Mastering Bio Digestive System

_____ is secreted by the _____ and acts to emulsify _____ in the _____.

Bile ... liver ... fats ... small intestine...Bile, produced by the liver and stored by the gall bladder, emulsifies fats in the small intestine. The smaller fat droplets present a greater surface area for the action of lipases.

Your small intestine can absorb ____ without their being further digested.

fructoses...Fructose is a monosaccharide, and monosaccharides can be absorbed without having to be broken down into smaller units.

What acid is responsible for stomach acidity?

hydrochloric acid...Hydrochloric acid, secreted by the stomach, is responsible for the acidity of the stomach.

Which major digestive process involves nutrient molecules passing across the mucosal layer of the gastrointestinal tract into the blood or lymph?

absorption

Malfunction of the lower esophageal sphincter may result in __________.

acid reflux...The lower esophageal sphincter opens to allow food to pass into the stomach and closes to prevent food from flowing back into the esophagus; if it malfunctions, the acid fluids of the stomach may flow back into the esophagus.

In response to a steak dinner, certain secretions are needed to aid digestion. What cells in the pancreas would provide these secretions?

acinar cells...Yes, in response to a high fat and protein meal, CCK would be stimulated and in turn would stimulate an enzyme-rich secretion from the pancreas.

When digested, proteins are broken down into _____.

amino acids...Proteins are composed of amino acids.

Which of these enzymes begins the breakdown of starch?

amylase...The digestion of starches, such as amylose, begins with the amylase secreted by the salivary glands.

The secretion in the large intestine consists of which of the following?

bicarbonate- and potassium-rich mucus...Yes, an alkaline mucus secretion of bicarbonate and potassium protects the large intestinal wall from acids produced by resident bacteria.

When digested, fats are broken down into _____.

both glycerol and fatty acids...Fats are composed of glycerol and fatty acids.

Which of the following macromolecules go directly from the lumen of the small intestine to the epithelial cells of the intestine and on through to the blood stream?

carbohydrates and proteins... Carbohydrates and proteins, once they have been broken down into their functional units, go directly from the lumen of the intestine, through the epithelial cells, and into the bloodstream.

Bile is produced by the _____ and stored by the _____ until it is secreted into the small intestine.

liver ... gall bladder....Bile is continuously produced by the liver and is stored in the gall bladder until CCK triggers its release.

Bile is produced by the __________ and stored by the __________.

liver; gallbladder...Bile is produced by the liver and stored in the gallbladder.

In the small intestine, which of the following enzymes breaks down maltose?

maltase...the enzyme maltase breaks down the bonds between the two glucose molecules of the disaccharide maltose.

Starch can be broken down into the disaccharide known as _____.

maltose...Starch is composed of many maltose units.

Which of the following foods would be the best source of complex carbohydrates?

oatmeal

Secretin stimulates the _____ to secrete _____.

pancreas ... bicarbonate....The acidity of the stomach contents triggers the small intestine to secrete secretin, which in turn stimulates the pancreas to secrete bicarbonate to neutralize this acidity.

Cholecystokinin (CCK) stimulates the _____ to secrete _____.

pancreas ... pancreatic enzymes....The presence of fatty acids and amino acids in the stomach contents triggers the small intestine to secrete CCK. CCK then stimulates the pancreas to secrete enzymes that play a role in the digestion of these nutrients.

Once a bolus of food has been formed in the mouth, it is passed by the tongue and jaws to the

pharynx

Which of the following represents the path taken by food after leaving the mouth?

pharynx, esophagus, stomach, small intestine, large intestine

Starch is a type of _____.

polysaccharide...Starch is a carbohydrate composed of many monomers (many monosaccharide units).

Which of the following nutrients are digested within the small intestine?

proteins carbohydrates lipids

Where does the chemical digestion of proteins begin?

stomach....Protein digestion begins in the acidic environment of the stomach.

