Digestive System Flashcards
The term gastrointestinal (GI) tract refers to the
A) oral cavity, pharynx, esophagus, stomach, small intestine and large intestine.
B) pharynx, esophagus, stomach, small intestine and large intestine.
C) esophagus, stomach, small intestine and large intestine.
D) stomach, small intestine and large intestine.
D) stomach, small intestine and large intestine.
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. See the below figure
The muscular contractions, which move material through the digestive tract, are called:
A) peristalsis
B) deglutition.
C) mass movements.
D) segmental contractions.
A) peristalsis
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. See the below figure
The nervous system or systems that can control peristalsis in the inferior esophagus, stomach, small intestine and large intestine is (are) the
A) somatic motor nervous system.
B) sympathetic nervous system.
C) sympathetic and parasympathetic nervous systems.
D) autonomic and somatic motor nervous systems.
C) sympathetic and parasympathetic nervous systems.
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.
Stimulation by the sympathetic nervous system will cause which one of the following effects in the inferior esophagus, stomach, small intestine and large intestine?
A) nothing, because skeletal muscle is found in the walls of these areas
B) increases peristalsis by stimulation of smooth muscle
C) decreases peristalsis by inhibition of smooth muscle
D) decreases peristalsis by stimulation of smooth muscle
C) decreases peristalsis by inhibition of smooth muscle
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.
Contractions that mix material in the small intestine are called
A) peristalsis.
B) deglutition.
C) mass movements
D) segmental contractions.
D) segmental contractions.
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. See the below figure
The secretions that lubricate the food so it moves easily through the digestive tract and also protects the epithelium are called
A) mucus.
B) water.
C) enzymes.
D) hormones.
A) 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.
Which one of the following is absorbed in the GI tract without being digested?
A) starch
B) proteins
C) vitamins
D) triglycerides
C) vitamins
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.
The epithelium of the mouth, oropharynx, esophagus and anal canal is
A) simple squamous.
B) stratified squamous.
C) simple columnar.
D) pseudostratified columnar.
B) stratified squamous.
The openings and ducts into and out of the digestive tract are lined with a protective epithelium called stratified squamous.
The stomach, small intestine and large intestine are lined by this epithelium.
A) simple squamous
B) stratified squamous
C) simple columnar
D) pseudostratified columnar
C) simple columnar
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 tunica muscularis in the superior esophagus is made up of ___________ muscle.
A) skeletal
B) cardiac
C) smooth
D) smooth and skeletal
A) skeletal
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.
Contractions of the smooth muscles in the tunica muscularis in the GI tract causes ___________ and is stimulated by ____________ plexus.
A) local secretions, Meissner’s or submucosal
B) peristalsis, Auerbach’s or myenteric
C) peristalsis, Meissner’s or submucosal
D) local secretions, Auerbach’s or myenteric
B) peristalsis, Auerbach’s or myenteric
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. See the below figure
The lamina propria and muscularis mucosa are found in the tunica
A) mucosa.
B) submucosa.
C) muscularis.
D) serosa.
A) mucosa.
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. See the below figure
The outer tunic of the esophagus grades into the surrounding connective tissue and is called the tunica
A) mucosa.
B) submucosa.
C) serosa.
D) adventitia.
D) adventitia.
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.
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 ______________.
A) adventitia, visceral peritoneum
B) serosa, visceral peritoneum
C) serosa, parietal peritoneum
D) adventitia, parietal peritoneum
B) serosa, visceral peritoneum
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. See the below figure
The enteric plexus in the tunica submucosa is called the_____________ plexus.
A) Meissner’s
B) Auerbach’s
C) myenteric
D) solar
A) Meissner’s
The enteric plexus contains autonomic axons and cell bodies. There are two enteric plexi, one in the tunica muscularis and one in the tunica submucosa. The enteric plexus in the tunica muscularis is called Auerbach’s or myenteric plexus and controls peristalsis. The enteric plexus in the tunica submucosa is called Meissner’s or submucosal plexus and controls local secretions. See the below figure
Stimulation of the parasympathetic neurons in the GI tract from Auerbach’s or myenteric plexus will cause
A) inhibition of local secretions.
B) inhibition of peristalsis.
C) stimulation of local secretions.
