Digestion and Stomach Function
Use the information found below to guide your research and to design your model. Guiding questions are broken down by assignment. Take notes, answer questions, and complete sketches in your laboratory journal. 1. Oral cavity, pharynx, (must also include accessory organs such as salivary glands, tongue, and teeth) What is the oral cavity and what does it contain? The oral cavity contains the tongue and teeth. What is the function of the salivary glands? Salivary glands are responsible for excreting saliva which helps with chewing and swallowing.
The saliva is the first step to digestion; enzymes in the saliva begin the process. What is the function of the tongue? The tongue is important for chewing and swallowing, as well as speech and taste. What is a bolus? A mass of food at the moment of swallowing. Where are the soft and hard palate located and what are their functions? The hard palate of the mouth is located behind the upper teeth, this palate holds the roots of the upper teeth and is important for speech.
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The soft palate is made up of muscles and is behind the hard palate, these muscles aid in swallowing and yawning.
What mechanical and chemical digestion occurs in the oral cavity? Mechanical digestion is when the food is being chewed, the chemical digestion occurs when the enzymes in the saliva begin the digestion of the food. What mechanisms are in place to make sure food does not “go down the wrong tube” and into the windpipe? The back part of the mouth, the soft palate of muscle closes off the nasal cavity so that food doesn’t go up the nose. As the food moves down the esophagus, the larynx moves forward and seals off the airway so that the food doesn’t go into the lungs. 2.
Esophagus and Stomach What is peristaltic movement and how does it function in the esophagus? Peristaltic movement is the waves of muscle that push food down the esophagus towards the stomach. Does any digestion of food occur in the esophagus? There is no digestion that occurs in the esophagus. What are the primary functions of the stomach? This is where proteins begin to be digested by and enzyme called pepsin. What is chyme and how does the stomach mix this material? Chyme is the food that is broken down into a watery substance which is then passed into the small intestine.
The stomach mixes its contents with its muscle action. What role does the stomach play in decontaminating the incoming food matter? The enzymes in the stomach break down food as well as kill bacteria. What cells in the stomach function to form enzymes and acids? Parietal cells in the stomach create hydrochloric acid and pepsin which digests proteins. Why doesn’t gastric juice digest the inside of the stomach? The stomach mucosa that lines the stomach is able to resist the juices of the stomach acid. What are sphincters and how are they related to the stomach?
The first is the cardiac sphincter located at the top of the stomach, separating the stomach from the esophagus. The second is the lilac sphincter, at the bottom of the stomach separating the small intestines from the stomach. The two sphincters regulate how much goes in and out of the stomach. What mechanical and chemical digestion occurs in the stomach? The muscles in the stomach act as a mixer and grinder of the food. This is the mechanical part of the digestion. The chemical digestion occurs when the acids are excreted from the lining of the stomach to break down the proteins.
Small Intestine and Large Intestine What are the three sections of the small intestine and what role does each section play in digestion or absorption? Duodenum is the first section of the small intestine, this is where the first part of digestion is completed. Food is mixed with bile and enzymes both of which help break down the food. Jejunum is where the foods nutrients are absorbed. Lleum is the last part of the small intestine where the bile acids are returned to the liver and any excess water is absorbed.
What is the pH within the small intestine and how is this pH maintained? The pH of the region is maintained at 7 or 8 this is the pH that is optimal for the enzymes to function. This is kept at a constant with the bile from the gallbladder. Where do bile and pancreatic enzymes enter the small intestine? The bile moves down the common bile duct, through the pancreatic duct and then into the duodenum and through the rest of the intestine. How does food move through the intestines? By 2 different types of contractions.
Peristalsis and segmentation, the movements mix the bile in the small intestines with the chyme from the stomach. What enzymes act inside the small intestine and what are the functions of these enzymes? What is the function of the large intestine in relation to digestion? The large intestine functions to absorb the remaining water from the indigestible food matter and then to pass the matter out of the body. What are the three sections of the large intestine and what roles does each play in digestion or absorption?
How does the large intestine help maintain a water balance in the body? 4. Pancreas, Liver and Gallbladder What are the size and the location of the pancreas? What are the different functions of the pancreas, and how is the pancreas directly related to digestion? How does the pancreas connect to the rest of the digestive system? What enzymes are produced by the pancreas and what are their functions? How is insulin related to the digestive system? What is the size of the liver and where is it located? How does the liver function in relation to digestion?
What are other functions of the liver in the body? What is the relationship between the liver and the gallbladder? What is the function of bile and where does it enter the digestive tract? Each group will be assigned one of the following bites of food. First, think about the class of molecule this food item represents and then identify the specific enzymes that would break this polymer into monomers. Remember to describe features that help mechanically digest this bite. Depending on your food item, you may need to do some additional research.