Mechanical Digestion Vs. Chemical Digestion: Know the Real Difference

Mechanical Digestion Vs. Chemical Digestion
In mechanical digestion, the food is broken down through physical means, while chemical digestion uses chemicals (enzymes, acids) to promote breakdown of food into simpler nutrients. This Bodytomy post tries to undertake a mechanical digestion vs. chemical digestion comparison.
Bodytomy Staff
Last Updated: Dec 21, 2017
Did You Know?
Leading a healthy lifestyle, which means following a healthy diet, eating small meals throughout the day and exercising daily, promotes better digestion.
It is often said that we are what we eat; our health reflects the food we eat. To be precise, how much is digested from what we consume reflects in our health status. Experts opine that digestion is the key to maintaining health and increasing longevity. This is because digestion is a process through which the body absorbs nutrients from ingested food.

Better digestion increases bio-availability of essential nutrients like vitamins, minerals, and proteins. This means, improved digestion allows your body to absorb more nutrition. Moreover, healthy digestion makes us feel energetic, gives us more stamina and also promotes weight loss.
Mechanical Digestion Vs. Chemical Digestion
What is it?
Girl eating pizza
Mechanical Digestion
♦ It is essentially a physical process and involves physically breaking down food into smaller pieces.
Human stomach anatomy
Chemical Digestion
♦ As the name suggests, in chemical digestion, certain chemicals are secreted in the stomach, which further promote breakdown of food.
Where does it occur?
Mechanical Digestion
♦ Mechanical digestion chiefly occurs in the mouth. It partly occurs in the stomach as the repeated muscular contractions of the stomach wall exert a churning action, which also helps in physical breakdown of food.

Chemical Digestion
♦ Chemical digestion mainly occurs in the stomach and small intestine. However, since saliva combines with food while chewing it in the mouth, one can also say that chemical digestion partially occurs in the mouth.
Which organs are involved?
Mechanical Digestion
♦ The 32 teeth in the mouth initiate mechanical digestion, which means they do the job of tearing, chewing, and grinding the food.

Chemical Digestion
♦ In chemical digestion, stomach acids and a wide range of enzymes including protease, amylase, trypsin, lipase, and nuclease are involved in the breakdown of food.
What is the process?
Mechanical Digestion
♦ In mechanical digestion, food is chewed thoroughly and broken down physically. This ensures that the ingested food passes smoothly through the digestive tract.

Chemical Digestion
♦ In chemical digestion, proteins are broken down into amino acids, starch is broken down into sugar, and fat is broken down into fatty acids and glycerol. All these are simpler organic compounds that get easily absorbed into the bloodstream.
These conversions are essentially chemical reactions in which the enzymes serve as biological catalysts, meaning they accelerate the rate at which the reaction occurs.
Why is it important?
Mechanical Digestion
♦ It is essentially a physical process that prepares the food for chemical digestion. If the food is not chewed properly or simply gobbled, it can cause obstruction and may even choke the esophagus.

Chemical Digestion
♦ Simply breaking down the food, physically, in mechanical digestion is not enough to promote its absorption. The nutrients from ingested food will be absorbed by the body only when it is broken down into simpler forms, which is done by enzymes and acids during chemical digestion.
On the whole, one should never eat in a hurry as it gives very little time for mechanical digestion. The act of chewing food thoroughly is extremely important as it makes chemical digestion in the stomach and the small intestine much easier, thereby improving overall digestion.