D) stimulation of peristalsis
D) stimulation of peristalsis
The enteric plexi consist of sensory neurons, sympathetic and parasympathetic motor neurons and interneurons. Meissner’s or submucosal plexus in the tunica submucosa controls the muscularis mucosae, which controls local secretions. Auerbach’s or myenteric plexus in the tunica muscularis controls peristalsis. Stimulation of the parasympathetic motor neurons in Auerbach’s plexus will stimulate peristalsis.
Branches of which autonomic nerve carry the parasympathetic motor neurons to the enteric plexi?
A) oculomotor
B) facial
C) glossopharyngeal
D) vagus
D) vagus
Cranial nerves III (oculomotor), VII (facial), and IX (glossopharyngeal) carry parasympathetic motor neurons to various regions of the head. Cranial nerve X (vagus) carries parasympathetic motor neurons to most of the target areas of the parasympathetic nervous system including the enteric plexi.
Which of the following is FALSE about the enteric nervous system?
A) It works through local control.
B) It consists of enteric sensory and motor neurons.
C) Enetric interneurons connect sensory and motor neurons together.
D) The eneteric neurons are incapable of controlling digestive tract functions without the central nervous system (CNS).
D) The eneteric neurons are incapable of controlling digestive tract functions without the central nervous system (CNS).
The enteric neurons can work independently, but normally work together with the CNS.
Which of the following cranial nerves carries sensation from the digestive tract to the CNS?
A) gastric
B) vagus
C) spinal accessory
D) None of the above.
B) vagus
The vagus nerve carries sensory information from the gastrointestinal tract to the CNS.
Organs that lie outside the abdominal cavity such as the duodenum, pancreas, urinary bladder and rectum are
A) covered with parietal peritoneum.
B) covered with visceral peritoneum.
C) retroperitoneal.
D) covered with serous membranes
C) retroperitoneal.
In the abdominal cavity organs are covered by a visceral peritoneum, and the internal wall of the cavity is lined by a parietal peritoneum. The visceral and parietal peritoneums are both serous membranes. Organs located outside of the abdominal cavity are outside of the peritoneums and are referred to as retroperitoneal. See the below figure
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?
A) lesser omentum
B) mesentery proper
C) greater omentum
D) falciform ligament
B) mesentery proper
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. See the below figure
If you place a pin through the greater omentum, through how many layers of simple squamous epithelium would the pin pass?
A) 0
B) 1
C) 2
D) 3
C) 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.
Accumulation of excess fluid in the peritoneal cavity is called
A) peritonitis.
B) a hiatal hernia.
C) an inguinal hernia.
D) ascites.
D) ascites.
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.
The coronary ligament attaches the
A) liver to the diaphragm.
B) liver to the anterior abdominal wall.
C) colon to the posterior body wall.
D) lesser curvature of the stomach and proximal end of the duodenum to the liver and diaphragm.
A) liver to the diaphragm.
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. See the below figure
Which of the following structures forms a cavity or pocket between the layers of mesenteries?
A) visceral pleura
B) parietal pleura
C) omental bursa
D) retroperitoneum
C) omental bursa
The omental bursa forms a pocket between the layers of mesenteries.
Which of the following ligaments attaches the liver to the anterior abdominal wall?
A) coronary ligament
B) falciform ligament
C) quadrate ligament
D) caudate ligament
B) falciform ligament
The falciform ligament attaches the liver to the anterior abdominal wall.
Which of the following structures would be considered retropertitoneal?
A) pancreas
B) stomach
C) jejunum
D) spleen
A) pancreas
The pancreas would be found behind the peritoneum.
A person who is “tongue-tied” can often be treated by surgically cutting the
A) uvula.
B) buccinator muscle.
C) frenulum.
D) labium.
C) frenulum.
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.” The lingual frenulum can be seen in the below figure
The fauces refer to the
A) opening into the oropharynx.
B) space between the cheek and gums.
C) cavity that contains the tongue and teeth.
D) opening into the larynx.
A) opening into the oropharynx.
The vestibule is the space between the cheek and gums, while the oral cavity contains the tongue and teeth. The glottis is the opening into the larynx. The opening into the oropharynx is called the fauces. The fauces can be seen in the below figure
The oral cavity and oropharynx are lined by _______________ epithelium.
A) simple squamous
B) simple columnar
C) stratified squamous
D) stratified cuboidal
C) stratified squamous
The oral cavity and oropharynx are lined by an epithelium that primarily protects against abrasion. This epithelium could not be simple. Stratified cuboidal epithelium is a fairly uncommon epithelium, while stratified squamous epithelium lines all the openings and ducts that enter or leave the body including the oral cavity, oropharynx and esophagus.
