DIGESTION and ABSORPTION

1. DIGESTION and ABSORPTION Learning Objectives: • Understand the physical and chemical processes of digestion • Learn the function of each organ in the digestive system • Gain an understanding of common Gastrointestinal Disorders

3. NUTRIENT DIGESTION in the SMALL INTESTINE • The neutralization is important because the enzymes in the SI need a neutral environment • Pancreatic juice and secretions from the intestinal wall cells contain a variety of digestive enzymes that help to digest fats, carbohydrates, and proteins

4. NUTRIENT DIGESTION in the SMALL INTESTINE • BILE is released from the gall bladder upon the appearance of fat in the SI • BILE acts as an emulsifier, and without it, lipids might not come into contact with pancreatic lipase, and would not be properly digested

5. NUTRIENT DIGESTION in the SMALL INTESTINE • With pancreatic and intestinal enzymes working together, digestion creates smaller compounds of protein, fat, and carbohydrate which can then be easily absorbed • Minerals, vitamins, and cholesterol are not broken down and are generally absorbedunchanged

6. NUTRIENT ABSORPTION in the SMALL INTESTINE • Most absorption occurs in the SI – 90% • Provides the surface area equivalent to a tennis court! • Nutrients are trapped in folds of the intestinal wall and absorbed through the microvilli • Each villus contains blood vessels and a lymph vessel which transport nutrients

8. NUTRIENT ABSORPTION in the SMALL INTESTINE • Water-soluble nutrients are absorbed directly into the bloodstream • Fat-soluble lipid compounds are absorbed into the lymph rather than the blood

10. NUTRIENT ABSORPTION in the SMALL INTESTINE • Duodenum and Upper Jejunum: most minerals (except sodium, chloride, and potassium) • Jejunum and Upper Ileum: carbohydrates, amino acids, water-soluble vitamins • Jejunum: lipids and fat-soluble vitamins • Terminal Ileum: Vitamin B12

11. LARGE INTESTINE • Is ~ 5 feet long and includes the cecum, colon, rectum, and anal canal

13. NUTRIENT DIGESTION in the LARGE INTESTINE • Little digestion occurs in the large intestine • The large population of bacteria digests small amounts of fiber • This bacterial activity forms: Vitamin K, Vitamin B12, Thiamin, Riboflavin, Biotin, and gases

14. NUTRIENT ABSORPTION in the LARGE INTESTINE • Little absorption occurs in the large intestine • However, it does absorb: water, sodium, potassium, chloride, and some of the Vitamin K produced by bacteria • It does not absorb Vitamin B12

15. Healthy Bacteria • Probiotics are live microorganisms (in most cases, bacteria) that are similar to beneficial microorganisms found in the human gut. • Probiotics are available to consumers mainly in the form of dietary supplements and foods. • Look for “live and active cultures”. The good bacteria most often comes from two groups: Lactobacillus or Bifobacterium.

16. Prebiotics are not digested in the SI, and are used as food by bacteria

17. NUTRITION and GI DISORDERS CONSTIPATION • Occurs when the colon absorbs too much water, or if the colon’s muscle contractions are slow and sluggish • CAUSES: • Not enough liquids in the diet • Not enough fiber in the diet • Sedentary lifestyle • Some medications • Abuse of laxatives • TREATMENT?

18. NUTRITION and GI DISORDERS DIARRHEA • Occurs when the colon absorbs too little water • CAUSES: • Most common: infection from bacteria, viruses, or parasites • Antibiotics • Chronic diarrhea may signal a more serious medical problem (Inflammatory Bowel Disease) • TREATMENT • BRAT diet (bananas, rice, applesauce, toast) • Rehydrate and replace electrolytes

19. NUTRITION and GI DISORDERS Gastroesophageal Reflux Disease • Basically, chronic “heartburn” CAUSES: • Hiatal Hernias • Foods that relax the lower esophageal sphincter (LES) • Frequently occurs in people with asthma, irritable bowel syndrome, and developmental disabilities • Concern because of increased risk of esophageal cancer

22. TREATMENT • Avoid foods that relax the LES • Don’t lie down or exercise too soon after eating, raise the head of the bed • Wear loose fitting clothing • Medications

23. NUTRITION and GI DISORDERS DIVERTICULOSIS • Result of rising pressure in the colon, believed to be caused by low-fiber diet and constipation DIVERTICULITIS • Infected or inflamed diverticulum (fecal matter or bacteria gets trapped) • May experience abdominal pain, indigestion, fever • Diverticulum may rupture causing infection, or can form scar tissue and create an obstruction

25. Diverticulosis/itis • TREATMENT • Diverticulosis – high fiber diet • Diverticulitis – low fiber diet

26. NUTRITION and GI DISORDERS IRRITABLE BOWEL SYNDROME • Disorder that interferes with normal functions of the colon. Symptoms are abdominal pain, bloating, constipation, and diarrhea • People with IBS have more sensitive colons and react more strongly to: stress, large meals, certain foods, caffeine, or alcohol • Diagnosed by symptoms and the absence of other diseases • TREATMENT • Reduce stress • Change diet • Medications

27. NUTRITION and GI DISORDERS ULCERS CAUSES: • Helicobacter pylori infection (most common), chronic use of anti-inflammatory drugs, and disorders that cause excessive gastric acid secretion • Not caused by spicy foods or stress

29. TREATMENT • Antibiotics • Medications (acid suppressors)

30. NUTRITION and GI DISORDERS LACTOSE INTOLERANCE CAUSES: • Inability to digest lactose, caused by a shortage of lactase • Symptoms: nausea, cramps, bloating, gas, and diarrhea • TREATMENT • Don’t eat dairy products! Or eat less, and more processed types (ex. Yogurt vs. milk )