Test Bank Guyton and Hall Textbook of Medical Physiology 14th Edition Hall

Test Bank Guyton and Hall Textbook of Medical Physiology 14th Edition Hall Table of Contents PREFACE ...................................................................................................................................... 4 Chapter 1. Functional Organization of the Human Body and Control of the “Internal Environment” .............................................................................................................................. 4 Chapter 2. The Cell and Its Functions ..................................................................................... 6 Chapter 3. Genetic Control of Protein Synthesis, cell function, and cell reproduction ...... 9 Chapter 4. Transport of Substances Through Cell Membranes ......................................... 12 Chapter 5. Membrane Potentials and Action Potentials ...................................................... 17 Chapter 6. Contraction of Skeletal Muscle ............................................................................ 23 Chapter 7. Excitation of Skeletal Muscle: Neuromuscular Transmission and .................. 29 Chapter 8. Excitation and Contraction of Smooth Muscle .................................................. 33 Chapter 9. Cardiac Muscle; The Heart as a Pump and Function of the Heart Valves ....... 35 Chapter 10. Rhythmical Excitation of the Heart................................................................... 37 Chapter 11. The Normal Electrocardiogram ......................................................................... 40 Chapter 12. Electrocardiographic Interpretation of Cardiac Muscle and Coronary Blood Flow Abnormalities: Vectorial Analysis .................................................................................. 41 Chapter 13.Cardiac Arrhythmias and Their Electrocardiographic Interpretation .............. 46 Chapter 14. Overview of the Circulation; Biophysics of Pressure, Flow, and Resistance . 50 Chapter 15. Vascular Distensibility and Functions of the Arterial and Venous Systems .. 53 Chapter 16. The Microcirculation and Lymphatic System: Capillary Fluid Exchange, Interstitial Fluid, and Lymph Flow .......................................................................................... 55 Chapter 17. Local and Humoral Control of Tissue Blood Flow .......................................... 59 Chapter 18. Nervous Regulation of the Circulation and Rapid Control of Arterial Pressure ................................................................................................................................................... 62 Chapter 19. Role of the Kidneys in Long-Term Control of Arterial Pressure and in Hypertension: The Integrated System for Aterial Pressure Regulation .............................. 65 Chapter 20. Cardiac Output, Venous Return, and Their Regulation ................................. 70 Chapter 21. Muscle Blood Flow and Cardiac Output During Exercise; the Coronary Circulation and Ischemic Heart Disease ................................................................................ 73 Chapter 22. Cardiac Failure .................................................................................................... 75 Chapter 23. Heart Valves and Heart Sounds; Valvular and Congenital Heart Defects ...... 78 Chapter 24. Circulatory Shock and Its Treatment................................................................ 80 Chapter 25. The Body Fluid Compartments: Extracellular and Intracellular Fluids; Edema ................................................................................................................................................... 83 Chapter 26. The Urinary System: Functional Anatomy and Urine Formation by the Kidneys ...................................................................................................................................... 83 Chapter 27. Glomerular Filtration, Renal Blood Flow, and Their Control .......................... 83 1Chapter 28. Renal Tubular Reabsorption and Secretion ...................................................... 83 Chapter 29. Urine Concentration and Dilution; Regulation of Extracellular Fluid Osmolarity and Sodium Concentration ................................................................................. 83 Chapter 30. Renal Regulation of Potassium, Calcium, Phosphate, and Magnesium; Integration of Renal Mechanisms for Control of Blood Volume and Extracellular Fluid Volume ...................................................................................................................................... 