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Test Bank For Principles of Human Physiology, 6th Edition

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    Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) In chemical communication between cells, a ________ cell secretes a chemical messenger that binds to ________ on the ________ cell. 1) A) secretory : connexons : gap B) secretory : connexons : target C) gap : connexons : secretory D) target : receptors : secretory E) secretory : receptors : target Answer: E 2) Direct communication between cells in contact with one another is accomplished through 2) A) receptors. B) endocrine hormones. C) gap junctions. D) ligands. E) paracrine chemical messengers. Answer: C 3) The number of bound receptors on a target cell depends on what two things? 3) A) the concentration of the messenger and the distance it has to travel B) the type and concentration of receptors C) the concentration of the messenger and signal transduction D) the secretory cell and target cell E) the concentration of the messenger and the concentration of receptors on the target cell Answer: E 4) Which type of chemical messenger, when released, binds to receptors on the cell that released the chemical messenger? 4) A) neurohormone B) autocrine C) cytokine D) neurotransmitter E) hormone Answer: B 5) Which type of chemical messenger is released into the bloodstream by an endocrine gland where it can affect target cells throughout the body? 5) A) paracrine B) cytokine C) neurotransmitter D) hormone E) autocrine Answer: D 1

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    6) Which type of chemical messenger is released from the axon terminal of a neuron and directly communicates with other cells? 6) A) hormone B) paracrine C) cytokine D) neurotransmitter E) autocrine Answer: D 7) Communication across a synapse is initiated by the release of a neurotransmitter from the ________ region of the neuron. 7) A) axon hillock B) axon terminal C) dendritic D) perisynaptic E) postsynaptic Answer: B 8) Vasopressin (antidiuretic hormone), which is released from the posterior pituitary, is an example of what type of chemical messenger? 8) A) cytokine B) autocrine C) neurotransmitter D) neurohormone E) paracrine Answer: D 9) Inflammation is characterized in part by redness and swelling. In inflammation, ________ increases blood flow to affected tissues (producing redness) and causes fluid to leak out of the blood vessels and into the tissue (producing swelling). 9) A) pyruvic acid B) histamine C) amine D) growth factor E) clotting factor Answer: B 10) The more specific a drug is for a certain ________ type, the more specific the therapeutic actions of the drug and the fewer the side effects. 10) A) target cell B) receptor C) neurotransmitter D) hormone E) ligand Answer: B 2

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    11) Which of the following chemical messengers is lipophilic and is therefore able to cross the cell membrane? 11) A) peptides B) amino acids C) amines (excluding thyroid hormone) D) eicosanoids E) proteins Answer: D 12) Histamine acts as a(n) ________ in its role in inflammation. 12) A) neurotransmitter B) cytokine C) hormone D) paracrine E) autocrine Answer: D 13) What molecules are hydrophobic and can easily cross the plasma membrane? 13) A) amino acids B) hydrophilic C) lipophobic D) lipophilic E) hyperdermic Answer: D 14) All the messengers in what class are derived from cholesterol? 14) A) eicosanoids B) peptides/proteins C) steroids D) amines E) amino acids Answer: C 15) Most amines are ________, meaning they dissolve in water and therefore cannot cross the cell membrane. The ________ hormones are an exception because they are ________ and can easily cross the cell membrane. 15) A) lipophilic : thyroid : lipophobic B) lipophilic : protein : lipophobic C) hydrophobic : steroid : hydrophilic D) lipophobic : thyroid : lipophilic E) amino acids : steroid : lipophilic Answer: D 16) Peptide hormones are made________, stored and released via ________. 16) A) on demand : active transport B) on demand : simple diffusion C) in advance : exocytosis D) in advance : receptor - mediated endocytosis E) in advance : pinocytosis Answer: C 3

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    17) Cells that secrete dopamine must contain which enzymes? 17) A) dopamine Ά - hydroxylase and dopa decarboxylase only B) tyrosine Ά - hydroxylase C) dopamine Ά - hydroxylase only D) dopa decarboxylase only E) tyrosine Ά - hydroxylase and dopa decarboxylase Answer: E 18) Cells that secrete epinephrine must contain which enzymes? 18) A) dopamine Ά - hydroxylase, tyrosine Ά - hydroxylase, and dopa decarboxylase only B) phenylethanolamine N - methyl transferase and dopa decarboxylase only C) tyrosine Ά - hydroxylase and phenylethanolamine N - methyl transferase only D) dopamine Ά - hydroxylase, tyrosine Ά - hydroxylase, phenylethanolamine N - methyl transferase, and dopa decarboxylase E) dopamine Ά - hydroxylase and dopa decarboxylase only Answer: D 19) Catecholamines are derived from what amino acid? 19) A) glycine B) tryptophan C) glutamate D) histidine E) tyrosine Answer: E 20) Thyroid hormones are synthesized from what amino acid? 20) A) glycine B) tryptophan C) histidine D) tyrosine E) glutamate Answer: D 21) Aspirin is a nonsteroidal anti - inflammatory drug (NSAID) that relieves pain. Which mechanism best describes how NSAIDs work? 21) A) Aspirin decreases the production of thromboxane A 2 , a chemical involved in blot clot formation, and COX inhibits A 2 and, therefore, blood clots do not form and cause pain. B) Prostaglandins (PG) are eicosanoids that produce pain and inflammation. Cyclooxygenase (COX) is an essential enzyme in the production of PG and aspirin inhibits COX and therefore relieves pain due to the reduced production of PG. C) Leukotrienes are eicosanoids that produce pain and inflammation. COX is used in the lipoxygenase pathway and therefore NSAIDs stop the conversion of arachidonic acid to leukotrienes thereby reducing inflammation. D) When aspirin dissolves in the interstitial fluid it causes a concentration gradient and fluid is pulled from the cell reducing inflammation. E) The COX receptors have a greater affinity for aspirin and these speed up the reactions of healing. Answer: B 4

