39. Digestive System

Digestion

How does your stomach help your digestion?

Carbohydrate (Glucose) Absorption

Digestive System

How your digestive system works - Emma Bryce

Digestion and Digestive Tracts

Mouth and Esophagus

Digestive System 7- Large intestine

 the gallbladder makes bile, which is necessary for fat emulsification 

 No. Bile is produced in the liver. It is stored in the gallbladder. 

 without the bile produced by the gallbladder, fats cannot be enzymatically hydrolyzed 

 No. Bile is not an enzyme, nor is it produced by the gallbladder. 

 the gallbladder stores the hormone cholecystokinin, necessary to digest fats 

 No. Cholecystokinin does not promote the chemical breakdown of fats. However, cholecystokinin does stimulate the release of bile from the gallbladder.  

 chylomicrons first enter the gallbladder before moving to the liver 

 No. Chylomicrons are initially transported by the lymphatic system. 

 the gallbladder stores large quantities of bile, which is used to emulsify fats 

Think about the functions of bile.

Gallstone surgery sometimes requires that the gallbladder be removed. Patients are then advised to avoid ingesting large amounts of fat because __________.

After surgical removal of the gallbladder, a person might need to limit his or her dietary intake of
a. starch.
b. protein.
c. sugar.
d. fat.

 No. Fat is not digested until acid chyme is neutralized in the duodenum. 

 is a mush made from boluses and hydrolytic enzymes secreted by the pancreas and duodenum 

 No. The chyme is not acid, but neutralized, when it encounters these enzymes in the small intestine. 

 No. A bacterium is thought to be the cause of stomach ulcers, which are subsequently irritated by acid chyme. 

 passes into the large intestine, where water is removed 

 No. By the time undigested food reaches this point, it is called feces. 

 contains food and gastric juice and moves through the pyloric sphincter 

Consider where chyme is formed.

Acid chyme __________.

Complete the following map summarizing the nutritional needs of animals that are met by a healthy diet. 
a. 
b. 
c. 
d. 
e. 
f. 
g. <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/77cdd5619508ae4c-1677718216081.jpg" style="width: 300px;">

 No. This only describes part of the correct answer. 

 No. This is only one example of the correct answer. 

 All of the listed responses are correct. 

 No. Only one choice describes both situations. 

What term describes both situations?

An insufficient supply of chemical energy in the diet or a shortage of one or more essential nutrients results in which of the following?

Which of the following is not a major activity of the stomach?
a. storage
b. HCl production
c. nutrient absorption
d. enzyme secretion

Nutrient Absorption

absorption

Digestive System, Part 1: Crash Course Anatomy & Physiology #33

 No. These serve to expand the intestine's surface area by providing more space for villi, but there is a more specific answer. 

 No. These are within the wall of the microvilli and pick up nutrients that have been absorbed. 

 No. Lacteals are lymphatic vessels found within each villus in the small intestine. 

 No. The villi are covered with an epithelium that bears the true absorptive surface. 

Consider what structure increases the surface area of the small intestine.

Where does absorption take place in the small intestine?

Why is it necessary for healthy vegetarians to combine different plant foods or eat some eggs or milk products?
a. to make sure they obtain sufficient calories
b. to provide sufficient vitamins
c. to make sure they ingest all essential fatty acids
d. to provide all essential amino acids for protein synthesis

If you put the following events in the order they occur in the human digestive system, the third event in the series would be
a. Cells in gastric pits secrete protons.
b. Pepsin activates pepsinogen.
c. HCl activates pepsinogen.
d. Partially digested food enters the small intestine.

 antibiotics are toxic to the colon's epithelium and to bacteria 

 No. If antibiotics were toxic, they would be taken as a medicine only as a last resort. 

 antibiotics interfere with the vitamin absorption normally occurring within the large intestine 

 No. Although some vitamins are absorbed in the large intestine, the problem is related to water balance. 

 after intestinal bacteria have been killed, an unusually large amount of water is reabsorbed 

 No. If this were true, constipation would become the problem rather than diarrhea. 

 antibiotics affect the hormones that control intestinal peristalsis 

 No. This is not known to be the cause of diarrhea. 

 the microbiome of the large intestine that normally breaks down undigested organic material is killed by the antibiotics 

Think about the digestive processes that occur in the colon.

