Digestive System

• Purpose:

  to break down ingested food into molecules, called nutrients, so that it can be absorbed into the blood stream.
• Parts: mouth, esophagus, stomach, small intestine, large intestine, rectum
• Mouth

  -mechanical digestion: teeth, jaw, tongue

  -chemical digestion: salivary glands,(enzymes)
• oesophagus

  (peristalsis, muscle movement)

  -tube located behind the "wind pipe"

  -leads to the stomach from the mouth
• Stomach

  -located under the lungs, in abdomen

  -digests food

  -> mechanically: churning (turning food)

  -> chemically: stomach acid (HCI)

  -stomach lining replaces itself often
• Small intestine

  -6m long

  -still digests food(first part)

  -absorbs nutrients
• Large intestine

  -1,5m

  -Colon

  -absorbs water
• Rectum

  -end of colon/large intestine

  -stores the stool temporarily
• Anus

  opening through which the stool/faeces'/undigested food exits
• Liver

  -accessory organ to the digestive system

  -produces bile ->stored in the gallbladder

  -bile helps with digestion

  -largest gland in the body
• Processes: (IDAE)-ingestion, digestion, absorption, egestion
• ingestion: intake of food by biting, chewing and swallowing
• digestion: mechanical and chemical process- mouth, stomach and first part of small intestine
• absorption: when soluble nutrients are taken by the blood stem in the small intestine and water in the large intestine.
• egestion: undigested food materials (faeces) pass out the body through the anus
• mechanical digestion

  -large food particles are broken down into small particles

  -> mouth- teeth and tongue

  -> churning movement in stomach

  -> peristaltic movement in oesophagus
• Chemical digestion

  -break down of small particles into soluble nutrients

  -> mouth- salivary glands

  -> stomach- stomach acid (contains enzymes)

  -> small intestine- enzymes
• enzymes: proteins that speed up chemical digestion
• Absorption:

  villi found on the inside wall of intestines
• Villi

  -contains blood vessels for absorption of nutrients

  -> special adptation as it increases surface area for absorption
• Health issues: constipation, diarrhoea

  , ulcers
• constipation: having less than 3 bowel movements a week, due to too little fibre in your diet
• diarrhoea: frequent bowel movements (more than 5 a day), stool is runny, caused by bacteria
• ulcers: breaks in the skin/mucus membrane in the mouth, stomach, or intestines that do not heal easily