Why do we yawn or sneeze or fart?

Question

What do you think? Why do you think that?

Answer 1

you yawn generally when you've been sitting or unactive, and it is because your body just hasn't been breathing enough and so it prompts you to take in a big gulp of air

you fart because in your large intestine there are bacteria that feed on your ****, and there excretions are the gas that you fart out, it builds up over time

you sneeze when dust and stuff in your nose cause your nose to tell your brain to make u sneeze to try to clear it out

Answer 2

Causes of yawning
1. An indication of tiredness, stress, over-work, or boredom.
2. An action indicating psychological decompression after a state of high alert.
3. A means of expressing powerful emotions like anger, rejection, apathy or tedium.
4. Caused by low oxygen in the brain

A yawn can express strong anti-social messages, and so in some cultures people try to mute or mask them by placing a concealing hand over the yawning mouth.

A previous long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain, however, that this hypothesis is not correct. One study has documented that this effect does not exist.[2]

A more recent hypothesis is that yawning is used for regulation of body temperature. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more of these compounds are activated in the brain, the frequency of yawning increases. Conversely, a greater presence in the brain of opiate neurotransmitters such as endorphins reduces the frequency of yawning. Patients taking the serotonin reuptake inhibitor Paxil (Paroxetine HCl) have been observed yawning abnormally often. Another theory is that yawning is similar to stretching. Yawning, like stretching, increases blood pressure and heart rate while also flexing many muscles and joints. It is also theorized that yawning helps redistribute an oil-like substance which coats the lungs and aids breathing. Some have observed that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is unsatisfying. As such, the stretching of jaw and face muscles seems to be necessary for a good yawn.

Some movements in psychotherapy such as Re-evaluation Counseling or co-counselling believe that yawning, along with laughter and crying, are means of "discharging" painful emotion, and therefore can be encouraged in order to promote physical and emotional healing.

Causes of sneezing
Sneezing is generally caused by irritation and some times bacterial clog up in the throat, lungs or in the passages of the nose. Allergens such as pollens, pet dander, house dust mites, as well as nonallergenic particles are usually harmless, but when they irritate the nose the body responds by expelling them from the nasal passages. The nose mistakes strong odors, sudden chills, bright lights (see photic sneeze reflex), and even orgasms in some people for nasal irritants, and it tries to defend itself with a sneeze.

and

Causes of farting
Fart (also called a blooper) is an English word which refers to the rapid evacuation of gases from the lower intestine through the anus which may result in an audible sound and accompanied by a foul odour due to a gas components such as hydrogen sulfied, skatole and indoleflatulence.

You could get more information from the 3 links below...

Answer 3

Release build up breath

To release clogged nose

to release built up gases

Answer 4

We are just taking advantage of our wonderful bodily functions.