Ch. 7 Digestive System Flashcards

Question

Muscularis

Answer 1

The main muscle layer of the GI Tract wall and is responsible for GI Motility. - The muscularis of the mouth, pharynx, and upper esophagus contains skeletal muscle that produces voluntary swallowing. - The muscularis in the rest of the GI Tract consists of smooth muscle that is arranged in two layers: an inner layer of circular muscle and an outer layer of longitudinal muscle. - The involuntary contractions of the smooth muscle layers are responsible for patterns of GI motility such as peristalsis and segmentation.

Answer 2

- The outermost layer of longitudinal muscle. - The involuntary contractions of the smooth muscle layers are responsible for patterns of GI motility such as peristalsis and segmentation. - The outermost layer of the GI tract is the serosa. The serosa consists of the following: Connective tissue & Epithelium. - The serosa forms a part of the peritoneum, a membrane that lines the abdominal cavity and covers the organs (especially the digestive organs) within that cavity.

Answer 3

The ENS consists of about 100 million neurons that extend from the esophagus to the anus

Answer 4

- The Submucosal Plexus (aka plexus of Meissner) - The Myenteric Plexus (aka Auerbach) Submucosal Plexus is found within the Submucosa Many of these neurons extend to the epithelium of the mucosa where they supply digestive glands, such as a gastro gland in the stomach or intestinal gland in the intestines. Thus, The Submucosal Plexus promotes GI secretion Myenteric Plexus is found between the longitudinal and circular smooth muscle layers of the muscularis. It supplies the muscles of the muscularis and controls GI Motility

Answer 5

In general, stimulation of the parasympathetic nerves that innervate the GI tract causes an increase in GI secretion and motility by increasing the activity of ENS neurons. In contrast, the sympathetic nerves that supply the GI tract cause a decrease in GI secretion and motility by inhibiting the neurons of the ENS.

Answer 6

Parasympathetic nerves (via the vagus nerves) innervate the organs of the GI tract. Stimulation of the parasympathetic nerves to the GI tract increases peristalsis and GI secretion of fluids (such as gastric juice, pancreatic juice, and intestinal juice) into the GI lumen.

Answer 7

- Saliva Amylase is an enzyme that breaks down starch into small chains of glucose molecules called dextrins. - Lipid Lipase is an enzyme that breaks down fat into 2 fatty acids and 1 monoglyceride.

Answer 8

- The Pharynx is a funnel-shaped tube that extends from the oral cavities, to the esophagus, and to the larynx. - It conveys (transports) food from the mouth to the esophagus.

Answer 9

- The Esophagus is a tube that extends from the pharynx to the stomach. At each end of the esophagus, the muscularis gives rise to two sphincters.

Answer 10

- The Upper Esophageal Sphincter - The Lower Esophageal Sphincter The Upper Esophageal Sphincter consists of Skeletal Muscle. The Upper Esophageal Sphincter regulates the movement of food from the pharynx into the esophagus. ----------------------------------------------------------------------------------- The Lower Esophageal Sphincter, which consists of Smooth Muscle. The Lower Esophageal Sphincter regulates the movement of food from the esophagus into the stomach.

Answer 11

- The Voluntary Stage - The Pharyngeal Stage - The Esophageal Stage VOLUNTARY STAGE: in this stage, the tongue voluntarily moves a small piece of food, known as a bolus, toward the back of the oral cavity and into the pharynx. THE PHARYNGEAL STAGE: In this stage, which is involuntary, begins as the bolus enters the pharynx. - The bolus stimulates receptors in the pharynx, which send action potentials to the deglutition center in the medulla oblongata and lower pons of the brain stem. The returning action potentials cause the soft palate and uvula to elevate to close off the upper part of the pharynx, preventing swallowed foods and liquids from entering the nasal cavity. In addition, the epiglottis closes off the opening to the larynx, preventing the bolus from entering the rest of the respiratory tract. The bolus then moves through the remainder of the pharynx. THE ESOPHAGEAL STAGE: In this stage, which is also involuntary, begins once the bolus enters the esophagus. - During this phase, peristalsis propels the bolus down the esophagus toward the stomach. As the bolus approaches the end of the esophagus, the lower esophageal sphincter relaxes and the bolus moves on into the stomach.

