Structures and Functions Science and Technology.pptx

structure and function

1. STRUCTURES AND FUNCTIONS: FOCUS ON THE DIGESTIVE SYSTEM Organs of the digestive system and their interaction with organs of the respiratory, circulatory, and excretory systems

2. MOTIVATION “Complete me! Construct me”

3. OBJECTIVES At the end of the lesson, the students must have: 1 . Described the coordinated functions of the organs of the digestive system. 2. Valued the important roles of enzymes in digesting food. 3. Locate the organs which are parts of the digestive system.

4. VIDEO PRESENTATION

5. WHAT DO YOU KNOW ABOUT “DIGESTIVE SYSTEM”?

6. DIGESTIVE SYSTEM is concerned to the system that makes food absorbable into the body.

7. DIGESTIVE SYSTEM Man’s digestive system has functions which basically involve the following processes 1) Ingestion or taking in food into mouth , 2) digestion and 3) absorption that refer to the processing of food into a form that will be assimilated into living cells and lastly 4) excretion or eliminating indigestible substances and certain wastes through the anus .

8. DIGESTIVE SYSTEM What enables man’s digestive system to perform such multifold functions? To carry out its numerous functions, man’s digestive system consists of the digestive tract or food tube and the so-called accessory digestive glands .

9. DIGESTIVE SYSTEM Suppose you are trapped in a place where there is no food and water. How long will you live? What will you do to survive? Have you gone to school without eating your breakfast? What do you feel? Can you understand your lessons well? Suppose you have a surprise quiz. Can you think well of the answer?

10. DIGESTIVE SYSTEM Food and digestion fuel the body to make it move, just as gasoline fuels the car to make it run. This also includes all parts of your body from the cellular level to enable them to perform their specific functions. Without food, you are like a car without fuel .

11. DIGESTION Digestion is the process by which the complex food taken into the body is transformed into simpler molecules that can pass through the cell membrane so the body can use them. The food that you eat – like fruits, vegetables, fish, meat or rice cannot be used directly by the body . The cells cannot absorb them.

12. DIGESTION Large molecules of carbohydrates and proteins are first changed to simpler molecules like amino acids, simple sugars, fatty acids and glycerol before they can pass through the cell membranes. This is made possible by the process of digestion with the aid of special protein molecules called enzymes. They act as catalysts that speed up the chemical reactions.

13. DIGESTION Digestion can be intracellular and extracellular . Intracellular digestion takes place inside a cell while extracellular digestion takes place outside the cell but inside the digestive cavity or digestive system . Digestion may also be complete or incomplete . Incomplete digestive system takes place in animals without anus.

14. DIGESTION Man’s digestive tract or food tube is about nine meters long , extending from the mouth down to the anus . It is a continuous tube of varying diameter and length.

15. MAN’S FOOD TUBE

16. MOUTH CAVITY Mouth cavity or digestive cavity . The mouth serves as the entrance of food . Inside the mouth are teeth, tongue and salivary glands .

17. MOUTH CAVITY The teeth cut and chew the food into small pieces . The tongue manipulates the food for better chewing action and mixes it with saliva which contains an enzyme. The back part of the tongue secretes mucus which lubricates the food and, thus, makes swallowing easier . Then it pushes the food particles to the pharynx , the funnel-shaped end of the mouth of the cavity that leads to the esophagus.

18. ESOPHAGUS Esophagus is a moist, muscular tube that connects the pharynx to the stomach . It delivers food to the stomach . From the mouth, the swallowed food is pushed down the food tube by a series of rhythmic wavelike contractions of the muscles of the esophagus. This muscular activity is called peristalsis . The food stays for a while at the lower end of the esophagus.

19. ESOPHAGUS The cardiac sphincter , a circular muscular valve at the upper end of the stomach , relaxes to allow the food into the stomach.

20. STOMACH Stomach is the saclike, most expanded portion of the food tube . The inner surface of the stomach is highly folded, allowing it to collapse when empty and expand as food fills it. Thus it can expand to hold as much as two to four liters of food and liquids when full . The walls of the stomach contain gastric glands that secrete substances for a preliminary digestion of food.

21. STOMACH As the food enters the stomach, another circular valve muscle called the pyrolic sphincter at the lower end of the stomach remains closed . After about two hours, the pyrolic sphincter relaxes. The partly digested food gradually leaves the stomach and enters the small intestine.

22. SMALL INTESTINE Small Intestine has three parts namely duodenum, jejunum and ileum . The upper part of the small intestine has a wider diameter while its lower potion has narrower diameter is highly coiled. Duodenum or the upper part receives the partly digested food mass from the stomach, digestive juice from the pancreas and bile from the liver and gall bladder . Meanwhile, absorption of fully digested food mass takes place at lower portion of the small intestine . The wall of this organ is covered with very tiny projections called intestinal villi (singular villus). They increase the absorbing capacity of the small intestine . Undigested food with other wastes pass on to large intestine by peristaltic action.

23. LARGE INTESTINE Large Intestine is also known as colon , this organ is referred to a large intestine because of its large diameter . Based on its position, the parts of the large intestine are ascending colon, transverse colon and descending colon. The last part of the large intestine ends into a short tube called rectum that leads to the lower opening of the food tube, the anus. The large intestine has no villi and is not as highly coiled as the small intestine.

24. LARGE INTESTINE In the large intestine, the undigested food passed on by the small intestine undergoes decomposition by bacterial action. The resulting refuse materials (called feces ), are compacted and stored temporarily in the large intestine. Defecation or bowel movement is the process by which the feces are being propelled out of the body. A sphincter controlled by the brain allows conscious effort to delay defecation.

25. ACCESSORY DIGESTIVE GLANDS Accessory Digestive Glands. There are certain organs that are associated with the food tube because they produce secretions that aid digestion. Known as accessory digestive glands, they include salivary glands, liver and pancreas . These digestive glands secrete saliva which contains a starch-digesting enzyme called salivary amylase or ptyalin . This enzyme changes starch into a double sugar called maltose. The liver is the largest accessory digestive gland in the body. It produces a yellow-green liquid called bile which is stored in the gall bladder . Meanwhile, the pancreas secretes pancreatic juice that contains digestive enzyme.

26. ACCESSORY DIGESTIVE GLANDS

27. VALUING If you were given a chance to have an enzyme that will speed up your success, will you accept it or not? Why?

28. APPLICATION Locate the organs which are part of the digestive system.

29. GENERALIZATION Supply the following : Ingestion means … Digestion and absorption refer to … Excretion is … Organs of digestive system starts with … followed by …

30. EVALUATION What are the functions of these organs?

31. AGREEMENT For your assignment, study some diseases of the digestive system. References: Science and Technology; pp. 215-220