system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What specifically are doctors looking for when they check your eyes, nose, mouth, and breathing? Why is this standard practice?
gpt
When looking in your eyes they want to make sure the pupils are dilating like they are supposed to. If not there could be a lesion among the cranial nerves. They also look at your retina. There are little arteries in your retinas that can look different with different types of heart disease. A problem with these can lead them to check other things. 

In your nose they are looking for any polyps or lesions. They’ll shine the light in there too to check to make sure your sinuses “light up” meaning they are clear. 

Checking the mouth, they look at your tonsils if you still have them. They’ll also look at your uvula (hangy ball) to make sure it isn’t leaning to one side. This can also mean a lesion in a cranial nerve. They check the tongue to make sure it isn’t deviated to one side or the other (if it is it means there is a lesion in a cranial nerve). 

The check your breathing to make sure your lungs are clear. Any weird sounds could mean infection, asthma, COPD, etc. 

They also check your heart at 4 separate points to check each valve of the heart for murmurs. 

They’ll use the stethoscope to check your neck for bruit (basically if there is blockage in the carotid arteries leading to the head it makes a weird sound through the stethoscope). 

They’re also supposed to check your neck under your chin from behind to feel for your thyroid. 


There are other things they are looking at while they are checking these things you just might not notice. 

TL;DR: they’re checking for abnormalities in the cranial nerves, heart and lungs. These are super easy tests and should be done to make sure something isn’t starting to go on with a patient before they even know themselves that it is.