The lips are lined by _____________ epithelium.
A) moist stratified squamous
B) dry stratified squamous
C) simple columnar
D) pseudostratified columnar
B) dry stratified squamous
The lips are lined by an epithelium that protects against abrasion so that rules out simple columnar and pseudostratified columnar epithelia. The skin is lined by a highly keratinized or dry stratified squamous epithelium, while the oral cavity in lined by a moist nonkeratinized stratified squamous epithelium. The lips are lined by a dry stratified squamous epithelium, but it is thinner and not as keratinized as the skin. Lips may dry out and crack especially in dry climates and many people often use a lubricant to prevent the lips from drying out and cracking.
The projection from the posterior edge of the soft palate elevates and helps close off the nasopharynx when swallowing. The projection is called the
A) buccal fat pad.
B) epiglottis.
C) uvula.
D) palatine tonsil.
C) uvula.
The buccal fat pad is found in the cheeks and helps round out the profile of the face. The epiglottis is one of the nine cartilages of the larynx and closes off the glottis when swallowing. The palatine tonsils are lymphoid masses located in the lateral wall of the fauces and are important in protection against pathogens entering the pharynx. The uvula is the projection from the posterior edge of the soft palate and helps close off the nasopharynx. Surgical removal of the uvula is sometimes done as a treatment for snoring. The uvula can be seen in the below figure
Which one of the following is not located in the oral cavity or oropharynx?
A) frenulums
B) lingual tonsils
C) palatine tonsils
D) pharyngeal tonsils
D) pharyngeal tonsils
The frenulums attach to the lips and tongue; the lingual tonsils are found on the posterior surface of the tongue; and the palatine tonsils are located in the lateral wall of the fauces. The pharyngeal tonsils or adenoids are located on the posterior surface of the nasopharynx. The location of the pharyngeal tonsils can be seen in the below figure
Which one of the following is most easily absorbed in the oral cavity?
A) glucose
B) water
C) fatty acids
D) peptides
C) fatty acids
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.
Out of a normal adult’s 32 teeth, how many are molars?
A) 2
B) 4
C) 8
D) 12
D) 12
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.
Humans normally have 20 deciduous or “baby” teeth and adults 32 permanent teeth. The 12 additional teeth in humans represent
A) incisors and canines.
B) canines and premolars.
C) premolars and molars.
D) all molars.
C) premolars and molars.
Deciduous teeth erupt between 6 months and 24 months of age. The permanent teeth begin replacing the deciduous teeth by about 5 years, and all the deciduous teeth are replaced by 11 years of age with additional permanent teeth erupting until the late teens or early twenties. The 20 deciduous teeth include: 8 incisors, 4 canines, 0 premolars and 8 molars. The 32 permanent teeth include: 8 incisors, 4 canines, 8 premolars and 12 molars. The adult with all of his or her permanent teeth has 8 premolars and 4 molars more than a child with 20 deciduous teeth. You can see the difference between deciduous and adult teeth in the below figure
The most common cause of tooth loss in adults is
A) periodontal disease.
B) gingivitis.
C) pyorrhea.
D) dental caries.
A) periodontal disease.
Dental caries or tooth decay is caused by the break down of enamel by acids produced by bacteria. Gingivitis is inflammation of the gingiva and may lead to periodontal disease. Pyorrhea is a condition in which pus occurs with periodontal disease. Periodontal disease is the inflammation and degradation of the periodontal ligaments, gingiva, and alveolar bone and is the leading cause of tooth loss in adults.
Chewing or mastication reflex originates in the _______________ and the ability to initiate or stop chewing originates in the _______________.
A) pons; cerebrum.
B) medulla oblongata; cerebrum.
C) spinal cord; medulla oblongata.
D) medulla oblongata; midbrain.
B) medulla oblongata; cerebrum.
Many reflexes are associated with the spinal cord, but not chewing. The midbrain coordinates skeletal muscle reflexes in response to visual and auditory stimuli. Food in the oral cavity stimulates four pairs of skeletal muscles in a reflex initiated in the medulla oblongata. The ability to initiate or stop chewing as well as the rate and intensity of chewing is controlled by the cerebrum.
Which two regions of a tooth contain living cells?
