Temperature regulation Practice Questions

Question 1

A 37-year-old man with a history of schizophrenia, obesity, anxiety, recurrent pneumonia, and depression is brought to the emergency department. He was recently discharged from inpatient psychiatric care where he was treated for an acute psychotic episode with fluphenazine and started on a new antidepressant. One week after discharge, during a period of cold weather, he is found outdoors confused and poorly dressed. His rectal temperature is 93.2°F (34°C). Which of the following medications is most likely contributing to his hypothermia?

Accepted Answer

Fluphenazine

Answer

Valproic acid

Answer

Diphenhydramine

Answer

Fluoxetine

Answer

Lithium

Question 2

A 15-year-old boy is brought to the emergency department by his father 10 minutes after falling into a frozen lake during ice fishing. He was in the water for less than 1 minute before his father managed to pull him out. On arrival, his clothes are still wet and he appears scared. His body temperature is 36.2°C (97.1°F), pulse is 102/min, blood pressure is 133/88 mm Hg. Which of the following mechanisms contributes most to maintaining this patient's core body temperature?

Accepted Answer

Involuntary muscular contractions

Answer

Inhibition of the thyroid axis

Answer

Activation of thermogenin

Answer

Increase in hypothalamic set point

Answer

Contraction of arrector pili muscles

Question 3

A 49-year-old woman presents to her primary care physician with fatigue. She reports that she has recently been sleeping more than usual and says her “arms and legs feel like lead” for most of the day. She has gained 10 pounds over the past 3 months which she attributes to eating out at restaurants frequently, particularly French cuisine. Her past medical history is notable for social anxiety disorder. She took paroxetine and escitalopram in the past but had severe nausea and headache while taking both. She has a 10 pack-year smoking history and has several glasses of wine per day. Her temperature is 98.6°F (37°C), blood pressure is 130/65 mmHg, pulse is 78/min, and respirations are 16/min. Physical examination reveals an obese woman with a dysphoric affect. She states that her mood is sad but she does experience moments of happiness when she is with her children. The physician starts the patient on a medication to help with her symptoms. Three weeks after the initiation of the medication, the patient presents to the emergency room with a severe headache and agitation. Her temperature is 102.1°F (38.9°C), blood pressure is 180/115 mmHg, pulse is 115/min, and respirations are 24/min. Which of the following is the mechanism of action of the medication that is most likely responsible for this patient’s symptoms?

Accepted Answer

Inhibition of amine degradation

Answer

Inhibition of serotonin and norepinephrine reuptake

Answer

Inhibition of the adrenergic alpha-2 receptor and serotonin-2 and -3 receptors

Answer

Inhibition of serotonin reuptake

Answer

Partial agonism of serotonin-1A receptor

Question 4

A 33-year-old man presents to the emergency department acutely confused. The patient was found down at a local construction site by his coworkers. The patient has a past medical history of a seizure disorder and schizophrenia and is currently taking haloperidol. He had recent surgery 2 months ago to remove an inflamed appendix. His temperature is 105°F (40.6°C), blood pressure is 120/84 mmHg, pulse is 150/min, respirations are 19/min, and oxygen saturation is 99% on room air. Physical exam is notable for a confused man who cannot answer questions. His clothes are drenched in sweat. He is not making purposeful movements with his extremities although no focal neurological deficits are clearly apparent. Which of the following is the most likely diagnosis?

Accepted Answer

Exertional heat stroke

Answer

Heat exhaustion

Answer

Nonexertional heat stroke

Answer

Neuroleptic malignant syndrome

Answer

Malignant hyperthermia

Question 5

A previously healthy 44-year-old man is brought by his coworkers to the emergency department 45 minutes after he became light-headed and collapsed while working in the boiler room of a factory. He did not lose consciousness. His coworkers report that 30 minutes prior to collapsing, he told them he was nauseous and had a headache. The patient appears sweaty and lethargic. He is not oriented to time, place, or person. The patient’s vital signs are as follows: temperature 41°C (105.8°F); heart rate 133/min; respiratory rate 22/min; and blood pressure 90/52 mm Hg. Examination shows equal and reactive pupils. Deep tendon reflexes are 2+ bilaterally. His neck is supple. A 0.9% saline infusion is administered. A urinary catheter is inserted and dark brown urine is collected. The patient’s laboratory test results are as follows:
Laboratory test
Blood
Hemoglobin 15 g/dL
Leukocyte count 18,000/mm3
Platelet count 51,000/mm3
Serum
Na+ 149 mEq/L
K+ 5.0 mEq/L
Cl- 98 mEq/L
Urea nitrogen 42 mg/dL
Glucose 88 mg/dL
Creatinine 1.8 mg/dL
Aspartate aminotransferase (AST, GOT) 210
Alanine aminotransferase (ALT, GPT) 250
Creatine kinase 86,000 U/mL
Which of the following is the most appropriate next step in patient management?

