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Nervous system:
2. Comparing
control systems:
endocrine - hormone systems and nerve cells -nervous system
Doc Brown's Biology exam study revision notes
There are various sections to work through,
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INDEX
of biology notes on the nervous system
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(2)
Reminder - comparing two control systems
(endocrine-hormone systems and nerve cells-nervous system)
The nervous system and endocrine hormone
system are two quite different mechanisms of control in the body,
BUT, in principle they function in similar ways AND interact with each other
too.
The endocrine system uses chemical
molecule messengers (hormones) to communicate information.
See
Homeostasis - introduction to how it functions (negative
feedback systems explained)
and
Hormone system - Introduction to the endocrine
system - role of thyroxine
The nervous system uses electrical
impulse messages to communicate information.
|
Endocrine hormone system |
Receptor detects changes in the environment |
Chemical messenger - hormone molecule
signal
Slower, but acts for much longer - carried in
blood to all organs, but only affects target organ |
Coordination centre A gland
e.g. pancreas
Receives signal and processes information |
Chemical messenger - hormone molecule
signal
Slower, but acts for much longer - carried in
blood to all organs, but only affects target organ |
Effector
A gland that secretes a hormone to restore an
optimum level or trigger some other chemical response |
|
Nervous system |
Receptor detects changes in the environment |
Electrical signal - nerve impulse
Rapid and short duration - carried in nerve
fibres to specific locations like muscles |
Coordination centre Brain or
spinal cord
Receives signal and processes information |
Electrical signal - nerve impulse
Rapid and short duration - carried in nerve
fibres to specific locations like muscles |
Effector
Muscles that respond to the signal |
Comparing nerve
and hormone functions
Hormones effectively act as
'chemical messages' to trigger particular biochemical reactions and their
effects are ..
more general around the body, but
tend to affect particular cells in particular organs,
and relatively long-lasting compared to e.g. the
fast but short-term nervous impulses and responses of a reflex arc.
Compared to the hormone
system of response and control in the body, nerve signals are
electrical (not chemical, except at synapses), the nerves act very fast - a short burst of a
nervous impulse for a short time, acting from one precise area to
another in the body.
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