A) dentin and enamel
B) anatomical crown and cementum
C) enamel and cementum
D) dentin and cementum
D) dentin and cementum
The anatomical crown is the entire enamel-covered part of the tooth. Enamel is an extremely hard nonliving material. The pulp cavity is surrounded by dentin, and the surface of the dentin in the root is covered with cementum. Both cementum and dentin contain living cells with cementum most closely resembling bone. These structures can be seen in the below figure
The center of the tooth that is filled with blood vessels and nerves is called the _____________ and the cavity within the root of the tooth is called the ________________.
A) clinical crown; root canal
B) pulp cavity; root canal
C) pulp cavity; dentin
D) dentin; root canal
B) pulp cavity; root canal
The clinical crown is the exposed part of the tooth in the oral cavity. Dentin lies immediately under the enamel of the anatomical crown and is a living, cellular, and calcified tissue. The cavity that contains the blood vessels and nerves is called the pulp cavity, which becomes the root canal in the root. The blood vessels and nerves enter and exist in the root canal through the apical foramen. The pulp cavity and root canal can be seen in the below figure
In a given tooth, the dentin is located ______________ to the enamel.
A) inferior
B) anterior
C) superior
D) posterior
A) inferior
As you can see from the below figure, dentin is located below or inferior to the enamel.
Mumps is inflammation of the _______________ salivary gland caused by a virus.
A) buccal
B) sublingual
C) submandibular
D) parotid
D) parotid
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 salivary gland that produces primarily mucus is the _____________ salivary gland.
A) parotid
B) labial
C) submandibular
D) sublingual
D) sublingual
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. All the salivary glands can be seen in the below figure
Salivary glands structurally are
A) compound tubuloacinar or tubuloalveolar glands.
B) compound alveolar or acinar glands.
C) compound tubular glands.
D) simple branched alveolar or acinar glands.
A) compound tubuloacinar or tubuloalveolar glands.
As you can see in the below figure, salivary glands have ducts that are both tubular and alveolar or acinar in shape. Because the ducts branch repeatedly, the salivary glands are also compound.
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.
A) submandibular
B) sublingual
C) palatine
D) parotid
A) submandibular
Palatine glands are in the cheek and add the secretions to the oral cavity, but are not salivary glands. The parotid salivary gland is a serous gland whose duct enters the oral cavity adjacent to the second upper molar. The sublingual salivary gland, which is a mixed gland that produces mostly mucus, opens into the floor of the oral cavity. The submandibular salivary gland is a mixed gland that produces more serous the mucous secretions. The ducts of this gland open inferiorly in the floor of the oral cavity next to the frenulum of the tongue. You can see the submandibular ducts open into the floor of the oral cavity in the below figure
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 ________________.
A) amylase; glucose
B) pepsin; maltose
C) amylase, maltose
D) maltase, glucose
C) amylase, maltose
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.
Saliva decreases gingivitis and caries because it contains immunoglobulin A and
A) lysozymes.
B) mucus.
C) salivary amylase.
D) water.
A) lysozymes.
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.
Salivary secretion is stimulated by
A) the salivary nucleus only.
B) the salivary nucleus and gastrin.
C) gastrin only.
D) the salivary nucleus and local reflexes in the tunica mucosa and submucosa.
A) the salivary nucleus only.
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.
Which part(s) of the pharynx normally conduct food?
A) oropharynx only
B) oropharynx, laryngopharynx and nasopharynx
C) nasopharynx only
D) oropharynx and laryngopharynx
D) oropharynx and laryngopharynx
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. You can see the three parts of the pharynx in the below figure
The esophagus pierces through an opening in the diaphragm called the
A) fauces.
B) hiatus.
C) glottis.
D) inguinal canal.
B) hiatus.
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.
The esophagus is different from the GI tract because the esophagus has
A) skeletal muscles at the superior end and smooth muscles at the inferior end.
B) no tunica submucosa.
C) villi and microvilli to increase surface area.
D) no tunica mucosa.
A) skeletal muscles at the superior end and smooth muscles at the inferior end.
The esophagus contains four tunics: mucosa, submucosa, muscularis, and adventitia. The tunica adventitia is different from the tunica serosa, because the tunica adventitia grades into the surrounding connective tissue. The tunica muscularis in the GI tract consists of smooth muscle only, while in the esophagus the superior part contains skeletal muscle and the inferior part contains smooth muscle.
A major secretion of the esophagus is
A) bile.
