Digestive System - Unit 3 PDF
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This document provides an overview of the digestive and respiratory systems. It details the different organs and processes involved in digestion and respiration, along with a set of activities and diagrams. The text is organized into sections, touching upon the mouth, stomach, intestines, and a breakdown of related functions.
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Unit 3: 1. The nutrition function ====================== 2. 1. 2. 3. 4. 5. 3. Respiratory system ================== 6. 7. +-----------------------+-----------------------+-----------------------+ | | | | +...
Unit 3: 1. The nutrition function ====================== 2. 1. 2. 3. 4. 5. 3. Respiratory system ================== 6. 7. +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | a. What is the | | | | function of the | | | | digestive system? | | | | And the function | | | | of the | | | | respiratory | | | | system? | | | | | | | | b. c. d. | | +-----------------------+-----------------------+-----------------------+ Nutrition function ================== - **The digestive system**. It processes and transforms food to obtain nutrients which cells are able to assimilate. - **The respiratory system**. It obtains oxygen from air and expels carbon dioxide from the vital activity. - **The circulatory system**. Its function is to distribute nutrients and oxygen throughout the body and collets the waste substances and carbon dioxide from cells. - **The excretory system**. Its function is to expel the waste substances out of the body. #### ACTIVITIES 1. **Nutrients are essential substances which living beings need to stay alive. Where can they find them?** 2. 3. Digestive system ================ Parts of the digestive system: ------------------------------ - **Digestive tract**. It is a long tube differentiated in several parts: mouth, pharynx, oesophagus, stomach, small intestine, large intestine and anus. It is formed by three layers of tissue: *mucosa* (the internal layer, very folded and lined with glands), *muscularis* (the middle layer formed by two layers of smooth muscle) and *serosa* (the connective tissue layer that joins the digestive tract to other organs) - **Digestive glands**. They secrete digestive juices into digestive tube (salivary glands, gastric glands, intestinal glands, liver and pancreas) b. Digestive functions: -------------------- - - **Digestion.** It is the transformation of food into simple nutrients which can be absorbed and used by cells. We can distinguish two types of processes: - -  - - #### ACTIVITIES 4. 5. 6. 7. a. Mouth: the beginning of digestion --------------------------------- ### Mastication (Chewing)  +-------------+-------------+-------------+-------------+-------------+ | INCISOR | Flat and | | | | | | sharp | | | | +-------------+-------------+-------------+-------------+-------------+ | CANINE | Conical and | | | | | | pointed | | | | +-------------+-------------+-------------+-------------+-------------+ | PREMOLAR | Wide and | | | | | | flat | | | | | | | | | | | | (2 | | | | | | protuberanc | | | | | | es) | | | | +-------------+-------------+-------------+-------------+-------------+ | MOLAR | Wide and | | | | | | flat | | | | | | | | | | | | (3 or 4 | | | | | | protuberanc | | | | | | es) | | | | +-------------+-------------+-------------+-------------+-------------+ ### Insalivation - - ### Deglutition (Swallowing) - -  #### ACTIVITIES 8. 9. 10. The stomach: the gastric digestion ---------------------------------- - **Cardia** connects with oesophagus and prevents food bolus goes back. - **Pylorus** separates the stomach from the duodenum and prevents that non-digest food passes into the small intestine. a. - - - It activates *pepsinogen* because reduce the pH (about 2), making the chemical environment very acid. It is transformed in *pepsin* (active enzyme) - - - b. #### ACTIVITIES 11. 12. 13. Intestinal digestion ==================== Small intestine --------------- - - - - - a. b. Pancreas -------- - - - - Sodium bicarbonate (neutralizes chyme acid and makes pH very alkaline, about 9, providing an optimal environment to enzymes work) Liver --------------------------- - Storage glycogen (polysaccharide formed by many molecules of glucose) - - - - - Bile acids (they emulsify lipids, break down large fat drops into small ones which are easier to attack by enzymes) - #### ACTIVITIES 14. b. c. d. 15. Intestinal absorption ============================================ - Monosaccharides and amino acids, mineral salts, water-soluble vitamins and water pass to **blood** - Fatty acids and glycerine, and fat-soluble vitamins pass to **lymph** #### ACTIVITIES 16. 17. The large intestine =================== - **Cecum**. It is the initial portion, separated from ileum by a valve. Joined to it, there is the appendix, a small blind prolongation. - **Colon.** It is the middle and largest portion. It is divided into: ascending, transverse descending and sigmoid colon. - **Rectum**. It is de final portion which ends in the anus, a double sphincter that controls defecation. - - The longitudinal muscle layer is limited to three bands (teniae coli) that create pouches (haustra) along the colon. #### ACTIVITIES 18. 19.
