BIOL1008 Lecture Notes - Lecture 6: Salivary Gland, Gastrointestinal Tract, Esophagus

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24 May 2018

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Lecture 6

Why is digestion important?

- Digestion makes the molecules require for life available for absorption

- Body uses molecules for energy, growth, and maintenance

- Healthy body: absorption of water, monosaccharides, amino acids, fatty acids and

glycerol, vitamins and minerals within an appropriate range

Macro molecules broken down into smaller sub units (which can then be absorbed by small

intestine)

Activities of the digestive system

- Ingestion of food into mouth

- Mechanical and chemical digestion of food to produce chime

- Movement of digesta along digestive tract

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- Absorption of released nutrients

- Microbial activity

- Monitoring/ regulation of intake

Elimination of indigestible substances and waste products via defecation

Anatomy of the digestive system

- Digestive tract/ alimentary canal/ GIT

 Mouth to anus (9m long)

 Tube covered by mucosa with glands that produce secretions to help digestion

- Accessory organs

 Secrete fluid/ enzymes into digestive tract

 Salivary glands

 Liver, pancreas release secretions through ducts into intestine for chemical

digestion

- Specialised organs, tissues, and cells

Oral cavity

- Lips, cheeks, tongue

 Biting and chewing (mechanical) chops food into small pieces for swallowing

- Three pairs of salivary glands (accessory organs)

 Parotid, submandibular and sublingual glands

 Produce saliva through ducts into mouth

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Saliva

- Mixture of serous and mucous fluids

- Serous (watery) component

 Moistens food for swallowing

 Dissolves food for tasting

 Contains enzyme amylase (carbohydrates → di- then monosaccharides, start of

chemical digestion)

- Mucous component

 Lubricates food

 Enzyme lysozyme is antibacterial

Oesophagus

- Muscular contractions of the oesophagus occur in peristaltic waves (pushing food

towards stomach)

 Waves of relaxation followed by waves of contraction along a tube

- The waves push food towards stomach (against gravity as well)

The stomach

- Mechanical and chemical action

- Huge muscular sac (1-3L) which acts like a food processor

- Food churned for mechanical breakdown

- Mixed with stomach secretions → chyme

- Food stays for 2-4 h

- Gradually moves by peristaltic waves into small intestine

Mechanical action of the stomach

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Document Summary

Digestion makes the molecules require for life available for absorption. Body uses molecules for energy, growth, and maintenance. Healthy body: absorption of water, monosaccharides, amino acids, fatty acids and glycerol, vitamins and minerals within an appropriate range. Macro molecules broken down into smaller sub units (which can then be absorbed by small intestine) Mechanical and chemical digestion of food to produce chime. Elimination of indigestible substances and waste products via defecation. Tube covered by mucosa with glands that produce secretions to help digestion. Liver, pancreas release secretions through ducts into intestine for chemical digestion. Biting and chewing (mechanical) chops food into small pieces for swallowing. Three pairs of salivary glands (accessory organs) Contains enzyme amylase (carbohydrates di- then monosaccharides, start of chemical digestion) Muscular contractions of the oesophagus occur in peristaltic waves (pushing food towards stomach) Waves of relaxation followed by waves of contraction along a tube. The waves push food towards stomach (against gravity as well)

Related Questions

2. General questions about the digestive tract A. Mechanical digestion of all foods begins in the oral cavity. Describe how food is digested mechanically in the oral cavity. B. What is the scientific name for swallowing? Which portions of the pharynx does food pass through when swallowing? What is the function of the esophagus? C. Cells lining the stomach release hydrochloric acid (HCl). How does HCl assist in food digestion? How are the cells lining the stomach protected from being auto-digested by HCl? D. Carbohydrates, fats, and proteins must be broken down into their smallest subunits (AKA building blocks) in order to be absorbed through the epithelial lining of the small intestine. Name the building blocks of each of the major classes of nutrients: complex carbohydrates (AKA polysaccharides), fats, and proteins. E. About 99% of all nutrients are absorbed in the small intestine. Name the 3 portions of the small intestine. In which of these 3 portions does the greatest amount of nutrient absorption occur (think about the location and length of each segment)? Which type(s) of nutrient(s) is/are absorbed into blood capillaries? Which type(s) of nutrient(s) is/are absorbed into lymphatic capillaries? F. The last portions of the digestive tract are the rectum, anal canal and anus. Name the 2 muscular sphincters located at the anus. When the rectum fills, the defecation reflex is initiated. Describe the events that occur during the defecation reflex. Name the 2 sphincters located at the anus. Which sphincter undergoes involuntary relaxation during the defecation reflex? Which division of the autonomic nervous system causes this sphincter to relax and open? Name the sphincter that you control consciously to stop or initiate defecation.

