BSC2010 CH.41

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

a chemical that kills bacteria in the stomach

Which of the following is the actual absorptive surface within the lumen of the small intestine?

microvilli

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

mouth ... salivary amylase

The natural antacid that protects the intestines against stomach acid is produced by the _____.

pancreas

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

peristalsis

The tongue does all of the following EXCEPT _____.

secrete saliva

In humans, most nutrient molecules are absorbed by the _____.

small intestine

Most digestive enzymes function in the _____.

small intestine

Which of the following animals uses only intracellular digestion?

sponge

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

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

The lungs consist of many small air sacs and blood vessels, which greatly increase surface area and improve the transfer of substances through their walls. The structures in the digestive system most similar in function to these air sacs and capillaries are the _____.

villi and microvilli

Appendix

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Co-factor

...

Villi

1. A finger-like projection of the inner surface of the small intestine. 2. A finger-like projection of the chorion of the mammalian placenta. Large numbers of villi increase the surface areas of these organs.

Pharynx

1. An area in the vertebrate throat where air and food passages cross. 2. In flatworms, the muscular tube that produces from the ventral side of the worm and ends in the mouth.

Salivary glands

A gland associated with the oral cavity that secretes substances that lubricate food and begin the process of chemical digestion.

Liver

A large internal organ in vertebrates that perform diverse functions, such as producing bile, maintaining blood glucose level and detoxifying poisonous chemicals in the blood.

Bolus

A lubricated ball of chewed food.

Esophagus

A muscular tube that conducts food, by peristalsis, from the pharynx to the stomach.

Sphincter

A ringlike band of muscle fibers that controls the size of an opening in the body, such as the passage between the esophagus and the stomach.

Nutrient absorption

Competition for sites of absorption by the cell.

Large intestine (colon)

Absorption of water used during digestion. It leads to the rectum and anus.

Which of the following statements regarding protein digestion is true?

Active pepsin is formed in the lumen of the stomach, where it helps to break down proteins.

Saliva

Amylase, mucin, buffers, antibacterial agents (such as lysozyme).

Essential amino acids

An amino acid that an animal cannot synthesize itself and must be obtained from food in prefabricated form.

Pepsin

An enzyme present in gastric juice that begins the hydrolysis of proteins. It is also a protease.

Protease

An enzyme that digests proteins by hydrolysis. Apart of the pancreas.

Stomach

An organ of the digestive system that stores food and performs preliminary steps of digestion.

Gall bladder

An organ that stores and concentrate bile made by the liver and relase it as needed into the small intestine.

Mucin

Apart of saliva digestion in the mouth.

Nuclease

Apart of the pancreas.

Mechanical digestion

Breaks food into smaller pieces, increasing the surface area available for chemical processes.

Chemical digestion

Carried our by 2 components of gastric juice: 1. HCL which disrupts the extracellular matrix that binds cells together in meant and plant materials. 2. Protease or protein-digesting enzyme, called pepsin. Pepsin works best in a strongly acidic environment.

Mucus cells

Cells that secrete mucus (protective lubricant).

Pancreas

Consist of bicarbonate, proteases, amylase, nucleases.

Which of the following statements about nutrition and digestion is true?

During absorption, small molecules such as amino acids and simple sugars are absorbed.

Peristalsis

Facilitates the movement of bolus through esophagus facilitated. It is the rhythmic contractions of muscles.

Amyalse

Found in saliva. It hydrolyzes starch and glycogen into smaller polysaccharides and the disaccharide maltose.

Gastric glands

Have 3 types of cells that secrete different components of the gastric juice. 1. Mucus cells 2. Chief cells 3. Parietal cells

Alimentary canal

Humans have a complete digestive track (two openings: mouth and anus)

Cecum

In herbivores, houses bacteria that digest cellulose in plant cell walls.

Complete digestive track

In mammals, the digestive system consists of the alimentary canal and various accessory glands that secrete digestive juices through ducts into the canal. The accessory glands are three pairs of salivary glands, the pancreas, the liver and the gallbladder.

Which of the following statements is true?

Ingestion is the act of eating.

Minerals

Inorganic nutrients, such as iron and sulfur, that are usually required in small amounts.

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

Mucous cells secrete a protective lubricant into the stomach.

Vitatamins

Organic molecules that have very diverse functions and are required in their diet in very small amounts.

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?

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

Antibacterial agents

Saliva- amylase, mucin, buffers, antibacterial agents (such as LYSOZYME)

Bile

Salty solutions that are made in the liver that helps break down lipids. It assists in digestion.

Parietal cells

Secrete H+ and Cl- ions (active transport and facilitated diffusion). HCl formed from these components in stomach.

Chief cells

Secrete pepsinogen which is converted to pepsin by acid in stomach.

Rectum

Storage of waste until it is eliminated through anus. The terminal portion of the large intestine, where the feces are stored prior to elimination.

Digestive system

System of organs for acquiring and processing food.

Chyme

The mixture of partially digested food and digestive juices in the stomach.

Ingestion

The first stage of food processing in animals: the act of eating or feeding.

Microvilli (brush border)

The folding of the inner lining into villi, and of the surface of the cells of the villi into microvilli, results in 300 m2 of surface area to facilitate that absorption.

Elimination

The fourth and final stage of food processing in animals: the passing of undigested material out of the body.

Pepsinogen

The inactive form of pepsin secreted by chief cells located in gastric pits of the stomach.

Small intestine

The longest section of the alimentary canal, so named because of its small diameter compared with that of the large intestine; the principal site of the enzymatic hydrolysis of food macromolecules and the absorption of nutrients.

Trachea

The portion of the respiratory tract that passes from the larynx to the bronchi; also called the windpipe.

Digestion

The second stage of food processing in animals: the breaking down of food into molecules small enough for the body to absorb.

Absorption

The third stage of food processing in animals: the uptake of small nutrient molecules by an organism's body.

Lymph vessel

Thin walled, valved structures that carry lymph.

Epiglottis

When you swallow, a flap of cartilage called the epiglottis- the vocal chords and the opening between them.

Which of the following processes, structures, or conditions are properly matched?

acid chyme backflow ... heartburn

Acid chyme _____.

contains food and gastric juice and moves through the pyloric sphincter

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

duodenum

Which of the following animals has a one-way digestive tract?

earthworm