Deck 6: Communication, Integration, and Homeostasis

Question 1

Receptor molecules are located

A) only in the outer cell membrane.
B) only in the cytosol.
C) only in the nucleus.
D) only on the cell surface.
E) in all of these places.

Answer 1

E

Question 2

Down-regulation may allow a target cell to

A) only increase its number of receptors for a ligand.
B) only decrease its number of receptors for a ligand.
C) only increase its binding affinity for a ligand.
D) decrease the receptors' binding affinity and increase its number of receptors.

Answer 2

B

Question 3

Receptor molecules on the surface of a cell

A) determine that cell's response.
B) may allow a particular ligand to bind.
C) bind to all ligands.
D) determine that cell's response and may allow a particular ligand to bind.
E) determine that cell's response and bind to all ligands.

Answer 3

D

Question 4

receives information about the regulated variable and initiates a response

Question 5

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

A) specificity
B) nature of the signal
C) speed
D) duration of action
E) All of the answers are correct.

Question 6

Cyclic AMP activates

A) a G protein.
B) adenylyl cyclase.
C) protein hormones.
D) protein kinase A.
E) hormone receptors.

Question 7

The most significant difference between a paracrine and an autocrine is

A) the cell that releases it.
B) the cell that responds to it.
C) the method of transport.
D) the route of transport.
E) There are no differences-they are the same.

Question 8

Second messenger molecules directly

A) change the regulation of ion channels.
B) increase intracellular calcium concentration.
C) change enzyme activity.
D) change regulation of gene expression.
E) All of the answers are correct.

Question 9

Which is NOT a basic method of cell-to-cell communication?

A) cytoplasmic transfer of signals
B) contact-dependent signals
C) diffused chemical signals
D) nerve and blood-transported signals
E) mechanical signals

Question 10

Inositol triphosphate

A) is a water-insoluble messenger molecule.
B) binds to the calcium channel of the endoplasmic recticulum.
C) is involved in the release of calcium into the cytosol.
D) is a second messenger that is involved in the release of calcium into the cytosol.
E) uses all of the mechanisms.

Question 11

What by-product results during the production of nitric oxide?

A) arginine
B) citrulline
C) nitric oxide synthase
D) carbon monoxide
E) carbon dioxide

Question 12

Lipophilic hormones

A) bind to receptors on the surface of the cell.
B) function by way of a second messenger system.
C) cannot diffuse through the cell membrane.
D) bind to receptors inside the cytoplasm or nucleus.
E) function by activating cAMP.

Question 13

Cells that respond to signals are usually called

A) responders.
B) receivers.
C) targets.
D) contacts.
E) junctions.

Question 14

the desired target value for a parameter

Question 15

When adenylyl cyclase is activated,

A) calcium ions are released from intracellular stores.
B) cAMP is formed.
C) cAMP is broken down.
D) protein kinases are metabolized.
E) steroids are produced.

Question 16

An integrating center

A) is the disturbance or change that sets the pathway in motion.
B) is an electrical and/or chemical signal that travels to the effector.
C) evaluates incoming signals and compares it with the setpoint.
D) is the minimum stimulus that must be achieved to set the reflect response in motion.

Question 17

Neurotransmitters and neurohormones both

A) are released by neurons.
B) affect only cells with a specific receptor.
C) travel in the blood to their target cell.
D) are released by neurons and affect only cells with specific receptors.
E) are produced by all cells.

Question 18

Diacylglycerol is produced from

A) cyclic AMP.
B) phospholipase C.
C) a G protein.
D) protein kinase A.
E) phosphatidylinositol bisphosphate.

Question 19

Usually,cytokine binding activates

A) JAK kinase.
B) tyrosine kinase.
C) intrinsic transducers.
D) calmodulin kinase.
E) citrulline kinase.

Question 20

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

A) Chemical signals are only delivered to specific cells.
B) Some cells lack the necessary receptors.
C) Some cells are completely without receptors.
D) Some cells are completely without ligands.
E) Signal chemicals often break down before reaching a distant target.

Question 21

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.

Question 22

To maintain ________,the body uses a combination of simple diffusion across small distances; wide spread distribution of molecules through the circulatory system and rapid,specific delivery of messages by the nervous system.

Question 23

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

Question 24

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

Question 25

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

Question 26

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

Question 27

Explain how epinephrine can cause intestinal blood vessels to constrict and cause skeletal muscle blood vessels to dilate.

Question 28

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.

Question 29

________ 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.

Question 30

________ 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.

Question 31

the organ or gland that performs the change

Question 32

A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a(n)________.

Question 33

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 ________.

Question 34

If the signal molecule acts on the cell that secreted it,the chemical is called a(n)________.

Question 35

All molecules secreted by nerve cells (neuromodulators,neurotransmitters,and neurohormones)are known as ________.

Question 36

Lipid signal molecules that act in a paracrine fashion and combine with G-protein coupled receptors include ________ and ________.

