Chapter 24: The Digestive System

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Which structures of the digestive system secrete digestive enzymes?

Digestive enzymes are produced by the salivary glands, tongue, stomach, pancreas, and small intestine.

What are the functions of the lamina propria?

The lamina propria has the following functions: (1) It contains blood vessels and lymphatic vessels, which are the routes by which nutrients are absorbed from the GI tract; (2) it supports the mucosal epithelium and binds it to the muscularis mucosae; and (3) it contains mucosa-associated lymphatic tissue (MALT), which helps protect against disease.

What are the functions of the myenteric and submucosal plexuses of the enteric nervous system?

The neurons of the myenteric plexus regulate GI tract motility, and the neurons of the submucosal plexus regulate GI secretion.

Which peritoneal fold binds the small intestine to the posterior abdominal wall?

Mesentery binds the small intestine to the posterior abdominal wall.

What is the function of the uvula?

The uvula helps prevent foods and liquids from entering the nasal cavity during swallowing.

What is the function of the chloride ions in saliva?

Chloride ions activate salivary amylase.

What type of tissue is the main component of teeth?

The main component of teeth is connective tissue, specifically dentin.

Which permanent teeth do not replace any deciduous teeth?

The first, second, and third molars do not replace any deciduous teeth.

In which layers of the esophagus are the glands that secrete lubricating mucus located?

The esophageal mucosa and submucosa contain mucus-secreting glands.

Is swallowing a voluntary action or an involuntary action?

Both. Initiation of swallowing is voluntary and the action is carried out by skeletal muscles. Completion of swallowing - moving a bolus along the esophagus and into the stomach - is involuntary and involves peristalsis by smooth muscle.

After a very large meal, does your stomach still have rugae?

After a large meal, the rugae stretch and disappear as the stomach fills.

Where is HCl secreted, and what are its functions?

Parietal cells in gastric glands secrete HCl, which is a component of gastric juice. HCl kills microbes in food, denatures proteins, and converts pepsinogen into pepsin.

What molecule is the source of the hydrogen ions that are secreted into gastric juice?

Hydrogen ions secreted into gastric juice are derive from carbonic acid.

Among the sources that stimulate HCl secretion, which one is a paracrine agent that is released by mast cells in the lamina propria?

Histamine is a paracrine agent released by mast cells in the lamina propria.

What type of fluid is found in the pancreatic duct?

The pancreatic duct contains pancreatic juice (fluid and digestive enzymes).

What type of fluid is found in the common bile duct?

The common bile duct contains bile.

What type of fluid is found in the hepatopancreatic ampulla?

The hepatopancreatic ampulla contains pancreatic juice and bile.

Which type of cell in the liver is phagocytic?

The phagocytic cell in the liver is the stellate reticuloendothelial (Kupffer) cell.

During the first few hours after a meal, how does the chemical composition of blood change as it flows through the liver sinusoids?

While a meal is being absorbed, nutrients, oxygen, and certain toxic substances are removed by hepatocytes from blood flowing through liver sinusoids.

Which portion of the small intestine is the longest?

The ileum is the longest part of the small intestine.

What is the functional significance of the blood capillary network and lacteal in the center of each villus?

Nutrients being absorbed in the small intestine enter the blood via capillaries or the lymph via lacteals.

What is the function of the fluid secreted by duodenal (Brunner's) glands?

The fluid secreted by duodenal (Brunner's) glands - alkaline mucus - neutralizes gastric acid and protects the mucosal lining of the duodenum.

A monoglyceride may be larger than an amino acid. Why can monoglycerides be absorbed by simple diffusion, but amino acids cannot?

Because monoglycerides are hydrophobic (nonpolar) molecules, they can dissolve in and diffuse through the lipid bilayer of the plasma membrane.

Which two organs of the digestive system secrete the most fluid?

The stomach and pancreas are the two digestive system organs that secrete the largest volumes of fluid.

Which portions of the colon are retroperitoneal?

The ascending and descending portions of the colon are retroperitoneal.

What is the function of goblet cells in the large intestine?

Goblet cells in the large intestine secrete mucus to lubricate colonic contents.

Why does food initially cause the pH of the gastric juice to rise?

The pH of gastric juices rises due to the buffering action of some amino acids in food proteins.

Which process is the function of the smooth muscle layer of the digestive system?

Mixing and Propulsion

Which process is the primary function of the mouth?

Ingestion

Which process is the primary function of the villi of the small intestine?

Absorption

Which accessory organ produces a fluid to soften food?

Salivary Glands

Which accessory organ produces a fluid that functions to emulsify dietary fats?

Liver

Which accessory organ stores bile?

Gallbladder

The capability of the GI tract to move material along its length is called

Motility and Propulsion

This layer of the GI tract is composed of areolar connective tissue containing blood and lymph vessels.

Lamina Propria

This layer of the GI tract is composed of areolar connective tissue that binds the mucosa to the muscularis.

