Digestive system

Digestion of Food

1. BY- NIHARIKA VERMA DIGESTIVE SYSTEM

2. DIGESTIVE SYSTEM The digestive system is a group of organs working together to convert food into energy and basic passes, through along tube inside the body known as the Alimentary canal or the Gastro intestinal tract (GIT Tract). Parts of Digestive System  Salivary Glands, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine, Rectum, Liver, Gall bladder, Pancreas (pancreatic juice). Accessory Digestive Organs- Liver(produce gastric juice/bile), Gall bladder (store gastric juice/bile). Digestion time varies between individuals and between men and women. After you eat, it takes about six to eight hours for food to pass through your stomach and small intestine. Food then enter your large intestine (colon) for further digestion, absorption of water and finally elimination of undigested food.

3. FUNCTIONS OF DIGESTIVE SYSTEM ESOPHAGUS- Carries food from the mouth to the stomach. STOMACH- The organ where digestion of protein begins. SMALL INTESTINE- The organ where most digestion occur. LARGE INTESTINE- Also called colon. It absorbs water and sodium from stool. APPENDIX- A pouch attached to the first part of the large intestine. No one can know its function. LIVER- The largest organ inside the body. Makes bile (fluid that helps break down fats and gets rid of wastes in the body). Changes food into energy and cleans alcohol, some medicines and poisons from the blood. GALL BLADDER- Stores the bile made in the liver, then empty it to help digest fats.

4. PANCREAS- A gland that makes enzymes for digestion and the hormone insulin (which helps the body) turn food into energy. RECTUM- The lower end of large intestine leading to the anus. ANUS- The opening at the end of the digestive tract where bowel movements leave the body.

5. THE DIGESTIVE PROCESS 1. The start of the process  The Mouth- The digestive process begins in the mouth. Food is partly broken down by the process of chewing and by the chemical action of salivary enzymes (these enzymes are produced by the salivary glands and break down the starches into smaller molecules). 2. On the way to the stomach  The Esophagus- After being chewed and swallowed, the food enters the esophagus, the esophagus is a long tube that runs from the mouth to the stomach. It uses rhythmic, wave like muscle movement (called Peristalsis) to force food from the throat into the stomach. This muscle movement gives us the ability to eat or drink even when we are upside down.

6. 3. In the stomach  The stomach is a large, like organ that churns the food and bathes it in a very strong acid (gastric acid). Food in the stomach that is partly digested and mixed with stomach acids is called Chyme . After being in the stomach, food enters the duodenum, the first part of the small intestine. It then enters the jejunum, and then the ileum (the final part of the small intestine). In the small intestine, bile (produced in the liver and stored in the gall bladder), pancreatic enzymes and other digestive enzymes produced by the inner wall of the small intestine help in the breakdown of food. 4. In the large intestine  After passing through the small intestine, food passes into the large intestine. In large intestine, some of the water and electrolytic (chemical, like sodium are removed from the food). Many microbes (bactericides, lactobacillus, acidophilus, E coli) in the large intestine help in digestive process. The first part of the large intestine is called the Cecum ( the appendix is connected to the cecum ). Food then travels upward in the ascending colon.

7. FUNCTION OF DIGESTIVE SYSTEM LIVER (ACCESSORY ORGANS) GALL BLADDER (ACCESSORY ORGANS) PANCREAS LARGE INTESTINE APPENDIX ESOPHAGUS STOMACH SMALL INTESTINE RECTUM ANUS

8. QNA Carbohydrates turned into  GLUCOSE Protein turns into  AMINO ACIDS Fats and oils are turned into  FATTY ACIDS AND GLYCEROL Salivary _GLANDS_ begins digestion of starch. Is bile is an enzyme?  NO The Gastrointestinal Tract  ORGANIZATION: MOUTH – ANUS Accessory Organs  SALIVARY GLANDS, LIVER, PANCREAS, GALL BLADDER Overview of Digestion  PHYSICAL MOVEMENT- Peristalsis, Segmentation  CHEMICAL REACTION- Enzymes, Other Secretions.

9. Physical Digestion The food we eat consists of large lumps of material. We must bite off small pieces and chew them up into even smaller ones before swallowing them. Once it gets to the stomach the food is further broken down by the stomach muscular walls. This is Physical Digestion.

10. Chemical Digestion But the substances which our body needs cannot be absorbed into our blood until they have been broken down further- converted into small soluble chemicals. This is done with the aid of enzymes and other chemicals in our gut, and is called Chemical Reaction.

11. DIGESTIVE ENZYMES The enzymes in our digestive system break down complex substances into simpler ones which can be absorbed. Enzymes work best at their optimum PH, so if the stomach, for example, does not have enough acid, its enzyme, pepsin, will not work properly. DIGESTION AND ABSORPTION Small intestine  sections of small intestine – Duodenum, Jejunum, Ileum.

12. DIGESTION Bicarbonate neutralizes stomach acid. Pancreatic and intestinal enzymes – Carbohydrates, Fat, Protein DIGESTION AND ABSORPTION Small Intestine – ABSORPTION - Folds, villi , microvilli expand absorptive surface. Most nutrients absorbed here. Fat soluble nutrients go into lymph. Other nutrients into blood.  Large Intestine – DIGESTION Nutrient Digestion already complete. Some digestion of fiber by bacteria. - ABSORPTION -Water Sodium, potassium, chloride Vitamin K (produced by bacteria)

13. SALIVARY GLANDS Salivary glands are a group of organ present in our mouth that secrets saliva. It is found in mammals only. It is an exocrine gland that secrets substances outside the body or within a body cavity. Saliva contains various chemicals with water including mucus, salts, anti bacterial substances, enzymes and chemicals that control Ph in the mouth.

14. FUNCTIONS OF SALIVARY GLANDS Saliva is a mixture of water, mucus, anti bacterial substances, and digestive enzymes. Therefore, saliva has many uses. One of the digestive enzyme alpha- amylase helps to break down the starch present in our food into a simpler one like glucose and maltose. Whenever we chew, we attractive these glands to secrete an enzyme to breakdown the food. Saliva has lubricating properties- It protects the inside cavity of our mouth, teeth, and throats as we begin to swallow the food bolus. It also cleanses the mouth after the meal and dissolves it into chemicals that we perceive as taste. Parotid gland is the largest salivary gland.