Protein digestion begins in the _____.

stomach...The secretion of gastric juice by the stomach begins the digestion of proteins.

What is the main component of gastric juice?

water...Water is the primary component of many secretions, including gastric juice.

What would happen if the liver were unable to produce enough bile salts?

Fatty acid absorption would decrease.....Bile salts facilitate the breakdown of complex fats into fatty acids, so decreased production of bile salts would result in decreased fatty acid absorption in the small intestine.

The hepatic portal system delivers nutrient-rich blood from the __________ to the __________.

GI tract; liver....The hepatic portal system connects the GI tract to the liver and delivers nutrient-rich blood to the liver.

What do the enzymes pepsin, chymotrypsin, trypsin, and carboxypeptidase have in common?

They are enzymes that participate in protein digestion.

Most of the digestion that takes place in the small intestine occurs in the __________.

duodenum.... is the first section of the small intestine and the site of most digestion.

The process by which undigested material is removed from the gastrointestinal tract is

elimination...

Another name for the alimentary canal is ________.

gastrointestinal tract

Elimination of undigested food material from the large intestine is controlled by

the defecation reflex

The gastrointestinal tract is composed of __________.

the hollow organs of the digestive system...The hollow organs of the digestive system form the gastrointestinal tract, a hollow tube that runs from the mouth to the anus.

The region of the digestive tract most responsible for absorption of nutrients is __________.

the small intestine

HCl secretions convert pepsinogen to the active hormone pepsin. What cells in the gastric pits produce pepsinogen?

chief...Yes, chief cells produce pepsinogen, the inactive form of pepsin.

The watery mixture of partially digested food produced in the stomach is called

chyme

Gingivitis occurs when tooth decay causes inflammation of the enamel and pulp of the tooth.

false

The breakdown products of which of the following are absorbed into lacteals?

fats...chylomicrons are absorbed into lacteals because they are too large to pass through the basement membrane of a capillary and into the blood.

Which of the GI tract tissue layers is most responsible for peristalsis and segmentation?

muscularis

Which of the following enzymes is important for the digestion of fat?

pancreatic lipase...Yes, pancreatic lipase is important for the digestion of fats. It is secreted by the pancreas and works in the small intestine.

Which of the following enzymes is important for breaking down protein?

pepsin...Yes, pepsin breaks down proteins in the stomach.

Enzymatic breakdown of which of the following compounds doesn't begin until it reaches the stomach?

protein....enzymatic breakdown of proteins begins in the stomach.

Which of the following statements about the organs of the digestive system is true?

Although protein digestion begins in the stomach, pancreatic enzymes break the final polypeptide chains into amino acids....Pancreatic enzymes finish up the protein digestive routes by breaking the polypeptide chains into amino acids.

Salivation is controlled almost entirely by the nervous system. Which of the following stimuli would inhibit salivation?

fear...Yes, fear, sleep, fatigue, and dehydration all inhibit salivation.

The presence of fatty acids and amino acids in the stomach contents triggers the small intestine to secrete a hormone known as _____.

cholecystokinin, or CCK...The presence of fatty acids and amino acids in the stomach contents triggers the small intestine to secrete CCK. CCK then stimulates the gall bladder to release bile and the pancreas to secrete pancreatic enzymes.

As chyme leaves the stomach, the acidic nature of the partially digested food stimulates the duodenum to release the hormone

secretin

An increase in HCl (hydrochloric acid) secretion in the duodenum would stimulate which hormone that would help to counteract the effects of HCl?

secretin.... stimulates the duct cells in the pancreas and liver to secrete a bicarbonate-rich solution that will bind hydrogen ions and increase the pH.

The acidity of the stomach contents triggers the small intestine to secrete a hormone known as _____.

secretin...The acidity of the stomach contents triggers the small intestine to secrete secretin; secretin then stimulates the pancreas to secrete bicarbonate to neutralize this acidity.

The digestion of fats, proteins, and carbohydrates is completed in the

small intestine