nutrition in humans

• buccal cavity: inside of mouth and beginning of alimentary canal

  mechanical digestion
• oesophagus: narrow, muscular tube (passing through thorax) connecting mouth to stomach
• PERISTALSIS

  peristalsis: rhythmic, wave-like muscular contractions in alimentary canal wall
• STOMACH


  Muscular bag with thick and well-developed walls which churns the food for up to four hours.
• RECTUM

  a muscular storage chamber where the undigested food (faeces) is held and moulded before being pushed out through the anus during egestion.

  when rectum contracts, faeces is expelled through anus
• ANUS

  The anus is the exit to the alimentary canal. It is

  closed by a ring of muscle (the anal sphincter)

  which is relaxed during egestion or defaecation.
• what is digestion?

  the break down of large and complex food substances into smaller and simple food substances that can be absorbed by cells in the body
• physical digestion: mechanical breakdown of large pieces of food into smaller pieces

  chemical digestion: process whereby large and complex food substances are broken down into smaller, soluble simple substances
• emulsification: breaking up of fats into tiny fat droplets