Question 1

Calcium ion

Accepted Answer

A) Concentration in the cytosol is increased by activation of phospholipase C 
B) Concentration in the cytosol is increased by activation of membrane calcium channels 
C) Release from the endoplasmic reticulum may be triggered by entry of calcium ion from the extracellular fluid 
D) Both concentration in the cytosol is increased by activation of phospholipase C and concentration in the cytosol is increased by activation of membrane calcium channels are correct 
E) All of the choices are correct 
A) Concentration in the cytosol is increased by activation of phospholipase C 
B) Concentration in the cytosol is increased by activation of membrane calcium channels 
C) Release from the endoplasmic reticulum may be triggered by entry of calcium ion from the extracellular fluid 
D) Both concentration in the cytosol is increased by activation of phospholipase C and concentration in the cytosol is increased by activation of membrane calcium channels are correct 
E) All of the choices are correct

Question 2

The second messenger that causes calcium ion to be released from intracellular stores is

Accepted Answer

A) Diacylglycerol 
B) Adenylyl cyclase 
C) Inositol triphosphate 
D) Phospholipase A 
E) None of the choices are correct 
A) Diacylglycerol 
B) Adenylyl cyclase 
C) Inositol triphosphate 
D) Phospholipase A 
E) None of the choices are correct

Question 3

Second messengers

Accepted Answer

A) Are necessary for all receptor signal transduction mechanisms 
B) Act in the cell cytoplasm 
C) Act as intercellular messengers 
D) Always function to activate enzymes 
E) Are always proteins 
A) Are necessary for all receptor signal transduction mechanisms 
B) Act in the cell cytoplasm 
C) Act as intercellular messengers 
D) Always function to activate enzymes 
E) Are always proteins

Question 4

Two cell types having the same type of receptor for a chemical messenger will always respond to that messenger in the same way.

Accepted Answer

A) True 
 B)False

Question 5

A ligand that is an effective agonist for a chemical messenger

Accepted Answer

A) May have a higher affinity than the messenger for the messenger's receptor 
B) May achieve 50 percent saturation of the messenger's receptor at a lower concentration than that required by the messenger 
C) Does not couple to the binding site of the messenger's receptor 
D) Both may have a higher affinity than the messenger for the messenger's receptor and may achieve 50 percent saturation of the messenger's receptor at a lower concentration than that required by the messenger are correct 
E) All of the choices are correct 
A) May have a higher affinity than the messenger for the messenger's receptor 
B) May achieve 50 percent saturation of the messenger's receptor at a lower concentration than that required by the messenger 
C) Does not couple to the binding site of the messenger's receptor 
D) Both may have a higher affinity than the messenger for the messenger's receptor and may achieve 50 percent saturation of the messenger's receptor at a lower concentration than that required by the messenger are correct 
E) All of the choices are correct

Question 6

Cocaine lowers the levels of a chemical messenger in the brain called enkephalin.Researchers have found the number of enkephalin receptors to be higher in cocaine addicts than nonaddicted people.This is an example of

Accepted Answer

A) Saturation 
B) Up regulation 
C) Antagonism 
D) Affinity 
E) Down regulation 
A) Saturation 
B) Up regulation 
C) Antagonism 
D) Affinity 
E) Down regulation

Question 7

Methadone is a drug given to treat heroin addicts.It works by binding to the same receptors as heroin but with greater affinity,thereby preventing heroin from binding.This is an example of

Accepted Answer

A) Competition 
B) Down regulation 
C) Signal transduction 
D) Agonistic behavior 
E) None of the choices are correct 
A) Competition 
B) Down regulation 
C) Signal transduction 
D) Agonistic behavior 
E) None of the choices are correct

Question 8

Cells can control their responsiveness to external chemical regulators by

Accepted Answer

A) Increasing the number of their transmembrane receptors by exocytosis 
B) Decreasing the number of their transmembrane receptors by endocytosis 
C) Uncoupling their receptors from the second message generator 
D) Both increasing the number of their transmembrane receptors by exocytosis and decreasing the number of their transmembrane receptors by endocytosis are correct 
E) Both decreasing the number of their transmembrane receptors by endocytosis and uncoupling their receptors from the second message generator are correct 
A) Increasing the number of their transmembrane receptors by exocytosis 
B) Decreasing the number of their transmembrane receptors by endocytosis 
C) Uncoupling their receptors from the second message generator 
D) Both increasing the number of their transmembrane receptors by exocytosis and decreasing the number of their transmembrane receptors by endocytosis are correct 
E) Both decreasing the number of their transmembrane receptors by endocytosis and uncoupling their receptors from the second message generator are correct

Question 9

Receptors for intercellular messengers are most commonly

Accepted Answer

A) Peripheral membrane proteins 
B) Integral membrane proteins 
C) Specialized phospholipids within the membrane 
D) Nucleic acids 
A) Peripheral membrane proteins 
B) Integral membrane proteins 
C) Specialized phospholipids within the membrane 
D) Nucleic acids

Question 10

Which of the following statements is true?

