BY 124 1st EditionExam # 3 Study Guide Lectures: 14 - 20Lecture 14What are the processing stages of the digestive system? Describe them.I. Ingestion – eat/consume food sourceII. Digestiona. Mechanical – break down food with teeth/mouthb. Chemical – break down food further with chemicals and enzymes within the mouth and the intestinesIII. Absorption – nutrients have been broken down enough so that they are able to enter the body cellsIV. Elimination – Undigested material leaves the body How many teeth do humans have? What are the four types of teeth? What is the specialized function of each type? What are the three parts of the tooth? How do teeth differ from carnivores to herbivores? Humans have 32 teethI. 4 incisors – used for bitingII. 2 canines – used for tearingIII. 4 flat premolars – used for grinding IV. 6 very flat molars – used for crushingParts of the toothI. Enamel on top (hard calcium substance – hardest substance in your body)II. Dentine underneath – thick and bone-likeIII. Pulp – majority of blood vessels and nervesSee Figure 41.16 for a visual representation of how teeth change relative to the type of food they eat.- Carnivores generally have many canines and incisors while lacking true molars as they are more prone to eating and tearing through flesh and swallowing rather than trying to crush or grind any food that they eat.- On the opposite site of the spectrum are herbivores which are more likely to house mostly flat premolars and molars with a few incisors in front. This is because they are going to need the two types of molars to grind and crush the vegetation that they eat so they can increase the surface area of it so it can be easily digested and the most nutrients can be absorbed. What are the parts of the palate? What is the purpose of the palate?The 2 parts of the palate are the hard palette (bony) and the soft palette (muscular). Thepurpose of the palate is to separate the mouth from the nasal cavity.What do salivary glands do? Where can they be found? What are the two different types of saliva produced by these glands? What is mucin? Salivary glands produce saliva that is used to help breakdown food and pass it down to the stomach. Saliva also helps move food down the throat, cleans the mouth, and moistens the tongue for speech. They can be found in the parotid (the cheeks), sublingually (under the tongue), and submandibularly (under the mandible/jaw). The two different types of saliva are watery and slimy saliva. Watery saliva helps dissolve dry foods. Slimy saliva uses mucin to help stick parts of food together into a bolus. Mucin is what sticks the food together to form a bolus to be swallowed.What is salivary amylase? What does it do? What secretes it? Salivary amylase is an enzyme in saliva used to break down polysaccharides into smaller disaccharides like maltose. Salivary amylase is found in the mouth where the salivary glands are.What happens when you swallow? (At least 2 things occur almost simultaneously) When you swallow, all of the tubes in your throat and mouth close except for the one leading the stomach. - nasopharyngeal opening closes- glottis closes (epiglottis blocks glottis from esophagus )What are the four layers of the stomach? Describe each layer. What are rugae? What do they do? What are the three regions of the stomach?The four layers of the stomach are as follows (Figure 40.6)- Mucosao Epithelial layer that lines lumen- Submucosao Matrix of connective tissue- Musculariso Smooth muscle and tissue- Serosa o NervesThe folds of epithelial tissue are called rugae which help increase surface area for better absorption.The three regions of the stomach are:1. Cardiac region – top of stomachi. Cardiac sphincter – stuff comes in2. Fundus – rounded area 3. Pyloric region – bottomii. Pyloric sphincter – where stuff exits Lecture 15There are three types of cells in the stomach. What are they and what do they do?I. Mucous cells – mucusII. Parietal cells – hydrochloric acid (HCl)III. Chief cells – pepsinogen (can be changed to pepsin by HCl given off by parietal cells)What is a zymogen? Can you find zymogens naturally produced in the body? What is the purpose of a zymogen?Zymogens are inactive enzymes. Yes, they are found naturally in the body. Basically it provides access to these enzymes without them being activated. This means that they are in the body and ready to go, they just need to be activated by something. This is important because it is another way to regulate the use of those enzymes.What is gastrin? Pepsin? Hydrochloric acid?Gastrin helps the release of pepsin and is controlled by nervous system and other hormonal release. Gastrin is produced by the lower part of stomach. It gets in blood and then moves into top of stomach.Pepsin reduces proteins to small polypeptides.HCl is not necessarily a protein but still breaks things down due to it being so acidic. It works by breaking down the “glue” between cells which is important because it increases surface area. It is also anantimicrobial agent for the stomach due to its acidity. Compare and contrast the digestive tract of carnivores vs herbivores. Why are they different in the ways that they are? What is the purpose of the differences? Carnivores have a longer small intestine, a short cecum, and a shorter large intestine. This is due to the fact that they need a longer small intestine to aid in digestion and do not really need a cecum because vegetables are not necessarily in their diet so they do need to house microorganisms to aid in digestion of cellulose in the cecum. Herbivores have a shorter small intestine, a long cecum, and a longer large intestine. Their small intestine is shorter because they do not need to absorb as many nutrients from their food as that is donein the really long cecum where food enters and cellulose is broken down by microorganisms housed there. Their large intestines are longer for increased water reabsorption. What are the three sections of the small intestine? Where would digestion typically occur? The most absorption? Where can you find a “brush border”?The three sections of the small intestine are: the duodenum, the jejunum, and the ileum. The duodenum is where most digestion occurs. The most absorption occurs in the ileum and also where you can find the brush border.What are villi? What are the parts of villi? How do lacteals work? Villi are small protrusions on the wall of the lower small intestine