Chapter 22 The Digestive System

What are the 4 sections of the colon and in what order do they occur?

Ascending colon, transverse colon, descending colon, sigmoid colon.

About 60% of the dry mass of the feces is made up of _________.

Bacteria

About how much saliva is produced every day?

1-1.5L/day

What is the normal pH of the stomach and why is this important?

1-2. The low pH is important for the activation of pepsinogen into pepsin.

What are the functions of the tongue?

Essential speech, contains taste buds, manipulates food while being chewed, aides in swallowing.

What are the 4 main digestive functions of the liver?

Formation of bile, nutrient metabolism, detoxification, excretion.

What are the 6 functions or processes of the digestive system?

Ingestion, secretion, propulsion, digestion, absorption, defecation.

What is the lumen of the digestive tract?

The cavity or channel within a tube or hollow organ such as the small intestine and stomach.

What is the definition of mastication?

The chewing of food.

What are the 2 divisions of the digestive system?

The digestive tract and accessory organs.

What is defecation?

The emptying of fecal material out of the large intestine.

What is the visceral peritoneum and where is it located?

The innermost of the peritoneal membranes and forms the outer layer of the organs.

What is glycogen and what is the importance of the glycogen stored in the liver? (how are they used)

The liver converts glucose into glycogen for storage. The glycogen can be broken down into glucose which can be secreted into the blood as needed to maintain blood glucose levels.

What is the palate, where is it located and what are the 2 parts of it?

The roof of the mouth. There is a hard and soft palate.

What is gastric rugae?

When the stomach is empty, the mucosa (and submucosa) are folded/wrinkled into layers called gastric rugae.

What is the normal pH of the mouth and why is this pH important?

6.8-7.0. This pH level is necessary for salivary amylase to work.

What are the components of pancreatic juice?

A mixture of water, enzymes, and buffers that are necessary for digestion in the small intestines.

What is peristalsis and what is its function?

A series of rhythmic contractions and relaxations that propels food down the esophagus.

What is the greater omentum and where is it located?

A type of mesentery which is suspended from the greater curvature of the stomach and covers the abdominal contents.

Identify the following regions of the stomach: greater curvature, lesser curvature, cardiac region, fundus, body, pylorus, pyloric antrum.

A. Greater Curvature: The left or lateral and inferior border of the stomach. B. Lesser Curvature: Extends between the cardiac and pyloric orifices; forms the right or medial border of the stomach. C. Cardiac Region: Small 3cm area surrounding the esophageal junction. D. Fundus: "dome" region superior to the cardiac region E. Body: Main part of the stomach. F. Pylorus: The terminal portion of thee stomach next to the small intestines. It is separated from the small intestine by the pyloric sphincter. G. Pyloric Antrum: The inferior portion of the stomach.

Define each of the following as it relates to the digestive system: Ingestion, secretion, propulsion, digestion, absorption, defecation

A. Ingestion: The process by which food and liquids are brought into the body. B. Secretion: Endocrine and exocrine glands in the digestive system secrete mucus, enzymes, acids, and hormones to aid the digestive processes. C. Propulsion: The process of moving ingested food and liquids through the digestive tract. D. Digestion: The process by which food is broken down. E. Absorption: The process by which molecules resulting from chemical digestion are moved from the GI tract into the blood and/or lymph vessels. F. Defecation: The process by which unused portions of food are eliminated from the body.

What is the importance of each of the following secretions of the stomach and where is each secreted: mucous, hydrochloric acid, intrinsic factor, pepsin, gastrin.

A. Mucous: Protects the gastrointestinal cells from the damage that gastric juices can cause. B. Hydrochloric Acid: Decreases the normal pH of the stomach to about 1-2. This pH is necessary to activate pepsin and to kill pathogens on the food we eat and in the saliva we swallow. C. Intrinsic Factor: Required for intestinal absorption of Vitamin B12. D. Pepsin: Breaks down proteins. E. Gastrin: Stimulates acid secretion and motility.

What is digested by each of the following enzymes: pancreatic lipase, pancreatic amylase, RNAase and DNAase, trypsin, chymotrypsin, and carboxypeptidase.

A. Pancreatic Lipase: Fats B. Pancreatic Amylase: carbohydrates C. RNAase and DNAase: RNA and DNA D. Trypsin: Proteins E. Chymotrypsin: Proteins F. Carboxypeptidase: Proteins

What are the 2 main functions of stomach acid?

Activates the enzyme pepsin which digest proteins and kills bacteria and other pathogens on the ingested food and drink.

How many teeth do adults have? How many do children have?

Adults have 32 teeth. Children have 20.

What are the 2 phases of swallowing?

Begins as a voluntary movement in the mouth, but once food reaches the back of the mouth, there is an automatic reflex which completes the task.

What is the function of the buffers in pancreatic juice?

Bicarbonate act to neutralize stomach acid.

What organ makes bile? What organ stores and releases it?

Bile is made by the liver, but stored and secreted by the gall bladder.

What is the stimulus that results in the release of bile?

Bile is released into the small intestine from the gall bladder in response to the presence of fat in the duodenum.

What are the 3 main sections of the large intestine and in what order do they occur?

Cecum, colon, and rectum

What is the hormone that mediates pancreatic secretion and from where is it produced?

Cells in the pancreatic islets secrete the hormones insulin and glucagon.

Explain the cephalic phase of gastric regulation---what stimulates, what is secreted, what happens, etc.

