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Chemical Signaling. Chemical Communication. Briefly describe the two major forms of intercellular communication in animal bodies. Which organ system s are responsible for this communication? Describe the type of intercellular communication called “ neuroendocrine ”.

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chemical communication
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
Endocrine Function is often Controlled by Negative Feedback

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.


basic mechanisms of chemical signaling
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 signal-transduction pathway?
  • What kinds of proteins might be made by the action of a lipophilic hormone?
classes of membrane receptors 1
Classes of Membrane Receptors (1):


“Links” between the

extracellular matrix

and the cytoskeleton.

Integrins are important in morphogenesis during embryonic development.

classes of membrane receptors 2 ligand gated ion channels
Classes of Membrane Receptors (2):Ligand-gated ion channels

In order for this to occur, what must be true about the distribution of ions?

How might the influx of ions induce

a biochemical response within a cell?

What other mechanisms of controlling

ion channels are there?

classes of membrane receptors 3 receptor enzymes
Classes of Membrane Receptors (3):Receptor Enzymes

How is this mechanism of signal transduction different from one in

which proteins are made after reception of the signal molecule(s)?

Compare and contrast receptor enzymes and G-protein-linked reception and transduction of extracellular chemical messages?

classes of membrane receptors 4 g protein linked receptor
Classes of Membrane Receptors (4):G-protein linked receptor

How is the intracellular

message controlled?

What are the roles of energy nucleotides (nucleoside triphosphates) in

signal transduction?

for practice biological signal transduction
For Practice:Biological Signal Transduction

What are the chemical characteristics of the signal molecule?

… of the receptor?

What do protein kinases do?

If this is the second

messenger, where is

the first messenger?

What are the two general ways that a cell may respond to an

extracellular chemical message (one that cannot enter the cell)?


…more practice

  • Identify the:
    • Transducer
    • Amplifier
    • Second messenger

G-proteins linked

with specific receptors

are either excitatory (+)

or inhibitory (-).

How would the cellular response be different in this model, if the G-protein were inhibitory?

overview of the transmembrane electrochemical potential
Overview of the Transmembrane Electrochemical Potential

How does the

Na-K pump

contribute to the


Why is the cell

membrane described

as “polarized”?

amplification in signal transduction
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?

terminating first messenger action
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. Ca2+ pumps)
  • Broken down enzymatically (e.g. phosphodiesterase destroys cAMP and cGMP)
integration of intercellular communication
Integration of Intercellular Communication

All multicellular animals utilize neurosecretory cells for internal chemical signaling

Many so-called endocrine glands contain neuro-secretory 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.

integration of intercellular communication17
Integration of Intercellular Communication

… and neurons may secrete hormones.

Describe the structural and functional connections between the anterior pituitary and the hypothalamus.

integration of intercellular communication18
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