The Digestive System: The Stomach

We continue our journey through the digestive system, we have already learnt about processes in inside the mouth and in the oesophagus.

human_digestive_system

The Stomach

This is where our food now a bolus is exposed to hydrochloric acid produced by the stomach for further digestion. Our saliva is slightly alkaline, so why this change in pH? In this case not only does the acidity destroy potentially harmful microorganisms which could have been swallowed with our food but also different enzymes, which breakdown food, are more effective at different pH values.

The enzyme pepsin for example is produced in the stomach and works best at a low pH level, thriving in an acidic environment. Pepsin breaks down protein into smaller peptides, it is known as a protease enzyme because it does this process by hydrolysis of peptide bonds. The resulting product: peptides, short chains of amino acids (the basic building blocks of the human body and essential for a healthy body). Protein found in meat, eggs, dairy and seeds are broken down by the enzyme pepsin.

This mixture of acid and enzymes are mixed thoroughly by the stomach muscles, softening, sterilising and digesting protein, making the bolus into chyme.

The stomach has three types of contractions:
Rhythmic, 3 per minute, synchronized contractions in the lower part of the stomach which create waves of food particles and juice which splash against a closed sphincter muscle to grind the food down into small particles.
Slow relaxations in the upper part of the stomach lasting a minute or more that follow each swallow and that allow the food to enter the stomach; at other times the upper part of the stomach shows slow contractions which help to empty the stomach.
Between meals, after all the digestible food has left the stomach, there are occasional bursts of very strong, synchronized contractions that are accompanied by opening of the sphincter muscle. The function is to sweep any indigestible particles out of the stomach. Another name for them is the migrating motor complex.

Chyme can stay in the stomach for up to 2-4 hours, this depends on dilution of the stomach acid (this is why it is best to avoid having a drink while eating your meal) and the amount of food you have eaten.

There are certain types of foods you may want to avoid, to decrease the chance of inflammation to the stomach lining. These irritants include:

  • Acidic and Spicy Foods
  • Animal Milks – Milk products are thought to increase acid production.
  • Coffee, Carbonated Beverages, Alcohol and Certain Fruit Juices, such as Citrus Juices
  • High-Fat Foods
  • Highly Salted Foods – can damage the gastric mucosa: the mucous membrane layer of your stomach.
  • Junk Foods and Processed Foods – often contain chemicals that irritate the stomach lining as the are hard to digest and increase acid production

If you are experiencing gastritis (an inflamed stomach lining), causing symptoms of indigestion, stomach pain, vomiting and feeling bloated, you may want to take Antacids. These come in chewable and liquid form and counteract / neutralise the acid build up in your stomach to relive pain, but these shouldn’t be taken on a regular basis.

The best thing is to try and avoid the type of foods above.

I hope this helps and explains the complex processes that are happening within your stomach, if you have a question or would like me to expand on any part please let me know in the comments section below and I will do my best to answer.

 

 

 

 

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