Upper respiratory tract infection

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Upper respiratory tract infection

Respiratory system


Upper respiratory tract infection


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USMLE® Step 1 questions

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High Yield Notes

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Upper respiratory tract infection

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USMLE® Step 1 style questions USMLE

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A 50-year-old woman is admitted to the emergency room for facial pain, weakness, and malaise. She also has a throbbing headache. Past medical history is significant for type II diabetes mellitus and HIV infection. Home medications include zidovudine, lamivudine, lopinavir, ritonavir and metformin. However, she admits to poor compliance with the medications. The patient’s CD4 count is 121 cells/mm3, and viral load is 50,000. Physical examination shows exquisite tenderness to palpation over the right maxillary sinus. Additionally, there is a black eschar over her nares and palate. Which of the following symptoms would suggest a severe complication of the patient’s condition?


Content Reviewers

An upper respiratory tract infection is any infection that involves the nasal cavity, paranasal sinuses, pharynx, or larynx, and it’s most often caused by an invading pathogen like a virus.

When you breathe in, air flows through the nostrils and enters the nasal cavity, which is lined by cells that release mucus.

That mucus is salty, sticky, and contains lysozymes, which are enzymes that help kill bacteria.

Nose hairs at the entrance of the nasal cavity get coated with that mucus and are able to trap large particles of dust and pollen as well as bacteria, forming tiny clumps of boogers.

The nasal cavity is connected to four sinuses which are air- filled spaces inside the bones that surround the nose, there’s the frontal, ethmoid, sphenoid, and maxillary sinus.

The paranasal sinuses help the inspired air to circulate for a bit so it has time to get warm and moist.

The paranasal sinuses also act like tiny echo-chambers that help amplify the sound of your voice, which is why you sound so different when they’re clogged with mucus during a cold!

So the relatively clean, warm, and moist air goes from the nasal cavity into the pharynx or throat.

At each side of the back of the throat, there is the pair of tonsils, which are small are clumps of lymphoid tissue that act as the body's first line of defense that swallow viruses and bacteria that enter through the mouth or nose.

The lower part of the pharynx is continuous with the larynx or the voice box.


An upper respiratory tract infection (URTI) is a viral or bacterial infection that affects the nasal passages, sinuses, pharynx, or larynx, typically causing symptoms such as congestion, runny nose, sore throat, cough, and fever. Common URTIs are tonsillitis, pharyngitis, laryngitis, sinusitis, otitis media, and the common cold. The transmission of URTI can occur through direct contact with an infected person or through exposure to airborne droplets from coughing or sneezing. Good hygiene practices and avoiding close contact with infected individuals can help prevent the spread of URTI.


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