1. The Digestive System

2. Small Intestine Longest part of alimentary canal (13-23 feet!)
Goes from pyloric sphincter to ileocecal valve
Mesentery helps support it in place
Bile and pancreatic enzymes meet to finish chemical digestion
Most food digestion and absorption takes place here
Food spends about 3-5 hours here

4. Divisions of Small Intestine
Ileocecal valve
Split between small & large intestine
Dogs Just Itch!
Duodenum
Attached to the stomach
Curves around the head of the pancreas
Where bile & pancreatic enzymes enter
Jejunum
Middle portion
Ileum
Last portion

6. Small Intestine Pancreatic Ducts Bile Duct
Emit pancreatic enzymes from pancreas to help with chemical digestion
Bile Duct
Emits bile from liver/gallbladder to help with chemical digestion

8. Small Intestine Microvilli / Villi / Circular Folds
Structures that help to increase surface area to help in absorption of nutrients into bloodstream

9. Small Intestine Peyer’s patches
Lymphatic tissue that prevents bacteria in digesting food from entering bloodstream

10. Large Intestine
Larger in diameter, shorter in length (approx. 5 feet in length)
Extends from ileocecal valve to anus
Dries out indigestible food residue by absorbing water, and eliminates from body as feces
Haustra (pouches) contract to move food along
Food spends about hours here!

12. Large Intestine Cecum First part of large intestine Looks like a pouch
Has “appendix” hanging off
Provides a place for bacteria (good and bad!) to accumulate. If too much accumulates, you can develop appendicitis.

15. FYI: The Appendix
The appendix has provided a lot of uncertainty among the medical community! While some believe it is a remnant of embryological development, others believe it is a safe-haven for beneficial bacteria. If illness takes over and digestive bacteria are flushed out (via diarrhea), the appendix can provide a place for “replacement” bacteria to be stored.

16. Colon Ascending Colon Transverse Colon Descending Colon
Travels up right side from cecum to right colic flexure
Transverse Colon
Travels across abdominal cavity to left colic flexure
Descending Colon
Travels down left side to sigmoid colon

19. Large Intestine Sigmoid Colon Rectum / Anal Canal / Anus
S-shaped part of Large Intestine in pelvis, curves to form the rectum
Rectum / Anal Canal / Anus
End of the large intestine
Anal canal has sphincters to help open anus during defecation
Anus opens to exterior

22. Goblet Cells
Large Intestine doesn’t need villi – no absorption of nutrients happens here!
However, does have goblet cells
Produce mucus to help in the passage of dried-out feces

24. Accessory Digestive Organs
Assists Alimentary Canal in digestive process
Includes…
Salivary glands
Teeth
Pancreas
Liver
Gallbladder

25. Salivary Glands Salivary Glands Empties saliva into mouth
Saliva is 98% water, containing enzymes & bacteria inhibitors
Moistens & helps food to bind together (bolus)
Salivary Amylase enzyme begins digestion (starch)
Saliva also lubricates & protects teeth, tongue, and mouth tissue
Three pairs of salivary glands include…

26. Salivary Glands
Parotid glands
Submandibular glands
Sublingual glands

28. Teeth
Teeth
Job of teeth is mastication (chewing) - mechanical breakdown of food
Complete the actions of cutting, tearing, and grinding

29. Pancreas
Gland that produces a wide spectrum of digestive enzymes that break down all categories of food
Enzymes are secreted into the duodenum (first part of small intestine)
Alkaline (basic) fluid introduced with enzymes neutralizes acidic chyme
Endocrine products of pancreas include:
Insulin
Glucagons
(we’ll talk about these with the endocrine system!!!)

30. Liver Largest gland in the body
Located on the right side of the body under the diaphragm
Consists of four lobes suspended from the diaphragm
Main job is to produce bile

32. Bile Produced by cells in the liver Composition
Bile salts
Bile pigments (bilirubin – dead RBC’s – what makes feces brown!)
Cholesterol
Phospholipids
Electrolytes
Only bile salts and phospholipids aid digestive process
Emulsify fats by breaking them down into smaller pieces, providing more surface area for enzymes to work on

33. Gallbladder
Liver connected to the gall bladder via the common hepatic duct
Sac found in inferior surface of liver
Stores bile from the liver & concentrates it by removal of water
Bile is introduced into the duodenum through the bile duct in the presence of fatty food
If bile stored for too long, or if too much water is removed, gallstones can form

35. Digestion
The entire process of digestion can take anywhere from hours
Most of this time will be spent in the small intestine
Ingestion of approximately 2000 mL of food & drink will result in the defecation of approximately 150 mL of feces

36. Absorption of water and nutrients
(goblet cells)
Absorption of water

37. Chemical Digestion: Carbohydrates
Break down into simple sugars (monosaccharides, such as glucose)
Remember, carbs are polysaccharides!
Digestion:
In Mouth: salivary amylase digests starches
In Small Intestine: Pancreatic enzymes, and additional secretions from walls of small intestine continue breakdown

38. Chemical Digestion: Proteins
Break down into amino acids
Digestion:
In Stomach: HCl causes proteins to denature (untangle), Pepsin begins breakdown process
In Small Intestine: Pancreatic enzymes continue breakdown

39. Chemical Digestion: Fats
Broken down into fatty acids and glycerol
Digestion:
In Small Intestine: Bile salts help to emulsify large fats, Pancreatic enzymes breaks down the fats into smaller components

40. Chemical Digestion: Fats

41. Role of Bacteria
The bacterial flora of the large intestine consist of:
Bacteria surviving the small intestine that enter the cecum and
Those entering via the anus
These bacteria:
Colonize the colon
Ferment indigestible carbohydrates
Release gases (flatus – methane and hydrogen sulfide)
Synthesize vitamins B and K

43. Conditions of the digestive system Gastric Surgery for weight loss
Gastric Band: An inflatable band is placed around the stomach to create a small pouch.
Roux En Y: Stomach is now a small pouch and can hold only 1 ounce of food at a time.

44. Diverticulitis
Small pouches in the large intestine become clogged and inflamed with bacteria & feces.
Typically treated with antibiotics however sometimes may need surgery to remove infected gut.

45. Bowel Obstruction
Partial or complete blockage of the small or large bowel.
Causes: severe constipation, tumors, scar tissue, or twisting or narrowing of the intestines.
Treatment: Laxatives or surgery

46. Ulcerative Colitis/ Crohn’s Disease
Disease of the intestines causing ulcers & inflammation.
Ulcerative Colitis is less invasive and only affects the large intestine
Crohn’s disease is more severe and can cause ulcers throughout the digestive tract.

47. Gastric Ulcers Also known as peptic ulcer.
Inflammation in either the stomach or the duodenal mucosa, with extension beyond the submucosa into the muscularis mucosa.
Most commonly caused is bacteria called Helicobacter pylori.
Other causes include medication induced or increase production of gastric secretions.

48. Alternative Nutrition
Enteral Nutrition:
Also known as tube feeding
Given via a tube through the mouth/nose/stomach and extends into either the stomach or intestines.
Special formulas used containing all nutrients.
“If the gut works, use it” But if it doesn’t work use Total Parental Nutrition (TPN)
Nutrition via blood.

49. Celiac Disease
Sometimes called “Slick Gut” because the lining of the small intestines becomes so inflamed food is unable to be absorbed and passes right through
Inflammation is caused by an allergy to gluten, a protein found in wheat.
Treatment: AVOID WHEAT! The following foods contain wheat: Bread, Pasta, Oats, Barley, Cookies, Cakes, Most Cereals, Most Processed Foods, Many Spices… And many more…