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
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
