Question 1

Your patient has been diagnosed with malignant hyperthermia after a surgical procedure. The most common cause of malignant hyperthermia in humans is an Abnormal response to general anesthetics involving the: A) Na⁺-Ca²⁺ exchanger B) Sarcoplasmic reticulum Ca²⁺ release channel C) IP₃ receptor D) Na⁺K⁺-ATPase E) Central nervous system (CNS)

Accepted Answer

The most common cause of malignant hyperthermia in humans is an abnormal response to general anesthetics involving the sarcoplasmic reticulum Ca2+ release channel, also known as the ryanodine receptor.

Question 2

Consider a patient with pH = 7.33; [HCO₃^-] = 36 mEq/L; PCO₂ = 70 mmHg. What is the acid-base status of the patient? A) Compensated metabolic alkalosis B) Compensated metabolic acidosis C) Compensated respiratory alkalosis D) Compensated respiratory acidosis E) Uncompensated respiratory alkalosis

Accepted Answer

The patient has a pH of 7.33, which is below the normal range (7.35-7.45), indicating acidosis. The bicarbonate level ([HCO3-]) is 36 mEq/L, which is higher than the normal range (22-26 mEq/L), suggesting a metabolic compensation. The PCO2 is 70 mmHg, which is above the normal range (35-45 mmHg), indicating primary respiratory acidosis. The elevated bicarbonate level is a compensatory mechanism to counteract the acidosis caused by the high PCO2, leading to the conclusion of compensated respiratory acidosis.

Question 3

Which of the following is correct for male sex differentiation?
A) The male phenotype is determined by the presence of either X or Y chromosomes.
B) Stimulation and development of the indifferent gonad is initiated by the sex-determining region of the Y chromosome (SRY) gene.
C) The müllerian ducts develop into the male reproductive tract.
D) Sertoli cells are stimulated to produce testosterone.
E) Testes have descended into the scrotum by 9 weeks' gestation.

Accepted Answer

The sex-determining region of the Y chromosome (SRY) gene is crucial for the initiation of male sex differentiation by stimulating the development of the indifferent gonad into a testis.

Question 4

In aging, if osteoclast activity is constant, but osteoblast activity progressively decreases, which disease will likely develop?
A) Osteoclastoma
B) Osteomalacia
C) Paget's disease
D) Osteoporosis
E) Scurvy

Accepted Answer

Osteoporosis is characterized by decreased bone mass and density, which can occur when osteoblast activity (bone formation) decreases while osteoclast activity (bone resorption) remains constant, leading to a net loss of bone.

Question 5

A patient complains of excessive urine output and constant thirst. Laboratory tests show an elevated plasma sodium concentration (151 mEq/L) and elevated plasma osmolality (320 mOsm/L). The urine osmolality is only 75 mOsm/L. Which of the following could explain the patient's problem? A) Defective epithelial sodium channel (ENaC) B) Defective ROMK proteins C) Defective V₂ receptor proteins D) Excessive antidiuretic hormone (ADH) secretion E) Defective atrial natriuretic peptide (ANP) secretion

Accepted Answer

The symptoms and lab results suggest diabetes insipidus, characterized by an inability to concentrate urine despite high plasma osmolality. This is often due to defective V2 receptor proteins, which are responsible for the action of ADH in the kidneys.

Question 6

A 58-year-old woman develops a fever and dyspnea approximately 24 h after undergoing a laparoscopic cholecystectomy. Physical examination shows decreased percussion, increased tactile fremitus, and decreased breath sounds in the right lower lobe. Which of the following is the most likely diagnosis?
A) Atelectasis
B) Lobar pneumonia
C) Lung abscess
D) Pulmonary infarction
E) Spontaneous pneumothorax

Accepted Answer

Atelectasis is common after surgery, especially abdominal surgery, and can cause fever, dyspnea, and physical exam findings such as decreased breath sounds and increased tactile fremitus due to lung collapse.

