Handbook Of Informatics for Nurses & Healthcare Professionals 5th Edition by Toni Lee Hebda – Test Bank A+

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Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition

Chapter 05: 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

1. 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?

1. Depolarization of the resting membrane potential
2. Hyperpolarization of the resting membrane potential
3. Increased intracellular potassium concentration
4. Potassium equilibrium potential becomes less negative

ANS: B

1. 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?

1. A decreased net driving force for potassium from cells
2. Decreased intracellular potassium concentration
3. Hyperpolarization of the resting membrane potential
4. More negative Nernst potential for potassium
5. More negative resting membrane potential

ANS: A

1. 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 are dry. The table shows serum Na⁺ and K⁺ values before and after the dehydration that 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 conductance or intracellular concentrations of Na⁺ or K⁺ ions?
2. −100 millivolts
3. −50 millivolts
4. −60 millivolts
5. −70 millivolts
6. −90 millivolts

ANS: D

1. 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 hypotension and skeletal muscle weakness. If the equilibrium potential for K⁺ in a neuron 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?

1. +20 mV
2. +48 mV
3. +80 mV
4. −25 mV
5. −48 mV
6. −96 mV

ANS: F

1. 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 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?

1. +62
2. +90
3. −13
4. −67
5. −84

ANS: D

1. 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?

1. Decreased conduction velocity of action potential or no action potential
2. Decreased energy requirement for successful action potentials
3. Increased conduction velocity of action potential
4. Increased velocity of salutatory conduction

ANS: A

1. The diagram shows an action potential for a nerve fiber. What is the threshold potential for this neuron?

1. −15 mV
2. −50 to −60 mV
3. −60 to −70 mV
4. −70 to −80 mV
5. −80 mV

ANS: C

1. In the diagram shown, E_m 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.

ANS: B

1. In the diagram shown, P_memb 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

1. 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?
2. W = X = Y = Z
3. W > X > Y > Z
4. W > Y > X
5. Y > W > Z
6. Z > Y > X > W

ANS: B

1. 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?

ANS: B

1. In the following graph, E_m 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 by the membrane potential when membrane conductance to ion Q is decreased to 0 mmho/cm².

ANS: D

1. 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?
2. −72 mV
3. −74 mV
4. −80 mV
5. −88 mV
6. −98 mV

ANS: C

1. A 24-year-old soldier suffers a burn injury over 60% of his body surface area, which leads to a decrease in the serum K⁺ concentration from a normal value of 4 mEq/L to a value of 2.5 mEq/L. Which of the following sets of changes best describe the resting membrane potential and the K⁺ Nernst potential in a cardiac myocyte after the injury?

Resting membrane potential K⁺ Nernst potential

1. Less negative Less negative
2. Less negative More negative
3. More negative Less negative
4. More negative More negative
5. No change No change

ANS: D

1. The diagram shows an action potential for a nerve fiber. Use the diagram to answer the question. Where on the curve does potassium conductance exceed sodium conductance?

1. V and Z
2. V, W, and X
3. V, X, and Z
4. W, X, and Y
5. X, Y, and Z

ANS: A

1. Consider the action potential shown. Which of the following changes in membrane conductances for Ca⁺ and K⁺ best account for the prolonged plateau (assume normal conductances for both ions during resting conditions, i.e., only the changes in conductances are important)?

Ca++

and

K+

ANS: A

1. A neuron from an extraterrestrial being has the intracellular and extracellular sodium and potassium concentrations shown in the table (in mM). During resting conditions, the sodium conductance is 100-fold greater compared to the potassium conductance. Which of the following (in mV) best describes the resting membrane potential (Vm) in this alien neuron (assume that Vm is dictated mainly by sodium and potassium conductances and that the Nernst equation applies)?
   1. +150
   2. +55
   3. 0
   4. −55
   5. −150

ANS: B

1. The intracellular concentration of ion Z is 100 milliequivalents per liter (mEq/L), and the extracellular concentration is 5 mEq/L. The molecular weight of molecule Z is ~40 daltons. This relatively high intracellular concentration of molecule Z is best explained by which of the following?