83 Chapter 31. Acid-Base Regulation .......................................................................................... 83 Chapter 32. Diuretics, Kidney Diseases ................................................................................ 95 Chapter 33. Red Blood Cells, Anemia, and Polycythemia ................................................... 98 Chapter 34. Resistance of the Body to Infection: I. Leukocytes, Granulocytes, the Monocyte-Macrophage System, and Inflammation ............................................................. 101 Chapter 35. Resistance of the Body to Infection: II. Immunity and Allergy ..................... 104 Chapter 36. Blood Types; Transfusion; Tissue and Organ Transplantation .................. 104 Chapter 37. Hemostasis and Blood Coagulation ............................................................... 106 Chapter 38. Pulmonary Ventilation ...................................................................................... 108 Chapter 39. Pulmonary Circulation, Pulmonary Edema, Pleural Fluid ............................. 111 Chapter 40. Principles of Gas Exchange; Diffusion of Oxygen and Carbon Dioxide Through the Respiratory Membrane .................................................................................... 115 Chapter 41. Transport of Oxygen and Carbon Dioxide in Blood and Tissue Fluids ....... 118 Chapter 42. Regulation of Respiration ................................................................................ 122 Chapter 43. Respiratory Insufficiency – Pathophysiology, Diagnosis, Oxygen Therapy . 125 Chapter 44. Aviation, High Altitude, and Space Physiology ............................................. 128 Chapter 45. Physiology of Deep-Sea Diving and Other Hyperbaric ................................. 130 Chapter 46. Organization of the Nervous System, Basic Functions of Synapses, and Neurotransmitters .................................................................................................................. 133 Chapter 47. Sensory Receptors, Neuronal Circuits for Processing Information ............. 136 Chapter 48. Somatic Sensations: I. General Organization, the Tactile and Position Senses ................................................................................................................................................. 138 Chapter 49. Somatic sensations: II. Pain, Headache, and Thermal Sensations .............. 141 Chapter 50. The Eye: I. Optics of Vision ............................................................................. 143 Chapter 51. The Eye: II. Receptor and Neural Function of the Retina ............................. 146 Chapter 52. The Eye: III. Central Neurophysiology of Vision ............................................ 149 Chapter 53. The Sense of Hearing ....................................................................................... 152 Chapter 54. The Chemical Senses – Taste and Smell ........................................................ 154 Chapter 55. Motor Functions of the Spinal Cord; the Cord Reflexes............................... 157 Chapter 56. Cortical and Brain Stem Control of Motor Function ..................................... 160 Chapter 57. Contributions of the Cerebellum and Basal Ganglia to Overall Motor Control ................................................................................................................................................. 162 Chapter 58. Cerebral Cortex, Intellectual Functions of the Brain, Learning, and Memory 2................................................................................................................................................. 165 Chapter 59. Behavioral and Motivational Mechanisms of the Brain – The Limbic System and the Hypothalamus .......................................................................................................... 168 Chapter 60. States of Brain Activity – Sleep, Brain Waves, Epilepsy, Psychoses, and Dementia ................................................................................................................................. 168 Chapter 61. The Autonomic Nervous System and the Adrenal Medulla ......................... 170 Chapter 62. Cerebral Blood Flow, Cerebrospinal Fluid, and Brain ................................... 172 Chapter 63. General Principles of Gastrointestinal Function – Motility, Nervous Control, and Blood Circulation ............................................................................................................ 174 Chapter 64. Propulsion and Mixing of Food in the Alimentary Tract .............................. 