Digestive System in grade 8 students.pptx
- 1. Directions: Use the words found inside the box in labeling your drawing. WORD BANK large intestine stomach small intestine rectum esophagus pancreas mouth liver ŚƩ ƉƐ͗ ͬ ͬ Ŭ ŝĚƐŚĞĂů ƚŚ ͘Žƌ Ő ͬ ĞŶͬ Ŭ ŝĚƐͬ ďĨƐͲ ĚƐĂĐ Ɵǀ ŝƚLJ͘Śƚŵů
- 2. Answers 1. Mouth 2. Esophagus 3. Liver 4. Large Colon 5. Stomach 6. Pancreas 7. Small Intestines 8. Anus
- 4. Digestion refers to the breakdown of food into smaller components that can be absorbed into the bloodstream. This digestion or catabolism is divided into two types, the mechanical digestion that occurs in the mouth when food is physically broken up into smaller pieces and the chemical digestion that takes place in the gastrointestinal tract when the digestive enzymes break down the food into small molecules (Mandal, 2019). Role of Digestion Provide energy and necessary nutrients for bodily processes such as: • Movement • Growth • Repair • Reproduction
- 5. Parts of Digestive System 1. The Mouth Each species of organisms has its own way of digesting food. Digestion in human starts in the mouth where food is chewed and broken down to smaller pieces for easier digestion. This is so called mechanical digestion. Initial chemical digestion starts also in the mouth. This is carried out by molecules that speed up chemical reactions called enzymes. Amylase, an enzyme present in saliva helps break down carbohydrates, which are large complex molecules, into simple ones that can be used by the body.
- 6. 2.The Pharynx The pharynx muscular walls function in the process of swallowing, and it serves as a pathway for the movement of food from the mouth to the esophagus. The constrictive circular muscles of the pharynx’s outer layer play a big role in peristalsis. A series of contractions will help propel ingested food and drink down the intestinal tract safely. The inner layer’s longitudinal muscles, on the other hand, will widen the pharynx laterally and lift it upward, thus allowing the swallowing of ingested food and drink.
- 7. 3. The Esophagus Approximately, the esophagus is 20 cm long. Its functions include secreting mucus and moving food from the throat to the stomach using muscle movement called peristalsis. 4. The Stomach The stomach is a J-shaped muscular bag that stores the food and breaks it down into tiny pieces. It mixes food with gastric juices that contain enzymes to break down proteins and lipids. Hydrochloric acid in the stomach kills bacteria. Food found in the stomach is called chyme.
- 8. 5. The Small Intestine The small intestine is a little over 5 meters long and lies in the abdominal cavity surrounded by the large intestine. In the small intestine, the chemical digestion of food is completed and most of the absorption of nutrients takes place. Lining of intestine walls has fingerlike projections called villi, to increase surface area. The small intestine comprises three main sections continuous with each other: a. DUODENUM. The duodenum is the first part of the small intestine. It is located between the stomach part of the small intestine, or jejunum. After foods mix with stomach acid, they move into the duodenum, where they mix with bile from the gallbladder and digestive juices from the pancreas. The absorption of vitamins, minerals, and other nutrients the duodenum.
- 9. b. JEJUNUM. It is the middle section of the small intestine and is about 2 meters long. The main function of the jejunum is absorption of important nutrients such as sugars, fatty acids, and amino acids. c. ILEUM. The ileum is the last part of the small intestine. It connects to the cecum (first part of the large intestine) and helps to further digest food coming from the stomach and other parts of the small intestine. In addition, ileum absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body.
- 11. 6. The Large Intestine In the large intestine absorption of water continues until the familiar semisolid consistency of feces is achieved. Mineral salts, vitamins, and some drugs are also absorbed into the blood capillaries from the large intestine. The entire colon is about 5 feet (150 cm) long, and is divided into five major segments. The rectum is the last anatomic segment before the anus. The ascending and descending colon are supported by peritoneal folds called mesentery. The right colon consists of the cecum, ascending colon, hepatic flexure and the right half of the transverse colon. The left colon consists of the left half of the transverse colon, splenic flexure, descending colon, and sigmoid.
- 13. 7. The Rectum and the Anal Canal The rectum is a straight, 8-inch chamber that connects the colon to the anus. The rectum's job is to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is able to detect rectal contents. It lets you know whether the contents are liquid, gas or solid.
- 14. Accessory Organs of The Human Digestive System 1. The Teeth The teeth are responsible for the mechanical digestion of food in the mouth – a process called mastication. Our teeth are classified into four types and each performs specific functions. The chisel-shaped frontal teeth are called incisors which is specialized in cutting. The fanglike teeth are called canine and are best for piercing and tearing. The premolars and molars are the teeth responsible for crushing and grinding.
- 15. 2. The Salivary Glands Salivary glands are present in the oral cavity and pour their secretions into the mouth. Saliva is the combined secretions from the salivary glands and the small mucus- secreting glands of the lining of the oral cavity. About 1.5 liters of saliva is produced daily. Salivary glands and saliva work as chemical digestion of polysaccharides. Saliva contains the enzyme amylase that begins the breakdown of complex sugars, reducing them to the disaccharide maltose. Dry food entering the mouth is moistened and lubricated by saliva before it can be made into a bolus ready for swallowing.
- 16. 3. The Pancreas A healthy pancreas produces the correct chemicals in the proper quantities, at the right times, to digest the foods we eat. As part of the exocrine system, the pancreas secretes enzymes that work in tandem with bile from the liver and gallbladder to help break down substances for proper digestion and absorption. These enzymes include trypsin and chymotrypsin to digest proteins; amylase for the digestion of carbohydrates; and lipase to break down fats.
- 17. 4. The Liver The liver is the largest gland in the body, weighing between 1 and 2.3 kg. It is situated in the upper part of the abdominal cavity. The liver directly affects digestion by producing bile. Bile helps digest fat. 5. Gall bladder The gall bladder is a small, thin-walled sac located beneath the liver. This organ stores and concentrates the bile produced in the liver which will be then used in the digestion of lipids.
- 18. HOW DIGESTION WORKS Digestion is the process by which the gastrointestinal system retrieves important nutrients for the body and chemically changes the unused food into waste. The first step of digestion is mastication or the chewing of food in the mouth. Saliva initiates digestion and changes the chewed food into a soft mass called bolus. Bolus is made slippery by saliva, making it easier to be swallowed and slip down the back of the throat and esophagus. Before it enters the stomach, the bolus passes through the esophageal sphincter. Hydrochloric acid is released inside the stomach that causes to break down large food molecules into smaller ones and liquefies the bolus. The liquefied bolus, now called chime, then passes through the pyloric sphincter and enters the first section of the small intestine, the duodenum. It is here that enzymes released from the pancreas, liver and gallbladder further breakdown chime into elements that can be easily absorbed and used by the body. The small intestine is lined with a heavily folded inner mucosa and small fingerlike projections called villi. The villi permit digested food to enter the bloodstream. All nutrients and vitamins are absorbed here in the small intestine. Chime can travel through up to 20 feet of small intestine before it passes through the ileocecal valve to enter the large intestine. A very little digestion occurs in the large intestine. Waste is formed from the deposits of undigested food in the large intestine. As the waste passes through the large intestine, it becomes more and more solid because of the water that is continuously being reabsorbed from the waste. Waste deposits in the rectum, or end of the large intestine, until the brain signals for it to be expelled from the body (Ahsan, 2015).