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    22) Doctors often prescribe baby aspirin (82 mg) to guard against the formation of blood clots instead of a higher dose of 350 mg found in a regular aspirin. Which statement best describes the distinction in dosages? 22) A) Aspirin causes several side effects, some good and some bad. Aspirin decreases thromboxane A 2 which causes blood clots; however, at higher dosages, it also decreases the production of PGI 2 (prostacyclin) that inhibits production of blood clots. Thus, higher dosages of aspirin would actually promote the formation of blood clots. B) Aspirin is an allosteric modulator that activates COX - 2 in the body and it is COX - 2 that primarily inhibits blood clot formation. C) Aspirin inhibits the production of PGE 2 in the stomach, which protects the stomach lining from stomach acid causing ulcers. Lower dosages do not inhibit PGE 2 and do not harm the stomach. D) Low dosages of aspirin inhibit a critical enzyme in the production of prostaglandins called cyclooxygenase (COX). There are two forms of COX: 1 and 2. Low dosages enhance the production of COX - 2 which reduces blood clots. COX - 1 receptors only reduce pain. E) Both dosages actually do the same thing to prevent blood clots but 82 mg of aspirin is much cheaper than 350 mg. Answer: A 23) Once a steroid hormone is synthesized, it is 23) A) bound to the mitochondria until released. B) stored in a unique protein structure that maintains steroids in the cell. C) immediately capable of diffusing across the membrane. D) stored in a vesicle until released. E) bound to albumin until released from the cell. Answer: C 24) What organelle packages peptide/protein messengers into secretory vesicles? 24) A) nucleus B) smooth endoplasmic reticulum C) rough endoplasmic reticulum D) Golgi apparatus E) lysosomes Answer: D 25) In order to synthesize eicosanoids, ________ catalyzes the release of ________ from a membrane phospholipid. 25) A) phospholipase C : cholesterol B) phospholipase A 2 : cholesterol C) phospholipase C : inositol biphosphate D) phospholipase A 2 : arachidonic acid E) phospholipase C : arachidonic acid Answer: D 5

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    26) An equilibrium exists between a hormone that is bound to a carrier protein and a free hormone such that, as the amount of free hormone increases, 26) A) more bound hormone will be released from its carrier proteins. B) more hormone must be synthesized to directly replace the free hormones. C) more free hormone will become bound to carrier proteins. D) the amount of bound hormone will not change. E) cells will be stimulated to secrete more free hormone. Answer: C 27) Lipophilic chemical messengers are poorly soluble in water. However, many of these lipophilic messengers are transported throughout the body. Their transport in blood (water) is facilitated by 27) A) carrier proteins. B) lipoproteins. C) white blood cells. D) chylomicrons. E) red blood cells. Answer: A 28) What enzyme catalyzes synthesis of prostaglandins from arachidonic acid? 28) A) lipoxygenase B) phospholipase A 2 C) phospholipase C D) cyclooxygenase E) tyrosine Ά - hydroxylase Answer: D 29) A half - life, in terms of a chemical messenger, refers to 29) A) how long the chemical messenger will be effective in the body. B) the radioactivity of the chemical messenger. C) the amount of time the messenger is bound to a protein. D) the time it takes for half of the chemical messenger in the blood to be degraded. E) the amount of time it takes to cross the plasma membrane. Answer: D 30) Androgens are precursor molecules for the synthesis of 30) A) progesterone. B) cholesterol. C) cortisol. D) aldosterone. E) estradiol. Answer: E 31) Progesterone is a potential precursor for the synthesis of 31) A) testosterone. B) dehydroepiandrosterone. C) cortisol. D) estradiol. E) androstenedione. Answer: C 6

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    32) Aspirin decreases inflammation by inhibiting the actions of what enzyme? 32) A) dopa decarboxylase B) protein kinase A C) cyclooxygenase D) lipoxygenase E) phospholipase A 2 Answer: C 33) Hormones that are dissolved in blood typically exhibit a half - life on the order of ________, whereas hormones that are bound to carrier proteins can remain undegraded for ________. 33) A) minutes : hours B) minutes : seconds C) hours : minutes D) seconds : hours E) seconds : minutes Answer: A 34) The location of receptors on a target cell depends on the solubility of the chemical messenger. Where would the receptors for lipophilic messengers be located? 34) A) on the outside of the cell B) on the inside of the cell C) at a free floating ribosome D) only in the nucleus of the cell E) It depends on if it is an alpha, beta, or delta type receptor. Answer: B 35) The Ά 1 adrenergic receptor has the greatest affinity for what messenger? 35) A) dopamine B) norepinephrine C) epinephrine D) serotonin E) epinephrine and norepinephrine equally Answer: E 36) The ΅ 1 adrenergic receptor has the greatest affinity for what messenger? 36) A) serotonin B) epinephrine C) dopamine D) norepinephrine E) epinephrine and norepinephrine equally Answer: D 37) Which of the following will NOT affect the magnitude of a cell's response to a specific hydrophilic ligand? 37) A) number of receptors B) affinity of the receptor for the ligand C) receptor upregulation D) ligand concentration E) lipid solubility of the ligand Answer: E 7

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    38) Chronic exposure to a ligand (messenger) ________ the receptor population for that chemical messenger on the target cell. 38) A) changes the conformation of B) decreases the specificity of C) upregulates D) down regulates E) decreases the affinity of Answer: D 39) Which of the following statements best describes the release of lipophobic messengers? 39) A) Lipophobic messengers are stored free in the cytosol and released by simple diffusion in response to a stimulus. B) Lipophobic messengers are stored in vesicles and released by exocytosis immediately after synthesis. C) Lipophobic messengers are stored in vesicles and released by simple diffusion in response to a stimulus. D) Lipophobic messengers are released immediately upon synthesis by simple diffusion. E) Lipophobic messengers are stored in vesicles and released by exocytosis in response to a stimulus. Answer: E 40) Which of the following statements best describes the release of a lipophilic messenger? 40) A) Lipophilic messengers are stored in vesicles and released by exocytosis in response to a stimulus. B) Lipophilic messengers are stored in vesicles and released by simple diffusion in response to a stimulus. C) Lipophilic messengers are stored in vesicles and released by exocytosis immediately after synthesis. D) Lipophilic messengers are stored free in the cytosol and released by simple diffusion in response to a stimulus. E) Lipophilic messengers are released immediately upon synthesis by simple diffusion. Answer: E 41) Lipophilic hormones are transported in blood ________ and bind to receptors located ________. 41) A) bound to carrier proteins : inside the target cell B) dissolved in the plasma : inside the target cell C) bound to carrier proteins : on the plasma membrane of the target cell D) inside red blood cells : inside the target cell E) dissolved in the plasma : on the plasma membrane of the target cell Answer: A 42) Much evidence suggests that depression might be associated with deficiencies in the biogenic amines serotonin and norepinephrine. If this is true and the body has reduced concentrations of these amines, one might predict the body would ________ in order to adapt to these lowered levels. 42) A) increase the half life B) upregulate C) increase the concentration of chemical messenger D) reduce the affinity E) downregulate Answer: B 8

