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Communication
within mammals
Joanna
George-Johnson, Contributor
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Members of the Bridgeport High School Choir give the photographer a sneak preview
of their singing prowess after the school's anniversary and awards ceremony, on
Friday, September 29, 2006. - Photo by Anthony Minott | A
very important characteristic of living organisms is the ability to respond to
stimuli. This may be internal or external. The ability to respond is very important
to an organism for it is the way that they are able to prevent themselves from
causing serious injury to them. Pain
is good! Many
of my students, when discussing this topic, tend to believe that we can live without
certain sense, chief of which is the ability to feel pain. Then I will point out
to them that the ability to sense pain is one of the most important ways to prevent
irreversible injury. For example: Most sports men and women would destroy their
bodies if they were unable to feel pain. They
would not know when they have reached their limit and, therefore, they would continue
until their bodies just give up. Also, if we think about it, most of the times
when we go to the doctor it's because of some sort of pain that we are feeling.
If it were not for pain, we could continue being sick without even knowing about
it. What
is needed? For
effective response certain components are needed. Some
sort of detection mechanism is needed to sense the change in the environment that
needs a response by the organism. After
detection has occurred, it is important that this is communicated efficiently
to the relevant organ. And since organisms are continually bombarded with many
stimuli, it is important that this organ is able to sort through the myriad of
messages that comes in and be able to give the appropriate response. There
is also a need for the message of the response to be communicated to the effector
organ so it can carry out the job of the actual response. How
do we do it? Higher-order
organisms such as mammals like us have two main systems of communication; namely,
endocrine and nervous systems. Although they are both communication systems they
are responsible for different types of stimuli. However, there are some times
when their jobs may overlaps. (see table at left). The
nervous system is often referred to as the primary integrator and the endocrine
system as the secondary integrator. The nervous system is adapted to make rapid
adjustments to external and internal stimuli (e.g., shunting of blood from GI
tract to skeletal muscle in exercise) and the endocrine system is most important
in the regulation of processes which require duration rather than speed (e.g.,
growth, differentiation, reproduction, metabolic rate, etc.). Questions
1.
What is a stimulus? 2.
Give three examples of responding to stimulus and their importance to the organisms.
(Give at least one plant example). 3.
The endocrine and nervous systems can be compared to everyday, real-life communication
systems - 'snail mail' and telephone systems. Write an essay depicting this comparison.
| Comparing
the different communication systems | | Endocrine
System | Nervous
System | | Uses
chemical messengers; Hormones | Uses
chemical messengers and electrical impulses; neurotransmitters, action potential
| | Usually
slow response and very prolonged effect: growth | Very
fast response, not usually a prolonged effect: blinking the eye | | Target
cells may be far from hormone production sites. | Target
cells tend to be near the source of the impulse | | Uses
secretory glands | Uses
neurones | | Hormones
travel through the blood stream. But only affects the target cells. (Hormones
are specific.) | The
electrical impulses travel through the neurones and are directed to the target
cells only. |
Written
by: Joanna George-Johnson and company. | 
