The document discusses the mammalian digestive system, examining the esophagus, stomach, and small intestines, and the adaptations that allow the small intestines to efficiently absorb nutrients. It describes how the villi and microvilli in the small intestines increase surface area for absorption and how a thin epithelium, capillaries, and concentration gradients aid absorption. Key nutrients like glucose and amino acids are absorbed and transported via the hepatic portal vein to the liver to be redistributed and utilized throughout the body.

1. Nutrition in MammalsChapter 6

2. Lesson recap

3. What did we learn the previous lesson?Introduction to Nutrition in MammalsOrgans in the Mammalian Digestive systemDetailed examination of Oesophagus,

4. Stomach

5. Small intestines4. Adaptations of the intestines for absorption

6. Two layers of smooth muscles: longitudinal & circular muscles What happens in the Oesophagus?Peristalsis-is the Wave like contraction of the walls of the gut to move food down from mouth to stomach

7. Circular muscle contracts; lumen constrictsAntagonistic musclesLongitudinal muscle relaxes

8. Demonstration

9. *StomachStructure of StomachDistensible = can stretch & expandSend “Full” signal to brainNumerous pits with gastric glandsPyloric splincter = ring of muscle connecting the small intestines.

10. What happens in our Stomach?What happens in the Stomach?Peristalsis occurs in the stomachPeristalsis- Wave like contraction of the walls of the gut to move food down from mouth to stomach

11. Small Intestines – Last chance to digest!

12. DemonstrationHow does the movement of the intestinal wall look like?

13. How do villi help to increase rate of absorption in the small intestine?ORHow does the villus structure help to increase rate of absorption in the small intestine?

14. Does surface area matter for absorption?

15. If the small intestines were only a hollow tube…0.5m2200.0m2

16. Increase Surface AreaInner walls have numerous folds

17. Lined with vili

18. Microvilli on villiAdaptation of the small intestines

19. How is the intestinal wall adapted for absorption?

20. Thin membrane – 1 cell thickOne-cell thick epitheliumEpithelium-the inner and outer tissue covering digestive tract organs.ukhealthcare.uky.edu/patient/glossary/glossary-e.htm-a type of tissue which lines a surface in the body.www.di.uq.edu.au/sparqglossaryAdaptation of the small intestines

21. Increased intestinal surface area1 cell thick epithelium

22. Numerous capillaries to maintain concentration gradientMany capillaries carry substance awayEach villus has a lacteal/lymphatic capillary surrounded by blood capillaries. Continuous transport of digested food substances awayAdaptation of the small intestines

23. Q. How is Concentration gradient maintained at the site of the intestinal villus?A concentration gradient is maintained at the villus by the continual transport of digested food substances away from the villus.Adaptation of the small intestines

24. Absorption at the small intestines villus

25. Glucose & amino acids enter into blood capillaries via diffusion & active transportGlycerol & fatty acid diffuse into the epithelium, then combines back to fat moleculeswhen they enter lactealWater & mineral salts also absorbed.How does absorption take place?

26. SummaryIntroduction to Nutrition in MammalsOrgans in the Mammalian Digestive system3. Examined:Oesophagus

27. Stomach

28. Small intestines4. Adaptations of the intestines for absorption

29. Today’s GuestMr. Liver

30. Q. How are food substances transported and utilized?Chapter 6 Pg 105

31. Liver Boss, I’m done with absorbing all the nutrients. My villus is rich. What do I do with them now?Good job! You’re done with all the goodies? Pass them to me and I’ll re-distribute!

32. But you’re quite a distance away,Can I send them to you by air mail? Huh? What is air-mail?There are no planes around the area. You need to ship the ‘goodies’ to me