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    43) What is a molecule that is similar in structure to a messenger and binds with that messenger's receptor to stimulate a similar response from the target cell? 43) A) antagonist B) protagonist C) synergist D) blocker E) agonist Answer: E 44) As a general rule, the magnitude of a target cell's response to a chemical messenger depends on which three factors? 44) A) (1) the concentration of the messenger, (2) the number of receptors, and (3) the affinity of the receptor for the messenger B) (1) the solubility of the chemical messenger, (2) the location of the receptor, and (3) the affinity of the receptor to the messenger C) (1) the concentration of the messenger, (2) the percent saturation of the receptor, and (3) the specificity of the receptor for the chemical messenger D) (1) the half life of the messenger, (2) the number of receptors, and (3) the percent saturation of those receptors E) (1) the solubility of the chemical messenger, (2) the location of the receptor, and (3) the class of the receptor Answer: A 45) The affinity of a receptor for its ligand is a measure of the 45) A) strength of binding between ligand and receptor. B) percent of receptors on a specific target cell with bound ligand. C) number of binding sites available for the ligand. D) response produced in the target cell when the ligand binds to the receptor. E) ability of the ligand to permeate the plasma membrane and reach its receptor. Answer: A 46) Typical responses to ________ messengers require a long time to develop because they necessitate transcription of mRNA and translation of that mRNA into a functional protein. 46) A) lipophilic B) lipophobic C) protein D) amino acid E) peptide Answer: A 47) Insulin is a peptide hormone and therefore lipophobic. When insulin is released due to high blood glucose levels, the response of the cells to this hormone will be ________ because it causes ________. 47) A) fast : new protein synthesis B) slow : a second messenger system to be activated C) neutral : transcription of mRNA and translation of that mRNA into a functional protein D) fast : enzyme - linked receptors to catalyze intracellular reactions E) slow : amplification of proteins Answer: D 9

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    48) Heroin overdose is usually treated with an opioid ________ such as naloxone (Narcan) or naltrexone, an opioid, which prevents heroin from binding to mu receptors and reverses the effects of heroin on the body. 48) A) ligand B) antagonist C) agonist D) antihistamine E) second messenger Answer: B 49) Differences in the rate of activity between fast and slow ligand - gated channels are caused by 49) A) G protein activity gating the fast channel. B) G protein activity gating the slow channel. C) ligand selectivity. D) ligand affinity. E) ligands gating both channels to the closed state. Answer: B 50) Opening channels for which of the following ions can trigger exocytosis? 50) A) potassium B) calcium C) magnesium D) sodium E) chloride Answer: B 51) Which of the following ions binds to calmodulin to ultimately activate a protein kinase? 51) A) chloride B) sodium C) magnesium D) calcium E) potassium Answer: D 52) A first messenger is an extracellular messenger that binds to its receptor on the ________ of the cell and therefore activates a second messenger system. 52) A) ribosome B) endoplasmic reticulum C) outside D) G protein E) inside Answer: C 53) Which of the following statements best describes the function of tyrosine kinase? 53) A) It catalyzes the formation of dopamine from L - dopa. B) It catalyzes the phosphorylation of a protein in the extracellular fluid. C) It catalyzes the phosphorylation of a protein inside a cell. D) It catalyzes the formation of norepinephrine from dopamine. E) It sequesters calcium in the cytosol. Answer: C 10

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    54) Cholera is the leading cause of death in children in developing countries, characterized by massive diarrhea. The effects stem from an extracellular toxin that the bacterium Vibrio cholerae releases into the gut. The toxin acts on a ________ that overstimulates ________ which causes a cascade of events that leads to electrolytes leaving the cell and causing water to follow them into the lumen of the intestine, resulting in severe diarrhea. 54) A) G proteins : adenylate cyclase B) protein kinases : calmodulin C) cAMP : G proteins D) protein - P : GTP E) calcium : muscles Answer: A 55) Which of the following is the most common second messenger in the human body? 55) A) cAMP B) IP 3 C) calcium D) cGMP E) DAG Answer: A 56) What terminates the cAMP second messenger system? 56) A) the release of the first messenger from the receptor B) a G protein C) the axon terminal D) degradation of cAMP by the liver E) the degradation of cAMP by the enzyme cAMP phosphodiesterase Answer: E 57) Cyclic AMP (cAMP) stimulates one's metabolic rate. Many supplement companies offer products claiming to increase the levels of this chemical within the body. If you had a patient on this supplement and they had high levels of cAMP in their body, what symptoms would you expect them to display? 57) A) increased heart rate and shallow breathing B) high G protein and sugar levels in their urine C) weight gain and lethargy D) hypoglycemia and low blood pressure E) weight loss and a high temperature Answer: E 58) The function of a second messenger system is to 58) A) facilitate the process of covalent modification of a protein. B) isolate the response to the inside of a cell. C) amplify the response of the first messenger. D) keep calcium involved in these responses. E) buffer a cell's response to a ligand. Answer: C 59) Based on your knowledge of signal amplification, which type of chemical messenger can have relatively small concentrations within the bloodstream and still get a large response? 59) A) steroid B) paracrine C) lipophilic D) autocrine E) lipophobic Answer: E 11