179 Chapter 65. Secretory Functions of the Alimentary Tract ................................................. 188 Chapter 66. Digestion and Absorption in the Gastrointestinal Tract .............................. 198 Chapter 67. Physiology of Gastrointestinal Disorders ...................................................... 207 Chapter 68. Metabolism of Carbohydrates and Formation of Adenosine Triphosphate 207 Chapter 69. Lipid Metabolism .............................................................................................. 211 Chapter 70. Protein Metabolism .......................................................................................... 217 Chapter 71. The Liver as an Organ ...................................................................................... 218 Chapter 72. Dietary Balances; Regulation of Feeding; Obesity and Starvation; Vitamins and Minerals ........................................................................................................................... 224 Chapter 73. Energetics and Metabolic Rate ........................................................................ 225 Chapter 74. Body Temperature Regulation and Fever ...................................................... 229 Chapter 75. Introduction to Endocrinology ........................................................................ 233 Chapter 76. Pituitary Hormones and Their Control by the Hypopthalamus .................... 235 Chapter 77. Thyroid Metabolic Hormones .......................................................................... 235 Chapter 78. Adenocortical Hormones ................................................................................. 240 Chapter 79. Insulin, Glucagon, and Diabetes Mellitus ...................................................... 244 Chapter 80. Parathyroid Hormone, Calcitonin, Calcium and Phosphate Metabolism, Vitamin D, Bone, and Teeth .................................................................................................. 248 Chapter 81. Reproductive and Hormonal Functions of the Male (and Function of the Pineal Gland) ........................................................................................................................... 252 Chapter 82. Female Physiology Before Pregnancy and Female Hormones ..................... 254 Chapter 83. Pregnancy and Lactation ................................................................................. 257 Chapter 84. Fetal and Neonatal Physiology ........................................................................ 259 Chapter 85. Sports Physiology ............................................................................................. 262 3PREFACE TEST BANK with Complete Questions and Solutions. To clarify, this is the TEST BANK, not the textbook. You get immediate access to download your test bank. You will receive a complete test bank; in other words, all chapters shown in the table of contents in this preview will be there. Test banks come in PDF format; therefore, you do not need specialized software to open them. Chapter 1. Functional Organization of the Human Body and Control of the “Internal Environment” Test Bank 1. The most abundant type of cell in the human body is which of the following? A. Neuron B. Epithelial cell C. Red blood cell D. White blood cell E. Vascular smooth muscle cell F. Skeletal muscle cell ANS: C 2. The most abundant substance in the human body and the approximate percentage of that substance in the body is which of the following? A. Protein, 30% B. Protein, 60% C. Water, 30% D. Water, 60% E. Carbohydrate, 30% F. Carbohydrate, 60% ANS: D 3. A large volume of blood is transfused to a person whose baroreceptor blood pressure control system is not functioning and arterial blood pressure rises from the normal level of 100 to 160 mm Hg. If the same volume of blood is infused into the same person when the baroreceptor system is functioning and this time the arterial pressure increases from the normal level from 100 mm Hg up to 120 mm Hg, calculate the gain of the baroreceptor system in this person. A. -3 B. -2 C. -1 D. 0 4E. +1 F. +2 G. +3 ANS: B 4. Which of the following substances has the highest extracellular fluid to intracellular fluid concentration ratio for most mammalian cells? A. Sodium ions B. Potassium ions C. Carbon dioxide D. Glucose E. Protei n ANS: A 5. Exchange of substances between the cardiovascular system and the interstitial fluid occurs mainly in which of the following? A. Arteries B. Arterioles C. Capillaries D. Venules E. Vein s ANS: C 6. Which of the following is the approximate