During some types of antibiotic treatments, patients often experience diarrhea because __________.

There are several key concepts introduced in this chapter: Structure correlates with function; an animal’s body has a hierarchy of organization with emergent properties at each level; and complex bodies have structural adaptations that increase surface area for exchange. Label the tissue layers shown in this section of the small intestine, and describe how this diagram illustrates these three concepts.. 
a. Microvilli 
b. Mucosa 
c. Muscularis 
d. Sub-serous layer 
e. Serosa<img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/a832f685a8f3dc35-1677718031789.jpg" style="width: 300px;">

The Role and Anatomy of the Pancreas

The path of food through the digestive system

Biology in Focus Ch 33 Animal Nutrition

Which of the following vitamins is mismatched with the disease that results from its underconsumption?
a. vitamin B6—beriberi
b. vitamin C—scurvy
c. vitamin A—vision loss
d. vitamin D—rickets

Among vertebrates, the large intestine exists only in lineages that are primarily terrestrial (amphibians, reptiles, and mammals). Propose a hypothesis to explain this observation.

GCSE Science Revision Biology "Absorption in the Small Intestine"

Digestive System 3, Pancreas

 No. The pyloric sphincter helps regulate the passage of chyme into the small intestine. 

 No. This is the middle region of the small intestine. This section functions mainly in the absorption of nutrients and water. 

 No. This is the last region of the small intestine. This section functions mainly in the absorption of nutrients and water. 

 No. This is another term for the large intestine. 

This is the first of three sections of the small intestine.

The liver and pancreas add their secretions to the partially digested food produced in the stomach, in the __________ of the small intestine.

HHMI BioInteractive: Fate of Fat

 No. This answer is partially correct; however, fats must first be mixed with other substances and rendered water-soluble before they can be absorbed by the lacteals. 

 No. Monosaccharides are water-soluble and thus absorbed into the bloodstream through the villus. 

 No. Amino acids are water-soluble and thus absorbed into the bloodstream through the villus. 

 No. Peptides are water-soluble and thus absorbed into the bloodstream through the villus. 

Consider what is absorbed into lacteals.

The lymphatic vessels in the villi absorb and transport __________.

 No. A shortage of carbohydrates would not likely affect bone structure in this way. Further, the grasses in the pasture probably provide good amounts of carbohydrates. 

 No. Undernutrition should not specifically affect bone structure in this way. 

 No. A shortage of fat would not likely affect bone structure. 

 No. Vitamin A deficiencies would likely lead to problems with vision. 

This component of the diet is in short supply in some soils.

Despite long days grazing on tall grasses, several of the cattle released into a new pasture have oddly shaped or broken legs and often lie down. These cattle might be suffering from __________.

How might our craving for fatty foods, which is helping to fuel the obesity crisis, have evolved through natural selection?

Oral Cavity, Pharynx and Esophagus

 All the listed responses are needs that must be supplied through diet. 

 No. Although all of the choices are essential to all animals, one of the listed responses is not obtained in the diet. 

This is something that is needed in large quantities.

Which of the following is acquired outside of an animal's diet?

Animation: Overview of the Human Digestive System

 It releases a hormone called gastrin, which stops gastric juice secretion. 

 No. Gastrin stimulates gastric juice production, decreasing the pH. 

 Bile neutralizes the acid soon after it enters the stomach. 

 No. Bile is not released into the stomach. It is released into the small intestine. In addition, bile would do little to neutralize stomach acids. 

 Parietal cells secrete a protective buffer to neutralize hydrochloric acid. 

 No. Parietal cells actually secrete HCl into the stomach. 

 The acid is neutralized quickly when it combines with pepsinogen to make pepsin. 

 No. The presence of HCl converts pepsinogen into its active form, pepsin, but the HCl is not neutralized. 

 Mucous cells secrete a protective lubricant into the stomach. 

Think about the defenses against the damaging HCl (hydrochloric acid).

How is the stomach lining protected from the strongly acidic pH of its contents?

 No. Taste buds are located on the tongue. 

 push food into the pharynx to begin swallowing 

Think about all the things the tongue does for you.

