Chapter 23 The Gastrointestinal System

1. Chapter 23 The Gastrointestinal System

2. Figure 23.1 The digestive system.

3. Main Organs of the Digestive System • Mouth • Esophagus • Pharynx • Stomach • Small intestine • Large intestine

4. Accessory Organs of the Digestive System • Teeth • Tongue • Salivary glands • Liver • Gallbladder • Pancreas

5. Physiology of the Digestive System • A series of hollow organs connected in a long tube • Extends from the mouth to the anus • Lined with protective mucosa that prevents acid from causing sores or ulcers

6. Physiology of the Digestive System (cont.) • In the mouth, stomach, and small intestine, the mucosa also contains tiny glands that produce the liquid digestive juices that help digest food • Other organs, such as the liver and pancreas, also produce products that aid in digestion

7. Three Categories of Nutrients • Macronutrients—nutrients that the body requires in larger quantities • Carbohydrates • Proteins • Fats (lipids) • Micronutrients—nutrients that the body requires in small quantities • Vitamins • Minerals

8. Three Categories of Nutrients (cont.) • Water—an indispensable component of the body

9. Carbohydrates • Break down into monosaccharides during digestion • Provide immediate energy • Most readily available sources of food energy • AMDR for carbohydrates—45 to 65 percent of daily caloric intake

10. Proteins • Break down into amino acids during digestion • The body uses amino acids to make and repair: • Body cells • Tissues • Muscle • AMDR for protein—10 to 35 percent of daily caloric intake

11. Fats (Lipids) • Break down into fatty acids and glycerol • The body uses fats or lipids to: • Provide lubrication • Store fat as an energy reserve • Store fat as insulation to provide warmth • Provide a cushion that act as a shock absorber to protect vital organs • Help metabolize carbohydrates and proteins more efficiently • Carry fat-soluble vitamins A, D, E, K

12. Fats (Lipids) (cont.) • AMDR for fats—20 to 35 percent of daily caloric intake • Not more than 10 percent of calorie intake should be saturated fat

13. Amino Acids • The body can produce 11 types of amino acids, referred to as nonessential • There are 9 types of amino acids that the body requires, but cannot produce • These are referred to as essential amino acids • Essential amino acids have to be derived from food intake

14. Table 23.9 Essential and Nonessential Amino Acids

15. Vitamin A (Retinol) • Helps with eyesight and epithelial cells and tissues (skin cells) • Deficiencies in vitamin A may cause: • Night blindness • Xerosis (dryness) of the conjunctiva and cornea • Xerophthalmia and keratomalacia • Keratinization of lung, GI tract, and urinary tract • Increased susceptibility to infections

16. Vitamin A (Retinol) (cont.) • DRI is 900 µg/day for males and 700 µg/day for females

17. Vitamin D • Helps with the absorption of calcium from the intestine to make stronger bones and teeth • Deficiency causes metabolic bone softening: • Called rickets in children • Called osteomalacia in adults

18. Vitamin D (cont.) • DRI is 5 µg/day (ages 19–50) for both males and females • DRI is 10 µg/day (ages 51–70) for both males and females

19. Vitamin E • A strong antioxidant for lipids • Deficiency is generally caused by malabsorption rather than lack of ingestion

20. Vitamin E (cont.) • Vitamin E deficiency may cause: • Disorders of the reproductive system • Abnormalities of muscle, liver, and bone marrow • Hemolysis of RBCs • Defective embryo genesis • Brain dysfunction • A disorder of capillary permeability • DRI is 15 mg/day for both males and females

21. Vitamin K • Necessary for blood coagulation • Controls formation of coagulation factors II, VII, IX, and X in the liver • Also needed for calcium uptake in bones • Can be used as an antidote for coumadin overdoses • Deficiency is rare • DRI is 120 µg/day for males and 90 µg/day for females

22. Vitamin B1 (thiamine) • Necessary for carbohydrate metabolism • Deficiency causes the disease beriberi • Affects the peripheral neurologic, cerebral, cardiovascular, and GI systems • DRI is 1.2 mg/day for males and 1.1 mg/day for females

