bio tema 3

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.

Human nutrition Digestive, respiratory, excretory and circulatory systems all play a role in nutrition. Digestive system: introduces foods into the body, and prepares and transforms it to enable its use by cells. Respiratory system: obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism. Circulatory system: transports nutrients and oxygen to cells and releases waste substances. Excretory system: releases wate substances outside the organism. The digestive system What is it? Breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract, and the accessory glands: liver, pancreas and salivary glands. Digestive functions: ingestion (entry of food into the digestive tract) and digestion (transformation of food into simple nutrients) Types of digestion Mechanical digestion: physical transformations such as chewing, squeezing, mixing, etc. to reduce the size of the food and make it easier for chemical digestion. Chemical digestion: transformation of complex nutrients from food into simple nutrients through chemical reactions. Carried out by enzymes in digestive juices such as stomach acid and bile. Absorption: the passing of nutrients from the digestive tract to the blood or lymph, done by the small intestine. Defecation: the expulsion of non-digested or non-usable parts of food. Parts of the digestive system GI/Digestive tract: A series of hollow organs joined in a long, twisting tube from the mouth to the anus where food moves through. The hollow organs that make up the GI tract are the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus. GI Tract Made up of three layers of tissue: Mucosa- internal layer, lined with glands. Muscularis- middle layer, two layers of smooth muscle. Serosa- connective tissue layer, joins digestive tract to other organs. Digestive glands Help carry out chemical digestion by secreting digestive juices into the digestive tract. Includes salivary glands, gastric glands, intestinal glands, the liver and pancreas. Organs involved in chemical digestion are the mouth (saliva), stomach (stomach acid & digestive enzymes), pancreas (pancreatic juice) , liver (bile), gallbladder (stores bile), small intestine (digestive juice). How does food move through the digestive tract? Food moves through the digestive tract through a process called peristalsis. The hollow organs of the GI tract have a layer of muscle which allows them to move, pushing and mixing the food forward through the GI tract. Mouth ⇢ esophagus ⇢ stomach ⇢ small intestine ⇢ large intestine ⇢ rectum Teeth functions Incisors: Biting and cutting food. Canines: Ripping and tearing food. Premolars: Crushing food. Molars: Chewing, crushing and grinding food. The digestive process The stomach An organ connected to the small intestine via the pylorus, a valve that is usually closed. Cardia: the valve at the entrance of the stomach which is always open. Food stays in the stomach for 3-4 hours, mixing with gastric juice, making chyme. Gastric juice contains pepsin, an enzyme that begins the digestion of proteins. It also contains hydrochloric acid, which activates pepsin and facilitates its action, and destroys bacteria. The inside of the stomach contains mucus which protects the stomach wall and prevents it from being attacked by hydrochloric acid and enzymes.When chyme becomes very acidic, the pylorus opens and it moves into the small intestine. Gastric acid is produced through involuntary processes. The small intestine A tube around 6 or 7 meters long. Located between the pylorus and ileocecal valve, which separates it from the large intestine. Here, chyme comes into contact with digestive juices secreted by the liver and pancreas. Divided into 3 parts: Duodenum: 1st section, U-shaped, around 25 cm long. Jejunum: 2nd & longest section. Ileum: final section, leads to large intestine. The liver Large organ in the top-right of the abdomen. Reddish brown color because it contains blood. Produces bile which enters the duodenum. Also carries out non-digestive functions, such as destroying toxins. Bile: Is stored in the gallbladder & only released when food enters the intestine. Does not contain digestive enzymes. Contains bile salts, which help to digest fats by emulsifying them.