B) amylase.
C) mucus.
D) hydrochloric acid.
C) mucus.
The esophagus does not secrete bile (liver), amylase (salivary glands and pancreas), or hydrochloric acid (stomach). The tunica submucosa in the esophagus contains numerous mucous glands that secrete a thick, lubricating mucus.
Which one of the following does not occur during swallowing?
A) The larynx raises.
B) The epiglottis moves anteriorly to close the glottis.
C) The uvula and soft palate move inferiorly to block the oropharynx.
D) The vestibular folds move medially.
C) The uvula and soft palate move inferiorly to block the oropharynx.
During swallowing the passages into the airways are blocked so food is moved down into the esophagus. The larynx raises, the vestibular folds move medially, and the epiglottis moves anteriorly to block the glottis. The nasopharynx is blocked as the soft palate (particularly the uvula) raises or moves superiorly; this allows the food to move down the oropharynx into the esophagus.
The pharyngeal phase of swallowing is ___________ , which is controlled by __________ muscle.
A) involuntary; smooth
B) voluntary; smooth
C) involuntary; skeletal
D) voluntary; skeletal
C) involuntary; skeletal
The pharyngeal phase of swallowing is initiated by stimulation of the swallowing center in the medulla oblongata. The swallowing center stimulates pharyngeal constrictor muscles to contract in succession. This is an involuntary process but the pharyngeal constrictor muscles are skeletal. You can see the pharyngeal phase in the below figure
Sometimes when you are talking and eating you initiate the gagging reflex. The gagging or coughing reflex is stimulated when foreign material enters the larynx. Some of the bolus you are swallowing enters the larynx when you are talking because the
A) epiglottis is not closed over the glottis.
B) soft palate moves inferiorly.
C) pharyngeal constrictor muscles relax.
D) esophageal sphincters relax.
A) epiglottis is not closed over the glottis.
In normal swallowing, the soft palate (particularly the uvula) moves superiorly, the pharyngeal constrictor muscles contract and the esophageal sphincters relax. If the soft palate moves inferiorly (you are breathing through your nose while swallowing) some of the bolus could enter the nasopharynx and initiate a sneezing reflex. When talking while swallowing, the epiglottis is open, which may allow some of the bolus to enter the larynx. This would initiate the gagging or coughing reflex. You can see the stages in swallowing in the below figure
The esophageal phase of swallowing is caused by the
A) peristaltic reflex.
B) enteric reflex.
C) swallowing center.
D) coughing reflex.
B) enteric reflex.
Food in the oropharynx stimulates the swallowing center to initiate the pharyngeal phase of swallowing. Foreign material in the larynx initiates the coughing reflex. Food in the esophagus stimulates the medulla oblongata to initiate peristaltic waves in the esophagus. This is called the esophageal phase, and the nervous system regulation of this phase is called the enteric reflex. The esophageal phase can be seen in the below figure
The region of the stomach around the opening from the esophagus is called the ___________ region.
A) pyloric
B) body
C) cardiac
D) fundus
C) cardiac
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. The cardiac region can be seen in the below figure
The cardiac or lower gastroesophageal sphincter is composed of ____________ muscle and prevents chyme from moving into the _____________.
A) smooth; esophagus
B) skeletal; esophagus
C) smooth; duodenum
D) skeletal; duodenum
A) smooth; esophagus
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 pyloric and gastroesophageal sphincters can be seen in the below figure
The stomach is unique to the GI tract because it contains
A) circular smooth muscle.
B) longitudinal smooth muscle.
C) skeletal muscle.
D) oblique smooth muscle.
D) oblique smooth muscle.
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. You can see the oblique smooth muscle in the below figure
The tunica submucosa and mucosa of the stomach are thrown into large folds called
A) epiploic appendages.
B) rugae.
C) plicae cirulares.
D) villi.
B) rugae.
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. Rugae can be seen in the below figure
Which one of the following cells in the gastric glands produce pepsinogen?
A) endocrine cells
B) mucous neck cells
C) chief or zymogenic cells
D) parietal or oxyntic cells
C) chief or zymogenic cells
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 cells of the gastric glands can be seen in the below figure
Surface area of the stomach is increased by
A) gastric pits.
B) plicae circulares.
C) villi.
D) microvilli.
A) gastric pits.
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. Gastric pits can be seen in the below figure
The major food digested by gastric secretions is
A) fat.
B) starch.