The tongue does all of the following except __________.

IGCSE BIOLOGY REVISION - [Syllabus 7.5] Absorption

 No. This is how some nutrients are absorbed. 

 sequential contraction of bands of skeletal muscles 

 No. The digestive tract is lined by smooth muscle. 

 No. Sphincters regulate the movement of material between major structures of the alimentary canal. 

This is a type of muscle activity.

In vertebrates, food is moved along the length of the digestive system by __________.

Digestion Intro Mecahnical and Chemical Digestion

Which of the following statements is false?
a. A healthy human has enough stored fat to supply calories for several weeks.
b. An increase in leptin levels leads to an increase in appetite and weight gain.
c. The interconversion of glucose and glycogen takes place in the liver.
d. After glycogen stores are filled, excessive calories are stored as fat, regardless of their original food source

One can come from sugar and the other from proteins.

Animals need two types of organic precursors from their food, __________, to serve as the raw materials for the synthesis of larger organic molecules.

Label the parts of the human digestive system below and indicate the functions of these organs and glands. 
a. 
b. 
c. 
d. 
e. 
f. 
g. 
h. 
i. 
j. 
k. 
l. <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/7643df3185fa3ac3-1677718177696.jpg" style="width: 300px;">

Digestion of proteins, carbohydrates, and fats

Why is it important that the small intestine has a much greater surface area than the stomach or esophagus?

 They are washed out of the body in water that daily passes into the digestive system. 

 No. Most of this water does not leave the body and so does not "cleanse" the digestive system of its contents. 

 In the presence of certain vitamins, prokaryotes are able to digest plant fibers. 

 No. The vitamins do not make plant fibers more digestible. 

 The bacteria cause rapid peristalsis, resulting in constipation, which retains plant fibers and vitamins in the lower intestine. 

 No. Rapid peristalsis results in diarrhea, not constipation. 

 They move through the terminal portion of the colon together and are voided as feces. 

 No. The vitamins are absorbed in the large intestine. 

 They are the contents of the large intestine. 

Consider the segments of the mammalian digestive system and the functions of each.

What relation do indigestible plant fibers, prokaryotes, and vitamins have with the digestive system?

Introduction to Large Intestine

Digestive Enzymes of Small Intestine and Pancreas

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory?

Suggest a function of the difference in relative gut lengths of herbivorous and carnivorous minnows.

Cellulose is fermented in which of the following structures in rabbits?
a. small intestine
b. cecum
c. abomasum
d. rumen

Earthworms, which are substrate feeders.
feed mostly on mineral substrates.
filter small organisms from the soil.
are bulk feeders that ingest large pieces of food.
eat their way through the soil, feeding on partially decayed organic matter.

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory?

Researchers compared the relative gut length—the length of the digestive tract divided by body length—in four species of herbivorous minnows and four species of carnivorous minnows. The results are shown in the graph provided here. Based on these data, what conclusion can you draw about the relationship between diet and gut length? <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/d0b333bcdb5832a8-1677307263666.jpg" style="width: 300px;">

 No. This is an adaptation to an herbivorous diet. 

 Large populations of symbiotic bacteria and protists in special fermentation chambers in the alimentary canal 

Think about differences between carnivores and herbivores.

Which of the following is an adaptation to a carnivorous diet?

 that it contains the essence of vegetables used to extract the nutrients 

No. The word essential has another meaning.

 that they can be made in the body but it is important to eat food containing these nutrients so that we do not waste essential energy in making them 

 No. This is not the definition of an essential nutrient. 

No. Though the vitamins and minerals may be necessary for life, the word essential here has a different meaning.

 that the nutrients must be supplied in the diet and cannot be made in the body 

Consider what makes these essential in a human's diet.

A breakfast cereal advertises that it contains essential vitamins and minerals. In this context, the word essential means __________.

 No. After absorption, carbohydrates move into the hepatic portal vessel, which leads to the liver. 

 No. After absorption, amino acids move into the hepatic portal vessel, which leads to the liver. 

 No. After absorption, nucleotides move into the hepatic portal vessel, which leads to the liver. 