distance from the capillaries to most cells of the body? A. Less than 50 angstroms B. Less than 50 microns C. Less than 50 millimeters D. Less than 100 angstroms E. Less than 100 microns F. Less than 100 millimeters ANS: A 7. When a person is at rest, how much time is required for the blood in the circulation to traverse the entire circulatory circuit? A. 1 second B. 1 minute C. 3 minutes D. 4 minutes E. 5 minutes ANS: B 8. feedback is often referred to as a "vicious cycle" because it leads to 5instability and sometimes death. A. Postitive, progressive B. Positive, diminished C. Negative, progressive D. Negative, diminished E. Adaptive, progressive ANS: A 9. Which of the following is an example of positive feedback in the body? A. Clotting of blood B. Return of blood pressure toward normal after a hemorrhage C. Increased respiration rate caused by accumulation of carbon dioxide in the blood D. Decreased sympathetic nervous system activity that occurs in response to increased blood pressure ANS: A Chapter 2. The Cell and Its Functions Test Bank Refer to the following list to answer questions 1-3: A. Nucleolus B. Nucleus C. Agranular endoplasmic reticulum D. Granular endoplasmic reticulum E. Golgi apparatus F. Endosomes G. Peroxisomes H. Lysosomes I. Cytosol Identify the cellular location for each of the following steps involved in the synthesis and packaging of a secreted protein. Initiation of translation. ANS: I Protein sorting and packaging. 6ANS: E Gene transcription. ANS: B 4. Which of the following is true for both pinocytosis and phagocytosis? A. Involves the recruitment of actin filaments B. Occurs spontaneously and non-selectively C. Permits the uptake of bacterium into the cytosol D. Is only observed in macrophages and neutrophils E. Does not require ATP ANS: A 5. The cell membrane is LEAST permeable to which of the following? A. Sodium B. Oxygen C. Ethanol D. Carbon Dioxide E. Wate r ANS: A 6. The term “glycocalyx” refers to: A. The negatively charged carbohydrate chains that protrude into the cytosol from glycolipids and integral glycoproteins B. The negatively charged carbohydrate layer on the outer cell surface C. The layer of anions aligned on the cytosolic surface of the plasma membrane D. The large glycogen stores found in “fast” muscles E. A mechanism of cell-cell attachment ANS: B 7. Proteins are sorted for their delivery to lysosomes, secretory vesicles and the plasma membrane in the: A. Golgi apparatus B. smooth endoplasmic reticulum C. nucleus D. endocytotic vesicle ANS: A 8. Ubiquinone, an electron acceptor in the electron transport chain (oxidative phosphorylation), is found in the: A. Inner mitochondrial membrane B. Mitochondrial matrix C. Outer mitochondrial membrane 7D. Nucleu s ANS: A 9. The citric acid cycle or Kreb’s cycle, takes place in the: A. Mitochondrial matrix B. Inner mitochondrial membrane C. Outer mitochondrial membrane D. Inner mitochondrial space ANS: A 10. Which of the following processes is NOT ATP-dependent? A. Ciliary movement B. Positive chemotaxis C. Movement of carbon dioxide across a lipid bilayer D. Endocytosis E. Smooth muscle contraction ANS: C 11. This cytoskeletal element plays a role in certain forms of cell movement and is an essential component of the mitotic spindle: A. Phospholipids B. Glycocalyx C. F-actin D. Microtubules E. Clathri n ANS: D 12. Lipid synthesis occurs in the: A. Trans-Golgi network B. Granular or “rough” endoplasmic reticulum C. Agranular or “smooth” endoplasmic reticulum D. Nucleus E. Lysosom e ANS: C 13. This cytoskeletal element plays a role in certain forms of cell movement and is an essential component of the mitotic spindle: A. Phospholipids B. Glycocalyx C. F-actin D. Microtubules E. Clathrin 8ANS: D 14. The abnormal cleavage of mannose residues during the post-translational processing of glycoproteins has been shown to result in the development of a lupus-like autoimmune disease in mice. The abnormal cleavage is due to a mutation of the enzyme -mannosidase II. Based on your understanding of the processing of membrane proteins, you would predict this enzyme to be localized to the: A. Nucleus B. Cytosol C. Golgi apparatus D. Lysosomes E. Peroxisom es ANS: C 15. The observation that abnormal cleavage of mannose residues from glycoproteins causes an autoimmune disease in mice is most consistent with the role of which of the following structures in the normal immune response? A. Cytoskeleton B. Glycocalyx C. Peroxisomes D. Lysosomes E. Microtubul es ANS: B 16. A pure phospholipid bilayer is most permeable to: A. Sodium B. Calcium C. Chloride D. Water E. Oxyge n ANS: E Chapter 3. Genetic