1. Lesson 3 The Autonomic Nervous System
Sunday, 29 January 2012
2. Lesson 2: The Human Nervous System
Exam Question
The peripheral nervous system contains
A. the skeletal muscles.
B. the brain and spinal cord.
C. all the nerves of the central nervous system.
D. all the nerves outside the brain and spinal cord.
Sunday, 29 January 2012
3. Lesson 2: The Human Nervous System
Exam Question
The peripheral nervous system contains
A. the skeletal muscles.
B. the brain and spinal cord.
C. all the nerves of the central nervous system.
D. all the nerves outside the brain and spinal cord.
Sunday, 29 January 2012
4. Lesson 3: The Autonomic Nervous System
Objectives:
# Define the Autonomic Nervous System
(ANS)
# Describe the role and function of the two
divisions of the ANS : sympathetic and
parasympathetic
# Identify the flight or fight response
Understand homeostasis
Sunday, 29 January 2012
5. Refresh - Last lesson Concept map of overall
nervous system.
This lessons focus ANS - Sympathetic and
Parasympathetic
Sunday, 29 January 2012
6. Role of ANS
Autonomic means not under voluntary control (i.e.
automatic, independent).
The autonomic nervous system is a network of
neurons connecting the CNS to our internal
muscles and organs.
It functions continuously whether we are awake,
asleep, or even under a general anaesthetic. It
may be the only part of the nervous system
keeping a person alive when all other parts of the
brain have shut down (eg. In a coma).
Sunday, 29 January 2012
8. Parasympathetic
The parasympathetic nervous system serves two main functions:
1. It returns the body to a calm state by reversing the direction of the
changes to physiological functions that had occurred as a result of the
action of the sympathetic nervous system.
2. It minimises energy use and keeps the internal systems of the body
constantly regulated. This process is known as homeostasis.
For most of the time, the parasympathetic system is dominant because it is
involved with normal everyday functioning, rather than in sudden reactions
to stressful or threatening situations. It regulates such functions as the
digestion of food, the elimination of wastes, and the production of tears.
Sunday, 29 January 2012
10. Sympathetic
The flight-fight response is an automatic reaction by the
sympathetic nervous system to prepare the body for dealing
with a physically or psychologically threatening situation.
Normally, when placed under threat, an organism will fight or
flee. In either case, its bodily resources need to be maximised
for survival. Therefore, instead of using energy digesting lunch,
blood and its energy giving substances (oxygen, sugar, fats) are
diverted to the muscles, especially those of the limbs, since
they are the ones most likely to be called upon whether the
fight or flight option is chosen, if the threat is a physical one.
Sunday, 29 January 2012
11. From the diagram above, it is clear that all the changes that
occur in SYMPATHETIC AROUSAL are those that are getting
the body ready for physical exertion. Because the body would
suffer if it was left in that state for long, as soon as the threat is
past, the PARASYMPATHETIC NERVOUS SYSTEM returns the
functions to the normal state of balance (homeostasis).
Sunday, 29 January 2012
12. An example of the Sympathetic Nervous System in action…..
It is a nice, sunny day...you are taking a nice walk in the park.
Suddenly, an angry bear appears in your path. Do you stay and fight
OR do you turn and run away? These are "Fight or Flight" responses. In
these types of situations, your sympathetic nervous system is called
into action - it uses energy - your blood pressure increases, your heart
beats faster, and digestion slows down.
An example of the Parasympathetic Nervous System in action…
It is a nice, sunny day...you are taking a nice walk in the park.
This time, however, you decide to relax in comfortable chair that you
have brought along. This calls for "Rest and Digest" responses. Now is
the time for the parasympathetic nervous to work to save energy - your
blood pressure decreases, your heart beats slower, and digestion can
start
Sunday, 29 January 2012