Answer 12

Deglutition. - Deglutition involves the mouth, pharynx, and esophagus and occurs in three stages stated above ^^^

Answer 13

- A J-shaped enlargement of the GI tract that connects the Esophagus to the Small Intestines. - The Cardia, Fundus, Body, and Pylorus. THE CARDIA: is the initial region of the stomach just below the lower esophageal sphincter. THE FUNDUS: is the region of the stomach that is superior and lateral to the cardia. THE BODY: is the large, central portion of the stomach. The pylorus is the lower portion of the stomach. THE PYLORIS: is divided into two subcomponents: the Pyloric Antrum and the Pyloric Canal. - The Pyloric Antrum is the portion of the pylorus located closest to the body of the stomach. - The Pyloric Canal is the portion of the pylorus that is located closest to the duodenum of the small intestine. The pyloric canal is separated from the duodenum of the small intestine by the pyloric sphincter, which consists of smooth muscle

Answer 14

Mucosa. Submucosa. Muscularis. Serosa

Answer 15

1. Produces gastric juice, about 2 liters on a daily basis 2. To convert food into chyme 3. It stores food, up to about 2 liters. fun fact: The majority of the food is stored in the fundus of the stomach. The food that is stored in the fundus is food that you ate at the end of a meal. The initial food that you ate is processed by the stomach first, while the last part of your meal is temporarily stored in the fundus waiting for its turn to be processed by the stomach :)

Answer 16

- The epithelium of the gastric mucosa consists of surface mucous cells that secrete mucus and also cells that extend downward to form gastric glands. - Gastric glands contain several types of cells: Mucous neck cells. Parietal cells. Chief cells. - Mucous neck cells, like surface mucous cells, secrete mucus. - Parietal cells secrete hydrochloric acid (or HCl) and intrinsic factor. - Chief cells, also known as zymogenic cells, secrete pepsinogen (the inactive form of the enzyme pepsin) and the enzyme gastric lipase. - The secretions of the mucous neck cells, parietal cells, and chief cells flow into the stomach lumen to form gastric juice. - In addition to the cell types just mentioned, gastric glands include a cell called a G cell. This cell secretes the hormone gastrin into the bloodstream in the lamina propria. - Therefore, gastrin is not a component of gastric juice. As you will learn later, gastrin stimulates several aspects of stomach activity.

