Nutrition in humans

• What is nutrition 


  Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body
• Nutrition has 5 main process

  Ingestion, Digestion, Absorption, Assimilation, Egestion
• What is Ingestion 


  Food is taken into the body
• What is digestion 


  Large insoluble food molecules are chemically broke. Into smaller soluble molecules
• What is absorption 


  Digested food molecules are absorbed into cells of the small intestine
• What is assimilation 


  Digested food molecules are used to provide energy or make new protoplasm
• What is egestion

  Undigested food is removed from the body as faeces
• Physical digestion 


  Involves mechanical break up of food into smaller piece, chewing, peristalsis, bile emulsifies fat, churning of stomach
• Chemical digestion 


  Involves chemical break down of large insoluble food molecules into smaller soluble molecules that can be absorbed, involves digestive enzymes
• Physical digestion of food increases its surface area to volume ratio for digestive enzymes to chemically digest the food molecules more efficiently
• Alimentary canal contains

  Mouth, salivary glands, oesophagus, stomach, small intestine, rectum, anus
• associated organs contain

  pancreas, gall bladder, liver
• Mouth + salivary gland functions

  Physical digestion= chewing action if the teeth mechanically break up large pieces of food into smaller pieces Chemical digestion= salivary gland secretes saliva which contain salivary amylase, salivary amylase chemically digests starch to maltose, saliva is neutral (PH 7) provides optimal PH for salivary to work in