Accepted Answer

A) Phosphorylation by protein kinase can stimulate or inhibit the activity of effector proteins 
B) Ca2+ and cyclic AMP are second messengers 
C) Phosphodiesterase converts GMP into cGMP 
D) Both phosphorylation by protein kinase can stimulate or inhibit the activity of effector proteins and Ca2+ and cyclic AMP are second messengers are true 
E) All of the choices are true 
A) Phosphorylation by protein kinase can stimulate or inhibit the activity of effector proteins 
B) Ca2+ and cyclic AMP are second messengers 
C) Phosphodiesterase converts GMP into cGMP 
D) Both phosphorylation by protein kinase can stimulate or inhibit the activity of effector proteins and Ca2+ and cyclic AMP are second messengers are true 
E) All of the choices are true

Question 11

The process whereby repeated exposure to a hormone can cause a decrease in the number of receptors for that hormone is called

Accepted Answer

A) Competition 
B) Inhibition 
C) Down regulation 
D) Antagonism 
E) Saturation 
A) Competition 
B) Inhibition 
C) Down regulation 
D) Antagonism 
E) Saturation

Question 12

Cellular receptors are classified as either intracellular or as plasma membrane bound receptors.Which of the following is not an integrated plasma membrane receptor related description?

Accepted Answer

A) Binding activates G proteins to, in turn, activate ion channels or enzymes 
B) Regulation of genetic transcription 
C) Function as directly regulated ion channels 
D) Represent membrane bound enzymes, i.e., tyrosine kinases 
E) bind to and activate JAK kinases 
A) Binding activates G proteins to, in turn, activate ion channels or enzymes 
B) Regulation of genetic transcription 
C) Function as directly regulated ion channels 
D) Represent membrane bound enzymes, i.e., tyrosine kinases 
E) bind to and activate JAK kinases

Question 13

Epinephrine activates the cyclic AMP pathway in liver cells.Therefore,epinephrine

Accepted Answer

A) Probably binds a specific transmembrane receptor in these cells 
B) Elicits its response in liver cells through second messengers 
C) Probably binds a receptor in the nucleus of liver cells 
D) Both probably binds a specific transmembrane receptor in these cells and elicits its response in liver cells through second messengers are correct 
E) Both elicits its response in liver cells through second messengers and probably binds a receptor in the nucleus of liver cells are correct 
A) Probably binds a specific transmembrane receptor in these cells 
B) Elicits its response in liver cells through second messengers 
C) Probably binds a receptor in the nucleus of liver cells 
D) Both probably binds a specific transmembrane receptor in these cells and elicits its response in liver cells through second messengers are correct 
E) Both elicits its response in liver cells through second messengers and probably binds a receptor in the nucleus of liver cells are correct

Question 14

Oxytocin is a peptide hormone that causes the smooth muscle of the uterus to contract,but it has no effect on the smooth muscle cells of the small intestine.This difference in responsiveness exists because

Accepted Answer

A) Oxytocin is inactivated prior to reaching the smooth muscle cells of the intestine 
B) Intestinal smooth muscle cells do not contain the proper second messenger system 
C) Uterine smooth muscle cells contain specific receptors for oxytocin 
D) Oxytocin is able to cross the plasma membrane of uterine cells but not intestinal cells 
E) Oxytocin is not delivered by the circulatory system to intestinal cells 
A) Oxytocin is inactivated prior to reaching the smooth muscle cells of the intestine 
B) Intestinal smooth muscle cells do not contain the proper second messenger system 
C) Uterine smooth muscle cells contain specific receptors for oxytocin 
D) Oxytocin is able to cross the plasma membrane of uterine cells but not intestinal cells 
E) Oxytocin is not delivered by the circulatory system to intestinal cells

Question 15

A fat cell responds to the presence of the hormone epinephrine by increasing cytosolic cyclic AMP production,which leads to the catabolism of both glycogen and fat.The best explanation for this phenomenon is:

Accepted Answer

A) Epinephrine is binding to two types of receptors in the plasma membrane 
B) The activated receptor complex stimulates production of two different second messengers 
C) Cyclic AMP can directly activate two kinds of enzymes 
D) Cyclic-AMP-dependent protein kinase can activate two kinds of enzymes 
E) All of the choices are correct 
A) Epinephrine is binding to two types of receptors in the plasma membrane 
B) The activated receptor complex stimulates production of two different second messengers 
C) Cyclic AMP can directly activate two kinds of enzymes 
D) Cyclic-AMP-dependent protein kinase can activate two kinds of enzymes 
E) All of the choices are correct

Question 16

Eicosanoids are a family of ubiquitous,fatty-acid-derived,local chemical messengers.