Question 37

continuously monitors its environment for a specific variable

Question 38

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

Question 39

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

Question 40

the minimum stimulus to trigger a response

Question 41

The intracellular effector in chemical signaling is often

A) a hormone.
B) a membrane receptor molecule.
C) ATP.
D) a protein kinase.
E) cholesterol.

Question 42

What is an orphan receptor?

Question 43

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

Question 44

The secretion of the hormone insulin in response to changes in blood glucose level is an example of a(n)________ reflex.

Question 45

An ion widely important in intracellular signaling is

A) sodium.
B) potassium.
C) calcium.
D) chloride.
E) cobalt.

Question 46

Compare and contrast the four basic methods of cell-to-cell communication.

Question 47

When calcium becomes available inside a cell,it comes from

A) extracellular fluid only.
B) intracellular storage only.
C) extracellular fluid and intracellular storage.
D) It is always available as a major cytosol cation.

Question 48

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 ________.

Question 49

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

A) adenylyl cyclase activation.
B) cyclic nucleotide formation.
C) G protein inhibition.
D) gene transcription.
E) protein kinase activation.

Question 50

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

A) the lipid solubility of the ligand.
B) the size of the ligand.
C) the size of the receptor molecule.
D) the location of the receptor molecule.

Question 51

One intracellular calcium-binding protein is

A) calmodulin.
B) calcitonin.
C) calcitriol.
D) IP₃.
E) nitric oxide.

Question 52

Each of the following is an example of homeostasis except one.Identify the exception.

A) Increased pressure in the aorta triggers mechanisms to lower blood pressure.
B) A rise in blood calcium levels triggers the release of a hormone that lowers blood calcium levels.
C) A rise in estrogen during the menstrual cycle increases the number of progesterone receptors in the uterus.
D) Increased blood sugar stimulates the release of a hormone from the pancreas that stimulates the liver to store blood sugar.
E) A decrease in body temperature triggers a neural response that initiates physiological changes to increase body temperature.

Question 53

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

Question 54

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

A) the two hormones bind to different cell surface receptors.
B) one hormone binds to a receptor on the cell membrane and the other to an intracellular receptor.
C) each of the two hormones uses a different second messenger.
D) both hormones interact with receptors at the cell nucleus.
E) the two hormones bind to different receptors and use a different second messenger.

Question 55

Signal molecule receptors exhibit

A) specificity only.
B) competition only.
C) saturation only.
D) competition and saturation only.
E) specificity, competition, and saturation.

Question 56

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

A) local control
B) reflex control
C) Cannon's law
D) down-regulation

Question 57

Homeostatic regulation usually involves a(n)________ that is sensitive to a particular stimulus (variable)and a(n)________ whose activity has an effect on the same stimulus.

Question 58

What is the half-life of a signal?

Question 59

Explain the two forms of down-regulation.

Question 60

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

Question 61

Brain cells are able to absorb glucose independent of insulin.What must be missing from brain cells compared to most other cell types? One of the risks of diabetes mellitus is diabetic coma,which results when insufficient glucose is available to the brain.Would you expect diabetic coma to be triggered when insulin is low or high? Explain.(Hint: Think about regulation of the number of glucose transporters in brain cells and how the hyperglycemia present prior to insulin treatment may affect transporters.)

Question 62

Section Title: Cell-to-Cell Communication
Learning Outcome: 6.2
Skill: Level III: Problem Solving (Bloom's Taxonomy: Synthesis)
Briefly explain the effects of the hormone insulin on glucose transport.What is diabetes mellitus? How are Types I and II different? Why do insulin injections help alleviate one type but not the other?

Question 63

Food items are occasionally shown to offer protective effects to those who eat them.Garlic,for example,may improve heart health.The pungency of garlic is due to sulfur-containing compounds.Explain how these compounds are good candidates for garlic's heart benefits.

Question 64

Describe the four classes of membrane receptor molecules.

Question 65

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.

Question 66

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

Question 67

Compare and contrast hormones,neurotransmitters,and neurohormones.

Question 68

Nobel Prizes were awarded to the discoverers of G proteins,the G protein-coupled adenylyl cyclase-cAMP system,and nitric oxide.Summarize each of these,and explain the importance of these discoveries to our understanding of signal pathways.

Question 69

Design a flow chart or concept map to summarize the information in the text under the heading "Cell-to-Cell Communication." This chart should make clear the four basic methods of cell-to-cell communication,and the relevance of and distinction between paracrine,autocrine,neurocrine,and cytokine chemicals.

Question 70

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

Question 71

Define tonic control and give a physiological example.

Question 72

"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?

Question 73

What are NSAIDs,what is their function,and what are some drawbacks to their use?

Question 74

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?

Question 75

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.

Question 76

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

Question 77

You are part of a research team designing a robot for competition.Your robot needs to be able to respond to painful stimuli like stepping on broken glass.What type of human control system will you model your robot's after and explain your reasons for choosing it.

Question 78

Describe the signal molecule derivatives of arachidonic acid.

Question 79

Describe or diagram the basic pattern of a biological signal transduction pathway.