1. Exocytosis
2. Extracellular assembly
3. Facilitative diffusion
4. Intracellular production
5. Primary active transport
6. Simple diffusion

ANS: E

1. Equilibrium potentials for Na, K, and Cl are shown. Assume that a cell is permeable to all three ions and has a resting membrane potential of −85 mV. Which of the following best describes the net movement of the various ions across the cell membrane by way of passive diffusion?

Sodium Potassium Chloride

1. Inward Inward Inward
2. Inward Inward Outward
3. Inward Outward Inward
4. Inward Outward Outward
5. Outward Inward Inward
6. Outward Inward Outward
7. Outward Outward Inward
8. Outward Outward Outward

ANS: D

Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition

Chapter 07: Excitation of Skeletal Muscle: Neuromuscular Transmission and Excitation-Contraction Coupling

Test Bank

1. A 45-year-old man has botulinum toxin (Botox®) injections in the frontalis muscles. Which of the following sets of changes are most likely to occur in the treated muscles with repeated injections over a period of ten years?

Fiber diameter Fiber number Contraction velocity

1. decreased decreased decreased
2. decreased decreased increased
3. decreased increased increased
4. increased decreased decreased
5. increased decreased increased
6. increased increased increased

ANS: A

1. Which of the following represents the correct temporal order of events for skeletal muscle?

First Second Third

1. End plate potential Muscle action potential Nerve action potential
2. End plate potential Nerve action potential Muscle action potential
3. Muscle action potential End plate potential Nerve action potential
4. Muscle action potential Nerve action potential End plate potential
5. Nerve action potential End plate potential Muscle action potential
6. Nerve action potential Muscle action potential End plate potential

ANS: E

1. Myasthenia gravis is an autoimmune disease in which antibodies damage which of the following?
2. Acetylcholine
3. Ligand-gated channels on postsynaptic membrane
4. Ligand-gated channels on presynaptic membrane
5. Voltage-gated channels on postsynaptic membrane
6. Voltage-gated channels on presynaptic membrane

ANS: B

1. Lambert-Eaton myasthenic syndrome is an autoimmune disease in which antibodies damage which of the following?

1. Acetylcholine
2. Ligand-gated channels on postsynaptic membrane
3. Ligand-gated channels on presynaptic membrane
4. Voltage-gated channels on postsynaptic membrane
5. Voltage-gated channels on presynaptic membrane

ANS: E

1. A 59-year-old college professor visits his physician because of muscle fatigue that worsens later in the day. The physician notices that the man has droopy eyelids and seems to have an overall weakness in his muscles. After the intravenous administration of Tensilon®, which blocks degradation of acetylcholine, the droopy eyelids and symptoms of muscle weakness appear to subside. Which of the following best describes the patient’s condition?

1. Encephalitis
2. Fibromyalgia
3. Flaccid paralysis
4. Myasthenia gravis
5. Poliomyelitis

ANS: D

1. A 3-year-old child is admitted to the emergency department of University Hospital. The child exhibits extreme salivation, lacrimation, tremors, and tachycardia. The slight erythema and mild edema found on the child’s hand suggest a spider bite. The mother acknowledges that the child has a fascination with spiders and has seen black widow spiders in the yard. The neurotoxic venom of the black widow spider (i.e., latrotoxin or latrophilin) can increase the flux of calcium ions into the presynaptic terminal. What is the likely outcome of a black widow spider bite?

1. Decreased acetylcholine release from nerve terminals
2. Hyperpolarization of postsynaptic membranes
3. Hyperpolarization of presynaptic membranes
4. Increased acetylcholine release from nerve terminals
5. Inhibition of acetylcholinesterase

ANS: D

1. An apparently healthy 12-year-old boy dies during a minor surgical procedure while under general anesthesia. An uncle had also died during a surgical procedure. Results of a halothane contracture test indicate that the child had malignant hyperthermia (MH). The MH crisis is associated with which of the following?
2. Decreased anaerobic metabolism
3. Decreased CO₂ production by muscles
4. Decreased lactic acid production by muscles
5. Defective ryanodine receptors
6. Decreased usage of ATP in muscles

