Ch. 7 Digestive System

Question 1

OVERVIEW OF THE DIGESTIVE SYSTEM

Answer 1

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Question 2

What is a key reaction that occurs inside our cells?

Answer 2

Cellular (Aerobic) Respiration

Question 3

What is a key reaction that occurs inside our cells?

Answer 3

Cellular (Aerobic) Respiration

In this reaction, Glucose, a Fatty Acid, or Amino Acid is broken down to produce Carbon Dioxide, Water, and a lot of energy in the form of ATP.

The nutrients that are broken down in this equation comes from the digestive tract. This means that the food that we eat ultimately gives us energy in the form of ATP via cellular respiration.

Question 4

Monomers vs Polymers

Answer 4

Monomers are small repeating units of large substances called polymers. ex:

Glucose = Monomer 
Starch = Polymer

Hint: The food we eat are polymers (if you can see the food). If it’s something we can’t see like amino acids then it’s a monomer.

Question 5

What’s the purpose of the digestive system?

Answer 5

• to break down the large polymers in our food into small, microscopic monomers

Question 6

What does the body use to break down food into monomers?

Answer 6

Digestive Enzymes

Question 7

Via the digestive system:

Protein (Fish, Chicken, Steak, Pork etc) turns into:

Starch (Baked Patato) turns into:

Triglyceride/Fat (Butter, Sour Cream) turns into:

Answer 7

.

AMINO ACIDS

GLUCOSE MOLECULES

2 FATTY ACIDS AND 1 MONOGLYCERIDE

ATP (ENERGY)

Question 8

Most carbohydrates and proteins are:

Carbs and proteins are usually broken down into monomers

Once monomers are formed via digestion, the monomers are absorbed into the blood stream which go into cells, which can use the monomers via cellular respiration to generate ATP.

Answer 8

Hydrophilic.

And digestive enzymes are able to easily interact with carbohydrates in our diet because enzymes are also hydrophilic. Most enzymes are protein

Triglycerides are overall hydrophobic and have a difficult time being digest by enzymes which are hydrophilic. Therefore, in most cases, triglyceride digestion is not complete

Question 9

Why is triglyceride digestion usually not complete?

Answer 9

Because triglycerides are hydrophobic, while digestive enzyme are hydrophilic, making triglycerides harder for a digestive enzyme to break them down.

Question 10

What are fatty acids?

What are monoglycerides?

Answer 10

Monomers

Dimers

Question 11

Once food is broken down into monomers, how is it used in the body?

Answer 11

Once monomers are formed via digestion, the monomers are absorbed into the blood stream which go into cells, which can use the monomers via cellular respiration to generate ATP.

Question 12

The 2 groups of organs in the digestive system are:

Answer 12

The Gastrointestinal Tract

&

The Accessory Digestive Organs

Question 13

What is The Gastrointestinal Tract?

What are the organs that make up the GI Tract?

Answer 13

A continuous tube from the mouth to the anus.

Mouth. Pharynx. Esophagus. Stomach. Small Intestines. Large Intestines

Question 14

What are The Accessory Digestive Organs?

Answer 14

These are the organs that play an ancillary (assisting, helpful) role in digestion.

Teeth. Tongue. Salivary Glands. Pancreas. Liver. Gallbladder.

Question 15

Name the 6 basic digestive processes:

Answer 15

Ingestion. Secretion. Motility. Digestion. Absorption. Defecation.

Question 16

Ingestion definition and give example -

Answer 16

This involves taking food and liquids into the mouth (Eating or Drinking).

Question 17

Secretion definition and give example -

Answer 17

• Refers to the production and release of digestive fluids by glands of the digestive system.
  
  • These fluids usually contain enzymes that digest the food that is present in the lumen of the GI Tract.

Question 18

Motility definition and give example -

Answer 18

• Refers to the contractions of smooth muscle in the wall of the GI Tract.
  
  • These contractions mix food and secretions and propel them toward the anus.

Question 19

Digestion definition and give example -

What are the TWO types of digestion and what do they do?

