Exam 6: Communication, Integration, and Homeostasis

Cells that respond to signals are usually called

In your own words restate and explain Cannon's four postulates for maintaining homeostasis.

The fight-or-flight reaction prepares an animal to respond to a threatening situation,by either fighting or running away.One aspect of this response is changes in blood flow such that the skeletal muscles and heart receive higher blood flow (vessels dilate)while digestive organs receive less (vessels constrict).Which signal molecule(s)is/are involved in this response,and how do they produce these changes in blood vessels? Explain how this example illustrates one or more of the following concepts: multiple ligands for one receptor,multiple receptors for one ligand,agonists and antagonists.

Describe the signal molecule derivatives of arachidonic acid.

A few gases are known to act as signal molecules,including ________,________,and ________.

When adenylyl cyclase is activated,

Blood glucose levels are kept fairly steady in healthy people through the action of the hormones insulin and glucagon.Insulin decreases blood glucose by promoting glucose uptake by cells,whereas glucagon increases blood glucose by promoting release of glucose from cells.Describe these hormone actions as simple reflex pathways,identifying the stimulus,integrating center,efferent pathway,and response.

Insulin increases glucose transport across the cell membrane of an adipocyte but not across the membrane of a liver cell.How can one hormone have two different effects?

Receptors in cell signaling are not to be confused with receptors that activate a reflex arc.Explain the difference,using specific examples.

"Too much of a good thing can hurt you." "It's all good." We've all heard phrases like this,and know that they contain some truth.For example,both life essentials water and sunshine can harm us.Not enough cholesterol in the body is worse than too much.What otherwise poisonous gas has recently been shown to be a signal molecule? What does it do in the body?

Peripheral cells sensitive to the presence of hormones are called ________.

What general action is shared by about half of the medical drugs currently in use?

Most long-distance communication between cells takes place through the ________ and ________ systems with their combination of chemical and electrical signals.

Receptor molecules are located

________ can be caused by alterations in receptors or by problems with G protein or second messenger pathways.

Inositol triphosphate

Match the term with its description: -the desired target value for a parameter

The most important factor determining which type of receptor a signal molecule will bind to is

Both insulin and glucagon are peptide hormones that target liver cells.The response of the target cells to each of these two hormones is opposite.This information implies that

Usually,cytokine binding activates