violetwombat627

The digestion process begins at the mouth. Food enters and then accessory digestive organs like the tongue, teeth, and salivary glands break down the substance. It then travels through the pharynx and esophagus into the stomach, where the stomach acid further breaks down the food (UXL Complete Health Resource). After that, the food travels through the small and large intestines where a majority of its nutrients are absorbed. The waste then exits through the end of the large intestine which is made up of the rectum and anus. After the teeth assist in chewing, food rolls over the tongue and reaches stomach through the esophagus within 8 seconds. General Tsoâs Chicken and Rice consist of carbohydrates, fats and proteins. However, carbohydrates are digested easily than the fats and proteins. After broken down in the stomach, most of the nutrients are absorbed from the small intestine, and it takes 6 to 8 hours to pass through small intestine. The remaining unabsorbed material, âmoves very slowly through the large intestine where the final absorption of water and other nutrients take placeâ (UXL Complete Health Resource). The parasympathetic nervous system encourages the food to move through the digestive tract and motivates digestion process. The sympathetic nervous system works against the parasympathetic nervous system by decreasing the contraction and relaxation of the digestive tract (Taylor). Mouth produces saliva, which contains amylase. Amylase is key in digesting carbohydrates. The stomach produces hydrochloric acid, pepsinogen, intrinsic factor, and mucus (Taylor). Hydrochloric acid kills the bacteria and other organisms that enter the stomach, and then continues to activate pepsinogen. Pepsinogen then changes into pepsin, which digests protein peptides. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases. Trypsin, chymotrypsin, and carboxypeptidases digest proteins, whereas lipases, phospholipases digest lipid molecules. Small intestine produces lactase, sucrase, maltase, lipases, and peptidases. Lactase, sucrase, and maltase digest carbohydrates (UXL Complete Health Resource). Saliva glands, pancreas, liver, and gallbladder are the accessory organs of the digestive process. Saliva glands produce mucus and amylase which digests starch into simple sugars and binds food particles together, while lubricating the palette when one swallows. The pancreas produces amylase, lipases, and proteinases etc. These digestive juices are responsible for breaking down carbohydrates, proteins, and fats. The liver is the largest gland in the body, âIt produces bile salts to emulsify lipids. It detoxifies metabolic end products to protect the bodyâ (UXL Complete Health Resource). Gallbladder stores bile juice. The chicken in the General Tsoâs contains proteins. Proteins cannot be digested in mouth. However, the mouth can physically digest chicken into smaller pieces. These partially digested chicken pieces travel to stomach, where it is digested by pepsin. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases (UXL Complete Health Resource). The chicken is then digested by trypsin, chymotrypsin, and carboxypeptidases in the duodenum of the small intestine. After the complete digestion, the chickenâs proteins change into amino acids, which are then absorbed into blood. The rice of the General Tsoâs is a carbohydrate. Carbohydrates are partially digested inside the mouth by amylase. The rest of the rice travels to the stomach where it is digested by pancreatic juices and enzymes that are produced by small intestine. The digestion of the rice produces monosaccharides that absorb into the blood stream. The left over, and undigested parts of the chicken and rice that are useless to the body are excreted by large intestine through rectum.

1) Based on your finding in the Module 3 Report, begin the Module 4 Report by identifying which metabolites are being absorbed and specifically which vessels of the cardiovascular or lymphatic system are the initial vessel of transport from the digestive system. 2) From the point that the specific metabolites are absorbed from the GI tract, trace the path of the resulting metabolites to the following locations in the body for incorporation into the body structure: Metabolites of protein for use in the Gastrocnemius muscle for muscle maintenance. Metabolites of the carbohydrates for energy to contract the cardiac muscle cells. Metabolites of fat to incorporate into the myelin sheaths of the Schwann cells of the Trigeminal nerve that innervates the Masseter muscle. Water for incorporation into the synovial fluid of the hip joint. Iron for incorporation into red blood cells in the bone marrow of the sternum.