Answer 19

The act of breaking down food into smaller particles

• Chemical digestion & Mechanical digestion

Mechanical: involves PHYSICALLY breaking down food into smaller components. Ex: when teeth cut and grind food into smaller pieces.

Chemical: Involves the use of digestive enzymes that break the chemical bond within polymers to release individual monomers.

Note that: Mechanical digestion helps facilitate Chemical digestion because the digestive enzymes can cleave bonds within molecules more easily if the food item has already been torn into pieces.

Question 20

Absorption definition and give example -

Answer 20

• The movement of the products of digestions (usually monomers) from the lumen of the GI Tract into blood or lymph.
  
  • Once absorbed, these substances circulate to the cells throughout the body.

Question 21

Defecation definition and give example -

Answer 21

• The process by which waste and indigestible substances from our food are released as stool or feces

Question 22

LAYERS OF THE GI TRACT

Answer 22

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Question 23

The wall of the GI tract from the esophagus to the anus has 4 layers, what are they?

Answer 23

Mucosa. Submucosa. Muscularis. Serosa

Question 24

Mucosa (or mucous membrane) Layers and details:

Answer 24

• The inner layer of the GI Tract
  
  • This mucosa has 3 layers (Epithelium, Lamina Propria aka connective tissue, Muscularis Mucosae aka small amount of smooth muscle)
  • The smooth muscle contracts to give the wall of the stomach and small intestines several folds that increase the surface area for digestion and absorption.
  NOTE - **The Muscularis Mucosae is NOT INVOLVED in GI MOTILITY. Instead, the muscularis (which is the third layer of the GI Tract) serves as the MAIN MOTILITY layer because it contains a lot of muscle.

Question 25

Muscularis

Answer 25

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.

Question 26

Serosa

Answer 26

• 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.

Question 27

ENTERIC NERVOUS SYSTEM

Answer 27

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Question 28

How many nerves/neurons are in the ENS?

Answer 28

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

Question 29

The neurons of the Enteric Nervous System are arranged into two plexuses, what are they?

Answer 29

• 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 secretionMyenteric 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

Question 30

note

Answer 30

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.

Question 31

AUTONOMIC INNERVATION OF THE GI TRACT

Answer 31

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Question 32

What do the Parasympathetic Nerves do?

Answer 32

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.

Question 33

MOUTH

Answer 33

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Question 34

What is Saliva Amylase? What does it does?

What is lingual or Lipid Lipase? What does it do?

Answer 34

• 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.

Question 35

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Answer 35

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Question 36

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Answer 36

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Question 37

PHARYNX AND ESOPHAGUS

Answer 37

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Question 38

What is the Pharynx? What does it do?

Answer 38

• 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.

Question 39

What is the Esophagus? What does it do?

Answer 39

• 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.

Question 40

At each end of the Esophagus, the Muscularis gives rise to 2 sphincters:

What are they, what do they consist of, what do they do?

Answer 40

• The Upper Esophageal Sphincter
  
  • The Lower Esophageal SphincterThe 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.

Question 41

Name the different stages of swallowing. What do they do?

Answer 41

• The Voluntary Stage
  
  • The Pharyngeal Stage
  • The Esophageal StageVOLUNTARY 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.

Question 42

What’s another name for swallowing?

Answer 42

Deglutition.

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

Question 43

THE STOMACH

Answer 43

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Question 44

What is the Stomach?

What are the 4 major regions of the Stomach?

Answer 44

• 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

Question 45

The stomach wall is composed of the same basic 4 layers as the rest of the GI tract: What are they?

Answer 45

Mucosa. Submucosa. Muscularis. Serosa

Question 46

What is the function of the stomach?

Answer 46

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 :)

Question 47

Several Mucous Cells of the Gastric Mucosa details:

Answer 47

• 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.

Question 48

What are the different components of gastric juice?

Why are they important?

Answer 48

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.

Question 49

Fun fact: does stomach acid need to be neutralized when entering the small intestine’s in order for the small intestine’s enzymes to work? YES. Here’s why.