23. Vitamin B2 (riboflavin) • Necessary for the health of the mucous membranes in the digestive tract • Aids absorption of iron and vitamin B6

24. Vitamin B2 (riboflavin) (cont.) • Deficiency leads to: • Oral, eye, skin, and genital lesions • Dizziness • Hair loss • Insomnia • Light sensitivity • Poor digestion • Retarded growth • Slow mental responses • Burning feet

25. Vitamin B2 (riboflavin) (cont.) • DRI is 1.3 mg/day for males and 1.1 mg/day for females

26. Vitamin B3 (niacin) • Important in oxidation-reduction reactions • Vital in protein metabolism • Deficiency leads to the disease pellagra: • Affects skin, mucous membranes, GI, and brain/CNS systems • Causes photosensitive rash, scarlet stomatitis, glossitis, diarrhea, and mental aberrations

27. Vitamin B3 (niacin) (cont.) • Deficiency found in diets high in corn • DRI is 16 mg/day for males and 14 mg/day for females

28. Vitamin B5 (pantothenic acid) • Important for secretion of hormones such as cortisone • Important for maintenance of healthy skin, muscles, and nerves • B5 deficiency extremely rare

29. Vitamin B5 (pantothenic acid) (cont.) • Symptoms of B5 deficiency include: • Insomnia • Depression • Nausea • Headache • Muscle spasm • DRI is 5 mg/day for both males and females

30. Vitamin B6 (pyridoxine) • Needed for: • Red blood cell formation • Antibody production • Cell respiration • Cell growth • Conversion of tryptophan to niacin • Helps convert stored carbohydrate to glucose to maintain normal blood sugar levels • Synthesis of neurotransmitters such as serotonin and dopamine

31. Vitamin B6 (pyridoxine) (cont.) • Deficiency can cause: • Anemia similar to iron-deficiency anemia • Decreased antibody production • Suppressed immune response • Symptoms such as dermatitis, a sore tongue, depression, confusion, and convulsions

32. Vitamin B6 (pyridoxine) (cont.) • DRI is: • 1.3 mg/day for males and females aged 19 to 50 • 1.7 mg/day males and 1.5 mg/day for females over the age of 51

33. Vitamin B9 (folic acid) • Important for: • Energy production • Formation of red blood cells • Strengthening immune system • Promoting healthy cell division and replication • Protein metabolism • Preventing depression and anxiety

34. Vitamin B9 (folic acid) (cont.) • Deficiency can be serious and may result in: • Anemia • Apathy • Digestive disturbances • Fatigue • Growth impairment • Insomnia

35. Vitamin B9 (folic acid) (cont.) • Deficiency can be serious and may result in: • Labored breathing • Memory problems • Paranoia • Weakness • DRI is 400 µg/day for both males and females

36. Vitamin B12 (cyanocobalamin) • Needed for healthy nerve cells, to make DNA, and for the formation of RBCs • Deficiency leads to irreversible nerve damage • Signs and symptoms include:

37. Vitamin B12 (cyanocobalamin) (cont.) • Signs and symptoms include: • fatigue • weakness • nausea • constipation • flatulence • loss of appetite • weight loss

38. Vitamin B12 (cyanocobalamin) (cont.) • Signs and symptoms include: • difficulty in maintaining balance • depression • confusion • poor memory • soreness of the mouth or tongue • DRI is 2.4 µg/day for both males and females

39. Vitamin C (ascorbic acid) • Antioxidant • Essential for collagen formation • Maintains integrity of connective tissue, bone, and teeth • Important for wound healing and recovery from burns • Helps the absorption of iron

40. Vitamin C (ascorbic acid) (cont.) • Severe deficiency results in scurvy: • Characterized by general weakness, bleeding gums, anemia, and skin bleeding • The DRI is 90 mg/day for males and 75 mg/day for females

41. Water • 60% of an adult’s body weight is water • Forms a major portion of every tissue • Provides the medium in which most of the body’s activities are conducted • Facilitates many of the metabolic reactions that occur in the body • Helps transport vital materials to the cells • Vehicle in which glycogen is transported into muscle cells