Submucosa

These are composed of prominent lymphatic nodules that function in the immune response.

MALT

This plexus is located between the longitudinal and circular smooth muscle layers of the muscularis.

Myenteric Plexus

Why do emotions such as anger or fear slow digestion?

Because they stimulate the sympathetic nerves that supply the GI tract.

This portion of the peritoneum drapes over the transverse colon and coils of the small intestine.

Greater Omentum

This portion of the peritoneum attaches the liver to the anterior abdominal wall and diaphragm.

Falciform Ligament

This portion of the peritoneum is largely responsible for carrying blood and lymph vessels to the intestines.

Mesocolon

True or False: The hard palate is the anterior portion of the roof of the mouth.

True

True or False: The hard palate is formed by the maxillae and palatine bones.

True

True or False: The hard palate is covered by a mucous membrane.

True

In the mouth, the tooth sockets are lined with

Periodontal Ligament

How many stages of deglutition are there?

3

This structure of the stomach allows greater distension for food storage.

Rugae

What secretes hydrochloric acid?

Parietal Cells

This cell secretes the hormone that promotes production of hydrochloric acid.

G Cell

This major duct carries a fluid rich in bicarbonate ions.

Pancreatic Duct

Which pancreatic enzymes digests lipids?

Lipase

This is found on the liver and is a remnant of the umbilical cord in a fetus.

Round Ligament

This is the principle bile pigment.

Bilirubin

What are the functions of the liver?

Secreting bile, carbohydrate metabolism, lipid metabolism, protein metabolism, processing of drugs and hormones, excretion of bilirubin, synthesis of bile salts, storage, phagocytosis, and activation of vitamin D.

Which small intestine cell secrete lysozyme?

Paneth Cells

What do Brunner's glands secrete?

An Alkaline Mucus

Which enzyme acts to produce monoglycerides as one product?

Lipase

Which pancreatic enzyme acts on glycogen and starches?

Amylase

Which pancreatic enzyme acts on peptide bonds?

Chymotrypsin

This hormone functions to counteract the effect of gastric acid in the small intestine.

Secretin

This hormone is stimulated by high levels of dietary fat in the small intestine.

Cholecystokinin

This digestive aid, produced by the stomach, begins digestion by denaturing proteins.

Hydrochloric Acid

This structure regulates the flow of material into the colon.

Ileocecal Sphincter

When you swallow, which structures rise to close off the nasopharynx?

Uvula and Soft Palate

True or False: The esophagus produces digestive enzymes.

False

What may occur in the digestive system as a result of aging?

Decreased response to pain and internal sensations, increased incidence of duodenal ulcers, dysregulated neurosensory feedback, and decreased sensitivity to mouth irritations and ulcers.

How does the digestive system assist the muscular system?

The liver converts lactic acid produced by muscles to glucose.

True or False: Dentin anchors the tooth in place.

False

The capillaries that nourish the epithelium and absorb digested nutrients lie in the ________.

Lamina Propria

True or False: Pepsinogen is the precursor to the gastric enzyme for protein digestion and is secreted by the parietal cells.

False

Name the peritoneal folds.

Greater omentum, falciform ligament, lesser omentum, mesentery, and mesocolon.

True or False: The myenteric nerve plexus provides the major nerve supply to the GI tract wall and controls GI motility.

True

True or False: Kupffer cells are found in the liver and are responsible for removing bacteria and worn-out cells.

True

There are some 20 known pathogens found in the large intestine; our Ig ________ antibody-mediated response restricts them from going beyond the mucosa and causing problems.

A

The dental formula for an adult is 2-1-2-3. What does the 1 stand for?

Canine Tooth

True or False: As food passes through the digestive tract, it becomes less complex and the nutrients are more readily available to the body.

True

True or False: Most nutrients are absorbed through the mucosa of the intestinal villi by active transport.

True

True or False: The stomach's contractile rhythm is set by pacemaker cells found in the spinal cord.

False

True or False: Saliva contains enzymes that begin the breakdown of proteins

False

True or False: The first phase of swallowing is involuntary and is controlled by the swallowing center in the thalamus and lower pons.

False

You have just eaten a meal high in complex carbohydrates. Which enzyme will help to digest the meal?

Amylase

True or False: There are 20 primary teeth, and by 24 months of age most children have all 20.

True

In addition to storage and mechanical breakdown of food, the stomach ________.

Initiates protein digestion and denatures proteins

True or False: The major role of absorption in the ileum is to reclaim bile salts to be recycled back to the liver.

True

The mechanical and chemical receptors that control digestive activity are located ________.

In the walls of the tract organs

Gastrin is a digestive hormone that is responsible for the stimulation of acid secretions in the stomach. These secretions are stimulated by the presence of ________.

Protein and Peptide Fragments

True or False: Hepatocytes produce digestive enzymes

False

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