Accepted Answer

A) True 
 B)False

Calcium ion

The second messenger that causes calcium ion to be released from intracellular stores is

Second messengers

Two cell types having the same type of receptor for a chemical messenger will always respond to that messenger in the same way.

A ligand that is an effective agonist for a chemical messenger

Cocaine lowers the levels of a chemical messenger in the brain called enkephalin.Researchers have found the number of enkephalin receptors to be higher in cocaine addicts than nonaddicted people.This is an example of

Methadone is a drug given to treat heroin addicts.It works by binding to the same receptors as heroin but with greater affinity,thereby preventing heroin from binding.This is an example of

Cells can control their responsiveness to external chemical regulators by

Receptors for intercellular messengers are most commonly

Which of the following statements is true?

The process whereby repeated exposure to a hormone can cause a decrease in the number of receptors for that hormone is called

Cellular receptors are classified as either intracellular or as plasma membrane bound receptors.Which of the following is not an integrated plasma membrane receptor related description?

Epinephrine activates the cyclic AMP pathway in liver cells.Therefore,epinephrine

Oxytocin is a peptide hormone that causes the smooth muscle of the uterus to contract,but it has no effect on the smooth muscle cells of the small intestine.This difference in responsiveness exists because

A fat cell responds to the presence of the hormone epinephrine by increasing cytosolic cyclic AMP production,which leads to the catabolism of both glycogen and fat.The best explanation for this phenomenon is:

Eicosanoids are a family of ubiquitous,fatty-acid-derived,local chemical messengers.

Homeostasis: a Framework for Human Physiology

Chemical Composition of the Body

Cellular Structure, Proteins, and Metabolism

Movement of Molecules Across Cell Membranes

Neuronal Signaling and the Structure of the Nervous System

Sensory Physiology

Consciousness, the Brain, and Behavior

Muscle

Control of Body Movement

The Endocrine System

Cardiovascular Physiology

Respiratory Physiology

The Kidneys and Regulation of Water and Inorganic Ions

The Digestion and Absorption of Food

Regulation of Organic Metabolism and Energy Balance

Reproduction

The Immune System

Medical Physiology: Integration Using Clinical Cases

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Exam 5: Control of Cells by Chemical Messengers

Calcium ion

The second messenger that causes calcium ion to be released from intracellular stores is

Second messengers

Two cell types having the same type of receptor for a chemical messenger will always respond to that messenger in the same way.

A ligand that is an effective agonist for a chemical messenger

Cocaine lowers the levels of a chemical messenger in the brain called enkephalin.Researchers have found the number of enkephalin receptors to be higher in cocaine addicts than nonaddicted people.This is an example of

Methadone is a drug given to treat heroin addicts.It works by binding to the same receptors as heroin but with greater affinity,thereby preventing heroin from binding.This is an example of

Cells can control their responsiveness to external chemical regulators by

Receptors for intercellular messengers are most commonly

Which of the following statements is true?

The process whereby repeated exposure to a hormone can cause a decrease in the number of receptors for that hormone is called

Cellular receptors are classified as either intracellular or as plasma membrane bound receptors.Which of the following is not an integrated plasma membrane receptor related description?

Epinephrine activates the cyclic AMP pathway in liver cells.Therefore,epinephrine

Oxytocin is a peptide hormone that causes the smooth muscle of the uterus to contract,but it has no effect on the smooth muscle cells of the small intestine.This difference in responsiveness exists because

A fat cell responds to the presence of the hormone epinephrine by increasing cytosolic cyclic AMP production,which leads to the catabolism of both glycogen and fat.The best explanation for this phenomenon is:

Eicosanoids are a family of ubiquitous,fatty-acid-derived,local chemical messengers.

Homeostasis: a Framework for Human Physiology

Chemical Composition of the Body

Cellular Structure, Proteins, and Metabolism

Movement of Molecules Across Cell Membranes

Neuronal Signaling and the Structure of the Nervous System

Sensory Physiology

Consciousness, the Brain, and Behavior

Muscle

Control of Body Movement

The Endocrine System

Cardiovascular Physiology

Respiratory Physiology

The Kidneys and Regulation of Water and Inorganic Ions

The Digestion and Absorption of Food

Regulation of Organic Metabolism and Energy Balance

Reproduction

The Immune System

Medical Physiology: Integration Using Clinical Cases

Filters