Question 7

Which of the following when administered to a normal individual produces effects similar to that observed in patients with myasthenia gravis?
A) Black widow spider toxin
B) Neostigmine
C) Curare
D) 'Nerve gas'
E) Edrophonium

Accepted Answer

Curare mimics the symptoms of myasthenia gravis by blocking acetylcholine receptors at the neuromuscular junction, leading to muscle weakness and fatigue similar to the condition.

Question 8

The primary source of estriol (E₃) during pregnancy is the: A) Maternal ovary B) Fetal ovary C) Fetal adrenal and placenta D) Endometrium E) Corpus luteum

Accepted Answer

Estriol during pregnancy is primarily produced from precursors made in the fetal adrenal gland and then further processed by the placenta. This collaboration between the fetus and the placenta is crucial for estriol production, distinguishing it from other estrogen sources.

Question 9

A 45-year-old woman arrives at the clinic and exhibits athetoid movements. She probably has a:
A) Cerebellar lesion
B) Lesion in the basal ganglia
C) Thalamic lesion
D) Frontal eye field lesion
E) Lesion in the cerebral cortex

Accepted Answer

Athetoid movements are characterized by slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet, and sometimes arms, legs, neck, and tongue. These movements are typically associated with damage to the basal ganglia, a group of nuclei in the brain involved in the regulation of movement.

Question 10

In a patient recovering from cholera, pH = 7.35; [HCO₃^-] = 16 mEq/L; PCO₂ = 30 mmHg. What is the acid-base status of the patient? A) Compensated metabolic alkalosis B) Compensated metabolic acidosis C) Compensated respiratory alkalosis D) Compensated respiratory acidosis E) Uncompensated respiratory alkalosis

Accepted Answer

The patient has a pH at the lower limit of normal (7.35), a decreased bicarbonate level ([HCO3-] = 16 mEq/L, indicating a primary metabolic acidosis), and a decreased PCO2 (30 mmHg, indicating respiratory compensation). This combination of findings is consistent with compensated metabolic acidosis.

Question 11

A 1-day-old neonate with acute respiratory distress syndrome (ARDS) has moderately severe hypoxemia. Physical examination reveals, dry inspiratory crackles in the lungs and a continuous harsh murmur heard over the entire precordium. Which of the following sets of oxygen saturation (SaO₂) values in the cardiac chambers and vessels most likely match those of this patient? $$\begin{array} { | l | l | } \hline \text { Right atrium (RA) } & \text { Normal } \mathrm { SaO } _ { 2 } ( \% ) \ \hline \text { Right ventricle (RV) } & 75 \ \hline \text { Pulmonary artery (PA) } & 75 \ \hline \text { Pulmonary veir (PV) } & 75 \ \hline \text { Left ventricle (LV) } & 95 \ \hline \text { Aorta } ( \mathrm { A } ) & 95 \ \hline \end{array}$$ $$\begin{array} { l l l l l l l } & \text { RA } & \text { RV } & \text { PA } & \text { PV } & \text { LV } & \text { A } \ & ( \% ) & ( \% ) & ( \% ) & ( \% ) & ( \% ) & ( \% ) \ \hline \text { A } & 75 & 80 & 80 & 95 & 95 & 95 \ \text { B } & 80 & 80 & 80 & 95 & 95 & 95 \ \text { C } & 75 & 75 & 80 & 95 & 95 & 95 \ \text { D } & 75 & 75 & 75 & 95 & 80 & 80 \ \text { E } & 75 & 75 & 75 & 95 & 95 & 95 \end{array}$$ A) $\begin{array} { l l l l l l } 75 & 80 & 80 & 95 & 95 & 95 \end{array}$ B) $\begin{array} { l l l l l l } 80 & 80 & 80 & 95 & 95 & 95 \end{array}$ C) $\begin{array} { l l l l l l } 75 & 75 & 80 & 95 & 95 & 95 \end{array}$ D)$\begin{array} { l l l l l l } 75 & 75 & 75 & 95 & 80 & 80 \end{array}$ E) $\begin{array} { l l l l l l } 75 & 75 & 75 & 95 & 95 & 95 \end{array}$

Accepted Answer

The answer of A 1-day-old neonate with acute respiratory distress...

