Download Chemical Signals in Animals

Chemical Signals in Animals
Learning Objectives (3/2/09)
• Differentiate between types of cellular chemical messages:
autocrine, paracrine, and neuroendocrine
• Compare the response time & duration for the two major
systems of internal communication in animals: nervous and
endocrine
• Compare and contrast the mechanisms of lipophilic and
lipophobic hormone action
• Describe the bases for the creation and maintenance of the
transmembrane electrochemical potential
• Discuss the sequence of events in a variety of second
messenger systems in signal transduction
• Describe examples of hormone interaction in the integration
of complex animal processes (e.g. water balance, and insect
development)
• Explain the role of neurosecretory cells in the hypothalamus
in the regulation of endocrine function
p. 1055
Chemical
Communication
Briefly describe the two
major forms of
intercellular
communication in animal
bodies. Which organ
systems are responsible
for this communication?
Describe the type of
intercellular
communication called
“neuroendocrine”.
What defines a “target
tissue”?
Endocrine Function is often
Controlled by Negative Feedback
See also p. 1065
Describe the body
functions typically
coordinated by endocrine
communication.
If the thyroid gland is
removed from a mammal,
continued survival
depends
on replacement of
thyroid
hormones, T3 and T4.
It is not necessary to
replace Calcitonin.
Explain….
Basic Mechanisms of Chemical Signaling
•What characteristic of the
message is related to
where the target cell
presents the receptor?
Explain.
•What are the advantages
of activating a signaltransduction pathway?
•What kinds of proteins
might be made by the
action of a lipophilic
hormone?
Overview of the Transmembrane
Electrochemical Potential
p. 1009
How does the
Na-K pump
contribute to the
potential?
Why is the cell
membrane
described
as “polarized”?
Amplification
in Signal
Transduction
What is the first
messenger in this
pathway?
Under what
circumstances is this
signal released?
Can you explain the
advantage of this type
of signal transduction
in this example?
p. 1075
Target Cells:
more than one type of signal transduction
Terminating First Messenger Action
First Messengers may be
– excreted in urine (after being degraded in liver or kidney)
– destroyed by intracellular digestion (in a lysosome after
endocytosis)
– broken down by extracellular enzymes at the receptor (e.g
cholinesterase)
– transported into neighboring cells (e.g. Serotonin re-uptake)
Second Messengers may be
– removed from the cell (e.g. Ca+2 pumps)
– Broken down enzymatically (e.g. phosphodiesterase destroys
cAMP and cGMP)
Integration of Intercellular
All multicellular Communication See p. 1061
animals utilize
neurosecretory
cells for internal
chemical
signaling
Many so-called
endocrine glands
contain neurosecretory cells, …
Which division of the mammalian nervous system is active during the
stress response? Describe the collaboration between the endocrine and
nervous systems in this example.
p. 1070
Integration of Intercellular
Communication
… and brain cells may
secrete hormones.
Describe the structural
and functional
connections between the
anterior pituitary and the
hypothalamus.
Integration of Intercellular
Communication
Several hormones may
interact to produce a complex
result.
Discuss one other example of
the interaction between the
nervous and endocrine
systems; and
….between two or more
hormones.
As a hormone that stimulates
the release of another
hormone, Brain Hormone is
correctly classified as a
_______ hormone.
+
Growth w/o metamorphosis