Answer 49

• 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.

Question 50

Is there any protein digestion in the mouth?

Answer 50

NOPE. There is no protein digestion in the mouth.

Question 51

If for some reason pepsin does not break down a protein into smaller peptides while in the stomach, what can?

Answer 51

• 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.

Question 52

1. What is propulsion? (moving down into small int.’s)
2. What is retropulsion? (moving back up into stomach)
3. What is the net result of the movements propulsion and retropulsion? (hint: chyme)
4. What is it called when the particles finally move through the pylorrix sphincter?

Answer 52

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.

Question 53

PANCREAS, LIVER, GALLBLADDER

Answer 53

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Question 54

What’s the pancreas?

Answer 54

• 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.

Question 55

What are pancreatic islets (or islets of Langerhans)?

What do their cells do?

What do they consist of?

Answer 55

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.

Question 56

Exocrine portion of the pancreas details:

Answer 56

• 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.

Question 57

1. Where does pancreatic juice function?
2. How is pancreatic juice released? Exam
3. How is the passage of pancreatic juice regulated?
4. What is pancreatic juice consistent of?
5. What are the enzymes in pancreatic juice?

Answer 57

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.

Question 58

Does bile from the liver and gallbladder also function in the small intestine to help promote digestion?

Answer 58

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

Question 59

What does Pancreatic Amylase do?

Answer 59

• 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.

Question 60

POWERPHYS ACTIVITY 14:

Answer 60

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Question 61

Where does the neural control of the mechanical movements in the GI tract come from?

Answer 61

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

Question 62

1. What controls voluntary movements?
2. What controls INvoluntary movements? hint ans and ens
3. What is the stimulus and response for involuntary movements?
4. What regulates mastication?

Answer 62

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

Question 63

What mixes chyme?

Answer 63

Haustral Churning

Question 64

What are the diverse variables of transit time?

Answer 64

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.

Question 65

1. What is the average transit time?
2. What happens if transit time is too fast?
3. What happens if transit time is too slow?
4. Why is normal transit time critical / important?
5. What are the average times for food to travel through each GI tract organ?

Answer 65

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

Question 66

Dietary Fiber

Answer 66

• 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).

Question 67

What is the purpose / function of fiber ? What does it do?

Answer 67

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

Question 68

Bile Secretion and Reabsorption

Answer 68

• 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.

Question 69

What is used to measure Transit time and Bile acid adsorption?

Answer 69

Radiopaque markers and a Spectrophotometer

Question 70

Radiopaque markers

Answer 70

• 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.

Question 71

What is used to measure Transit time

What tool is used to measure Bile acid adsorption?

Answer 71

Radiopaque markers

Spectrophotometer

Question 72

PRE LAB QUIZ QUESTIONS

Answer 72

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Question 73

Transit time can be defined as the amount of time it takes for

Answer 73

food to travel completely through the gastrointestinal tract

Question 74

Transit time can be defined as the amount of time it takes for

Answer 74

Food to travel completely through the gastrointestinal tract

Question 75

Bile acids are reabsorbed in the body

Answer 75

Reabsorbed routinely by the small intestine

Question 76

Cholesterol is converted in the liver and secreted from the body in the form of

Answer 76

Bile acids

Question 77

Bile salts improve digestion by

Answer 77

emulsifying fat

Question 78

Which of the following is NOT a health advantage due to increased fiber digestion?

Answer 78

reduction of chemical digestion

Question 79

Transit time is affected by

Answer 79

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

Question 80

The purpose of chemical digestion is to

Answer 80

reduce the size of food molecules

Question 81

Fiber in foods usually consists of the following two types

Answer 81

soluble and insoluble

Question 82

Soluble fiber can be distinguished from insoluble fiber because it

Answer 82

creates a viscous gel

Question 83

Average transit time is

Answer 83

25 — 36 hours

Question 84

EXPERIMENT

Answer 84

.