Question 12

A 56-year-old right-handed woman states that her right hand shakes when she tries to open a door. Her physician does not observe a tremor when the patient's hands are resting in her lap. She further states that she falls frequently, usually to the right side. The most likely cause of these findings is a lesion in the:
A) Left internal capsule
B) Left precentral gyrus
C) Right caudal medulla
D) Right cerebellum
E) Right lateral corticospinal tract

Accepted Answer

The symptoms described, including a tremor that occurs with movement (action tremor) and frequent falls to one side, suggest a problem with coordination and balance. These are functions primarily controlled by the cerebellum. Since the symptoms are on the right side of the body, the lesion would most likely be in the right cerebellum, as cerebellar pathways do not cross (decussate) to the opposite side of the body.

Question 13

A 30-year-old female patient with hypercapnia that is not the result of compensation for an acid-base disturbance is seen in the clinic. Thus, this patient is suffering from:
A) Nothing, the patient has normal acid-base balance.
B) Respiratory acidosis
C) Respiratory alkalosis
D) Metabolic acidosis
E) Metabolic alkalosis

Accepted Answer

Hypercapnia, which is an elevated level of carbon dioxide (CO2) in the blood, typically indicates inadequate respiratory function and leads to respiratory acidosis when it is not part of a compensatory mechanism for an acid-base disturbance.

Question 14

You determine that your 1-year-old male patient has cryptorchidism. Cryptorchidism is the term used to describe non-descent of the testes. Which of the following statements is correct in connection with this process?
A) Fertility is unaffected in males with undescended testes.
B) Hormone treatment is not effective to induce descent.
C) Leydig cell function is reduced in boys with undescended testes.
D) There is an increased rate of testicular malignant change in cryptorchidism.
E) Klinefelter's syndrome may be responsible for testicular non-descent.

Accepted Answer

There is an increased rate of testicular malignant change in cryptorchidism.

Question 15

Suppose the plasma membrane of a particular mammalian cell is much more permeable to water and urea than to any other solute. The water permeability is higher than the urea permeability. The cell is initially in a normal physiological saline solution and then is suddenly moved into a solution consisting of 600 mM urea as the only solute. The cell will:
A) Swell initially and continue to swell until lysis
B) Swell initially until it reaches osmotic equilibrium with the medium
C) Shrink initially and then swell until lysis
D) Shrink initially and stay shrunken
E) Swell initially and then shrink back to normal volume

Accepted Answer

The answer of Suppose the plasma membrane of a particular...

Question 16

A medical student complains of severe vomiting and diarrhea for 2 days since eating at the Roadkill Café. His blood pressure is 120/70 mmHg supine and 90/50 mmHg standing. His skin and mucous membranes are dry. Which of the following laboratory finding would you expect to find?
A) Low serum aldosterone concentration
B) High atrial natriuretic peptide (ANP) levels
C) Low plasma renin activity
D) Low urinary sodium concentration
E) High urine volume

Accepted Answer

The patient's symptoms of severe vomiting and diarrhea lead to significant fluid loss, resulting in dehydration. This dehydration causes the body to conserve water and sodium to maintain blood pressure and volume. Aldosterone, a hormone that promotes sodium (and thus water) reabsorption in the kidneys, would be elevated in response to the decreased blood volume and pressure, leading to a low urinary sodium concentration as the body tries to retain sodium to conserve water.

Question 17

Which one of the following statements is correct regarding salivary secretion?
A) The secretion of saliva is essential for the complete digestion of starch.
B) It is primarily under hormonal control.
C) It does not prevent decalcification of the teeth.
D) It is an acidic solution that begins the digestion of protein in the mouth.
E) It is the only hypotonic gastrointestinal secretion.

Accepted Answer

Saliva is hypotonic compared to plasma, which is unique among gastrointestinal secretions.