C) protein.
D) nucleic acids.
C) protein.
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 hydrogen ions that form hydrochloric acid of the stomach come from
A) pyruvic acid.
B) lactic acid.
C) carbonic acid.
D) citric acid.
C) carbonic acid.
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. These reactions can be seen in the below figure
The low pH of the stomach activates enzymes that digest _____________ while inactivating enzymes that digest ______________.
A) lipids; proteins
B) proteins; starch
C) starch; proteins
D) nucleic acids; starch
B) proteins; starch
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.
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.
A) hydrochloric acid; B12
B) mucus; D
C) pepsinogen; D
D) intrinsic factor; B12
D) intrinsic factor; B12
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.
The stomach produces acids, which denature protein, and pepsin that digests protein. The cell membranes of the epithelial cells lining the stomach contain protein. The protein in the epithelial cells are not denatured or digested because
A) the membranes contain a different type of protein that resists denaturation and digestion.
B) mucus coats the epithelium.
C) cell membranes are destroyed but mitotic activity replaces cells with new ones every few hours.
D) hormones produced by the endocrine cells protect the cell membranes and neutralize the acid pH.
B) mucus coats the epithelium.
The environment of the stomach with a pH between 1 and 3 and with pepsin digesting proteins is a very hostile environment for the simple columnar cells that line the stomach. Endocrine cells produce hormones, but these play no direct role in changing the pH of the stomach. The proteins in the cell membranes can be denatured and digested by pepsin, and the life span of a gastric cell is only about 3 days. Mucus from surface mucous cells and mucous neck cells is a viscous and alkaline secretion and forms a protective layer over the epithelial cells 1-1.5 mm thick.
The painful or burning sensation in the chest usually associated with acid reflux in the esophagus is called
A) a peptic ulcer.
B) heart burn.
C) angina.
D) a duodenal ulcer.
B) heart burn.
Ulcers occur when the epithelium of the GI tract is eroded away. Peptic ulcers caused by stomach acids and pepsin, which erode through the protective mucous lining. A duodenal ulcer refers to the specific location of the ulcer. Angina is pain often mistaken for indigestion that results from a reduced blood supply to cardiac muscle. The cardiac sphincter is not a particularly strong sphincter and sometimes the acid chyme moves from the stomach to the esophagus. This is called acid reflux and results in a burning sensation in the chest called heartburn.
One of your family members has developed peptic ulcers and is consulting you for advice. You can tell your family member that there may be a chance of permanently curing this ulcer by
A) giving up smoking and alcohol.
B) taking meditation classes to reduce stress.
C) taking antibiotics that destroy Helicobacter pylori.
D) taking Tagment or Zantac.
C) taking antibiotics that destroy Helicobacter pylori.
In the past, the major causes of peptic ulcers were thought to be stress and that smoking and alcohol would cause excess acid secretion resulting in ulcers. For temporary relief, both Tagamet and Zantac are histamine blockers that inhibit gastric acid secretion. Most ulcers (possibly as high as 80%) are caused by an infection of a bacterium, Helicobacter pylori. A medical office can test for H. pylori, and antibiotic treatment has been very successful in permanently eradicating people’s ulcers.
Parasympathetic stimulation causes endocrine cells in the stomach to release the hormone
A) gastrin.
B) pepsinogen.
C) histamine.
D) secretin.
A) gastrin.
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.
In the regulation of stomach secretions, distension of the stomach activates local reflexes and a parasympathetic reflex. This is called the _____________ phase.
A) cephalic
B) gastric
C) intestinal
D) enterogastric
B) gastric
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. The gastric phase is shown in the below diagram
Cells in duodenum monitor chyme coming from the stomach that has a pH of 1. You would expect the duodenal cells to
A) release gastric inhibitory polypeptide and cholecystokinin, which inhibits gastric secretions.
B) initiate the enterogastric reflex, which increases gastric secretions.
C) release secretin, which inhibits gastric secretions.
D) release enterogastrone, which inhibits gastric secretions.
C) release secretin, which inhibits gastric secretions.
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 intestinal phase can be seen in the below figure
The stomach contractions, which move the chyme from near the periphery of the stomach toward the pyloric sphincter, are called
A) the pyloric pump.
B) peristaltic waves.
C) mixing waves.
D) mass movements.
B) peristaltic waves.
