Functions of the
Nervous System
Sensory input — gathering
information
– Sight, Touch, Hearing,
Tasting & smelling
– To monitor changes occurring
inside and outside the body
– Stimuli causes a reaction by
the body
Integration – how we use
information provided by all the
sensations coming from within the
body and from the external
environment
Functions of the Nervous System
Motor output
– A response to
integrated stimuli
– The response activates
muscles or glands to
perform a specific
action
Example: Timing and
muscle coordination
needed to slide into
second base gracefully.
Functions of the Nervous System
Nervous System Organization
Central nervous system
– Brain
– Spinal cord
Peripheral nervous
system
– Nerves outside the brain
and spinal cord
Functions of
the Peripheral Nervous System
Afferent  Sensory division
– Nerve fibers that carry
information to the central
nervous system
– Info sent to brain for processing
Efferent  Motor division
– Nerve fibers that carry
impulses away from the central
nervous system
– Info sent away from brain to
muscles and glands
Motor Division of Peripheral
Nervous System
Efferent  Motor division
– Two subdivisions
Somatic nervous system = voluntary
- You actively control these reactions
- Skeletal muscles
Autonomic nervous system = involuntary
- You do NOT control these reactions
- Example: sneezing to get rid of foreign substance in
nasal passage
Autonomic Involuntary
Nervous System
The autonomic nervous system acts to
maintain normal internal functions. It
controls the involuntary functions of organs
like, digestion, breathing, metabolism or
blood pressure. Consists of two branches.
Sympathetic Branch
– controls “fight-or-flight”
response - brain gives off
messages which triggers the
release of adrenaline
it uses energy, your blood
pressure increases, your heart
beats faster, and digestion slows
down.
Autonomic Involuntary
Nervous System
The autonomic nervous system acts to
maintain normal internal functions. It
controls the involuntary functions of organs
like, digestion, breathing, metabolism or
blood pressure. Consists of two branches.
Parasympathetic Branch
– lowers heart rate and blood
pressure, diverts blood back to
skin and the digestive tract,
contracts pupils, constricts
bronchiole tubes in lungs,
resumes digestion.
The sympathetic system
undoes the
parasymphathetic effects
on the body.
After a stressful event,
the parasymphathetic
system returns the
body’s levels back to a
homeostatic balance.
Homeostasis is the
ability to maintain a
constant internal
environment in response
to environmental
changes.