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    60) Functionally, G proteins are classified into what three types? 60) A) those that affect ion channels, stimulatory G proteins, and inhibitory G proteins B) first, second, and third messengers C) slow, fast, and opened or closed D) alpha, beta, and gamma E) those that affect proteins, those that affect enzymes, and those that affect specific genes Answer: A 61) When the alpha subunit of the G protein is activated, it can stimulate ion channels to do what? 61) A) open only B) close only C) either open or close D) degrade E) alter the ion that travels through the channel Answer: C 62) The enzyme that catalyzes synthesis of cAMP is called ________ and is activated by ________. 62) A) phosphodiesterase : a G s protein B) phosphoprotein phosphatase : a G i protein C) adenylate cyclase : a G i protein D) phosphodiesterase : a G i protein E) adenylate cyclase : a G s protein Answer: E 63) What enzyme is activated by cAMP? 63) A) protein kinase C B) phosphodiesterase C) tyrosine kinase D) adenylate cyclase E) protein kinase A Answer: E 64) In order to terminate a cAMP - mediated response, the enzyme ________ can be activated to degrade cAMP. 64) A) cAMP protein kinase B) cAMP phosphodiesterase C) cAMP hydrogenase D) cAMP decarboxylase E) cAMP hydrolase Answer: B 65) When associated with G protein, guanylate cyclase will activate what enzyme? 65) A) phosphodiesterase B) protein kinase G C) protein kinase A D) protein kinase C E) phospholipase C Answer: B 12

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    66) What molecule, whose synthesis is catalyzed by phospholipase C, triggers the release of calcium from the endoplasmic reticulum? 66) A) inositol biphosphate B) inositol triphosphate C) phosphatidylinositol biphosphate D) cGMP E) diacylglycerol Answer: B 67) Which of the following proteins is directly activated by a G protein? 67) A) phospholipase A 2 B) protein kinase G C) tyrosine kinase D) adenylate cyclase E) calmodulin Answer: D 68) Which of the following are second messengers? 68) A) cAMP only B) calcium only C) inositol triphosphate only D) both cAMP and inositol triphosphate E) cAMP, calcium, and inositol triphosphate Answer: E 69) What two systems primarily control homeostasis due to their ability to communicate over long distances? 69) A) nervous and cardiovascular B) nervous and endocrine C) endocrine and cardiovascular D) endocrine and respiratory E) cardiovascular and respiratory Answer: B 70) The chemical messenger of the nervous system is ________ and chemical messenger of the endocrine system is ________. 70) A) neurotransmitter : hormone B) neurohormone : adrenocorticoid C) neurotransmitter : neurohormone D) hormone : neurotransmitter E) autocrines : paracrines Answer: A 71) The target cells of the nervous system are 71) A) other neurons. B) glial cells. C) neurons, muscles, or glands. D) muscle cells. E) all the cell types in the body. Answer: C 13

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    72) The nervous system communicates via the ________ and the endocrine system communicates via the ________. 72) A) neuron : endocrine gland B) glial cell : hormone C) muscle cells : specific target cells of hormones D) synapse : bloodstream E) electrical signals : chemical signals or paracrine cells Answer: D 73) Which of the following statements is true for the nervous system but NOT the endocrine system? 73) A) A messenger communicates to target cells by binding to specific receptors. B) Effector organs are scattered throughout the body. C) Communication occurs over long distances. D) There is a special anatomical arrangement between the secretory cell and the target cell. E) A messenger is transported in the bloodstream. Answer: D 74) What part of a neuron releases neurotransmitter by exocytosis? 74) A) axon terminal B) soma C) dendrites D) axon hillock E) All of the answers are correct. Answer: A 75) What chemical messenger diffuses to neighboring cells to exert an effect? 75) A) autocrine B) neurotransmitter C) hormone D) paracrine E) neurohormone Answer: D 76) What chemical messenger is released from endocrine glands into the bloodstream? 76) A) paracrine B) hormone C) neurotransmitter D) autocrine E) neurohormone Answer: B 77) What chemical messenger is released by a presynaptic cell? 77) A) neurotransmitter B) hormone C) paracrine D) neurohormone E) autocrine Answer: A 14

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    78) Which of the following enzymes catalyzes phosphorylation of a protein? 78) A) tyrosine kinase B) phospholipase A 2 C) tyrosine Ά - hydroxylase D) adenylate cyclase E) phosphodiesterase Answer: A 79) Which of the following enzymes catalyzes synthesis and release of arachidonic acid? 79) A) tyrosine Ά - hydroxylase B) phospholipase A 2 C) tyrosine kinase D) phosphodiesterase E) adenylate cyclase Answer: B 80) Which of the following enzymes catalyzes synthesis of epinephrine from norepinephrine? 80) A) dopa decarboxylase B) dopamine Ά - hydroxylase C) phospholipase C D) phenylethanolamine N - methyl transferase E) phosphoprotein phosphatase Answer: D 81) Which of the following enzymes catalyzes synthesis of cAMP? 81) A) tyrosine kinase B) tyrosine Ά - hydroxylase C) phosphodiesterase D) phospholipase A 2 E) adenylate cyclase Answer: E 82) Which of the following enzymes catalyzes synthesis of prostaglandins and thromboxanes? 82) A) cyclooxygenase B) phospholipase C C) dopamine Ά - hydroxylase D) phenylethanolamine N - methyl transferase E) phosphoprotein phosphatase Answer: A 83) Which of the following enzymes catalyzes dephosphorylation of a protein? 83) A) cyclooxygenase B) phenylethanolamine N - methyl transferase C) dopamine Ά - hydroxylase D) phosphoprotein phosphatase E) phospholipase C Answer: D 15

