11 Digestive system

2,908 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
2,908
On SlideShare
0
From Embeds
0
Number of Embeds
1,427
Actions
Shares
0
Downloads
18
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

11 Digestive system

  1. 1. The digestive system
  2. 2. A Mouth B B Salivary gland Salivary glands Pharynx C D Epiglottis E Oesophagus Stomach F Liver G Gall bladder H I Pancreas J Duodenum K Small intestine L Colon M Caecum N Appendix Large intestine O Rectum P Q Anus
  3. 3. Mouth <ul><li>Mechanical breakdown of food </li></ul><ul><li>Saliva – lubrication </li></ul><ul><li>Salivary amylase – breakdown of starch and carbohydrates </li></ul><ul><li>Tongue – gathers food in to a bolus </li></ul>
  4. 4. Oesophagus <ul><li>Entry regulated by epiglottis </li></ul><ul><li>Soft muscular tube </li></ul><ul><li>Moves food through rhythmic muscular movement called peristalsis </li></ul><ul><li>DEMONSTRATION </li></ul>
  5. 5. Stomach <ul><li>Can expand from an empty volume of 50ml to a full volume of 1.5 L </li></ul><ul><li>Gastric juices are a mixture of mucouse, enzymes, hydrochloric acid and water </li></ul><ul><li>Pepsin – breaks down proteins </li></ul><ul><li>Muscular contractions – further mechanical breakdown </li></ul><ul><li>Hormones secreted to pre-warn pancreas and gall bladder of incoming chyme </li></ul>
  6. 7. Pancreas <ul><li>Creates enzymes and other products and secretes them in to the common bile duct: </li></ul><ul><li>Bicarbonate – neutralise stomach acid </li></ul><ul><li>Amylase – continue breakdown of carbs </li></ul><ul><li>Protease – continue breakdown proteins </li></ul><ul><li>Lipase – breaks down lipids </li></ul><ul><li>Nucleases – breaks down DNA, RNA and cellular organelles </li></ul>
  7. 8. Liver & Gall Bladder <ul><li>The liver secretes bile (greenish fluid containing bile salts, cholesterol & pigment) in to common bile duct. </li></ul><ul><li>Bile stored in gall bladder if no digestion is taking place. </li></ul><ul><li>Bile salts emulsify fat (break it in to smaller droplets (eg milk & detergent) </li></ul>
  8. 9. Pancreatic disorders – Cystic Fibrosis <ul><li>A CF patient’s blocked pancreatic duct </li></ul><ul><li>The amount of enzyme replacement capsules required to be taken every day </li></ul>
  9. 10. Small Intestine <ul><li>Composed of the duodenum, jejunum and ileum </li></ul><ul><li>Food spends 3 to 6 hours here </li></ul><ul><li>Around 90% of absorption of nutrients takes place here </li></ul><ul><li>Surface area is greatly increased by entire inner lining covered in villi, and each of these villi covered in microvilli. </li></ul><ul><li>Also approx. 8.5L of water is absorbed from food daily. </li></ul>
  10. 11. Villi <ul><li>Each villus has a huge network of capillaries running through it. </li></ul><ul><li>Absorption of nutrients is by means of diffusion and active transport. </li></ul>
  11. 12. Large Intestine <ul><li>Composed primarily of the colon, caecum and the rectum </li></ul><ul><li>Any undigested food gets further processed by bacterial breakdown </li></ul><ul><li>Another 0.5L of water is reabsorbed daily </li></ul><ul><li>Waste called faeces (undigested food, water, dead cells & bacteria) passes out of the rectum through the anus. </li></ul>
  12. 13. Flatus <ul><li>A gas called flatus also passes through the anus, it is the result of swallowed air or gas produced during bacterial breakdown </li></ul>

×