Control of Protein Synthesis, cell function, and cell reproduction Test Bank 1. Facioscapulohumeral muscular dystrophy (FSHD) is characterized by the deletion of a DNA sequence on chromosome 4q35. This deletion correlates with both the inability of a specific protein complex to bind to the DNA and an overexpression of the genes upstream of the deletion. The sequence deleted in FSHD most likely functions normally as: 9A. An activator protein B. A repressor protein C. An activator element D. A repressor element E. A promoter sequence ANS: D 2. In comparing two cell types from the same person (e.g. a neuron and an epithelial cell) the variation in their proteomes, or the proteins expressed by each cell type, reflects: A. Differences in the DNA contained in the nucleus of each cell B. Variation in the numbers of copies of specific genes in their respective genomes C. Cell-dependent expression and/or repression of specific genes D. Differences in the number of chromosomes in each cell E. The loss of genes from each genome over time ANS: C 3. Which of the following correctly describes the sequence of events that occur during the synthesis and packaging of a secreted protein? A. The gene is transcribed in the cytosol; mRNA is translated by ribosomes bound to “rough” endoplasmic reticulum; the protein is packaged for secretion in the trans- Golgi network B. The gene is transcribed in the nucleus; RNA polymerase binds to the start codon; the protein is packaged for secretion in the trans-Golgi network C. Translation is initiated in the cytosol; the protein is carried in membrane- bound vesicles to the cis-Golgi apparatus; the protein is packaged for secretion in the trans- Golgi network D +. Translation is initiated in the cytosol; new polypeptide is co- transported with across the outer ER membrane; the protein is glycosylated in the Golgi apparatus Na E. Translation is initiated by small ribosomal subunits anchored to the ER membrane; protein is glycosylated in the Golgi apparatus; the protein is packaged into lysosomes ANS: C 4. Which of the following does NOT play a direct role in the process of transcription? A. Helicase B. RNA polymerase C. A chain terminating sequence D. “Activated” RNA molecules E. A promoter 10sequence ANS: A 5. “Redundancy” or “degeneration” of the genetic code occurs during which of the following steps of protein synthesis? A. DNA replication B. Transcription C. Post-transcriptional modification D. Translation E. Protein glycosylation ANS: B 6. Which of the following bases is NOT present in RNA? A. Cytosine B. Thymine C. Adenine D. Guanin e ANS: B 7. The process of translation takes place: A. In the cytosol and on the surface of the “rough” endoplasmic reticulum B. In the nucleus and on the surface of the “rough” endoplasmic reticulum C. In the cytosol and the trans-Golgi network (TGN) D. In the nucleus and on the outer mitochondrial membrane ANS: A 8. Which of the following statements about translation is NOT true? A. Multiple ribosomes can simultaneously translate a single mRNA molecule B. Each codon codes for one amino acid C. One mRNA molecule can code for multiple proteins, depending on which start codon is recognized by the small ribosomal subunit D. Translation is terminated when the release factor binds to the stop codon ANS: C 9. The following statements accurately describe the process of DNA replication EXCEPT: A. The entire genome is replicated only once per cell cycle B. It occurs during the M phase of the cell cycle C. Nucleotides are incorporated into the growing DNA strand at the 3’ end D. DNA “proofreading” is performed by DNA polymerase ANS: C 10. The mechanism by which allolactose regulates the transcription 11of the beta- galactosidase gene is best described as: A. De-repression B. Repression C. Activation D. Negative feedback E. Positive feedback ANS: A 11. Which of the following does NOT occur during the process of mitosis? A. Replication of the genome B. Condensation of the chromosomes C. Fragmentation of the nuclear envelope D. Alignment of the chromatids along the equatorial plate E. Separation of the chromatids into two sets of 46 “daughter” chromosomes ANS: A 12. “Redundancy” or “degeneration” of the genetic code occurs during which of the following steps of protein synthesis: A. DNA replication B. Transcription C. Post-transcriptional modification D. Translation E. Protein glycosylation ANS: B 13. The appearance of which of the following distinguishes eukaryotic cells from lower units of life like bacteria and viruses? A. DNA B. RNA C. Membranes D. Protein E. Nucleu s ANS: E Chapter 4. Transport of Substances Through Cell Membranes Test Bank 1. An artificial membrane is created consisting of a lipid bilayer without protein molecules in the membrane. The lipid composition of the membrane is essentially the same as that of a normal, biological membrane. Which of the following substances permeates the membrane more readily than water molecules? 