Question 85

Dependent Variable

Answer 85

number of radiopaque markers in GI tract

Question 86

Effect of Dietary Fiber on Transit Time

• Dependent Variable

Answer 86

number of radiopaque markers in GI tract

Question 87

Controlled Variables

Answer 87

calories in meal

nutrients in meal

Question 88

Effect of Dietary Fiber on Bile Acid Adsorption:

• Dependent Variable

Answer 88

amount of bile acids in solution

Question 89

Effect of Dietary Fiber on Bile Acid Adsorption:

• Dependent Variable

Answer 89

amount of bile acids in solution

Question 90

Independent Variable

Answer 90

amount of fiber in meal

Question 91

Controlled Variables

Answer 91

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

Question 92

EQUATIONS

Answer 92

Equations (fx)

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%.

Question 93

POST EXPERIMENT QUESTIONS

Answer 93

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Question 94

For the STANDARD meal, what is the average percentage of markers remaining in the stomach at 60 min, 180 min, and 240 min?

Answer 94

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

Question 95

For the meal with INSOLUBLE fibers, what is the average percentage of markers remaining in the stomach at 60 min, 180 min, and 240 minutes?

Answer 95

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

Question 96

For the meal with SOLUBLE fibers, what is the average percentage of markers remaining in the stomach at 60 min, 180 min, and 240 min?

Answer 96

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

Question 97

Which meal had the GREATEST average percentage of markers in the stomach at 180 minutes?

Answer 97

SOLUBLE FIBER-RICH DIET

..HAD THE GREATEST AVERAGE PERCENTAGE OF MARKERS AT 180 MINS

Question 98

For the STANDARD meal, what is the average percentage of markers in the right colon (RC), left colon (LC), sigmoid colon (SC) and total colon at 24, 48, and 96 hours?

Answer 98

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

Question 99

For the meal with INSOLUBLE fibers, what is the average percentage of markers in the right colon (RC), left colon (LC), sigmoid colon (SC) and total colon at 24, 48, and 96 hours?

Answer 99

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

Question 100

For the meal with SOLUBLE fibers, what is the average percentage of markers in right colon (RC), left colon (LC), sigmoid colon (SC) and total colon at 24, 48, and 96 hours?

Answer 100

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

Question 101

Which meal had the least percentage of markers in the total colon at 24 hours?

Answer 101

INSOLUBLE FIBER

Question 102

Which had the greatest average OD (amount of bile acid in filtrate), the standard meal with bile acid or the fiber-rich meal with bile acid?

Answer 102

Standard Meal With Bile Acid

Question 103

Which had the greatest average 1- OD (amount of bile acid adsorbed to meal particles), the standard meal with bile acid or the fiber-rich meal with bile acid?

Answer 103

Fiber-Rich Meal With Bile Acid

Question 104

Approximately how long did it take for a meal to move through the stomach, less than 60 minutes, between 60 and 180 minutes, or between 180 and 240 minutes?

Answer 104

Between 180 and 240 minutes

Question 105

Which meal spent the most time in the stomach? Explain your choice based on your results.

Answer 105

Soluble Fiber-Rich Diet

because it still had 8 markers left at 240 minutes when the other meal options had 4.

Question 106

Approximately how long did it take for a meal to move through the colon for the standard diet, the soluble fiber-rich diet, and insoluble fiber-rich diet?

Answer 106

About 96 hours for each meal type.

Question 107

Which meal spent the least time in the colon? Explain your choice based on your results.

Answer 107

Insoluble Fiber-Rich Diet

Question 108

Based on the average number of markers in the right colon and the average total number of markers in the colon at 24 hours, which meal do you think spent the least amount time in the small intestine? Explain your choice based on your results.

Answer 108

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.

Question 109

Does fiber increase or decrease the amount of bile lost in feces? Explain your choice based on your results.

Answer 109

Increases because the averages were higher after the dietary fiber

Question 110

Explain why eating a high fiber diet may reduce your serum cholesterol level.

Answer 110

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.

Question 111

Based on your results, speculate why eating a high fiber diet may prevent large changes in blood glucose levels.

Answer 111

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.