Answer 17

``` Gastric juice contains: Hydrochloric acid (or HCl) Mucus Intrinsic factor The enzymes Pepsin and Gastric lipase ``` HYDROCHLORIC ACID: The HCl in gastric juice is a strong acid that causes gastric juice to have a pH of 2. The strong acidity of gastric juice kills many microbes that may be present in food. It also partially denatures (or unravels) proteins in food, making it easier for digestive enzymes to function. - It also provides the acidic pH that is required for the enzymes pepsin and gastric lipase to function in the stomach. Most enzymes in the GI tract and in the body, for that matter, require a neutral to slightly alkaline to function. However, the enzymes pepsin and gastric lipase, which are produced by the stomach, both require an acidic pH to function. If the pH is neutral to slightly alkaline, these enzymes do not function. Hence, ***having HCl present in gastric juice provides the acidic pH that pepsin and gastric lipase need to function.*** MUCOUS: This coats the surface of the gastric mucosa, protecting the cells from the strong acidity of gastric juice. - Without the mucous barrier, gastric juice would burn a hole through the wall of the stomach, resulting in the formation of an ulcer. THE INTRINSIC FACTOR: The intrinsic factor that is present in gastric juice doesn't function until gastric juice enters the small intestine via peristalsis. In the small intestine, intrinsic factor causes the absorption of vitamin B12, which is a vitamin important for the production of red blood cells. PEPSIN: This enzyme starts protein digestion. Note that there is no protein digestion in the mouth, so because of pepsin, protein digestion begins in the stomach. - Pepsin severs (or cuts) certain peptide bonds between amino acids, breaking down a protein into smaller peptide fragments. Recall that pepsin requires an acidic pH to function. GASTRIC LIPASE: This also requires an acidic pH to function. Note that gastric lipase works in the same manner as lingual lipase, which functions in the mouth to break down triglycerides in small fat globules into fatty acids and monoglycerides.

Answer 18

- The stomach contents enter into the small intestine via peristalsis, gastric juice has to be neutralized by the intestinal juice present in the small intestine because the enzymes in the small intestine are typical enzymes that require a pH that is neutral to slightly alkaline to function. - The mucus found in gastric juice coats the surface of the gastric mucosa, thereby protecting the cells from the strong acidity of gastric juice. Without the mucous barrier, gastric juice would burn a hole through the wall of the stomach, resulting in the formation of an ulcer.

Answer 19

NOPE. There is no protein digestion in the mouth.

Answer 20

- Then in the small intestine there are additional enzymes that can do the same thing and help break down the protein (trypsin, chymotrypsin, and elastase). Once smaller peptides have been formed, then they are cleaved into individual amino acids via the enzymes aminopeptidase and carboxypeptidase.

Answer 21

1. - When peristaltic waves move gastric contents from the body of the stomach down into the pylorus, it is a process called propulsion. 2. - When the food particles are forced back up into the body of the stomach, a process referred to as retropulsion. 3. - The net result of these movements is that gastric contents are mixed with gastric juice, eventually becoming reduced to a soupy liquid called chyme. 4. - Gastric Emptying is when the particles can finally pass through the pyloric sphincter. - Several minutes after food enters the stomach, waves of peristalsis pass over the stomach. Each peristaltic wave moves gastric contents from the body of the stomach down into the pylorus, a process known as propulsion. - The pyloric sphincter normally remains almost, but not completely, closed. Because most food particles in the stomach initially are too large to fit through the narrow pyloric sphincter, the food particles are forced back up into the body of the stomach, a process referred to as retropulsion. Another round of propulsion then occurs, moving the food particles back down into the pylorus. If the food particles are still too large to pass through the pyloric sphincter, retropulsion occurs again as the particles are squeezed back up into the body of the stomach. - Once the food particles in chyme are small enough, they can pass through the pyloric sphincter, a phenomenon known as gastric emptying. Gastric emptying is a slow process. Only about 2 milliliters of chyme move through the pyloric sphincter at a given time.

Answer 22

- A gland located behind the stomach and lateral to the duodenum of the small intestine. The pancreas is both an endocrine gland and an exocrine gland.

Answer 23