Mass movements occur in the colon. The stomach has three types of movements. The most common contractions are peristaltic-like contractions that occur about every 20 seconds and mix the ingested material with the secretions of the stomach. The pyloric pump causes powerful contractions that move liquid chyme through the partially closed pyloric opening. Peristaltic waves move chyme from near the periphery toward the pyloric sphincters. The various movements in the stomach can be seen in the below figure
The small intestine contains fingerlike projections called ____________, whose function is to ___________.
A) villi; secret mucus
B) rugae; allow for expansion
C) Crypts of Lieberkuhn; produce mucus, digestive enzymes and hormones
D) villi; increase surface area
D) villi; increase surface area
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. You can see villi in the below figure.
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.
A) 1
B) 6-7
C) 92
D) 99
D) 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. This can be seen in the below figure.
Brunner’s glands produce __________ and are found in the _____________.
A) hormones; duodenum
B) mucus; duodenum
C) enzymes; ileum
D) mucus; ileum
B) mucus; duodenum
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. You can see these Brunner’s or duodenal glands in the below figure
In the tunica mucosa and submucosa of the small intestine, a series of folds called the ____________ functions to __________________.
A) plicae circulares; increase surface area
B) villi; increase surface area
C) microvilli; allow the small intestine to expand
D) rugae; allow the small intestine to expand
A) plicae circulares; increase surface area
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 villi and plicae cirulares or circular folds can be seen in the below figure
The pancreas and liver release their secretions into the
A) stomach.
B) ileum.
C) duodenum.
D) jejunum.
C) duodenum.
The stomach receives the bolus from the esophagus and releases chyme into the duodenum. The pancreas and liver also release secretions into the duodenum. The common bile duct and the ducts from the pancreas can be seen in the below figure
You have a situation where the hepatopancreatic ampullar sphincter or sphincter of Oddi will not relax. You would expect
A) chyme not to be released into the stomach.
B) the feces to contain a much higher percentage of fat than normal.
C) the feces to contain a much higher percentage of starch and protein than normal.
D) chyme not to be released into the large intestine.
B) the feces to contain a much higher percentage of fat than normal.
The pyloric sphincter regulates the passage of chyme from the stomach to the duodenum. The ileocecal sphincter regulates the passage of chyme from the ileum to the large intestine. The hepatopancreatic ampullar sphincter or sphincter of Oddi regulates the entrance of bile from the common bile duct to the duodenum. Bile contains bile salts that emulsifies fat and makes it more efficient to digest the fat into fatty acids and glycerol and absorb these digestion products in the small intestine. A decrease in bile reduces the digestion of fat and causes feces to contain a much higher percentage of fat than normal, which is often called fatty stools. The hepatopancreatic ampulla can be seen in the below figure, and the sphincter would be around the ampulla.
The lymphatic capillaries in the villi of the small intestine are called
A) lacteals.
B) Peyer’s patches.
C) Crypts of Lieberkuhn.
D) microvilli.
A) lacteals.
Crypts of Lieberkuhn are tubular invaginations of the tunica mucosa in the small intestine while Peyer’s patches are lymph nodules in the tunica mucosa and submucosa of the ileum. Microvilli are cytoplasmic extensions on the absorptive cells. Villi are fingerlike projections that contain blood capillary networks and lymphatic capillaries called lacteals. A villus with a blood capillary network and a lacteal can be seen in the below figure
The longest region of the small intestine is the
A) duodenum.
B) ileum.
C) jejunum.
D) colon.
B) ileum.
Ninety percent of the absorption and digestion in the GI tract occurs in the small intestine. The small intestine is about 6 m long. The duodenum is about 25 cm long; the jejunum is about 2.5 m long and the ileum is about 3.5 m long. The three regions of the small intestine can be seen in the below figure
The hepatic sinusoids receive oxygenated and unoxygenated blood. The blood vessels that provide mixed blood to the sinusoids are the
A) hepatic artery and hepatic vein.
B) hepatic vein and hepatic portal vein.
C) hepatic portal artery and hepatic portal vein.
D) hepatic artery and hepatic portal vein.
D) hepatic artery and hepatic portal vein.
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. These vessels can be seen in the below figures
You are tracing a drop of blood from the blood capillary network in the small intestine to the inferior vena cava. The pathway is
A) hepatic vein → sinusoid → central vein → hepatic portal vein → inferior vena cava.
B) hepatic portal vein → sinusoid → inferior vena cava.
