Chapter 24 Sofferman Version

Out of a normal adult's 32 teeth, how many are molars? (p. 867)

12 Feedback: Normal adults have 32 teeth that are divided into four quadrants. Each quadrant contains 2 incisors, 1 canine, 2 premolars and 3 molars. Adults have a total of 12 molars, the third molars in each of the four quadrants are also called wisdom teeth. These teeth usually appear in a person's late teens or early twenties.

If you place a pin through the greater omentum, through how many layers of simple squamous epithelium would the pin pass? (p. 864)

2 The greater omentum is a mesentery that attaches to the greater curvature of the stomach. All of the mesenteries of the abdominal cavity are composed of two layers of serous membranes with a thin layer of loose connective tissue between them. Each of the serous membranes is lined composed of a simple squamous epithelium, so the pin would pass through two layers of simple squamous epithelium

Each day about 9 liters of water enter the gastrointestinal tract. By the time the contents leave the large intestine as feces, about ______% of water is reabsorbed. (p. 881)

99 About 9 liters of water enter the GI tract each day. About 92% is reabsorbed in the small intestine, 6-7% is reabsorbed in the large intestine leaving only about 1% of the water excreted as part of the feces. The GI tract reabsorbs about 99% of the water added to it per day.

The liver is a major storehouse for all of the following except one. Which one of the following substance or substances are not stored in the liver. (p. 886) A) copper and iron B) calcium C) Vitamins A, B12, D, E and K. D) glycogen

B) Calcium Feedback: Most people who like liver benefit from the many substances stored in the liver. Copper and iron are stored as well as the fat-soluble Vitamins A, B12, D, E and K. Glucose is stored in the liver as glycogen. Most of the calcium in the body is stored in bone.

Which one of the following hormones is released by both the stomach and small intestine? A) gastrin B) secretin C) cholecystokinin D) gastric inhibitory polypeptide

Gastrin Feedback: In the intestinal phase, in response to a chyme that has a pH below 2 or contains fatty acids, the endocrine cells of the duodenum release hormones to inhibit gastric secretions. These hormones include secretin (pH below 2), cholecystokinin (fatty acids), and gastric inhibitory polypeptide (fatty acids). An increase in protein in the chyme stimulates the endocrine cells of the duodenum to release gastrin. Gastrin is also released by the endocrine cells of the stomach and whether gastrin is released by the stomach or small intestine, gastric secretions are increased.

The tunica muscularis in the superior esophagus is made up of ___________ muscle. (p. 862)

Skeletal Feedback: Throughout most of the digestive tract, the tunica muscularis is made up of two or three layers of smooth muscle. The inferior esophagus has smooth muscle while the superior esophagus has skeletal muscle in the tunica muscularis. Even though the superior esophagus has skeletal muscle, the bolus moves down the entire esophagus by involuntary peristaltic contractions.

The salivary gland that produces primarily mucus is the _____________ salivary gland.

Sublingual Feedback: The labial glands are in the lips and add to the secretions of saliva but are not salivary glands. Parotid salivary glands are serous glands, and submandibular salivary glands are mixed glands producing both serous and mucous secretions. The sublingual salivary glands, the smallest salivary glands, are also mixed glands, but produce primarily mucus.

The outer tunic of the esophagus grades into the surrounding connective tissue and is called the tunica (p. 863)

adventitia. Feedback: The outer tunic in the digestive tract is either the tunica serosa or adventitia. In the GI tract, the outer tunic (or tunica serosa) consists of a thin layer of connective tissue and a simple squamous epithelium. In the esophagus and retroperitoneal organs, the outer tunic grades into the surrounding connective tissue and is called the tunica adventitia.

If you suck on a plain piece of bread, it will begin to taste sweet after a few moments. Saliva contains the digestive enzyme ________________, which breaks down starch into ________________.

amylase, maltose Feedback: Pepsin is an enzyme produced by the stomach and digests proteins to peptides. Maltase is an enzyme that is produced by the small intestine and breaks down maltose to glucose. Both the salivary glands and the pancreas produce the enzyme amylase, which breaks down starch to isomaltose and maltose. Maltose stimulates the sweet taste buds located on the anterior tip of the tongue.

Accumulation of excess fluid in the peritoneal cavity is called (p. 864)

ascites Feedback: Inflammation of the peritoneal membranes is called peritonitis. A rupture in the abdominal wall in the inguinal region is called an inguinal hernia, while a hiatal hernia is a widening in the diaphragm through which the esophagus passes. Accumulation of excess serous fluid in the peritoneal cavity is called ascites and may accompany peritonitis, starvation, alcoholism or liver cancer

Most of the enzymes produced in the large intestine and the formation of Vitamin K occurs in (p. 895)

bacteria. Feedback: Teniae coli are three bands of longitudinal muscle that run the length of the colon. Goblet cells are special simple columnar cells that are very numerous in the large intestine but produce mucus. The simple columnar cells do not produce enzymes nor synthesize Vitamin K. This occurs in bacteria call colic bacteria.

The major part of the aqueous component (other than water) of pancreatic juice is (p. 890)

bicarbonate ions. Feedback: Pancreatic juice is composed of two components: the aqueous component and enzymatic component; neither component contains much mucus. The enzymatic component contains many enzymes including trypsinogen, chymotrypsinogen and procarboxypeptidase. The aqueous component contains water, sodium ions, potassium ions and bicarbonate ions. Bicarbonate ions, which neutralize the acid chyme coming from the stomach, are a major part of the aqueous component. Secretin is a hormone that stimulates the pancreatic acini to secrete the aqueous component.

Hepatocytes or hepatic cells produce bile, which is secreted into the (p. 885)

bile canaliculi Feedback: Bile is produced by the hepatocytes or hepatic cells from the hepatic cords around the hepatic sinusoids. Bile is secreted into a cleft-like lumen called the bile canaliculus.

Which one of the following is the correct pathway of bile from the hepatocytes to the gallbladder? (p. 885)

bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder. Feedback: Bile is produced by the hepatocytes in liver lobules and secreted into a bile canaliculus, not into the blood (hepatic sinusoids). The common bile duct carries bile from the gallbladder to the duodenum. The correct pathway of bile to the gallbladder is bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder.

The hydrogen ions that form hydrochloric acid of the stomach come from (p. 875)

carbonic acid Feedback: In the parietal cells of gastric glands, carbon dioxide combines with oxygen to form carbonic acid, which dissociates into hydrogen ions and bicarbonate ions. The bicarbonate ions diffuse into the plasma and are exchanged with chloride ions. The chloride ions and hydrogen ions diffuse into the gastric pits and form hydrochloric acid.

The region of the stomach around the opening from the esophagus is called the ___________ region. (p. 873)

cardiac Feedback: The stomach consists of four regions: the cardiac, fundus, body and pyloric. The pyloric region is where the stomach joins the duodenum. The body is the largest part of the stomach, and the fundus is located lateral to the cardiac region. The cardiac region is located where the esophagus joins the stomach, and the opening is called the gastroesophageal or cardiac opening.

Which one of the following cells in the gastric glands produce pepsinogen? (p. 873)

chief or zymogenic cells Feedback: The gastric glands of the stomach contain four types of cells. Endocrine cells produce hormones such as gastin and histamine; mucous neck cells produce mucus; and parietal cells produce hydrochloric acid and the intrinsic factor. Chief or zymogenic cells produce the major enzyme of the stomach, pepsinogen.

The gallbladder contracts in response to (p. 889)

cholecystokinin and vagal stimulation Feedback: The gallbladder stores 40-70 mL of bile and contracts shortly after a meal. The hormone secretin, and a low pH of chyme have no feedback effects on the gallbladder. The hormone cholecystokinin, in response to fatty acids and other lipids in the duodenal chyme, stimulates the gallbladder to contract and sphincter of Oddi to relax. Vagal stimulation can also stimulate the gallbladder to contract but to a lesser degree.

Gall stones result from the precipitation of _____________ in the gallbladder. (p. 889)

cholesterol Feedback: Crystals of calcium salts may cause kidney stones, while crystals of uric acid salts may result in gout. Urea is very water-soluble and is less likely to form crystals. Cholesterol, which can be taken in via the diet and is also a waste product of saturated fat metabolism, is one of the components of bile. Cholesterol may precipitate out in the gallbladder and help to form gallstones. Drastic dieting with rapid weight loss may lead to gallstone production.

Which one of the following enzymes is not part of the enzymatic component of the pancreatic juice? (p. 891)

chymotrypsin Feedback: The enzymatic component of the pancreatic juice contains enzymes to digest all four of the major organic compounds. Amylase digest starch; lipase digests lipids; and nucleases digest DNA and RNA. The protein digesting enzymes are secreted as inactive forms: trypsinogen, chymotrypsinogen, and procarboxypeptidase. Trypsinogen will all be activated in the small intestine by the intestinal enzyme, enterokinase, to trypsin. Trypsin will active chymotrypsinogen to chymotrypsin in the small intestine.

An individual has the following symptoms: jaundice, pale in color, liver with a buildup of connective tissue. This individual most likely has (p. 889)

cirrhosis. Feedback: An individual who has a yellowish color (jaundice) of the integument and sclera is not excreting enough bile into the duodenum. Bilirubin, a breakdown product of hemoglobin, builds up in the tissue and is the major cause of jaundice. Bile is not being adequately formed in the liver or adequately excreted into the duodenum. Pathologies of the stomach (gastritis) and pancreas (panceatitis) will not influence bile production. Gallstones may cause jaundice, but jaundice with the buildup of connective tissue in the liver is cirrhosis. Hepatocytes die and are replaced by connective tissue. The buildup of connective tissue may impede blood flow in the liver resulting in a pale color. Cirrhosis frequently develops in alcoholics.

Salivary glands structurally are

compound tubuloacinar or tubuloalveolar glands.

Stimulation by the sympathetic nervous system will cause which one of the following effects in the inferior esophagus, stomach, small intestine and large intestine?

decreases peristalsis by inhibition of smooth muscle Feedback: The walls of the inferior esophagus, stomach, small intestine and large intestine contain smooth muscle which is innervated by fibers of the autonomic nervous system. Normal secretions and peristalsis in the digestive tract is stimulated by the parasympathetic nervous system. The sympathetic nervous system or fight-or-flight system stops or decreases activities that for a short period of time are not essential for survival. Sympathetic nervous system decreases secretions and inhibits peristalsis in the digestive tract.

The pancreas and liver release their secretions into the (p. 884/889)

duodenum Feedback: The stomach receives the bolus from the esophagus and releases chyme into the duodenum. The pancreas and liver also release secretions into the duodenum.

One of the major functions of bile salts is to (p. 886)

emulsify fat to fatty droplets. Feedback: The liver produces and secretes about 600-1000 mL of bile each day. Bile contains water, bilirubin, cholesterol, fats, fat-soluble hormones, lecithin, bicarbonate ions, and bile salts. Many of the components of bile are waste products, but bile does play two roles in digestion. Bile helps neutralize the acid chyme (via bicarbonate ions) coming from the stomach. Bile salts emulsify fats to fatty droplets, which increases the surface area for the digestive enzyme lipase. Lipase can now very efficiently and quickly breakdown the fatty droplets to fatty acids and glycerol.

Trypsinogen when activated by ___________ will break down proteins in the ___________. (p. 891)

enterokinase; small intestine Feedback: The pancreatic juices contain an enzymatic component consisting of three major protein digesting enzymes: trypsinogen, chymotrypsinogen, and procarboxypeptidase. These inactive enzymes are secreted into the pancreatic duct and dumped into the duodenum. Enterokinase, an enzyme produced by cells lining the small intestine, activates trypsinogen to trypsin. This activation occurs in the small intestine. Secretin is a hormone that stimulates the secretion of the aqueous component of the pancreatic juices.

Which of the following ligaments attaches the liver to the anterior abdominal wall? (p. 864)

falciform ligament Feedback: The falciform ligament attaches the liver to the anterior abdominal wall.

Which one of the following is most easily absorbed in the oral cavity? (p. 896)

fatty acids Feedback: Not much absorption occurs in the oral cavity due to its stratified squamous epithelium. Peptides need to be broken down to amino acids before being absorbed. Some glucose, water and fatty acids may be absorbed in the oral cavity but lipid-soluble materials like fatty acids are most readily absorbed. Nitroglycerin is a lipid-soluble drug which when placed under the tongue is absorbed in less than one minute.

A person who is "tongue-tied" can often be treated by surgically cutting the

frenulum Feedback: The uvula is a projection from the posterior edge of the soft palate that is sometimes removed to treat people who snore. The bucinnator muscle flattens the cheek against the teeth, and the labium is another term for your upper or lower lip. There are three different frenulums: one attaches to the alveolar process of the maxilla, one attaches to the alveolar process of the mandible, and one attaches to the tongue. This last frenulum is often called the lingual frenulum and may be cut to allow the tongue more freedom of movement that is hampered in people who are "tongue-tied."

In the regulation of stomach secretions, distension of the stomach activates local reflexes and a parasympathetic reflex. This is called the _____________ phase. (p. 875)

gastric Feedback: There are three phases in the regulation of stomach secretions. The cephalic phase is stimulated by taste and smell of food and tactile sensation in the mouth. The intestinal phase is controlled by the duodenum in response to the chyme from the stomach. Distention of the stomach activates local reflexes and a parasympathetic reflex. This is called the gastric phase.

Surface area of the stomach is increased by

gastric pits Feedback: The small intestine's surface area for digestion and absorption is increased by plicae circulares, villi and microvilli. In the stomach, gastric glands line the numerous tube-like gastric pits that increase the surface area for digestion.

Parasympathetic stimulation causes endocrine cells in the stomach to release the hormone (p. 875)

gastrin Feedback: Pepsinogen is an enzyme produced by chief cells in the stomach, while secretin is a hormone produced by endocrine cells in the duodenum. The endocrine cells of the stomach produce two major hormones: gastrin and histamine. Histamine stimulates parietal cells to secrete hydrochloric acid. Gastrin not only stimulates gastric secretions, but also increases gastric motility, relaxes the pyloric sphincter and stimulates the release of histamine.

The hepatic sinusoids receive oxygenated and unoxygenated blood. The blood vessels that provide mixed blood to the sinusoids are the (p. 885)

hepatic artery and hepatic portal vein. Feedback: The hepatic sinusoids in the lobules of the liver receive oxygenated blood from the hepatic artery. The lobules receive blood are also part of the hepatic portal system. The hepatic sinusoids also receive blood high in nutrients but low in oxygen from the hepatic portal vein.

You are tracing a drop of blood from the blood capillary network in the small intestine to the inferior vena cava. The pathway is (p. 885)

hepatic portal vein → sinusoid → central vein → hepatic vein → inferior vena cava Feedback: The hepatic portal system is associated with the liver. Normally blood flows from an artery through a capillary bed and into a vein. In a portal system, blood flows from a capillary bed to a portal vessel (usually a vein) to a second capillary bed and then to a vein. The blood capillary network receives water, ions and nutrients that are absorbed by epithelial cells of the small intestine and passes this blood to the hepatic portal vein which then carries the blood to the hepatic sinusoids (a second capillary bed) in the liver lobules. The blood then passes to a central vein and then to the hepatic vein, which feeds into the inferior vena cava.

The esophagus pierces through an opening in the diaphragm called the (p. 871)

hiatus Feedback: The fauces are the opening from the oral cavity into the oropharynx. The glottis is the opening from the larynopharynx to the larynx. The inguinal canal is an opening in the inferior wall of the abdominal cavity where nerves, blood vessels, and ductus deferens pass out of the abdominal cavity to the testes. The esophagus passes through an opening in the diaphragm called the hiatus. Hiatal hernia is the most common hernia and may allow part of the stomach to expand into the thorax.

Stimulation of the internal anal sphincters by the sympathetic nervous system or stimulation of the external anal sphincter by the somatic motor nervous system would (p. 895)

inhibit the defecation reflex Feedback: The internal and external sphincter are not associated with mass movements. The internal anal sphincter is composed of smooth muscle, which is stimulated by the sympathetic nervous system and inhibited by the parasympathetic nervous system. The external anal sphincter is stimulated by the somatic motor nervous system. To have a defecation reflex, both the internal and external anal sphincters must relax. Either sympathetic stimulation of the internal anal sphincter or somatic stimulation of the external anal sphincter will inhibit the defecation reflex.

The pancreatic islets produce (p. 889)

insulin, glucagon, and somatostatin Feedback: The acinar glands of the pancreas are exocrine glands that produce and secrete a variety of digestive enzymes. One of the protein digestive enzymes, trypsinogen, becomes activated by the enzyme, enterokinase, produced by the small intestine. The pancreatic islets or Islets of Langerhans is an endocrine gland that produces the hormones insulin, glucagon and somatostatin. Neither the exocrine nor the endocrine part of the pancreas produces mucus.

The parietal cells in the gastric glands of the pyloric region produce _____________ that bonds with Vitamin _______ to make it more readily absorbed in the ileum. (p. 873)

intrinsic factor; B12 Feedback: The chief cells of the stomach produce pepsinogen which when activated breaks down proteins to form peptides. Parietal cells produce hydrochloric acid, which kills bacteria, activates pepsinogen to pepsin, and inactivates salivary amylase. Vitamin D is produced in the integument and is activated by the parathyroid hormone in the kidneys. Vitamin D has nothing to do with the stomach. Mucous neck cells and surface mucous cells produce mucus, which protects the stomach epithelium from acid and pepsin. Parietal cells also produce the intrinsic factor which bonds to Vitamin B12 to make it more readily absorbed in the ileum.

Bacteria and other foreign material absorbed by the small intestine are destroyed by ___________ cells found lining the hepatic sinusoids. (p. 888)

kupffer Feedback: The acinar cells are found in the pancreas and produce the enzymatic component of pancreatic juice. The hepatic cells or hepatocytes line the outside of the sinusoids and perform many functions including absorbing oxygen and nutrients, detoxifying materials like alcohol, storing as well as releasing nutrients back into the blood, and producing bile. Endothelial cells are very thin simple squamous cells making up the wall of the sinusoid along with kupffer cells or hepatic phagocytic cells that phagocytize bacteria and other foreign material.

The coronary ligament attaches the (p. 864)

liver to the diaphragm. Feedback: The falciform ligament attaches the liver to the anterior abdominal wall, and the mesocolon attaches the colon to the posterior abdominal wall. The lesser omentum attaches the lesser curvature of the stomach and proximal end of the duodenum to the liver and diaphragm. The mesentery that attaches the liver to the diaphragm is the coronary ligament.

In the small intestine, movement of chyme is regulated primarily by (p. 883)

local and mechanical stimulation Feedback: The small intestine's endocrine cells produce the hormones secretin and cholecystokinin, which regulate the stomach, liver and pancreas. The parasympathetic nervous system via the vagus nerve does regulate movement of chyme through the small intestine, but its effect is minor. The enterogastric reflex is stimulated by irritating substances entering the duodenum and regulates the stomach secretions and motility. The major regulation of movement of chyme in the small intestine is local and mechanical stimulation

Saliva decreases gingivitis and caries because it contains immunoglobulin A and

lysozymes Feedback: Saliva contains water, which liquefies the food and is the medium for digestion; mucus that lubricates the food and protects the epithelial cells and gives saliva a lubricating quality; and the salivary amylase, which breaks down starch to maltose and isomaltose. The antibacterial enzyme, lysozyme, is found in a number of secretions including saliva and tears. In the oral cavity this antibacterial enzyme reduces the occurrence of gingivitis and caries.

These contractions occur 3 to 4 times a day and involve large parts of the transverse and descending colon. These contractions are called (p. 893)

mass movements Feedback: The teniae coli are three bands of longitudinal smooth muscle that cause the formation of haustral pouches in the colon. The defecation reflex is initiated by distension of the rectal wall and pushes the feces out of the body. Mass movements are very common after meals. The presence of chyme in the stomach or duodenum can initiate these mass movements, which occur 3-4 times a day. In mass movements, large parts of the transverse and descending colon undergo strong peristaltic waves propelling the fecal material into the rectum.

Which one of the connective tissue sheets listed below consists of two layers of serous membranes with a thin layer of connective tissue between them and attaches to the small intestine? (p. 864) A) lesser omentum B) mesentery proper C) greater omentum D) falciform ligament

mesentery proper Feedback: In the abdominal cavity connective sheets that consist of two layers of serous membranes with a thin layer of connective tissue between them are called mesenteries. The mesentery that connects to the lesser curvature of the stomach is called the lesser omentum. The greater curvature of the stomach is connected to a mesentery called the greater omentum, and the falciform ligament is a mesentery that attaches to the liver. The mesentery that connects to the small intestine is called mesentery proper.

The lamina propria and muscularis mucosa are found in the tunica (p. 862)

mucosa Feedback: The lamina propria is composed of loose connective tissue, and the muscularis mucosae is a thin ring of smooth muscle controlled by Meissner's or submucosal plexus. Both regions are located in the tunica mucosa.

The major secretory product of the colon is (p. 893)

mucus Feedback: Hydrochloric acid is secreted by the stomach, while most of the digestive enzymes are secreted by the pancreas and small intestine. Bicarbonate ions are secreted by the colon in response to acid, but the major secretion of the colon is mucus.

The secretions that lubricate the food so it moves easily through the digestive tract and also protects the epithelium are called (p. 859)

mucus Water is the most common secretion of the digestive tract; it liquefies food and provides the medium for digestion. Enzymes are secreted in the oral cavity, by the stomach, small intestine and pancreas and are responsible for the chemical digestion of food. Hormones are produced by the stomach and small intestine and stimulate or inhibit secretions and/or movements along the GI tract. Mucus is secreted along the entire digestive tract and functions to lubricate the food and protect the epithelium from abrasion, acids, and enzymes.

Brunner's glands produce __________ and are found in the _____________. (p. 881)

mucus; duodenum Feedback: The epithelial cells that line tubular invaginations (Crypts of Lieberkuhn) in the small intestine produce mucus, enzymes, and hormones. The stomach dumps acid chyme into the duodenum, and the liver dumps bile into the duodenum. To protect it's lining, the duodenum contains Goblet cells that produce mucus as well as Brunner's glands (also called duodenal glands), which produce large amounts of mucus.

The stomach is unique to the GI tract because it contains

oblique smooth muscle. Feedback: The GI tract (stomach, small intestine and large intestine) all contain circular and longitudinal smooth muscles. The stomach contains a third inner layer of oblique smooth muscle.

Which of the following structures forms a cavity or pocket between the layers of mesenteries? (p. 864)

omental bursa Feedback: The omental bursa forms a pocket between the layers of mesenteries.

Which part(s) of the pharynx normally conduct food? (p. 871)

oropharynx and laryngopharynx Feedback: The nasopharynx is lined by ciliated pseudostratified columnar epithelium and is part of the respiratory tract. The oropharynx and larynopharynx are parts of both the respiratory and digestive tracts. Because these two regions of the pharynx come in contact with food, their epithelium is the protective, moist, stratified squamous epithelium.

Which of the following structures would be considered retropertitoneal? (p. 864)

pancreas Feedback: The pancreas would be found behind the peritoneum.

Histamine stimulates the ________________ cells to release ______________. (p. 875)

parietal; HCl Feedback: Chief cells produce pepsinogen; mucous neck cells produce mucus; but neither cell is stimulated by histamine. Parietal cells produce intrinsic factor and HCl, but histamine binds to histamine receptors (H2 receptors) on parietal cells to stimulate the release of HCl.

Mumps is inflammation of the _______________ salivary gland caused by a virus.

parotid Feedback: The buccal glands add to the secretions of the oral cavity but are not salivary glands. The largest salivary gland, the parotid, is subject to inflammation called parotiditis. The most common cause of parotiditis is a virus, and the condition is called mumps. The parotid gland can be seen in the below figure

The muscular contractions, which move material through the digestive tract, are called (p. 859)

peristalsis Feedback: Swallowing or deglutition moves food from the oral cavity to the esophagus. Mass movements occur in the large intestine to move fecal material into the rectum. Segmentation contractions are mixing contractions, which occur in the small intestine. Peristalsis creates waves of contractions through most of the digestive tract to move the material along.

Contractions of the smooth muscles in the tunica muscularis in the GI tract causes ___________ and is stimulated by ____________ plexus.

peristalsis, Auerbach's or myenteric Feedback: In the GI tract the tunica submucosa contains Meissner's or submucosal plexus that contains autonomic fibers. Stimulation of this plexus may cause contraction of the muscularis mucosa, which stimulates local secretions. The tunica muscularis contains Auerbach's or myenteric plexus, which also contains autonomic fibers. Stimulation of the myenteric plexus may cause contraction of the smooth muscles of the tunica muscularis, which results in peristalsis.

In the tunica mucosa and submucosa of the small intestine, a series of folds called the ____________ functions to __________________. (p. 881)

plicae circulares; increase surface area Feedback: The stomach contains folds called rugae in the tunica mucosa and submucosa, which allow the stomach to expand. The small intestine has several modifications that allow its surface area to increase about 600 fold over a tube that has no modifications. Microvilli are cytoplasmic extensions on individual epithelial cells, and villi are fingerlike projections of the tunica mucosa. The tunica mucosa and submucosa form a series of folds called circular folds or plicae circulares.

The major food digested by gastric secretions is

protein Feedback: Nucleic acids are digested by enzymes produced by the pancreas and small intestine. Starch is digested in the stomach but from salivary amylase that is produced by the salivary glands. Fat may be digested by enzymes produced by salivary glands, and in infants the chief cells in the stomach produce lipase. In the adult, however, the only enzyme produced by the chief cells is pepsinogen that is activated by acidic conditions to form pepsin. Pepsin digests protein to peptides.

The low pH of the stomach activates enzymes that digest _____________ while inactivating enzymes that digest ______________. (p. 875)

proteins; starch Feedback: Hydrochloric acid causes the pH of the stomach to be between 1 and 3. This low pH kills bacteria and also effects enzyme activity. Nucleic acids are digested in the small intestine. There is some digestion of lipids from saliva (lingual lipase). The acid pH activates pepsinogen to pepsin, which digests proteins and inactivates salivary amylase, which digests starch.

Cells in duodenum monitor chyme coming from the stomach that has a pH of 1. You would expect the duodenal cells to (p. 878)

release secretin, which inhibits gastric secretions. Feedback: In the intestinal phase of gastric regulation, the entrance of chyme coming from the stomach is regulated by the duodenum. Decrease in fatty acids initiates the release of two hormones, gastric inhibitory polypeptide and cholecystokinin, which decrease gastric secretions. Hypertonic solutions may cause the release of the hormone enterogastrone, which may inhibit gastric secretions. The acid pH would initiate the enterogastric reflex, but this reduces gastric secretions. Chyme with a pH of less than 2 will cause the endocrine cells of the duodenum to release the hormone secretin, which inhibits gastric secretions.

The tunica submucosa and mucosa of the stomach are thrown into large folds called (p. 873)

rugae Feedback: Epiploic appendages attach to the outer surface of the colon. Plicae circulares are large folds in the mucosa and submucosa of the small intestine, while villi are fingerlike projections of the mucosa in the small intestine. Rugae are folds in the tunica submucosa and mucosa of the stomach to allow the stomach to expand.

Bile secretion is stimulated by the hormone ______________ in response to ______________. (p. 886)

secretin; low pH of the chime Feedback: The duodenum monitors the chyme entering from the stomach. In response to fatty acids and other lipids, the endocrine cells release the hormone cholecystokinin. In response to an acid chyme (low pH), the endocrine cells release the hormone secretin. One type of the cells controlled by secretin are hepatocytes, which increases their secretions of bicarbonate ions and increases the volume of bile.

Contractions that mix material in the small intestine are called (p. 859)

segmental contractions. Feedback: Deglutition or swallowing moves the bolus from the oral cavity into the esophagus. Peristalsis moves material along most of the digestive tract, and mass movements move material from the transverse colon to the rectum. Segmental contractions occur in the small intestine to mix the contents to allow for more rapid digestion and absorption.