1. Clusters of cells located in the Endocrine portion of the pancreas. The pancreatic islets comprise 1% of the total weight of the pancreas and are found scattered throughout the pancreas. 2. The cells of the pancreatic islets secrete hormones into the bloodstream. 3. The two major types of cells found in the pancreatic islets are alpha cells and beta cells: - Alpha cells secrete the hormone glucagon. - Beta cells secrete the hormone insulin.

Answer 24

- This constitutes about 99% of the total weight of the pancreas. It consists of clusters of cells called acini (singular is acinus) that are are attached to small ducts. The acinar cells secrete pancreatic juice into the small ducts and then from the small ducts, the pancreatic juice enters the large pancreatic duct.

Answer 25

1. In the small intestines to help digest food. 2. The pancreatic duct unites with the common bile duct coming from the liver and gallbladder to form a duct called the Hepatopancreatic ampulla (or ampulla of Vater), which in turn empties into the small intestine. 3. The passage of pancreatic juice and bile through the hepatopancreatic ampulla is regulated by a sphincter called the sphincter of the hepatopancreatic ampulla (or sphincter of Oddi). And this sphincter consists of smooth muscle. The pancreas produces about 2 liters of pancreatic juice on a daily basis. Pancreatic juice consists mostly of water, but it also contains bicarbonate ions and several enzymes 4. Pancreatic juice is mostly of water, but it also contains bicarbonate ions and several enzymes. 5. The enzymes that digest proteins into smaller peptides are Amylase, Pancreatic lipase, Trypsin, Chymotrypsin, Elastase, and Carboxypeptidase. PANCREATIC LIPASE: breaks down starches into short chains of glucose called alpha dextrins. Pancreatic amylase functions the same way as salivary amylase and is essentially a backup copy of salivary amylase. Random note: The bicarbonate ions give pancreatic juice a slightly alkaline pH that buffers acidic gastric juice in chyme that enters the small intestine, stops the action of pepsin from the stomach, and creates the proper pH for the action of digestive enzymes in the small intestine.

Answer 26

- Yes, bile from the liver and gallbladder passes along the common bile duct to enter the hepatopancreatic ampulla and then into the small intestine.

Answer 27

- Pancreatic amylase breaks down starches into short chains of glucose called alpha dextrins. Pancreatic amylase functions the same way as salivary amylase, and is essentially a backup copy of salivary amylase.

Answer 28

CNS - central nervous system ANS - Autonomic nervous system aka long reflexes ENS - enteric nervous system

Answer 29

1. The CNS - central nervous system controls voluntary swallowing movements 2. ANS - autonomous nervous system aka long neural reflexes include a CNS control center in the spinal cord or brain. ANS regulates involuntary smooth muscle movements. ENS reflexes utilize the plexuses embedded in the wall of the GI tract 3. Stimulus is distension /// Response is increase or decreased contraction of the muscularis 4. CNS

Answer 30

Haustral Churning

Answer 31

1. Diverse factors that can cause variances in transit time in an individual include: - meal composition, hydration, activity level, medications, and psychological stress. 2. Additional factors that contribute to variability among individuals are: - age, gender, and reproductive status. All of these factors make it extremely difficult to estimate the exact length of ‘normal’ transit time.

Answer 32

1. 25 — 36 hours. 2. Malabsorption, which can lead to malnutrition, occurs if food moves through the GI tract too quickly (less than 18 hours) because nutrients don't have enough time to be absorbed into the intestines. 3. Degenerative Diseases can occur if transit time is too long (longer than 48 hours) because the substances will sit in the intestines and putrefy, allowing toxins to be absorbed into the body. 4. It is critical for a person to have good health. 5. The following are estimates of ‘average’ transit times for food to travel through GI tract organs: Esophagus — seconds Stomach — 4 – 5 hours Small Intestine — 5 – 6 hours Large Intestine — 16 – 36 hours

Answer 33

- aka roughage affects digestion, absorption, and elimination of food and plays a role in the prevention of chronic diseases. Fiber content is often listed on the Nutrition Facts label under "Total Carbohydrates". Because fiber is undigested, it is not absorbed and includes zero calories. Dietary fiber may be categorized as either soluble (dissolves in water) or insoluble (does not dissolve in water).

Answer 34

1. - Fiber provides bulk, making elimination easier, helping to prevent constipation and abrasion. 2. - It also fills the stomach, reducing appetite, and could decrease eating, leading to weight loss. Most Foods contain BOTH types of fibers