ANS: D

1. Skeletal muscle and cardiac muscle contract when calcium binds to which structure or molecule?
2. Active sites
3. Calmodulin
4. Myosin head
5. Tropomyosin
6. Troponin-C

ANS: E

1. Which of the following represents the correct temporal order of events for skeletal muscle?

First Second Third

1. Muscle action potential Muscle contraction Nerve action potential
2. Muscle action potential Nerve action potential Muscle contraction
3. Muscle contraction Muscle action potential Nerve action potential
4. Muscle contraction Nerve action potential Muscle action potential
5. Nerve action potential Muscle action potential Muscle contraction
6. Nerve action potential Muscle contraction Muscle action potential

ANS: E

1. Binding of calcium to which structure or molecule initiates a contraction in smooth muscle, skeletal muscle, and cardiac muscle?

Smooth muscle Skeletal muscle Cardiac muscle

1. Active sites Calmodulin Troponin
2. Active sites Troponin Calmodulin
3. Calmodulin Tropomyosin Active sites
4. Calmodulin Troponin Troponin
5. Myosin heads Tropomyosin Troponin
6. Myosin heads Troponin Tropomyosin

ANS: D

1. A 23-year-old man loses consciousness while driving, hits a tree, and dies within 15 minutes. The police find his stiff body five hours later. Rigor mortis is caused by a decrease in which of the following?

1. Acetylcholine
2. Actin-myosin cross-bridges
3. Myoplasmic calcium levels
4. Interstitial lactate levels
5. Muscle ATP levels

ANS: E

1. A father and his 10-year-old daughter died suddenly of suffocation after ingesting smoked whitefish chubs from the Great Lakes. Three other family members are sick, complaining of dry mouths despite drinking copious amounts of fluids. Their upper eyelids droop. Their vision is clear, but their pupils are wide and do not narrow when a light is flashed. Two of them require artificial respiration. The suspect is botulism (Clostridium botulinum). The surviving patients begin improving soon after receiving the only treatment available, E antitoxin. The deadly effect of botulinum toxin results from which of the following?

1. Decreased release of acetylcholine
2. Decreased release of norepinephrine
3. Depletion of muscle calcium stores
4. Skeletal muscle tetany
5. Stimulation of ryanodine receptors

ANS: A

1. Which of the following best describes the dynamics of calcium release and calcium uptake during the development of frequency-induced muscle tetany?
   1. Release from longitudinal tubules exceeds uptake by terminal cisternae
   2. Release from longitudinal tubules exceeds uptake by T-tubules
   3. Release from terminal cisternae exceeds uptake by longitudinal tubules
   4. Release from terminal cisternae exceeds uptake by T-tubules
   5. Release from T-tubules exceeds uptake by longitudinal tubules
   6. Release from T-tubules exceeds uptake by terminal cisternae

ANS: C

1. Which of the following best describes the correct temporal order of events for the opening of nicotinic acetylcholine (nACh) channels on the muscle membrane, the opening of voltage-gated sodium channels on the muscle membrane, and initiation of presynaptic action potentials (AP)?

First Second Third

1. nACh channels Presynaptic AP Voltage gated Na channels
2. nACh channels Voltage gated Na channels Presynaptic AP
3. Presynaptic AP nACh channels Voltage gated Na channels
4. Presynaptic AP Voltage gated Na channels nACh channels
5. Voltage gated Na channels nACh channels Presynaptic AP
6. Voltage gated Na channels nACh channels Presynaptic AP

ANS: C

Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition

Chapter 11: The Normal Electrocardiogram

Test Bank

1. The Q-T interval is the time that approximates the time of ventricular contraction. The normal Q-T interval is:

1. 0.04 seconds
2. 0.08 seconds
3. 0.16 seconds
4. 0.20 seconds
5. 0.35 seconds

ANS: E

Questions 2-3: A seventy-year old female had an electrocardiogram performed at her annual checkup, and the following lead II recording was made.