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    84) Which of the following enzymes catalyzes synthesis of diacylglycerol and inositol triphosphate? 84) A) phenylethanolamine N - methyl transferase B) phosphoprotein phosphatase C) phospholipase C D) dopamine Ά - hydroxylase E) cyclooxygenase Answer: C 85) A target cell will respond to a chemical messenger once that molecule has bound to a 85) A) G protein. B) receptor. C) protein kinase. D) complex in the nucleus. E) calcium channel. Answer: B 86) A(n) ________ is transported in the bloodstream. 86) A) autocrine B) neurotransmitter C) glial cell D) paracrine E) hormone Answer: E 87) Histamine is an example of a(n) 87) A) hormone. B) paracrine. C) glial cell. D) neurotransmitter. E) autocrine. Answer: B 88) Lipid - soluble molecules are not only hydrophobic, but are also 88) A) lipophilic. B) cellulose. C) lipophobic. D) amino acids. E) disaccharides. Answer: A 89) Catecholamines, such as dopamine, norepinephrine, and epinephrine, are derived from the amino acid 89) A) tyrosine. B) glycine. C) glutamate. D) leucine. E) isoleucine. Answer: A 16

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    90) Identify the two enzymes involved in converting tyrosine into dopamine. 90) A) andenylate cyclase and phospholipase C B) dopamine Ά - hydroxylase and propeptide C) cyclooxygenase and lipoxygenase D) tyrosine Ά hydroxylase and dopa decarboxylase E) cortisol and dehydroepiandrosterone Answer: D 91) Eicosanoids are derived from what phospholipid? 91) A) thromboxanes B) arachidonic acid C) prostoglandins D) leukotrienes E) prostacycline Answer: B 92) Steroid messengers are derived from what precursor molecule? 92) A) calmodulin B) tyrosine C) histamine D) cholesterol E) arachidonic acid Answer: D 93) Catecholamines are released from the secretory cell by 93) A) simple diffusion. B) exocytosis. C) endocytosis. D) active transport. E) signal transduction. Answer: B 94) Steroids are released from the secretory cell by 94) A) active transport. B) endocytosis. C) simple diffusion. D) signal transduction. E) exocytosis. Answer: C 95) What protein in the blood that is relatively non - specific with respect to its ability to bind and transport chemical messengers in the blood? 95) A) cytokine B) corticosteroid - binding globulin C) protein kinase D) albumin E) hemoglobin Answer: D 17

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    96) As free hormones bind to their receptors and no more hormone is released from their cell of origin, the concentration of hormone bound to carrier proteins will 96) A) denature. B) have a greater affinity. C) increase. D) become saturated. E) decrease. Answer: E 97) The strength with which a ligand (chemical messenger) will bind with a receptor is referred to as its 97) A) affinity. B) enzyme - substrate complex. C) prohormone. D) binding strength. E) prepropeptide. Answer: A 98) As the concentration of receptors on the cell membrane decreases, the response of the target cell will 98) A) decrease. B) remain the same due to saturation. C) increase its affinity. D) oscillate with the concentration of the chemical messenger. E) increase. Answer: A 99) Which of the following chemical messengers are lipophilic? 99) A) thyroid hormones B) eicosanoids C) peptides/proteins D) steroids E) steroids, eicosanoids, and thyroid hormone Answer: E 100) Which of the following chemical messengers are lipophobic? 100) A) steroids B) peptides/proteins C) thyroid hormones D) peptides/proteins and steroids E) amino acids Answer: E TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 101) Lipophobic chemical messengers communicate a message to the target cell by binding to receptors on that cell's membrane. 101) Answer: True False 102) The target cell of a neurotransmitter is the postsynaptic cell. 102) Answer: True False 18

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    103) Endocrine glands secrete neurohormones. 103) Answer: True False 104) Tyrosine is one of four amino acids that function directly as chemical messengers. 104) Answer: True False 105) Steroid hormones are produced within cells and stored in vesicles until they are released. 105) Answer: True False 106) Steroid hormones are derived from the hormone testosterone. 106) Answer: True False 107) All catecholamine - secreting cells synthesize dopamine. 107) Answer: True False 108) Eicosanoids are released immediately upon synthesis. 108) Answer: True False 109) The location of the receptor depends on whether the messenger is lipophilic or lipophobic. 109) Answer: True False 110) A single cell can have receptors for different messengers. 110) Answer: True False 111) Most receptors are relatively non - specific for the ligand that will bind to them. 111) Answer: True False 112) Receptors for lipophilic chemical messengers are only located on the surface of a cell's membrane. 112) Answer: True False 113) Tyrosine kinases are enzymes that add a phosphate group to tyrosine residues on other proteins, changing the conformation of those proteins. 113) Answer: True False 114) The higher concentration of messenger, the greater the response in the target cell. 114) Answer: True False 115) Enkephalin is an opiate produced in the body. When enkephalin binds to opioid receptors, it produces analgesia (a lack of pain sensation). Morphine can also bind to opioid receptors and produce analgesia. Morphine is an opiate antagonist. 115) Answer: True False 116) Thyroid hormones alter the transcription of mRNA in the target cell. 116) Answer: True False 117) If calcium channels open in the plasma membrane, calcium ions enter the cell. 117) Answer: True False 19