Cephalic Phase: Initiated by the sight, smell, taste, and/or thought of food. Increase in gastric motility and gastric secretion. Directed by the parasympathetic nervous system: 1. Triggers the release of hydrochloric acid 2. Triggers the release of pepsin 3. Triggers the release of histamine. 4. Triggers the release of gastrin.

What are the 3 phases of gastric secretion and activity?

Cephalic phase, gastric phase, and intestinal phase.

What effect will the presence of fat have on gastric emptying? Why is this necessary?

Chyme needs to be diluted and further digested. Fats take longer to digest and the presence of fat in the chyme will slow gastric emptying.

What are the 4 functions of saliva?

Contains Salivary Amylase, contains mucus, gets rid of bacteria in the mouth, maintains mouth pH at around 6.7-7.0.

Describe the manner in which the stomach contents are emptied into the duodenum. Why is this necessary?

Decrease in gastric motility allows the gastric emptying to be slow and controlled which is necessary to ensure complete digestion by the small intestine.

Which step of gastric regulation is responsible for the majority of gastric secretions?

Gastric phase.

What are the 3 divisions of the small intestines? In what order do they occur?

Duodenum, jejunum, ileum

The duodenum receives secretions from the __________ and the ____________.

Gall bladder and exocrine pancreas.

What is flatus and what produces it?

Gas which is expelled as flatulence. Bacteria normally ferment cellulose and other undigested carbohydrates and fat which produces flatus.

Explain the gastric phase of gastric regulation.

Gastric Phase: Initiated by food. Results in basically the same actions as the cephalic phase. 1. Direct release of HCl 2. Triggers the release of pepsin. 3. Release of histamine which increases the release of HCl. 4. Release of gastrin which increases the release of HCl and increased gastric motility. Gastric phase is responsible for 2/3 of al gastric secretions. Food breakdown into smaller pieces. Chemical digestion.

What effect will a low pH of the chyme have on gastric emptying? Why is this necessary?

Gastric emptying is slowed when there is a low pH. Chyme is acidic and needs to be neutralized to prevent damage to the duodenum.

What are the names of the ducts which take bile from the liver to the gall bladder?

Hepatic Ducts into the cystic duct

What is the name of the sphincter between the ileum and the cecum?

Ileocecal valve (ileocecal sphincter)

Where is the appendix located?

In the cecum

Explain the Intestinal Phase.

Initiated when chime moves into the duodenum. Results in a decrease of gastric secretions and motility. The decrease in gastric motility allows gastric emptying to be slow and controlled which is necessary to ensure complete digestion by the small intestine. Gastric emptying occurs in small 3ml portions every 1.5 minutes.

What are the exocrine secretions associated with the digestive system?

Insulin and glucagon

Explain how bile functions to assist the breakdown.

It contains bile salts which act to emulsify fats. (Surrounding fats and breaking them into smaller droplets)

The majority of absorption occurs in which segment of the small intestine?

Jejunum

The majority of digestion occurs in which segment of the small intestine?

Jejunum

Where is the parietal peritoneum located?

Lining the abdominal cavity and covering the abdominal organs.

Where is the gall bladder located and what does it store and release?

Located embedded on the underside of the liver. Stores, concentrates, and then secretes bile.

What are the 2 types of digestion?

Mechanical and chemical.

What are the 4 types of cells located in the mucosa of the stomach?

Mucous Neck Cells, Parietal Cells, Chief Cells, and G-Cells.

What is secreted by each of the following cells: mucous neck cells, parietal cells, chief cells, g-cells.

Mucous Neck Cells: Secrete mucous. Parietal Cells: Secrete Hydrochloric Acid (HCL) and Intrinsic Factor. Chief Cells: Secrete Pepsinogen G-Cells: Secrete the hormone gastrin.

What are the 6 types of enzymes contained in pancreatic juice?

Pancreatic Lipase, Pancreatic Amylase, RNAase, DNAase, Trypsin, chymotrypsin, carboxypeptidase.

What are the 4 main functions of the bacteria flora that live in the large intestines?

Produce vitamins such as vitamin K, metabolize undigested materials, deter the growth of harful bacteria, stimulate the immune system.

What stimulates the release of cholecystokinin?

Produced by the duodenum in response to the presence of lipids and partial digested proteins in the duodenum.

The last 3cm of the large intestine is known as ___________.

Rectum

What enzyme is contained in saliva and what does it digest?

Salivary Amylase and it begins carbohydrate digestion in the mouth.

Differentiate between segmentation and peristalsis.

Segmentation is random contractions and mixing. Peristalsis is coordinated muscle contractions and relaxations which slowly propel chyme.

What does the term deglutition refer to?

Swallowing

What is the dentition?

Teeth collectively

What are the 6 accessory organs and structures of the digestive tract?

Teeth, tongue, salivary glands, liver, gall bladder, pancreas.

Where is the lower esophageal sphincter and what is its function?

The lower end of the esophagus is surrounded by the esophageal sphincter. The LES is normally tightly closed which keeps stomach contents from re-entering the esophagus.

What are the 3 divisions of the pharynx and where are each located relative to the others?

The nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is superior to the oropharynx, the oropharynx is superior to the laryngopharynx.

What divisions of the pharynx are shared by the digestive and respiratory systems?

The oropharynx and laryngopharynx.

Where is the pharynx located?

The pharynx is commonly known as the throat.

What is the name of the sphincter between the stomach and the duodenum and how does it function?

The pyloric sphincter. It controls the emptying of the stomach into the small intestines.

The serosa of the digestive tract is also known as____________?

Visceral Peritoneum