Why formality as the first lesson?

As a medical professional, courtesy is vital. This is recognized through the formal tense. All of the translations in on the website will be written in the formal tense as is proper when speaking with a patient. You can read more about it here, but below is an example of what we are discussing:

Formal	Informal
Ponga su barbilla aquí, por favor.	Pon tu barbilla aquí.
Place your chin here, please.	Place your chin here.

You can also add a title to your requests as an additional sign of respect.

Señor, ponga su barbilla aquí, por favor.

Sir, place your chin here, please.

For women, you would use señorita for an unmarried woman (usually younger than 35) or señora for an married woman (older than 35). However, I generally avoid using titles to not offend anyone by calling them older than they appear. I recommend only using señor and señora when the individual is clearly of an older (55+) age.

Señorita, ponga su barbilla aquí, por favor.	Miss, place your chin here, please.
Señora, ponga su barbilla aquí, por favor.	Madam, place your chin here, please.

I also recommend that you also follow this Golden Rule:

As someone who will be guiding patients through a difficult procedure, it helps a lot to go the extra mile and convey respect through tone and words.

Practice