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    118) An amplifier enzyme catalyzes the synthesis of a second messenger. 118) Answer: True False 119) In its active form, a G protein has a GDP bound to its alpha unit. 119) Answer: True False 120) Generally, the nervous system is a more rapid means of communication than the endocrine system. 120) Answer: True False 121) The site of communication between two neurons is called a synapse. 121) Answer: True False ESSAY. Write your answer in the space provided or on a separate sheet of paper. 122) Compare and contrast the synthesis, release, transport, and signal transduction of lipophilic and lipophobic chemical messengers. Answer: Lipophilic (hydrophobic) messengers include the steroids, eicosanoids, and thyroid hormones. They are secreted via simple diffusion from the cell that secretes them and must be bound to a carrier protein in the bloodstream. The location of the receptor on their target cell is either in the nucleus or cytosol and their action on the target cell requires the synthesis of a new protein. Due to this new protein synthesis, these chemical messengers have a relatively slow response time but a long duration and a long have life in the body. In contrast, lipophobic (hydrophilic) messengers include those chemical messenger classes of amino acids, amines, and peptides. They are usually made in advance via protein synthesis, stored in secretory vesicles, and released into the bloodstream via exocytosis where they dissolve into the plasma. Since they are lipophobic, the receptor on their target cell is located on the outside of the cell and, therefore, once they bind to the receptor, they activate a second messenger system within the cell which has a fast response time due to the amplification of activated enzymes within the cell. Lipophobic messengers have a short half - life and a short duration of response. 123) Aspirin, also known as acetylsalicylic acid, is one of the most widely used medications in the world. To what group of medications does aspirin belong? Explain its mechanism of action for preventing pain and inflammation as well as its ability to prevent blood clots. Aspirin also has some undesirable side effects, especially in higher doses. Explain what these side effects are and why they occur. Answer: Aspirin is one of a number of nonsteroidal anti - inflammatory drugs (NSAIDs). Their mechanism of action is to target the enzyme cyclooxygenase (COX), which has two forms COX - 1 and COX - 2. COX is a critical enzyme in the synthesis of prostaglandins (PG), eicosanoids that cause pain and inflammation. COX - 1 is present in many cells of the body and helps maintain homeostasis and synthesizes PG. Aspirin, however, nonselectively inhibits both forms of the COX enzyme but it is the inhibition of COX - 2 that results in pain relief. Several side effects occur when aspirin inhibits the COX - 1 enzyme because aspirin decreases the production of thromboxane A 2 , a chemical that is involved in the formation of blood clots. However, at higher doses, aspirin also decreases the production of PGI 2 (prostacyclin), a chemical that inhibits the production of blood clots. Therefore, a lower dose of 82 mg (a baby aspirin) will decrease the production of thromboxane A 2 causing a beneficial side effect of taking aspirin. In larger dosages (like those found in regular aspirin), although they will reduce pain and inflammation, they will also actually promote the formation of blood clots due to decreasing the production of PGI 2 . Another undesirable side effect of aspirin is the formation of ulcers and stomach bleeding and upset because aspirin also inhibits the production of PGE 2 which indirectly protects the lining of the stomach from stomach acid. 20

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    124) Describe the factors that affect the magnitude of a target cell's response. Assume that there is a receptor on the cell for the ligand. Answer: The first factor that affects a target cell's response to a ligand is the concentration of the ligand. The kinetics of a ligand's binding to a receptor is shown as M + R  M*R  Response, where M is the messenger (ligand), R is the receptor, and M*R is the messenger - receptor complex. As the concentration of ligand increases, the number of bound receptors will increase until all receptors on the target cell are bound by ligand (saturated). This relationship between ligand and receptor means that the response to a ligand will also be affected by the number of receptors available. At any concentration of ligand, the number of receptors bound depends upon the total number of receptors on the target cell. In order to change the number of receptors on the target cell, some time is required to alter the regulation of protein synthesis or degradation of that receptor. If the concentration of ligand is low for long periods of time, cells tend to upregulate (increase) the number of receptors for that ligand. In that way, the cell can be more responsive to lower concentrations of ligand. Alternatively, long periods of high ligand concentration may downregulate that ligand's receptor population, thereby reducing the cell's responsiveness to the ligand. Finally, a cell's responsiveness to a ligand is determined by the affinity of the receptor for the ligand. As the receptor affinity increases, more receptors will be bound at the same ligand concentration. This is especially important when there are several classes of receptors that have different affinities for a ligand such as epinephrine. Two types of receptors are capable of binding the catecholamine epinephrine: ΅ and Ά 2 adrenergic receptors. Both of these receptors are found on blood vessels and have the opposite effect on those vessels: ΅ adrenoreceptors induce vasoconstriction, whereas Ά 2 adrenoreceptors induce vasodilation. However, in the presence of epinephrine, the Ά 2 adrenoreceptor - induced vasodilation will predominate because the Ά 2 adrenoreceptor has a greater affinity for epinephrine than the ΅ adrenoreceptor. 125) Describe the function of both slow and fast channel - linked receptors. Include the role of calcium as a second messenger. Answer: Channel - linked receptors function in the gating of an ion channel into the open or closed states in response to ligand - receptor binding. These ligand - gated channels are usually very specific for a particular ion and fall into two categories: fast and slow channels. Fast channels are those where the receptor and channel are directly coupled. With slow channels, the receptor and channel are linked by confusing a G protein. The binding of a ligand to a fast channel receptor will increase the likelihood that an ion channel will open. That channel will only remain open for a short period of time, allowing the flux of a particular ion across the membrane either into or out of the cell, depending upon that ion's electrochemical gradient. The flux of ions across a membrane can alter cellular function in two ways: by changing that cell's membrane potential, and/or the ion can act as a second messenger inside the cell. The movement of sodium into a cell induces a rapid depolarization. Alternatively, if the channel is specific for calcium, then the influx of calcium can trigger a series of responses by binding to the cytosolic protein calmodulin or by binding to other proteins. The calcium - calmodulin complex activates a protein kinase which catalyzes phosphorylation of a protein. Calcium is well suited to this role due to its low cytosolic concentration, making the cell very responsive to changes in intracellular calcium. The cytosolic concentration of calcium is kept low by: 1) the active transport of calcium out of the cell; 2) sequestration of calcium by cytosolic binding proteins; and 3) the active transport of calcium into the smooth endoplasmic reticulum and mitochondria. 21

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    126) Describe G protein - linked receptors, including a discussion of the different enzyme pathways activated by G protein. Answer: G proteins act as a bridge between a receptor and a channel. Receptor - ligand binding activates a G protein within the cell membrane. G proteins can act through a number of second messenger pathways. cAMP is the most common pathway. A ligand binding to its receptor will activate Gs (or Gi, depending upon the receptor). The ΅ subunit of the G protein is released to activate the enzyme adenylate cyclase. This step appears to be the most important because several other enzymes can be activated by the ΅ subunit of the G protein. Adenylate cyclase catalyzes the conversion of ATP to cAMP. Once produced, cAMP will activate protein kinase A (cAMP - dependent protein kinase) by phosphorylating it. Protein kinase A uses ATP to phosphorylate another enzyme, thereby altering that protein's function and causing a response within the cell. This cascade of reactions can be halted by the action of the cAMP phosphodiesterase, which degrades cAMP. At the same time, the protein activated by protein kinase A can be inactivated by a phosphatase enzyme that removes the phosphate group. As stated above, the ΅ subunit of G protein could activate other enzymes like guanylate cyclase, which would stimulate the production of cGMP and ultimately activate protein kinase G. In addition, the ΅ subunit of G protein could activate the enzyme phospholipase C. This enzyme is part of the phosphatidylinositol system. Activation of phospholipase C cleaves the membrane phospholipid phosphatidylinositol 4,5 - biphosphate (PIP 2 ) into diacylglycerol (DAG) and inositol triphosphate (IP 3 ). DAG remains in the membrane and activates protein kinase C, which stimulates other enzymes to initiate a cellular response. IP3 moves into the cytosol and stimulates the release of calcium from the endoplasmic reticulum. In this case, it is calcium that stimulates the cellular response through its binding to calmodulin or another protein with a calcium binding site. 22