12A. Carbon Dioxide B. Glucose C. Glycerol D. Sodium E. Ure a ANS: A 2. A cell is equilibrated in an aqueous solution of 300 mOsm/L sodium chloride. Which of the following best describes what will happen to cell volume when the cell is placed in an aqueous solution of 300 mOsm/L calcium chloride? A. Decrease B. Decrease and then increase C. Increase D. Increase and then decrease E. No change ANS: E -4 3. The intracellular calcium ion concentration of ventricular muscle cells averages 10 mmol/L during diastole. The calcium ion concentration in transverse tubules (T-tubules) averages 2.5 mmol/L at rest. A protein transporter on the membrane of the T-tubule exchanges sodium for calcium. The transporter uses the transmembrane sodium gradient to fuel the exchange. Which of the following transport mechanisms best describes this type of transporter? A. Facilitated diffusion B. Primary active transport C. Secondary active co-transport D. Secondary active counter-transport E. Simple diffusion ANS: D 4. Human red blood cells (RBCs) and rabbit RBCs are equilibrated in separate solutions of isotonic saline (300 mOsm/L NaCl). The human RBCs are then placed in a solution of 300 mOsm/L glycerol, which causes them to swell and burst. However, rabbit RBCs placed in 300 mOsm/L glycerol neither swell nor shrink. Based on this information, which of the following can be concluded about a 300 mOsm/L solution of glycerol for the different cell types? Human RBCs Rabbit RBCs A. Hypertonic and hyperosmotic B. Hypotonic and hypoosmotic C. Hypotonic and isoosmotic D. Isotonic and hypoosmotic E. Isotonic and isoosmotic F. Isotonic and hyperosmotic Hypotonic and hypoosmotic Hypertonic and hyperosmotic Isotonic and isoosmotic Isotonic and hyperosmotic Hypotonic and isoosmotic Isotonic and 13isoosmotic ANS: C 5. The molarity of a 2% solution of NaCl is 340 mmol/L. The molecular weight of NaCl is 58.5. What is the osmolarity of a 2% solution of NaCl (in mOsm/L)? A. 170 B. 340 C. 510 D. 680 ANS: D 6. Secondary active transport typically moves which of the following substances against a concentration gradient? Glucose Amino acids Sodium ions A. No B. No C. Yes D. Yes E. Yes Yes ANS: D 7. Which of the following transport mechanisms can move sodium ions across a cell membrane? Primary active Secondary active No No Yes Yes Yes ANS: E 8. The diagram illustrates possible changes in red blood cell volume resulting from a change in extracellular fluid composition for a cell equilibrated in a 150 mmol/L solution of sodium chloride (NaCl) at time zero. Which curve best illustrates the volume change caused by immersion of the cell in an aqueous solution of 300 mOsm/L calcium chloride (CaCl2)? ANS: C 9. The diagram illustrates possible changes in red blood cell volume resulting from a change in extracellular fluid composition for a cell equilibrated in a 14 Simple transport transport diffusion No Yes No Yes Yes No Yes Yes No Yes No No No Yes Yes No Yes Yes No150 mmol/L solution of sodium chloride (NaCl) at time zero. Which curve best illustrates the volume change caused by immersion of the cell in an aqueous solution of 200 mOsm/L NaCl and 200 mOsm/L glycerol? ANS: B 10. Which of the following pairs of aqueous solutions will exert equal osmotic pressures across a normal cell membrane after steady-state conditions have been established? Solution A Solution B A. 10% albumin B. 100 mmol/L NaCl C. 300 mOsm/L glucose D. 300 mOsm/L glycerol E. 300 mOsm/L glycerol urea ANS: E 11. Two compartments (X and Y) are separated by a typical biological membrane (i.e., lipid bilayer). The concentrations of a permeant solute (i.e., urea) at time zero are shown. Which of the drawings below represents the volumes of X and Y when the system reaches equilibrium? 10% IgG 200 mmol/L CaCl2 300 mOsm/L urea 300 mOsm/L NaCl 300 mOsm/L ANS: A 12. The diagram illustrates possible changes in red blood cell volume resulting from a change in extracellular fluid composition for a cell equilibrated in 150 mmol/L NaCl at time zero. Which curve best illustrates the volume caused by immersion of the cell in an aqueous solution of 150 mmol/L CaCl2? ANS: E 13. Two compartments (X and Y) are separated by a typical biological membrane (lipid bilayer). The concentrations of a non-permeant molecule (glucose) at time zero are shown. Which of the drawings below represents the volumes of X and Y when the system reaches equilibrium? 