Human Digestive system

• Digestion begins in the mouth, where food is chewed and mixed with saliva.
• The digestive system is responsible for breaking down food into smaller molecules that can be absorbed and used by the body.
• Food digestion is the process of breaking down complex and large food molecules into small, simple, and soluble molecules that can be absorbed by the cells of the body.
• The human digestive system consists of the digestive tract (mouth, oesophagus, stomach, duodenum, small intestine, large intestine, rectum, and anus) and other organs (liver, gall bladder, pancreas, salivary glands).
• Physical digestion occurs in the mouth with the help of teeth, tongue, and saliva, while chemical digestion occurs in the mouth, stomach, duodenum, and intestine with the help of enzymes.
• The small intestine secretes enzymes such as maltase and protease, while the large intestine is responsible for water reabsorption and storage of undigested food (faeces) in the rectum before excretion through the anus.
• The flow of food in the digestive tract starts with chewing in the mouth, followed by the process of peristalsis in the oesophagus pushing the food into the stomach, secretion of protease and hydrochloric acid in the stomach, and bile production in the liver and gall bladder.
• The liver produces bile, which helps in the digestion and absorption of fats.
• The salivary glands produce amylase, an enzyme that breaks down carbohydrates into smaller molecules.
• The pancreas produces enzymes such as amylase, lipase, and protease that aid in the digestion of carbohydrates, fats, and proteins, respectively.
• The stomach plays a key role in digestion by secreting gastric juices that help break down proteins and kill bacteria.
• Pancreas releases pancreatic juice which contains:

  • pancreatic amylase
  • protease
  • lipase
• Pancreatic amylase: digests starch into maltose
• Protease: digests polypeptides into dipeptides
• Lipase: digests fats into fatty acids and glycerols
• Protease is produced in the stomach
• Bile is an alkaline fluid that aids digestion and is secreted by the liver and stored in the gallbladder
• Villi function is to absorb nutrients from the food we eat and then transport them to the bloodstream so they can travel to where it’s needed.
• The wall of the villus is very thin, only one cell thick, to increase the rate of absorption.
• Human Digestive system

  A) Mouth

  B) Salivary Glands

  C) Oesophagus

  D) Stomach

  E) Liver

  F) Duodenum

  G) Gall Bladder

  H) Small Intestine

  I) Pancreas

  J) Rectum

  K) Large Intestine

  L) Anus