 No. One type of molecule follows a path that does not go directly to the liver. 

Consider the absorption of nutrients into capillaries and lacteals.

Researchers provided radioactively labeled food to a dog and traced the movement of absorbed molecules. Which type of molecule moved along a path different from all the others?

 No. Carbohydrate digestion begins before the food enters the stomach. 

 No. Carbohydrate digestion begins before the food enters the small intestine, and lipase is not responsible for carbohydrate digestion. 

 No. Carbohydrate digestion begins before the food enters the small intestine. 

 No. Although salivary amylase does begin carbohydrate digestion, it begins in the mouth, not the stomach. 

Think about the first things that happen when you start eating.

Chemical digestion of carbohydrates begins in the __________ with the action of __________.

Evaluate the following statements regarding digestion; select True or False for each statement.

T/F Salivary amylase completes the digestion of starch into monosaccharides.
T/F Pepsin digests proteins in the stomach.
T/F Trypsin digests disaccharides into monosaccharides.
T/F Pancreatic lipase performs the majority of chemical digestion of lipids.

Chemical and Mechanical Digestion - More Science on the Learning Videos Channel

Explain the role in nutrition of each of the following structures: bird crop, cow rumen, and elephant cecum.

The Digestive Process - University of Michigan Health System

Minnows are mainly carnivorous, eating insects and other small animals. However, herbivory has evolved independently in minnows several times. What changes in digestive structure and function are associated with the evolution of herbivory?

Which of the following is true of the digestive tracts of minnows?
a. They are incomplete but have both a mouth and an anus.
b. They are complete, facilitating compartmentalization of digestion in different organs.
c. They are incomplete, with no accessory organs.
d. They are complete and include a large gastrovascular cavity.

Mechanism Process Food in Mouth, Esophagus and Stomach

Human Physiology - Functional Anatomy of the Mouth, Pharynx, and Esophagus

Large Intestine

SCIENTIFIC THINKING Consider the relationship between ­correlation and causation with respect to some pairs of human traits. For example, are freckles and red hair correlated? Is there causation? How does this concept relate to the study of human nutrition? Can you name examples of correlation in humans with respect to obesity? Explain each answer.

Animation: Digestive System Function

 No. Vitamins are not a source of energy. 

 structural components of cell membranes 

 No. Other molecules form cell membranes. 

 No. B vitamins are not broken down into something else. 

 No. However, other vitamins have antioxidant properties. 

B vitamins are components of molecules such as FAD and NAD.

In general, B vitamins function in your body as __________.

 A chemical that stimulates the parietal cells of the gastric pits 

 No. Parietal cells produce HCl, which both activates pepsin and directly attacks the epithelial layer of the stomach. 

 A chemical that inhibits epithelial cells in the stomach that produce mucus 

 No. Mucus is an important way that the stomach lining is protected from the actions of pepsin and HCl. 

 A chemical that stimulates the secretion of bile 

No. There is no evidence that bile kills Helicobacter pylori, and even if there were such evidence, bile is released into the small intestine, not the stomach.

 A chemical that stimulates the chief cells of the gastric pits 

 No. Chief cells produce pepsinogen. When activated by HCl, pepsinogen becomes pepsin, a potent hydrolytic enzyme. Much of the damage caused by an ulcer is related to the action of pepsin on the stomach lining. 

 A chemical that kills bacteria in the stomach 

Consider the major cause of stomach ulcers.

Which of the following might make the most effective anti-ulcer medication?

 The activity of pepsin will speed up in the small intestine because the pH becomes less acidic. 

 No. Pepsinogen is secreted by and pepsin acts in the stomach. 

 Pepsin will continue to work at the same rate as it moves through the intestines until all the protein is broken down. 

 No. Pepsin works best at a low pH. The pH of the small intestine is much higher. 

 Salivary amylase activates pepsin, converting it to a functioning form in the stomach. 

 No. Salivary amylase plays no such role. 

 Pepsin will cease to function in the small intestine as basic secretions from the pancreas neutralize the pH. 

Consider differences between the stomach and the small intestine.

Pepsin is an enzyme produced in the stomach that attacks proteins to break them down into smaller peptide molecules. Which of the following statements about this enzyme is true?