The Autonomic Nervous System(2).ppt - The Autonomic Nervous...

The Autonomic Nervous
System
Human Anatomy & Physiology II
(BIO 202)

Objectives
•
Define Autonomic Nervous System
•
Compare and contrast the general structure and
function of the parasympathetic and sympathetic
divisions of the ANS
•
Define cholinergic and adrenergic fibers and list
the different types of receptors for each
•
Specifically describe the effects of sympathetic
and parasympathetic innervation on the following
organs: heart, blood vessels, GI tract, lungs,
adrenal medulla, and external genitalia

Structural Organization of the
Nervous System

Autonomic Nervous System
•
Portion of the nervous
system that operates in
comparative secrecy
•
It manages a multitude of
unconscious processes
responsible for the body’s
homeostasis
•
Homeostasis cannot be
maintained without the
ANS
•
Play major role in the
stability of our internal
environment

General Properties of the ANS
•
Automatic nervous system
( ANS ) consists of motor
neurons that:
–
Innervate smooth muscles,
cardiac muscle, and glands
–
Make adjustments to ensure
optimal support for body activities
•
Shunts blood to areas that need it
and adjusts heart rate, blood
pressure, digestive processes, etc.
–
Operate via subconscious control

Somatic Motor Pathways vs
Autonomic Motor Pathways

Somatic Motor Pathways vs
Autonomic Motor Pathways
Two-neuron chain
Effectors
Efferent Pathways
and Ganglia
Responses
to NTs

Divisions of ANS
•
Two arms of ANS:
–
Parasympathetic division : promotes
maintenance functions, conserves energy
–
Sympathetic division : mobilizes body during
activity
•
Dual innervation : all visceral organs are
served by both divisions, but these
divisions cause opposite effects
–
Dynamic antagonism between two divisions
maintains homeostasis

Parasympathetic Division
•
Promotes
maintenance
functions and
conserves body
energy
•
Sometimes called
the “rest and digest”
system

Sympathetic Division
•
Mobilizes the body
during activity
•
Often called “fight or
flight” system
•
Exercise, excitement,
emergency,
embarrassment
activates sympathetic
system

Anatomical Differences
Between ANS Divisions

Table 14.1 Anatomical and Physiological Differences between the Parasympathetic and Sympathetic
Divisions

Parasympathetic
Division

Parasympathetic Division
•
Also called craniosacral division
because fibers originate from brain stem