maroonguinea-pig686

Food that we consume is composed of very complex molecules. During the digestive process these compounds are broken down into smaller and smaller subunits in preparation for use by the body as building blocks needed for the many components of the human body. The digestion process begins at the mouth. Food enters and then accessory digestive organs like the tongue, teeth, and salivary glands break down the substance. It then travels through the pharynx and esophagus into the stomach, where the stomach acid further breaks down the food (UXL Complete Health Resource). After that, the food travels through the small and large intestines where a majority of its nutrients are absorbed. The waste then exits through the end of the large intestine which is made up of the rectum and anus. After the teeth assist in chewing, food rolls over the tongue and reaches stomach through the esophagus within 8 seconds. General Tsoâs Chicken and Rice consist of carbohydrates, fats and proteins. However, carbohydrates are digested easily than the fats and proteins. After broken down in the stomach, most of the nutrients are absorbed from the small intestine, and it takes 6 to 8 hours to pass through small intestine. The remaining unabsorbed material, âmoves very slowly through the large intestine where the final absorption of water and other nutrients take placeâ (UXL Complete Health Resource). The parasympathetic nervous system encourages the food to move through the digestive tract and motivates digestion process. The sympathetic nervous system works against the parasympathetic nervous system by decreasing the contraction and relaxation of the digestive tract (Taylor). Mouth produces saliva, which contains amylase. Amylase is key in digesting carbohydrates. The stomach produces hydrochloric acid, pepsinogen, intrinsic factor, and mucus (Taylor). Hydrochloric acid kills the bacteria and other organisms that enter the stomach, and then continues to activate pepsinogen. Pepsinogen then changes into pepsin, which digests protein peptides. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases. Trypsin, chymotrypsin, and carboxypeptidases digest proteins, whereas lipases, phospholipases digest lipid molecules. Small intestine produces lactase, sucrase, maltase, lipases, and peptidases. Lactase, sucrase, and maltase digest carbohydrates (UXL Complete Health Resource). Saliva glands, pancreas, liver, and gallbladder are the accessory organs of the digestive process. Saliva glands produce mucus and amylase which digests starch into simple sugars and binds food particles together, while lubricating the palette when one swallows. The pancreas produces amylase, lipases, and proteinases etc. These digestive juices are responsible for breaking down carbohydrates, proteins, and fats. The liver is the largest gland in the body, âIt produces bile salts to emulsify lipids. It detoxifies metabolic end products to protect the bodyâ (UXL Complete Health Resource). Gallbladder stores bile juice. The chicken in the General Tsoâs contains proteins. Proteins cannot be digested in mouth. However, the mouth can physically digest chicken into smaller pieces. These partially digested chicken pieces travel to stomach, where it is digested by pepsin. The pancreas produces trypsin, chymotrypsin, carboxypeptidases, lipases, and phospholipases (UXL Complete Health Resource). The chicken is then digested by trypsin, chymotrypsin, and carboxypeptidases in the duodenum of the small intestine. After the complete digestion, the chickenâs proteins change into amino acids, which are then absorbed into blood. The rice of the General Tsoâs is a carbohydrate. Carbohydrates are partially digested inside the mouth by amylase. The rest of the rice travels to the stomach where it is digested by pancreatic juices and enzymes that are produced by small intestine. The digestion of the rice produces monosaccharides that absorb into the blood stream. The left over, and undigested parts of the chicken and rice that are useless to the body are excreted by large intestine through rectum. 1) Based on your finding in the Module 3 Report, begin the Module 4 Report by identifying which metabolites are being absorbed and specifically which vessels of the cardiovascular or lymphatic system are the initial vessel of transport from the digestive system. 2) From the point that the specific metabolites are absorbed from the GI tract, trace the path of the resulting metabolites to the following locations in the body for incorporation into the body structure: Metabolites of protein for use in the Gastrocnemius muscle for muscle maintenance. Metabolites of the carbohydrates for energy to contract the cardiac muscle cells. Metabolites of fat to incorporate into the myelin sheaths of the Schwann cells of the Trigeminal nerve that innervates the Masseter muscle. Water for incorporation into the synovial fluid of the hip joint. Iron for incorporation into red blood cells in the bone marrow of the sternum.

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BIOL1008 Lecture Notes - Lecture 6: Salivary Gland, Gastrointestinal Tract, Esophagus

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