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    Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A secondary endocrine organ is one that 1) A) secretes at least two hormones. B) secretes hormones, but is better known for another function. C) is the target of tropic hormones. D) secretes tropic hormones. E) receives communication from at least two hormones. Answer: B 2) Which of the following endocrine organs essentially secretes hormones from neurons? 2) A) pancreas B) hypothalamus C) adrenal cortex D) thymus E) gonads Answer: B 3) What is another name for the posterior lobe of the pituitary gland? 3) A) paraventricular nucleus B) neurohypophysis C) melanocyte D) pineal gland E) adenohypophysis Answer: B 4) What hormone, released by the posterior pituitary, functions in uterine contraction and milk letdown in the breast? 4) A) oxytocin B) prolactin C) somatomedin D) vasopressin E) antidiuretic hormone Answer: A 5) Secretion of hormones from the anterior pituitary is stimulated by ________ released from the ________. 5) A) releasing hormones : thalamus B) tropic hormones : hypothalamus C) stimulating hormones : posterior pituitary D) oxytocin : hypothalamus E) neurotransmitters : hypothalamus Answer: B 1

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    6) What ensures that blood levels of a specific releasing hormone are locally high in order to stimulate the pituitary? 6) A) pulsatility of tropic hormone release B) hypothalamic - pituitary portal system C) degradation rates of tropic hormones D) affinity of the tropic hormones E) hepatic portal system Answer: B 7) Which of the following is NOT a hormone released from the anterior pituitary? 7) A) follicle stimulating hormone B) luteinizing hormone C) prolactin inhibiting hormone D) growth hormone E) adrenocorticotropic hormone Answer: C 8) Which tropic hormone is responsible for controlling the release of follicle stimulating hormone from the anterior pituitary? 8) A) follicle releasing hormone B) growth hormone releasing hormone C) follicle stimulating releasing hormone D) corticotropin releasing hormone E) gonadotropin releasing hormone Answer: E 9) Which of the following correctly describes a pathway for secretion of a hormone under the control of tropic hormones? 9) A) TRH stimulates TSH release, which stimulates thymosin release. B) PRH stimulates PH release, which stimulates prolactin release. C) GHRH stimulates GH release, which stimulates insulin - like growth factor release. D) CRH stimulates ACTH release, which stimulates somatomedin release. E) GnRH stimulates PH release, which stimulates prolactin release. Answer: C 10) Which of the following tropic hormones is also known as the catecholamine, dopamine? 10) A) growth hormone inhibiting hormone B) luteinizing hormone C) growth hormone D) prolactin releasing hormone E) prolactin inhibiting hormone Answer: E 11) Which of the following is a CORRECT example of long - loop negative feedback? 11) A) TSH stimulates the release of TRH. B) GH stimulates the release of GHIH. C) FSH inhibits the release of GnRH. D) Glucocorticoids inhibit the release of CRH. E) TSH inhibits the release of TRH. Answer: D 2

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    12) Which of the following is a CORRECT example of short - loop negative feedback? 12) A) Thyroid hormones inhibit the release of TSH. B) TRH inhibits the release of TSH. C) Thyroid hormones inhibit the release of TRH. D) TRH stimulates the release of thyroid hormones. E) TSH inhibits the release of TRH. Answer: E 13) The release of ________ from the pineal gland is important for establishing ________. 13) A) prolactin : circadian rhythm B) prolactin : breast milk production C) melatonin : thirst D) melatonin : circadian rhythm E) melanin : thirst Answer: D 14) The thyroid gland secretes what hormone(s)? 14) A) thyroid hormones only B) thymosin only C) calcitonin only D) both thyroid hormones and thymosin E) both thyroid hormones and calcitonin Answer: E 15) What is triiodothyronine? 15) A) a catecholamine released from the adrenal medulla B) the hormone secreted from the pineal gland C) the hormone secreted from the thymus D) a catecholamine released from the adrenal cortex E) a thyroid hormone, also known as T 3 , secreted from the thyroid gland Answer: E 16) Which of the following hormones is NOT released from the adrenal gland? 16) A) cortisol B) adrenocorticotropic hormone C) aldosterone D) androgens E) epinephrine Answer: B 17) Which of the following hormones is NOT secreted by the endocrine region of the pancreas? 17) A) pancreatic polypeptide B) cholecystokinin C) somatostatin D) insulin E) glucagon Answer: B 3

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    18) What hormone is secreted by the zona glomerulosa layer of the adrenal gland? 18) A) epinephrine B) aldosterone C) cortisol D) progesterone E) androgens Answer: B 19) What layer of the adrenal cortex secretes androgens? 19) A) zona reticularis only B) zona fasciculata only C) zona glomerulosa only D) both zonae reticularis and fasciculata E) both zonae reticularis and glomerulosa Answer: D 20) A person with a pheochromocytoma (a functioning adenoma) is experiencing symptoms created by its hypersecretion of epinephrine, including high blood pressure, elevated heart rate, excessive sweating, anxiety, and weight loss. Where would this neuroendocrine tumor be located? 20) A) neurohypophysis of pituitary gland B) hypothalamus C) adrenal medulla D) adrenal cortex E) adenohypophysis of pituitary gland Answer: C 21) What cells secrete epinephrine from the adrenal gland? 21) A) B cells B) A cells C) chromaffin cells D) zona reticularis cells E) D cells Answer: C 22) All of the following paired hormones have antagonistic effects EXCEPT 22) A) insulin and glucagon. B) epinephrine and norepinephrine. C) PRH and dopamine. D) ANP and aldosterone. E) calcitonin and PTH. Answer: B 23) Which of the following hormones is NOT secreted by gonads? 23) A) testosterone B) estradiol C) androstenedione D) oxytocin E) progesterone Answer: D 4

