What is the first enzyme that starts to digest food

by Howard F. Loomis Jr., D.C.

Table of Contents Show

Breaking it down
How does it taste?
The role of your teeth
On to the stomach
What is the first enzyme that starts to digest food quizlet?
What is the 1st enzyme?
What is the 1st step in digestion?

Digestion begins in the mouth. When you chew your food it is mixed with saliva, which not only supplies moisture but also the carbohydrate-digesting enzyme, amylase. When you eat raw food, its enzymes work with the salivary amylase to begin digestion.

Swallowing prevents food from remaining in the mouth long enough for any significant amount of digestion to occur. However, the food and salivary enzymes continue the digestion process until the secretion of stomach acid causes the pH to drop below 3.0, which is the activity range of plant enzymes. Before food arrives, the stomach normally has a pH between 5.0 and 6.0. In young and healthy adults it takes about 45 minutes before enough acid is generated to drop the pH to 3.0. This is because stomach acid is secreted into the stomach in response to the expansion of the stomach wall. During this time a considerable amount of digestive work can be accomplished if plant enzymes, either indigenous to the raw food ingested or from a supplemental source, are present. Unfortunately, the amount of time necessary to make stomach acid increases with age. Studies have proven that older adults often suffer from inadequate stomach acid levels.

There is a common misconception that enzymes are destroyed by stomach acid. Nothing could be further from the truth. Stomach acid does not digest protein. Rather, it activates an enzyme called pepsinogen which then becomes pepsin that is secreted by the stomach wall. This enzyme is only active within the pH range of 3.0 to 5.0 and requires the acid to maintain that pH. Pepsin is very specific in its action and is simply incapable of digesting food enzymes, which are very large molecules and are more than just protein.

More than seventy years ago, Olaf Bergeim conducted a series of experiments on salivary digestion at the Laboratory of Physiological Chemistry in the University of Illinois, College of Medicine in Chicago. He found that an average of 59-76% of ingested carbohydrates is digested within 15-30 minutes after a meal. He concluded that a very considerable degree of starch digestion may be brought about by saliva if food is chewed properly.

The pH within the stomach rarely, if ever, drops below 3.0. Pure stomach acid has a pH of 1.8 when it first enters the stomach, but is quickly diluted in the presence of food. Regardless, plant enzymes are not destroyed by the highly acidic environment of the stomach. They simply become dormant until reaching the higher pH levels in the small intestine, where they again become active and continue the digestive process. Once their digestive function in the gastrointestinal tract is completed, a large number of enzymes are absorbed through the gut wall into the bloodstream.

A lot of research remains to be done to determine the exact fate of these enzymes after they pass through the gut wall into blood. However, it is known that plant enzymes will pass from the body into the urine after they have completely lost their usefulness.

Digestion is a several-step process that begins the moment you put a piece of food in your mouth or sip a drink.

Breaking it down

When you begin chewing, glands in your mouth and throat begin to secrete saliva. This process can start with the sight or smell of food. The liquid aids digestion, moistens your mouth, reduces infections in the mouth and throat, and helps protect your teeth and gums. You have 3 major pairs of salivary glands:

Parotid glands, the largest, are on both sides of your face, in front of your ears
Submandibular glands are underneath your jawbone
Sublingual glands are underneath your tongue

Your upper digestive tract and your esophagus also contain smaller clusters of salivary glands. Saliva contains special enzymes that help digest the starches in your food. An enzyme called amylase breaks down starches (complex carbohydrates) into sugars, which your body can more easily absorb. Saliva also contains an enzyme called lingual lipase, which breaks down fats.

A condition known as dry mouth (xerostomia) occurs when you don’t have enough saliva in your mouth. This can make it difficult for you to chew and swallow food. Stress or dehydration can cause occasional xerostomia. Certain medicines or more serious conditions such as diabetes and Sjogren syndrome can also cause it. To reduce the symptoms of dry mouth, drink plenty of water, take sips of water while eating, and don't have caffeinated or alcoholic beverages. These can make dry mouth worse.

How does it taste?

When your saliva begins to break down your food, the taste buds on your tongue and on the roof of your mouth sense how the food tastes. Taste buds contain gustatory cells, which send taste signals to the brain. This is how you sense the 5 basic tastes of food: sour, sweet, salty, bitter, and savory. Nerves in your nose, mouth, eyes, and throat let you experience the other qualities of food, like the heat of spicy foods and the coolness of peppermint.

The role of your teeth

Your teeth are also part of the digestive process. Teeth break down food for swallowing and further digestion. The incisors, located in the middle front of the lower and upper jaws, cut and gnaw pieces of food. The molars, in the back of the mouth, grind and chew. To keep your teeth at their healthiest, follow these simple preventive measures:

Eat a healthy diet rich in protein, fruits and vegetables, calcium, and whole grains.
Limit eating and drinking between meals.
Limit sugary foods and beverages.
Brush your teeth and tongue twice a day with fluoride toothpaste, and floss once a day.
Visit your dentist regularly for professional cleanings and exams.

On to the stomach

After you chew and swallow your food, it enters your esophagus. This tube connects your throat to your stomach. A series of muscular contractions, known as peristalsis, pushes your food downward and into your stomach. There, it mixes with more digestive enzymes to continue the breakdown process.

Revisor médico: Jen Lehrer MD
Revisor médico: Raymond Kent Turley BSN MSN RN
Revisor médico: Rita Sather RN

Última revisión: 1/1/2021