2. Liver & Gall Bladder
Liver produces Bile  mainly water and some bile salts
Bile is stored in the Gall Bladder  the gall bladder absorbs water making the bile more concentrated
Bile releases into duodenum via bile duct

3. Bile Salts
Emulsify Fats (Emulsify - To make a suspension of small globules of one liquid in a second liquid in which the first will not mix)

4. Bile continued Mechanical digestion:
Emulsification – bile salts break down fat globules into smaller droplets so that they can be digested by enzymes.
Purpose – To increase surface area!

6. Other Liver Functions Regulate blood glucose levels (stores glycogen)
Breakdown and synthesis of lipids and fats
Protein breakdown and protein/non-essential amino acid synthesis
Stores vitamins (A, B12, D, K) and iron
Breaks down hormones, antibiotics, and other toxic substances (detoxifier)
Breaks down the by-products of RBC recycling
Note** these are main functions. Liver is thought to do about 500 separate functions
Removes effect of poison

7. Gall Stones
Crystalline mass formed from bile pigments, cholesterol, and calcium salts.
Cause severe pain and blockage of bile duct

8. gallstone - A small, hard object, in the shape of a pebble, that sometimes forms in the gallbladder or bile duct; composed of cholesterol, bile pigments and calcium salts

10. Liver Cirrhosis
Most commonly caused by alcohol, hepatitis B, hepatitis C, and fatty liver disease.
Gradual build up of scar tissue that replaces normal tissue
Leads to liver failure

11. Ethyl alcohol is toxic to the liver

12. Healthy Liver

13. Liver cirrhosis
Note extensive scarring

14. Chronic alcoholism will typically lead to damage of the liver characterized by scarring. The damaged liver often turns an orange color. This damage of the liver is called “cirrhosis”.
Cirrhosis of the liver

15. Jaundice
One of the by-products of RBC destruction is bilirubin (yellow color)
The liver filters out bilirubin from blood, and excretes in bile.
If liver is failing, or bile duct is blocked, bilirubin builds up in body, causing jaundice  a yellowing of skin and whites of eyes.

18. Check your understanding
What function does the liver have in the body?
What is jaundice? And what causes it?
What is the main purpose of bile salts? Explain.

19. Gastrointestinal Disorder Project
So now that you know (almost) a lot about the normal functioning of the digestive system, it’s time to investigate some disorders!

20. Plagiarism Source all the materials you use!
In University if caught plagiarizing you will automatically receive a zero on the assignment with the potential of receiving a failing grade in the course or a suspension from the University!

21. http://www.youtube.com/watch?v=yQHx9W EfT-Y&safe=active

22. Small Intestine Small Intestine is 7 meters in length
Three parts to small intestine:
Duodenum – first cm Area of most digestion.
Jejunum
Ileum

23. When chyme enters the small intestine it stimulates the release of secretin and cholecystokinin by the duodenum walls.
Secretin regulates pH  inhibits gastric HCl production and stimulates bicarbonate ion secretion (pancreas) Cholecystokinin causes release of bile (gall bladder) and digestive enzymes (pancreas).
9 liters of chyme a day

24. Pancreas
Secretes pancreatic juice into the duodenum

25. Pancreatic juice contains:
Bicarbonate –
changes pH of chyme from highly acidic (pH 2) to weakly basic (pH 8)
Important pH for pancreatic enzymes to function

26. Enzymes
lipase - breaks down triglycerides into fatty acids and glycerol.

27. Protease – to digest proteins
Amylase – to digest carbohydrates
Nucleases – to digest nucleic acids

28. Insulin
Glucagon
Regulation of
blood glucose levels

29. Check your understanding!
What accessory gland produces a secretion with no digestive enzymes?
What kinds of foods are broken down by the pancreas?
Most enzymes are secreted as zymogens (inactive), why do you think that is?

30. Check your understanding!
Explain two functions of pancreatic fluid.
Someone recently has had a cholecystectomy, a surgical procedure to remove his gall bladder. Now he must take medication to prevent diarrhea. Why would the removal of the gall bladder cause diarrhea?

31. Endoscopy
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32. Mesentery Tissue that supports the intestinal tract.
A double layer of connective tissue in which blood vessels, nerves, lymphatics and other structures are contained.

33. Thin walls of small intestine with blood supply.
Mesentery

35. The intestines are held in place by a pair of membranes called the mesenteries (1). The mesenteric arteries run between these parallel membranes, and give rise to a vast number of tiny arteries (2) that take blood to the jejunum and ileum. These in turn break up into the thousands of arterioles that supply the villi and help to absorb food.
Near the base of the mesenteries is a row of white, fatty-looking bumps. These are lymph nodes on the lymph ducts that drain the lacteals. Since you take so much foreign material into your gut, it makes sense that you should have a strong line of defense against any invading microorganisms that might escape the digestive processes.