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    24) What anterior pituitary hormone is NOT a tropic hormone? 24) A) growth hormone B) prolactin C) follicle stimulating hormone D) luteinizing hormone E) adrenocorticotropic hormone Answer: B 25) Which of the following hormones regulates plasma calcium levels? 25) A) calcitonin only B) calcitrol only C) parathyroid hormone only D) both calcitonin, and oxytocin E) calcitonin, calcitrol, and parathyroid hormone Answer: E 26) What hormone is secreted by the heart? 26) A) atrial natriuretic peptide B) somatostatin C) thymosin D) erythropoietin E) epinephrine Answer: A 27) Where does the neural input for circadian rhythmicity of the pineal gland and hypothalamic tropic hormones originate? 27) A) lateral geniculus B) cerebrum C) supraoptic nucleus D) paraventricular nucleus E) suprachiasmatic nucleus Answer: E 28) Abnormal hormone secretions from an endocrine gland due to altered tropic hormone release are called 28) A) secondary secretion disorders. B) tertiary secretion disorders. C) primary secretion disorders. D) hypersecretions. E) hyposecretions. Answer: A 29) Which of the following changes in plasma levels would be observed in a primary hyposecretion of cortisol? 29) A) decreased CRH, decreased ACTH, and increased cortisol B) increased CRH, decreased ACTH, and decreased cortisol C) decreased CRH, decreased ACTH, and decreased cortisol D) increased CRH, increased ACTH, and increased cortisol E) increased CRH, increased ACTH, and decreased cortisol Answer: E 5

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    30) A 10 - year - old with precocious puberty is found to have a space - occupying tumor in the arcuate nucleus of the hypothalamus, leading to excessive prolactin release. Which of the following correctly describes changes in plasma levels of hormones? 30) A) increased PRH, decreased PIH, and decreased prolactin B) decreased PRH, increased PIH, and increased prolactin C) increased PRH, increased PIH, and increased prolactin D) decreased PRH, decreased PIH, and decreased prolactin E) decreased PRH, decreased PIH, and increased prolactin Answer: E 31) A person with Cushing's disease is found to have a functioning adenoma in the anterior pituitary causing an increase in ACTH secretion. Which of the following CORRECTLY describes changes in plasma levels of hormones? 31) A) increased CRH, decreased ACTH, and decreased cortisol B) decreased CRH, decreased ACTH, and decreased cortisol C) decreased CRH, decreased ACTH, and increased cortisol D) decreased CRH, increased ACTH, and increased cortisol E) increased CRH, increased ACTH, and decreased cortisol Answer: D 32) The mechanism of insulin catabolism in target cells is best described as degradation by 32) A) mitochondrial enzymes following receptor - mediated endocytosis. B) peroxisomal enzymes. C) insulin - degrading enzyme following receptor - mediated endocytosis. D) lysosomes following receptor - mediated endocytosis. E) proteases in the extracellular fluid. Answer: C 33) The concentration of free hormone in the blood depends on all of the following EXCEPT the 33) A) rate of receptor downregulation. B) rate at which the hormone is metabolized. C) rate of hormone secretion. D) amount of hormone transported bound to carrier proteins. E) amount of hormone temporarily stored in adipose tissue. Answer: A 34) When the response to two hormones is greater than the sum of the individual responses, the response is described as 34) A) agonistic. B) antagonized. C) permissive. D) synergistic. E) additive. Answer: D 6

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    35) All of the following hormones are produced in the adrenal cortex EXCEPT 35) A) androgens. B) aldosterone. C) cortisol. D) epinephrine. E) both male and female sex hormone precursors. Answer: D 36) Which of the following produces the hormone calcitonin? 36) A) posterior pituitary B) adrenal cortex C) pancreas D) thyroid gland E) adrenal medulla Answer: D 37) The hormones somatostatin, insulin, and glucagon are all produced by what mixed endocrine/exocrine gland? 37) A) pancreas B) thyroid gland C) adrenal cortex D) adrenal medulla E) posterior pituitary Answer: A 38) Vasopressin works on the kidney to decrease urine output, as does aldosterone, but has an effect on blood vessels that is similar to yet another hormone, which is 38) A) ACTH. B) atrial natriuretic peptide. C) epinephrine. D) cortisol. E) rennin. Answer: C 39) Oxytocin is produced by neurons of the supraoptic nucleus in the hypothalamus, but is released into the bloodstream where? 39) A) hypothalamic - pituitary portal system B) uterus and breast tissue C) neurohypophysis D) capillary beds of the median eminence E) anterior pituitary Answer: C 40) Which hormone's release is governed by GnRH? 40) A) cortisol B) insulin - like growth factors C) glucagon D) sex hormones E) thyroid hormone Answer: D 7

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    41) Which hormone's release is ultimately affected by CRH? 41) A) cortisol B) thyroid hormone C) sex hormones D) glucagon E) insulin - like growth factors Answer: A 42) Which hormone's release is ultimately affected by GHRH? 42) A) cortisol B) insulin - like growth factors C) thyroid hormone D) glucagon E) sex hormones Answer: B 43) Which hormone's release is ultimately affected by TRH? 43) A) thyroid hormone B) insulin - like growth factors C) sex hormones D) glucagon E) cortisol Answer: A 44) Which pancreatic cell type secretes somatostatin? 44) A) beta cells B) F cells C) alpha cells D) gamma cells E) delta cells Answer: E 45) Which pancreatic cell type secretes insulin? 45) A) alpha cells B) F cells C) gamma cells D) delta cells E) beta cells Answer: E 46) Which pancreatic cell type secretes glucagon? 46) A) F cells B) alpha cells C) beta cells D) gamma cells E) delta cells Answer: B 8

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