Answer 35

- The liver converts cholesterol into the two main bile acids: Cholic and Chenodeoxycholic Acids that are necessary for fat emulsification. The liver secretes bile acids into the gallbladder to be stored until fatty food reaches the duodenum, at which time the gallbladder contracts to release the bile acids into the duodenum. The bile acids attach to, and emulsify fat to facilitate the ability of lipases to break down lipid molecules into smaller molecules that can be absorbed. The body reabsorbs approximately 95 percent of the bile acids through the lining of the ileum for transport back to the liver in the bloodstream. Bile acid molecules recirculate by this process and are used about 15 to 20 times before being excreted from the body in the feces. Increased fecal excretion of bile acids results in the liver removing cholesterol from the bloodstream to produce more bile acids, thus lowering serum cholesterol levels.

Answer 36

Radiopaque markers and a Spectrophotometer

Answer 37

- Used to measure transit time. Radiopaque markers are small capsules that are ingested and appear opaque on X rays as they pass through the digestive tract. Transit time will be estimated by measuring the amount of markers remaining in stomach and colon at various times after ingestion.

Answer 38

Radiopaque markers Spectrophotometer

Answer 39

food to travel completely through the gastrointestinal tract

Answer 40

Food to travel completely through the gastrointestinal tract

Answer 41

Reabsorbed routinely by the small intestine

Answer 42

Bile acids

Answer 43

emulsifying fat

Answer 44

reduction of chemical digestion

Answer 45

- amount of water in diet - amount and type of food eaten - activity of person

Answer 46

reduce the size of food molecules

Answer 47

soluble and insoluble

Answer 48

creates a viscous gel

Answer 49

25 — 36 hours

Answer 50

number of radiopaque markers in GI tract

Answer 51

number of radiopaque markers in GI tract

Answer 52

calories in meal | nutrients in meal

Answer 53

amount of bile acids in solution

Answer 54

amount of bile acids in solution

Answer 55

amount of fiber in meal

Answer 56

moisture in meal size of meal particles calories and nutrients in meal

Answer 57

Equations (fx) Use these formulas for making your calculations. Round your answer to the nearest tenth. -------------------- AVERAGES: Add the values from the three trials (or subjects); divide by three. PERCENTAGE of the number of markers in GI tract: Divide the number (n) of the markers observed by 24 and multiply by 100: (n/24)* 100%.

Answer 58

STANDARD MEAL AT 60 MINS = 79 180 MINS = 25 240 MINS = 4

Answer 59

INSOLUBLE FIBER MEAL AT 60 MINS = 75 180 MINS = 29 240 MINS = 4

Answer 60

SOLUBLE FIBER MEAL AT 60 MINS = 79 180 MINS = 42 240 MINS = 8

Answer 61

SOLUBLE FIBER-RICH DIET ..HAD THE GREATEST AVERAGE PERCENTAGE OF MARKERS AT 180 MINS

Answer 62

STANDARD MEAL AVERAGE PERCENTAGES: ``` RIGHT COLON(RC) 24 HOURS = 46 48 HOURS = 17 96 HOURS = 0 ``` ``` LEFT COLON (LC) 24 HOURS = 29 48 HOURS = 17 96 HOURS = 0 ``` ``` SIGMOID COLON (SC) 24 HOURS = 8 48 HOURS = 17 96 HOURS = 13 ``` (TOTAL COLON) 24 HOURS = 83 48 HOURS = 50 96 HOURS = 13

Answer 63

INSOLUBLE FIBERS MEAL AVERAGE PERCENTAGES: ``` RIGHT COLON (RC) 24 HOURS = 17 48 HOURS = 8 96 HOURS = 0 ``` ``` LEFT COLON (LC) 24 HOURS = 33 48 HOURS = 13 96 HOURS = 0 ``` ``` SIGMOID COLON (SC) 24 HOURS = 21 48 HOURS = 17 96 HOURS = 4 ``` (TOTAL COLON) 24 HOURS = 71 48 HOURS = 38 96 HOURS = 4

Answer 64

SOLUBLE FIBERS MEAL AVERAGE PERCENTAGES: ``` RIGHT COLON (RC) 24 HOURS = 42 48 HOURS = 17 96 HOURS = 0 ``` ``` LEFT COLON (LC) 24 HOURS = 33 48 HOURS = 17 96 HOURS = 0 ``` ``` SIGMOID COLON (SC) 24 HOURS = 8 48 HOURS = 17 96 HOURS = 4 ``` (TOTAL COLON) 24 HOURS = 83 48 HOURS = 46 96 HOURS = 8

Answer 65

INSOLUBLE FIBER

Answer 66

Standard Meal With Bile Acid

Answer 67

Fiber-Rich Meal With Bile Acid

Answer 68

Between 180 and 240 minutes

Answer 69

Soluble Fiber-Rich Diet because it still had 8 markers left at 240 minutes when the other meal options had 4.

Answer 70

About 96 hours for each meal type.

Answer 71

Insoluble Fiber-Rich Diet

Answer 72

Insoluble Fiber-Rich Diet spent the least amount of time in the small intestine because it was already at 17 markers when the other meal types were still had over 40 markers at 24 hours.

Answer 73

Increases because the averages were higher after the dietary fiber

Answer 74

Eating a high fiber diet may reduce my serum cholesterol level because bile acid it adheres to food particles instead of allowing it to be absorbed into the blood stream.

Answer 75

because it doesn't get digested or absorbed, it just goes through the GI tract. This means it won't really have a great affect on changing glucose levels.

Ch. 7 Digestive System Flashcards

(111 cards)