Ask A Scientist© Zoology Archive

name       Caroline
status     student
age        13

Question - I was wondering how much stomach acid is contained in your
stomach. Also, how long medication would take to reach your stomach? And
Would stomach acid dissolve enteric-coated medications. It would be
great if you could answer these questions as thoroughly as possible, its for
science fair Thanx, Caroline

Hi Caroline, good look with your science fair!
Let's see...it is not the amount of acid contained at the stomach that
is important, that will depend upon many local factors, even the
stomach size concerned. What is important is the acidity of the
gastric juice. A healthy stomach has an acidity level (pH) between 1-2,
that is around one million times more acid than pure water.
The digestive process takes place as food passes through the mouth,
stomach, small intestine and large intestine. At the stomach, the
gastric acid helps to break down proteins for further digestion at
the small intestine. The time consumed for the whole digestion
will depend upon the way the whole process passes. The food
at the mouth must be well prepared: grounded and chewed, with
the help of good teeth and saliva. Saliva contains an enzime which
acts on starch to convert it into sugar. Then the food passes through
the esophagus into the stomach, where it is further desintegrated
and acted upon by the stomach juices, that contains besides the
hydrchloridic acid, pepsin and other enzymes.
The stomach usually requires about 4 hours of both mechanical
(with the help and movements of their muscles) and chemical
action on food to complete its function. From the stomach
the partly digested food passes into the small intestine, where
both the mechanical and chemical actions continue.By other
hand after one hour digestion the food begins to enter the
small intestine.

Your another question about enteric coated pills: they are soft
gel pills that is coated in a manner that do not allow the capsule to
break down until after it has passed through the stomach and reaches
the small intestine. It is used when the medicine is intented to
act at the intestine only and if it was released at the stomach
would interact with the gastric juice and finally would
prejudice the stomach lining.
And thanks for asking NEWTON!
Mabel
(Dr. Mabel Rodrigres
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1. Stomach acid is hydrochloric acid at a pH of 1, which means that it is at
a concentration of 0.1 moles/liter.
2. When something is swallowed, it reaches the stomach within seconds.
3. Stomach acid does not dissolve enteric coatings.  That's the whole point
of an enteric coating;  it doesn't break down until the small intestine.  In
fact, there's a really interesting picture in a recent (I don't think it's
earlier that August 2000) New England Journal of Medicine of an
enteric-coated aspirin lodged in a stomach ulcer.  The coating was perfectly
intact, so that you could still read the printing on it.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
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