerves extending from the brain and
spinal cord
 Spinal nerves—carry impulses to
and from the spinal cord
 Cranial nerves—carry impulses to
and from the brain
o Functions
 Serve as communication lines
among sensory organs, the brain
and spinal cord, and glands or muscles
B. Functional Classification
 Sensory (afferent) division= Gather and sense stimuli; 5 sense organs, sense of smell
o Nerve fibers that carry information to the central nervous system
 Somatic sensory (afferent) fibers carry information from the skin,
skeletal muscles, and joints
 Visceral sensory (afferent) fibers carry information from visceral organs
 Motor (efferent) division=responds
o Nerve fibers that carry impulses away from the central nervous system organs
to effector organs (muscles and glands)
o Two subdivisions
 Somatic nervous system = voluntary
Consciously (voluntarily) controls skeletal muscles
 Autonomic nervous system = involuntary
Automatically controls smooth and cardiac muscles and glands
Further divided into the sympathetic and parasympathetic nervous
systems


Nervous Tissue: Support Cells




3