An 82-year-old woman is brought to the emergency department after losing consciousness at her nursing home. She had been watching TV for several hours and while getting up to use the bathroom, she fell and was unconscious for several seconds. She felt dizzy shortly before the fall. She does not have a headache or any other pain. She has a history of hypertension, intermittent atrial fibrillation, and stable angina pectoris. Current medications include warfarin, aspirin, hydrochlorothiazide, and a nitroglycerin spray as needed. Her temperature is 36.7°C (98.1°F), pulse is 100/min and regular, and blood pressure is 102/56 mm Hg. Physical exam shows a dry tongue. A fold of skin that is pinched on the back of her hand unfolds after 2 seconds. Cardiopulmonary examination shows no abnormalities. Further evaluation of this patient is most likely to show which of the following findings?
AElevated serum concentration of cardiac enzymes
BElevated serum creatine kinase concentration
CAbsent P waves on ECG
DElevated blood urea nitrogen concentration
EHypodense lesions on CT scan of the head
A 23-year-old woman is brought to the emergency department 30 minutes after stepping on a piece of broken glass. Physical examination shows a 3-cm, ragged laceration on the plantar aspect of the left foot. The physician uses hydrogen peroxide to clean the wound. Which of the following is the most likely mechanism of action of this disinfectant?
AFormation of free radicals
BIntercalation of DNA
CCrosslinking of proteins
DHalogenation of nucleic acids
ECongealing of cytoplasm
What is the primary mechanism for maintaining constant cerebral blood flow despite changes in systemic blood pressure?
AEndothelial factors
BBaroreceptor reflex
CMyogenic autoregulation
DMetabolic control
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