1. What is her heart rate in beats/minute?

1. 68
2. 78

1. 84

1. 94
2. 104

ANS: A

1. According to Einthoven’s Law, if the QRS voltage in her lead III is 0.5 mV, what is the QRS voltage in Lead I?

1. 0.05 mV
2. 0.50 mV
3. 1.05 mV
4. 1.25 mV
5. 2.05 mV

ANS: B

1. The P-R interval is the time between the beginning of atrial depolarization and ventricular depolarization. The normal P-R interval is:

1. 0.04 seconds
2. 0.08 seconds
3. 0.16 seconds
4. 0.20 seconds
5. 0.35 seconds

ANS: C

1. When recording lead I on an EKG, the right arm is the negative electrode and the positive electrode is the:

1. Left arm
2. Left leg
3. Right leg
4. Left arm + left leg
5. Right arm + left leg

ANS: A

Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition

Chapter 15: Vascular Distensibility and Functions of the Arterial and Venous Systems

Test Bank

1. A 65-year-old woman visits her family practitioner for an examination. She has a mean blood pressure of 95 mmHg and a heart rate of 74 bpm. Further tests by a cardiologist revealed that the patient has moderate aortic regurgitation. Which one of the set of changes would be expected in this patient?

Pulse Pressure Stroke Volume Systolic Pressure

1. ­ ­ ­
2. ­ ¯ ­
3. ­ ¯ ¯
4. ­ ­ ¯
5. ¯ ¯ ¯
6. ¯ ­ ¯
7. ¯ ­ ­
8. ¯ ¯ ­

ANS: AE

1. Which one of the following would increase venous hydrostatic pressure in the legs?

1. A decrease in right atrial pressure
2. Pregnancy
3. Movement of leg muscles
4. Hemorrhage

ANS: B

1. Which one of the following parts of the circulation has the highest compliance?

1. Capillaries
2. Venules
3. Veins
4. Aorta
5. Arteries

ANS: C

1. A 60-year-old man visits his family practitioner for his yearly examination. He has a blood pressure of 180/100 mmHg, a heart rate of 78 bpm, and a pulse pressure of 80 mmHg. His plasma cholesterol level is in the upper 25th percentile. A decrease in which of the following is the most likely explanation for the high pulse pressure in this patient?

1. Stroke volume
2. Arterial pressure
3. Heart rate
4. Arterial compliance
5. Total peripheral resistance

ANS: D

1. Which one of the following would tend to decrease pulse pressure?
2. An increase in metabolic rate
3. An increase in stroke volume
4. An increase in arterial compliance
5. An increase in venous return
6. An increase plasma volume

ANS: C

1. A 65-year-old man is suffering from congestive heart failure. He has a cardiac output of 4.0 L/min, arterial pressure of 115/85, and a heart rate of 90 bpm. Further tests by a cardiologist reveal that the patient has a right atrial pressure of 10 mmHg. An increase in which of the following would be expected in this patient?
2. plasma colloid osmotic pressure
3. interstitial colloid osmotic pressure
4. arterial pressure
5. cardiac output
6. vena cava hydrostatic pressure

ANS: E

1. Which of the following components of the circulatory system has the largest distribution of blood volume?

1. Arteries
2. Capillaries
3. Veins
4. Pulmonary circulation
5. Heart

ANS: C

1. A 35-year-old woman visits her family practitioner for an examination. She has a mean blood pressure of 105 mmHg and a heart rate of 74 bpm. Further tests by a cardiologist revealed that the patient has moderate aortic valve stenosis. Which one of the set of changes would be expected in this patient?

Pulse Pressure Stroke Volume Systolic Pressure

1. ­ ­ ­
2. ­ ¯ ­
3. ­ ¯ ¯
4. ­ ­ ¯
5. ¯ ¯ ¯
6. ¯ ­ ¯
7. ¯ ­ ­
8. ¯ ¯ ¯

ANS: H

1. A 36-year-old female cash register attendant visits her physician complaining about the large surface veins in her legs. Her blood pressure is 125/94 mmHg and she has a heart rate of 78 bpm. She is 5’3” tall and weighs 125 lbs. As a part of her weight loss program, she has been jogging two miles each day for the past two months. Which of the following is the most likely cause of the varicose veins in this woman?
2. Hypertension
3. Obesity
4. Tachycardia
5. Excessive jogging on a hard surface
6. Chronic exposure to excess venous pressures in her legs