The digestive system or gut takes a surface area of 32 square meters. The role of the gut is to digest food. It means breaking down food into a form that can be easily absorbed. These provide nutrients such as proteins, carbohydrates, and fats . Our body requires these nutrients for growth. Along with digestion, It also hosts microbiota - a community of bacteria. It can be symbiotic ( help the gut to digest food) or pathogenic (disease-causing)
The gastrointestinal wall comprises of
1. Mucosa: The innermost part of the gastrointestinal tract that faces the lumen (the space inside a hollow structure).Mucosa aid in the absorption of nutrients from the lumen.
2. Submucosa: It surrounds the mucosa and consists of lymph nodes, nerves, and blood vessels.
3. Muscularis: It comprises smooth muscle cells. They are longitudinally outward and circularly inward. It helps the digestive tube in movement.
4. Serosa: the outermost layer that lines the digestive tract.
Digestion begins as soon as you consume food, and it involves a series of intricate steps and components working together to break down the food into nutrients that your body can absorb and utilize. Let's delve deeper into the journey of food through the digestive system :
1. Mouth: The digestion process commences in the mouth. Here, food is mechanically broken down by chewing, and saliva is released into the mouth by salivary glands to moisten and soften the food. This mixture forms a bolus, which is then swallowed, passing through the pharynx(windpipe) and larynx(voice box).
2. Esophagus: The food travels down the esophagus, a muscular tube that employs a wave-like motion called peristalsis to propel the food toward the stomach. At the end of the esophagus, a sphincter prevents food from flowing back into the esophagus.
3. Stomach: Upon reaching the stomach, the food is mixed with gastric juices that contain digestive enzymes and hydrochloric acid. These components work together to break down the food further, resulting in a semi-liquid mixture known as chyme. The stomach also plays a role in sterilizing the ingested food.
4. Small Intestine: The chyme is then gradually released into the small intestine, a lengthy and convoluted tube. Here, the pancreas secretes digestive enzymes that aid in breaking down carbohydrates, proteins, and fats. The liver produces bile, which emulsifies fats, making them more accessible for digestion. Villi and microvilli are tiny finger-like projections that significantly increase the surface area for nutrient absorption in the small intestine. Nutrients, such as amino acids, fatty acids, and sugars, are absorbed through the intestinal walls and transported into the bloodstream.
5. Large Intestine: Any undigested food particles, with water and electrolytes, enter the large intestine. Here, water is reabsorbed, and the remaining material solidifies to form feces. The large intestine also houses a diverse community of beneficial bacteria that aid in the fermentation of certain indigestible substances and the synthesis of certain vitamins.
6. Rectum and Anus: The fully formed feces are stored in the rectum until they are ready to be eliminated. When the rectal walls are stretched, nerve impulses signal the need for a bowel movement. The feces are then expelled through the anus.
Throughout this intricate process, several key components play crucial roles:
- Salivary Glands: Produce saliva, which contains enzymes like amylase to initiate the digestion of starches in the mouth.
- Pancreas: Releases digestive enzymes (amylase, lipase, protease) into the small intestine to further break down carbohydrates, fats, and proteins.
- Liver: Produces bile, which aids in the emulsification and digestion of fats.
- Gallbladder: Stores and releases bile into the small intestine when needed for fat digestion.
In summary, the digestive process is a coordinated sequence of events involving various organs, enzymes, and mechanisms to ensure the breakdown of food into absorbable nutrients and the elimination of waste products from the body.