36. Adhesions often form following abdominal surgery or after an abdominal infection (peritonitis).

38. Peritonitis can also follow a penetrating abdominal injury.

39. Made up of three parts:
Duodenum
Jejunum
Ileum
Small Intestine

42. Segmentation
Smooth muscle contractions in both directions that mix and further break down contents of small intestine (chyme)
Is this mechanical or chemical digestion?

43. Absorption The small intestine absorbs the majority of nutrients
such as
The breakdown products of
Carbohydrates
Protein
Fats
Vitamins
Minerals
by active and passive mechanisms

44. Intestinal villi

46. Each villus contains blood capillaries and a lymph capillary (lacteal)
Each villus contains blood capillaries and a lymph capillary (lacteal). Each villus is covered with microvilli.

47. Microvilli – “brush border”  further increases surface area
Villi – tiny, finger-like projections on the walls of the small intestine
Microvilli – “brush border”  further increases surface area
Absorptive surface 185m !

48. Within villi structures are blood vessels that carry the absorbed nutrients to the rest of the body
Also contained in the villi are structures called lacteal, which absorbs fats to be delivered into the bloodstream

49. The liver and homeostasis
Almost all the blood circulating from the intestines to the heart passes through the liver. Therefore, everything you eat that gets into the bloodstream passes through your liver.

50. Liver
Almost all the blood circulating from the intestines to the heart passes through the liver.
The liver then either stores the nutrients absorbed or further metabolizes them

51. Other Liver Functions Regulate blood glucose levels (stores glycogen)
Breakdown and synthesis of lipids and fats
Protein breakdown and protein/non-essential amino acid synthesis
Stores vitamins (A, B12, D, K) and iron
Breaks down hormones, antibiotics, and other toxic substances (detoxifier)
Breaks down the by-products of RBC recycling
Note** these are main functions. Liver is thought to do about 500 separate functions
Removes effect of poison

52. The Colon (AKA large intestine)

53. Water absorption 9 liters of water every day in digestive juices.
Over 90% of water is reabsorbed! If not enough water is reabsorbed an individual will experience diarrhea. If too much water is absorbed an individual will experience constipation.

54. Chemical Digestion
Indigestible food matter (e.g. cellulose) is digested by enteric bacteria (ex. E. Coli) that thrive in the large intestine.
These bacteria produce vitamin K and some B vitamins which are absorbed.

55. Appendix Vestigial organ  has lost function but retained structure
However, some scientists now think it does serve a function stores good bacteria to help repopulate gut after infection.

56. These wax models of human anatomy were made in the 19th century to help train doctors. They are now seen in the medical wing of this great museum in Vienna, (Wien).

57. Endoscopic view of appendix
Cecum

58. Rectum Connected to the sigmoid colon of the large intestine
Damp Mass of indigestible food remaining in large intestine is called FECES.
Temporarily stores feces before elimination (egestion)

59. Anus
The ending portion of the gastrointestinal tract in which feces (undigested food matter) leaves the body
Anal sphincter controls opening of anus.

60. Bowel Movement
Receptors in the walls of the large intestine give the central nervous system (brain) signals when a bowel movement is needed.
Some substances stimulate the bowel movements like caffeine.

61. Defecation to eliminate feces.

62. Check you understanding!!!
In your table groups discuss the major functions of the large intestine.

63. Main Functions of the Large Intestine
Water absorption
Absorption of vitamins produced by bacteria
Mass movements (defecation) – removes undigested food

64. Summary

65. Digestion Time Summary
50% of stomach contents emptied 2.5 to 3 hours
Total emptying of the stomach 4 to 5 hours
50% emptying of the small intestine 2.5 to 3 hours
Transit through the colon 30 to 40 hours
Digestion takes different lengths of time depending on the food being consumed. For healthy adults, it's usually between 24 and 72 hours.

66. Washing your hands is essential!
Bacteria
Food poisoning
Parasites
Worms (Tapeworms)
* All can be transferred
through the mouth!

68. The Bacteria in your Gut?
Good, bad or ugly?
Good √
E.coli helps you digest food that you could not digest otherwise.
Bad √
 The bacteria that help you out, also produce flatulence as a by-product. Gas is a normal part of digestion.
Ugly √
 Some bacteria cause food poisoning, resulting in severe stomach cramps, vomiting and diarrhea.

70. More important stuff...
Our bodies make two hormones that contribute to homeostasis.
GASTRIN: Releases gastric juice (HCl) and relaxes gastric sphincter.
SECRETIN: Help release bicarbonate ions that neutralize HCl.
Our pancreas also helps with homeostasis in regulating blood glucose.

72. Insulin and Glucagon in Digestive System
Two hormones secreted by pancreas.
Work with liver to control level of glucose in body (blood).
Insulin released after meal  allows cells to become permeable to glucose.
Excess glucose stored by liver as glycogen.
Can change back to glucose if blood glucose becomes too low  Glucagon

73. Check your understanding
What is the purpose of villi and microvilli as it pertains to absorption of nutrients ?
What role does the large intestine play in the body?
Are all bacteria in your G.I. tract bad ? Explain your reasoning.
Describe one negative feedback loop in the digestive system.