Please enable JavaScript.

Coggle requires JavaScript to display documents.

Biology chapter 5: nutrition in humans - Coggle Diagram

- - - - the circular muscles and the longitudinal muscles are antagonistic muscles, when one set of muscles contract, the other set relaxes, they CANNOT contract at the same time
- - - - food in the stomach stimulates the gastric glands to secrete gastric juice into the stomach, peristalsis, in the stomach churns and breaks up food and mixes the food with gastric juice, gastric juice in the stomach contains hydrochloric acid, mucus and pepsin, which is a protease, the hydrochloric acid stops the action of amylase by denaturing it, provides a low pH environment which is about pH 2 for the protease to digest proteins, and kill bacteria in the food, the proteins in the food is then digested into polypeptides, the mucus layer in the stomach wall prevents the stomach from being digested, and moistens the food in the stomach, food stays in the stomach for 3-4 hours as it turns into chyme, chyme then passes into small amounts into the small intestine
    - - when cyme enters the small intestine, it stimulates the pancreas to secrete pancreatic juice, the pancreatic juice passes through the pancreatic duct into the duodenum, which contains pancreatic amylase, protease, and lipase, the gall bladder also releases bile which passes through the bile duct into the duodenum, the epithelial cells in the small intestine produces maltase, protease, lipase the pancreatic juice, bile and intestinal juice are alkalis which neutralise the acidic chyme, and provide and alkaline environment for the enzymes
    - - the food in the mouth stimulates the salivary glands to secrete saliva, which is mixed with food to soften it, saliva contains amylase, which digests starch into maltose, the optimum pH is at pH 7. Chewing breaks the food into smaller pieces which increases the surface area to volume ratio for the amylase to work on, the tongue rolls the food into the bolus, which is then swallowed and passed into the oesophagus via the pharynx, peristalsis pushes the food down into the stomach
- - - - when there is enough glucose, fats are not broken down and are used to build protoplasm, for example, cell membranes, when glucose is in short supply, fats are broken down to provide energy for the vital activities, excess fats are stored in adipose tissues which acn be found under the skin, around the heart and the kidneys, adipose tissues protect these organs by acting as shock absorbers