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The Digestive System

The Digestive System. The Physiology. Review. Show the passage of food from input to output, including the accessory organs Use pictures OR words. Function of the Digestive System. 6 processes Ingestion: Propulsion Digestion Mechanical digestion Chemical digestion Absorption

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The Digestive System

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  1. The Digestive System The Physiology

  2. Review • Show the passage of food from input to output, including the accessory organs • Use pictures OR words

  3. Function of the Digestive System • 6 processes • Ingestion: • Propulsion • Digestion • Mechanical digestion • Chemical digestion • Absorption • Defecation • These processes occur more or less in order from start to finish (lucky for you!), although the different organs can carry out more than one of these functions

  4. Color is your friend. • Get out 6 colors, one for each function. • Ingestion • Propulsion • Mechanical digestion • Chemical digestion • Absorption • Defecation

  5. Ingestion • Food must be placed in the mouth

  6. Propulsion • Moving food from one digestive organ to the next • Swallowing • Peristalsis • Wave-like contraction and relaxation to move food through a tube

  7. Digestion: Mechanical • Mixing of food in the mouth • Tongue and teeth! • Mixing of food in the stomach • Stomach churning • Mixing of food in the small intestine • Segmentation: moving of foodstuff back and forth across the organ walls

  8. Digestion: Chemical • Enzymes break down foodstuff • Carbohydrates  simple sugars (monosaccharides) • Proteins  amino acids • Fats  fatty acids and glycerides

  9. Absorption • Digested foods must enter the blood or lymph vessels • Active transport • Passive transport

  10. Defecation • Elimination of indigestible substances from the body • Feces (poo)

  11. Here’s how we are going to play… • From here on out, we are going to go through the passage of food, from mouth to anus, and will connect the functions back to those 6 processes on the previous slide • Get ready!

  12. The Mouth • Predict: The mouth would perform which of the 6 functions? • Functions: • Ingestion • That is the food’s first stop! • Propulsion (aka peristalsis) • We have to swallow to move the food to the next organ • Wait….what is the next organ? • The esophagus!  • Mechanical digestion • We masticate our food • Means that we chew it and mix it with saliva using our tongue and teeth “I was distracted by the half-masticated cow rolling around in your wide-open trap!” --Miss Congeniality

  13. The Mouth • Chemical digestion • Carbohydrates are broken down • Saliva • Saliva is secreted by salivary glands • Contains an enzyme called salivary amylase • Once the food is masticated, it is called a bolus

  14. Esophagus • Predict: What functions would the esophagus perform? • Functions • Peristalsis • There are layers of smooth muscle to help deliver the bolus to the stomach

  15. Stomach • Predict the functions • Functions • Peristalsis • Has to get the food to the SI • Mechanical digestion • Your stomach churns to further break up the food • Chemical digestion • There are many enzymes that can help break down food • Once the stomach has churned the food, it is called chyme http://www.youtube.com/watch?v=o18UycWRsaA

  16. Small Intestine • Predict the functions • Functions • Peristalsis • Move the food along! • Chemical digestion • Break the macromolecues down further • With the help of: • Pancreas • Digestive enzymes • Liver/gall bladder • Liver produces bile • Bile is stored in the gall bladder • Bile helps to break down fat • Absorption • Nutrients are absorbed so the body can use them • Carbs, proteins, and fats are absorbed

  17. Large Intestine • Predict the functions • Functions • Chemical digestion • There are no digestive enzymes in the LI, only bacteria • Absorption • Mostly absorb water • Propulsion • Moving it along!! • Defecation • Poo!

  18. Interesting • The bacteria in our large intestines are vital to our survival • Symbiotic relationship (mutualism) • If we ingest too many antibiotics from misuse or a prolonged infection, we can decrease the amount of good bacteria in our colon and can lead to an increase in the bad bacteria • Can lead to colitis (inflammation of colon), constipation, irritable bowel syndrome • Treatment? • Fecal bacteriotherapy • This means that feces from a healthy person is transplanted into the patient • This will transfer that good bacteria into your system • http://www.voanews.com/content/fecal-transplants-used-to-cure-intestinal-disorders/1723974.html • YUM!

  19. Let’s make a table Color code the different organs within our GI tract and list them under the correct function. The mouth has been done for you.

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