Accepted Answer

Ice water immersion

Answer

Dantrolene

Answer

Acetaminophen therapy

Answer

Hemodialysis

Answer

Evaporative cooling

Question 6

You have been asked to deliver a lecture to medical students about the effects of various body hormones and neurotransmitters on the metabolism of glucose. Which of the following statements best describes the effects of sympathetic stimulation on glucose metabolism?

Accepted Answer

Epinephrine increases liver glycogenolysis.

Answer

Norepinephrine causes increased glucose absorption within the intestines.

Answer

Without epinephrine, insulin cannot act on the liver.

Answer

Peripheral tissues require epinephrine to take up glucose.

Answer

Sympathetic stimulation to alpha receptors of the pancreas increases insulin release.

Question 7

A group of investigators is studying thermoregulatory adaptations of the human body. A subject is seated in a thermally insulated isolation chamber with an internal temperature of 48°C (118°F), a pressure of 1 atmosphere, and a relative humidity of 10%. Which of the following is the primary mechanism of heat loss in this subject?

Accepted Answer

Evaporation

Answer

Convection

Answer

Conduction

Answer

Piloerection

Answer

Radiation

Question 8

An 18-year-old man presents to his primary care physician with a complaint of excessive daytime sleepiness. He denies any substance abuse or major changes in his sleep schedule. He reports frequently dozing off during his regular daily activities. On further review of systems, he endorses falling asleep frequently with the uncomfortable sensation that there is someone in the room, even though he is alone. He also describes that from time to time, he has transient episodes of slurred speech when experiencing heartfelt laughter. Vital signs are stable, and his physical exam is unremarkable. This patient is likely deficient in a neurotransmitter produced in which part of the brain?

Accepted Answer

Hypothalamus

Answer

Hippocampus

Answer

Midbrain

Answer

Pons nucleus

Answer

Thalamus

Question 9

A healthy 22-year-old male participates in a research study you are leading to compare the properties of skeletal and cardiac muscle. You conduct a 3-phased experiment with the participant. In the first phase, you get him to lift up a 2.3 kg (5 lb) weight off a table with his left hand. In the second phase, you get him to do 20 burpees, taking his heart rate to 150/min. In the third phase, you electrically stimulate his gastrocnemius with a frequency of 50 Hz. You are interested in the tension and electrical activity of specific muscles as follows: Biceps in phase 1, cardiac muscle in phase 2, and gastrocnemius in phase 3. What would you expect to be happening in the phases and the respective muscles of interest?

Accepted Answer

Increase of tension in all phases

Answer

Increase of tension in experiments 2 and 3, with the same underlying mechanism

Answer

Recruitment of large motor units followed by small motor units in experiment 1

Answer

Fused tetanic contraction at the end of all three experiments

Answer

Recruitment of small motor units at the start of experiments 1 and 2

Question 10

Cardiac muscle serves many necessary functions, leading to a specific structure that serves these functions. The structure highlighted is an important histology component of cardiac muscle. What would be the outcome if this structure diffusely failed to function?

Accepted Answer

Failure of propagation of the action potential from the conduction system

Answer

Failure of potassium channels to appropriately open to repolarize the cell

Answer

Ineffective excitation-contraction coupling due to insufficient calcium ions

Answer

Inappropriate formation of cardiac valve leaflets

Answer

Outflow tract obstruction

Temperature regulation

Study Resources

Lessons

Questions

Flashcards

Lessons

Core body temperature maintenance

Hypothalamic thermoregulation

Heat production mechanisms

Heat loss mechanisms

Behavioral thermoregulation

Fever pathophysiology

Fever patterns and significance

Hyperthermia vs fever

Hypothermia pathophysiology

Temperature regulation in neonates

Exercise and thermoregulation

Environmental stress responses

Age-related changes in thermoregulation

Practice Questions

Flashcards

About Temperature regulation for USMLE

Lessons in Temperature regulation

Master Temperature regulation