15ANS: B 14. The diagram shows a model cell that transports substance X across the cell membrane. The cell is equipped with a Na-K-ATPase pump as shown. Substance X enters the cell by a coupled transport mechanism and exits the cell by carrier-mediated diffusion. Treatment with a substance that inhibits the Na-K-ATPase pump inhibits the transport of X by which of the following mechanisms? A +. Decreasing intracellular K B. + C. + Decreasing intracellular Increasing intracellular D +. Increasing intracellular concentration Na Na K ANS: D 15. The diagram shows a bag (with permeability characteristics similar to that of a normal cell) that contains a 100 mM solution of urea at time zero. The bag is placed in a beaker containing 100 mM glucose. Which of the following best describes the tonicity and osmolarity of the glucose solution as well as any changes in bag volume (assume that the bag volume is infinitely small compared to beaker volume)? Osmolarity Tonicity Bag volume A. Hyperosmotic Hypertonic Decreases B. Hyperosmotic Hypotonic Increases C. Hyperosmotic Isotonic No change D. Hypoosmotic Hypotonic Decreases E. Hypoosmotic Isotonic Increases F. Hypoosmotic Hypertonic No change G. Isoosmotic Hypertonic Decreases H. Isoosmotic Hypotonic Increases I. Isoosmotic Isotonic change ANS: G No concentration concentration concentration 16Chapter 5. Membrane Potentials and Action Potentials Test Bank 1. The diagram shows compound action potentials recorded percutaneously from a single site a certain distance from a stimulating electrode indicated by the arrow. Which peak is most likely to represent action potentials from small, non-myelinated motor neurons? ANS: D 2. A 42-year-old woman decides to lose weight on a diet prescribed by an anorexic friend. She loses about 30 pounds in 45 days, but her serum potassium level falls to 2.1 mmol/L (normal: 3.5 to 5.0 mmol/L). Which of the following changes is most likely to occur in this young woman? A. Depolarization of the resting membrane potential B. Hyperpolarization of the resting membrane potential C. Increased intracellular potassium concentration D. Potassium equilibrium potential becomes less negative ANS: B 3. An 22-year-old man is admitted to the emergency department after an automobile accident. He has not lost a large amount of blood, but he suffers from a severe crush injury to his right leg. He is conscious and exhibits flaccid paralysis. Electrocardiogram results show a shortened QT interval and an increase in the P-R interval (i.e., decreased duration of action potential and decreased conduction velocity). Laboratory results indicate that his serum potassium level has increased to a value of 6.5 mEq/L (normal: 3.5 to 5.0 mEq/L). This increase in serum potassium causes which of the following? A. A decreased net driving force for potassium from cells B. Decreased intracellular potassium concentration C. Hyperpolarization of the resting membrane potential D. More negative Nernst potential for potassium E. More negative resting membrane 17potential ANS: A 4. An 88-year-old nursing home resident has diabetes mellitus and is taking diuretics for hypertension. His blood glucose concentration has recently been greater than 350 mg/dL. He is disoriented and has had limited oral intake for about five days. His vital signs include a temperature of 100.5°F, a supine blood pressure and pulse of 150/90 mm Hg and 100 beats per minute, and an upright blood pressure and pulse of 130/88 mm Hg and 118 beats per minute. The findings on examination of the heart are normal, and his axillae + ar +e dry. The table shows serum Na and K the dehydration that values before and after has occurred in this patient. The resting membrane potential of a cardiac myocyte was about −70 millivolts before dehydration occurred. What is the resting membrane potential of a cardiac myocyte after dehydration occurred, assuming no change in membrane + co +nductance or intracellular concentrations of Na K A. −100 millivolts B. −50 millivolts C. −60 millivolts D. −70 millivolts E. −90 millivolts ANS: D 5. or ions? A 44-year-old man is recovering from third degree burns over 50% of his body surface area. His serum potassium level is low (2.9 mEq/L). He exhibits postural h +ypotension and skeletal muscle weakness. If the equilibrium potential for K in a n +euron is 105 mV and the equilibrium potential for − Na is +55 mV, what would be an approximate value for the resting membrane potential for a neuron in this man? A. +20 mV B. +48 mV C. +80 mV D. −25 mV E. −48 mV F. −96 mV ANS: F 6. A 23-year-old man receives a crush injury to his right leg in an automobile accident. + His serum potassium level is 6.4 mEq/L. The equilibrium potential for K in a 18+ motoneuron is −73 mV, and the equilibrium potential for Na is +59 mV. Which of the following best describes the resting membrane potential (in mV) for a typical motoneuron in this man? A. +62 B. +90 C. −13 D. −67 E. −84 ANS: D 7. A 56-year-old woman is referred to the neurology clinic for evaluation of her long- term problem of a stumbling gait and a tendency to fall. Her visual acuity also seems to change periodically. Neurological findings suggest multiple sclerosis. This diagnosis is further supported by magnetic resonance imaging, which shows of areas of demyelination in the central nervous system. Other tests show the presence of oligoclonal bands in the spinal fluid. The loss of myelin from a nerve fiber has which of the following effects? A. Decreased conduction velocity of action potential or no action potential B. Decreased energy requirement for successful action potentials C. Increased conduction velocity of action potential D. Increased velocity of salutatory conduction ANS: A 8. The diagram shows an action potential for a nerve fiber. What is the threshold potential for this neuron? A. −15 mV B. −50 to −60 mV C. −60 to −70 mV D. −70 to −80 mV E. −80 mV ANS: C 9. In the diagram shown, Em represents the measured initial membrane potential for a hypothetical cell in vivo. In relation to this membrane potential, the equilibrium potentials of three ions (X, Y, Z) are represented. Pick the path most likely taken by the membrane potential when membrane conductance for ion Y is increased. 19ANS: B 10. In the diagram shown, Pmemb represents the initial membrane potential for a hypothetical cell. In relation to this membrane potential, the equilibrium potentials of three ions (Q, R, S) are represented. Pick the path most likely taken by the membrane potential when membrane conductance for ion Q and ion S are increased simultaneously by 1000-fold. ANS: C 11. The diagram shows compound action potentials recorded percutaneously from a single site at a certain distance from a stimulating electrode (S) indicated by the ARROW. What can be concluded from the diagram concerning action potential velocity for the various categories of neurons? A. W = X = Y = Z B. W X Y Z C. W Y X D. Y W Z E. Z Y X W ANS: B 12. Five hypothetical neurons are shown below. Neurons A and B are myelinated, whereas neurons C, D, and E are not myelinated. Which neuron is most likely to have the fastest conduction velocity? A. B. C. D. E. ANS: B 13. In the following graph, Em represents the measured initial membrane potential for a hypothetical cell in vivo. In relation to this membrane potential, the equilibrium potentials of three ions (Q, R, S) are represented. During resting conditions, the conductance for Q and S ions is the same, which is 1000 times greater than that of ion R. Pick the path most likely taken 20by the membrane potential when membrane conductance to ion Q is 2 decreased to 0 mmho/cm . ANS: D 14. A 63-year-old man is dehydrated after three days of alcohol abuse. His serum sodium level has increased from a normal value of 140 mEq/L to 147 mEq/L. The resting membrane potential of a typical neuron was −80 mV before dehydration. What is the most likely resting membrane potential of a typical neuron after the dehydration, assuming no change in resting sodium conductance? A. −72 mV B. −74 mV C. −80 mV D. −88 mV E. −98 mV ANS: C 15. A 24-year-old soldier suffers a burn injury over 60% of his body surface area, which l +eads to a decrease in the serum K value of 4 mEq/L to a concentration from a normal value of 2.5 mEq/L. Which of the following sets of changes best describe the resting m +embrane potential and the K after the injury? R +esting membrane potential K A. Less negative B. Less negative C. More negative D. More negative E. No change Nernst potential in a cardiac myocyte Nernst potential Less negative More negative Less negative More negative No change ANS: D 16. The diagram shows an action potential for a nerve fiber. Use the diagram to 21answer the question. Where on the curve does potassium conductance exceed sodium conductance? A. V and Z B. V, W, and X C. V, X, and Z D. W, X, and Y E. X, Y, and Z ANS: A 17. Consider the action potential shown. Which of the following changes in membrane + co +nductances for Ca K and prolonged plateau (assume normal best account for the conductances for both ions during resting conditions, i.e., only the changes in conductances are important)? A. B. C. D.