Question 18

Insulin binding to its receptor tyrosine kinase leads to: A) Activation of Janus kinase-signal transducer and activator of transcription (JAK-STAT) B) Mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK) activation C) Insulin-receptor binding to the MAPK promoter D) G_s activation and substrate phosphorylation by PKA E) G_i activation of phosphodiesterase (PDE)

Accepted Answer

Insulin binding to its receptor, a receptor tyrosine kinase, leads to a cascade of events including the activation of the MAPK/ERK pathway, which is involved in cell growth and differentiation. This pathway is distinct from the JAK-STAT pathway, which is not directly activated by insulin receptor signaling.

Question 19

Which of the following statements best describes ARDS (acute respiratory distress syndrome)?
A) It occurs only in adults.
B) It is best described as a diffuse pulmonary process with decreased thickness of the pulmonary membrane.
C) A direct pulmonary insult is required for ARDS to develop.
D) Hypercarbia is the most common finding in the early stages of ARDS.
E) Mortality rate has been decreasing over the past 5 years.

Accepted Answer

Mortality rates for ARDS have been decreasing due to advances in supportive care and treatment strategies, such as lung-protective ventilation.

Question 20

Two people have the same total body mass (70 kg) but one has a much higher percentage of body fat than the other. They both habitually ingest 2.5 L of water per day.
The individual with the higher percentage of fat will have a:
A) Higher extracellular fluid (ECF) volume than the other individual
B) Lower rate of water turnover than the other individual
C) Higher rate of water turnover than the other individual
D) Positive water balance
E) Negative water balance

Accepted Answer

The individual with the higher percentage of fat will have a higher rate of water turnover than the other individual because fat tissue has a higher water content than lean tissue.

Quiz 2: Physiology of Cells and Molecules

Your patient has been diagnosed with malignant hyperthermia after a surgical procedure. The most common cause of malignant hyperthermia in humans is an Abnormal response to general anesthetics involving the:

Consider a patient with pH = 7.33; [HCO₃^-] = 36 mEq/L; PCO₂ = 70 mmHg. What is the acid-base status of the patient?

Which of the following is correct for male sex differentiation?

In aging, if osteoclast activity is constant, but osteoblast activity progressively decreases, which disease will likely develop?

A patient complains of excessive urine output and constant thirst. Laboratory tests show an elevated plasma sodium concentration (151 mEq/L) and elevated plasma osmolality (320 mOsm/L) . The urine osmolality is only 75 mOsm/L. Which of the following could explain the patient's problem?

A 58-year-old woman develops a fever and dyspnea approximately 24 h after undergoing a laparoscopic cholecystectomy. Physical examination shows decreased percussion, increased tactile fremitus, and decreased breath sounds in the right lower lobe. Which of the following is the most likely diagnosis?

Which of the following when administered to a normal individual produces effects similar to that observed in patients with myasthenia gravis?

The primary source of estriol (E₃) during pregnancy is the:

A 45-year-old woman arrives at the clinic and exhibits athetoid movements. She probably has a:

In a patient recovering from cholera, pH = 7.35; [HCO₃^-] = 16 mEq/L; PCO₂ = 30 mmHg. What is the acid-base status of the patient?

A 30-year-old female patient with hypercapnia that is not the result of compensation for an acid-base disturbance is seen in the clinic. Thus, this patient is suffering from:

You determine that your 1-year-old male patient has cryptorchidism. Cryptorchidism is the term used to describe non-descent of the testes. Which of the following statements is correct in connection with this process?

A medical student complains of severe vomiting and diarrhea for 2 days since eating at the Roadkill Café. His blood pressure is 120/70 mmHg supine and 90/50 mmHg standing. His skin and mucous membranes are dry. Which of the following laboratory finding would you expect to find?

Which one of the following statements is correct regarding salivary secretion?

Insulin binding to its receptor tyrosine kinase leads to:

Which of the following statements best describes ARDS (acute respiratory distress syndrome) ?

Two people have the same total body mass (70 kg) but one has a much higher percentage of body fat than the other. They both habitually ingest 2.5 L of water per day. The individual with the higher percentage of fat will have a: