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Cells that respond to signals are usually called

Mechanical signals

Which is NOT a basic method of cell to cell communication?
Cytoplasmic transfer of signals
Contact dependent signals
Nerve and blood transport signals
Mechanical signals

The cell that responds to it

The most significant difference between a paracrine and an autocrine is

Are released by neurons and affect only cells with specific receptors

Neurotransmitters and neurohormones both

Some cells lack the necessary receptors

Why do some normal cells fail to respond to a chemical signal?

Determine that cells response and may allow a particular ligand to bind

Receptor molecules on the surface of a cell

In all these places: outer cell membrane, cytosol, nucleus, cell surface

Receptor molecules are located

Only decrease its number of receptors for a ligand

Down- regulation may allow a target cell to

Is a second messenger that is involved in the release of calcium into the cytosol

Inositol triphosphate

Bind to receptors inside the cytoplasm or nucleus

Lipophilic hormones

cAMP is formed

When adenylyl cyclase is activated


Second messenger molecules directly

Protein kinase A

Cyclic AMP activates

Phosphatidylinositol bisphosphate

Diacylglycerol is produced from

JAK kinase

Usually, cytokine binding activates


What by product results during the production of nitric oxide

Evaluates incoming signals and compares it with the setpoint

An integrating center

ALL: specificity, nature of the signal, speed, duration of action

Which of the following are considered differences between endocrine and neural control systems


The desired target value for a parameter

Integrating center

Receives information about the regulated variable and initiates a response


The minimum stimulus to trigger a response


The organ or gland that performs the change

Sensory receptor

Continuously monitors its environment for a specific variable


Peripheal calls sensitive to the presence of hormones

Nitric oxide, carbon monoxide, hydrogen sulfide

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

Endothelial cells, endothelial derived relaxing factor

Before nitric oxide was identified, its action was observed in ___ and it was given the name ___


Can be caused by alterations in receptors or by problems with G protein or second messenger pathways

Eicosanoids, sphingolipids

Lipids signal molecules that act in a paracrine fashion and combine with G protein coupled receptors include

Signal transduction, first messenger, second messenger

__ is a process by which an extracellular signal molecule, called the ___, activates a membrane receptor that in turn alters intracellular molecules, called the __, to create a response


A gap junction forms when opposing membrane spanning proteins called __ on two adjacent cells unite, creating a protein channel that is capable of opening and closing


A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a


If the signal molecule acts on the cell that secreted it, the chemical is called an


All molecules secreted by nerve cells are called


___ are molecules that bind to the receptor in such a way that they block the normal ligand from binding and turning the receptor on. As a result, the signal pathway remains inactive

Up regulation

If the concentration of an endocrine ligand decreases, the target cell may insert more receptors into the cell membrane in an attempt to keep its response at a normal level, in a process known as

Internal Environment

The nervous system has a role in preserving the "fitness" of the

G proteins

The ___ link membrane receptors to either ion channels or to membrane enzymes located on the cytoplasmic face of the membrane

Protein kinases

Many second messenger systems activate ___, enzymes that transfer a phosphate group from ATP to a protein. The phosphorylation of proteins sets off a series of intracellular events that lead to the ultimate cellular response.


To maintain ___, the body uses a combination of simple diffusion across small distances; wide spread distribution of molecules through the circullatory system and rapid, specific delievery of messages by the nervous system

Nervous, endocrine

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

Second messenger

An intracellular signal molecule that translates a signal from a neurotransmitter or hormone into an intracellular response is called a

Simple endocrine

The secretion of the hormone insulin in response to changes in blood glucose level s an example of a __ reflex

Receptor, effector

Homeostatic regulation usually involves a ___ that is sensitive to a particular stimulus and an ___ whose activity has an effect on the same stimulus

Constric, dilate

When epinephrine combines with alpha adrenergic receptors on smooth muscle in intestinal blood vessels, the blood vessels ___; however when epinephrine binds to beta-2 adrenergic receptors on certain skeletal muscle blood vessels, the vessels ___

Half life of a signal

The time required for a signal to lose half its activity

Orphan receptor

A receptor that has no known ligand

Protein Kinase

The intracellular effector in chemical signaling is often

The lipid solubility of the ligand

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


An ion widely important in intracellular signaling is

Extracellular fluid and intracellular storage

When calcium becomes available inside a cell, it comes from


One intracellular calcium binding protein is

Specificity, competition, and saturation

Signal molecule receptors exhibit

Gene transcription

The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers

The two hormones bind to different receptors and use a different second messenger

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

Local control

Homeostatic control that takes place at the tissue or cell by using paracrine or autocrine signals is called ___

Tonic control

A phisiological parameter which is regulated in an up down fashion by signals that are always present but change in intensity is said to be under

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