The outer layer of the GI tract is composed of connective tissue and a simple squamous epithelium. This tunic is called the tunica ______________ and the simple squamous epithelium is called the ______________. (p. 863)

serosa, visceral peritoneum Feedback: The outer tunic in the esophagus and retroperitoneal organs grade into the surrounding connective tissue and is called the tunica adventitia. In the GI tract, the outer tunic or tunica serosa consists of connective tissue and a simple squamous epithelium called the visceral peritoneum. The parietal peritoneum lines the internal wall of the abdominal cavity.

The stomach, small intestine and large intestine are lined by this epithelium. (p. 862)

simple columnar Feedback: Digestion and absorption in the GI tract requires a simple epithelium for absorption and cells large enough to produce the variety of secretions which include the following: mucus, enzymes, hormones, and acids. The epithelium of most of the respiratory tract is pseudostratified columnar. The epithelium of the GI tract is simple columnar.

The cardiac or lower gastroesophageal sphincter is composed of ____________ muscle and prevents chyme from moving into the _____________. (p. 871)

smooth; esophagus Feedback: Both the cardiac and pyloric sphincters are composed of smooth muscle. The pyloric sphincter regulates the movement of chyme into the duodenum and prevents the chyme from moving back into the stomach. The cardiac sphincter prevents chyme from moving into the esophagus. If this occurs, irritation of the esophagus or hearth burn may result.

The term gastrointestinal (GI) tract refers to the (p. 859)

stomach, small intestine and large intestine. Feedback: The digestive tract consists of the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, and anus plus the following accessory organs: teeth, tongue, salivary or other oral glands, tonsils, mucous glands, liver, gallbladder, appendix and pancreas. The term GI tract just refers to the stomach, small intestine and large intestine.

The epithelium of the mouth, oropharynx, esophagus and anal canal is (p. 861/862)

stratified squamous Feedback: The openings and ducts into and out of the digestive tract are lined with a protective epithelium called stratified squamous.

The salivary gland which is mixed but produces more serous than mucous secretions and whose duct opens inferiorly in the floor of the oral cavity next to the frenulum of the tongue is the ______________ salivary gland.

submandibular

The nervous system or systems that can control peristalsis in the inferior esophagus, stomach, small intestine and large intestine is (are) the

sympathetic and parasympathetic nervous systems. Feedback: The walls of the inferior esophagus, stomach, small intestine and large intestine contain smooth muscle, and waves of contractions of these muscles are called peristaltic waves. The autonomic nervous system is composed of the sympathetic and parasympathetic nervous systems or divisions and control the contraction of smooth muscle in the walls of the inferior esophagus, stomach, small intestine and large intestine. The tongue, pharynx, superior esophagus and external rectal sphincter contain skeletal muscle, which is controlled by the somatic motor nervous system.

Salivary secretion is stimulated by (p. 871)

the salivary nucleus only. Feedback: Secretions along the digestive tract can be stimulated by the automatic nervous system, by local reflexes in the tunica mucosa and submucosa and by hormones. Typically secretions are stimulated by either the nervous system or release of hormones. Salivation, however, is only stimulated by the nervous system. The tactile stimulation in the oral cavity, stimulation of taste buds, as well as the smell or thought of food stimulates the salivary nucleus in the brainstem. Normal salivation is stimulated by the parasympathetic nervous system.

The small intestine contains fingerlike projections called ____________, whose function is to ___________. (p. 881)

villi; increase surface area Feedback: The small stomach contains folds in the tunica mucosa and submucosa called rugae, which allows the stomach to increase its volume as it is filled. The small intestine contains villi and Crypts of Lieberkuhn or intestinal glands, which are tubular invaginations whose epithelial cells produce mucus, digestive enzymes, and hormones. The villi are fingerlike projections of the tunica mucosa, which increase the surface area for digestion and absorption of food.

Which one of the following is absorbed in the GI tract without being digested? (p. 860)

vitamins Feedback: Before being absorbed across the wall of the GI tract, starch is broken down to glucose, protein is broken down to amino acids, and triglycerides are broken down to glycerol and fatty acids. Minerals, water and vitamins are not broken down and can be absorbed as is.