C) hepatic portal vein → sinusoid → central vein → hepatic vein → inferior vena cava.
D) hepatic portal vein → hepatic vein → sinusoid → central vein → inferior vena cava.
C) hepatic portal vein → sinusoid → central vein → hepatic vein → inferior vena cava.
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 pathways can be put together from the below two figures.
Hepatocytes or hepatic cells produce bile, which is secreted into the
A) hepatic portal vein.
B) bile canaliculi.
C) hepatic sinusoid.
D) lacteal.
B) bile canaliculi.
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. You can see bile canaliculi in the below figure
Which one of the following is the correct pathway of bile from the hepatocytes to the gallbladder?
A) bile canaliculus → hepatic duct → common hepatic duct → common bile duct → gallbladder.
B) bile canaliculus → hepatic duct → cystic duct → common hepatic duct → gallbladder.
C) hepatic sinusoid → central vein → hepatic vein → gall bladder.
D) bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder.
D) bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder.
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. This pathway can be traced in the below two figures
Bile secretion is stimulated by the hormone ______________ in response to ______________.
A) cholecystokinin; high pH of the chyme
B) cholecystokinin; low pH of the chyme
C) secretin; high pH of the chyme
D) secretin; low pH of the chyme
D) secretin; low pH of the chyme
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. You can see the control of bile secretion in the below figure
Which one of the following functions best describes the effects of the hormone cholecystokinin?
A) inhibits gastric secretions
B) increases gastric secretions
C) inhibits gastric secretions, stimulates pancreatic secretions (high in enzymes), stimulates contraction of the gall bladder and relaxation of the sphincter of Oddi
D) inhibits gastric secretions, stimulates pancreatic secretions (high in bicarbonate ions) and increases the secretions of bile, intestinal juice and mucus
C) inhibits gastric secretions, stimulates pancreatic secretions (high in enzymes), stimulates contraction of the gall bladder and relaxation of the sphincter of Oddi
Gastric inhibitory polypeptide inhibits gastric secretions, while gastrin increases gastric secretions. Secretin, in response to acid chyme, inhibits gastric secretions, stimulates pancreatic secretions rich in bicarbonate ions, and increases the secretions of bile, intestinal juice and mucus. Cholecystokinin (CCK), in response to fatty acids and other lipids in the duodenum, inhibits gastric secretions, stimulates pancreatic secretions rich in enzymes, stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi. You can see the effects of CCK in the below figure
The pancreatic juice, produced by acinar cells, is secreted into the
A) stomach
B) duodenum
C) jejunum
D) ileum
B) duodenum
The acinar cells of the pancreas produce aqueous and enzymatic components that form the pancreatic juice. The pancreatic juice is secreted into the duodenum by way of a pancreatic duct, which joins the common bile duct to form the hepatopancreatic ampulla. A second pancreatic duct, the accessory pancreatic duct, is present in most people and it secretes directly into the duodenum. These ducts can be seen in the below figure.
The aqueous component of pancreatic juice is produced by the
A) intercalated duct.
B) pancreatic islets.
C) acinar cells.
D) duodenum.
A) intercalated duct.
The aqueous component of pancreatic juice is secreted into the duodenum, and the pancreatic islets produce the hormones somatostatin, insulin and glucagon. The enzymatic component of pancreatic juice is produced by acinar cells. The aqueous component is produced by cells of the intercalated duct. This can be seen in the below figure.
In the production of the aqueous component of pancreatic juice, _________ ions are actively transported into the intercalated duct and sodium ions are exchanged for _________ ions.
A) bicarbonate; hydrogen
B) sodium; potassium
C) bicarbonate; potassium
D) hydrogen; potassium
A) bicarbonate; hydrogen
The aqueous component of pancreatic juice is composed of water, sodium ions, and bicarbonate ions. In the cells that line the intercalated duct, water and carbon dioxide are stimulated by the enzyme carbonic anhydrase to form carbonic acid. The carbonic acid dissociates into bicarbonate ions and hydrogen ions. Bicarbonate ions are actively transported into the intercalated duct. The hydrogen ions are exchanged for sodium ions between the cell and the capillary. Sodium ions and water follow the actively transported bicarbonate ions into the intercalated duct lumen by diffusion. These reactions can be seen in the below figure.
Secretion of the enzymatic component of pancreatic juice is stimulated by the hormone
A) gastric inhibitory polypeptide.
B) secretin.
C) gastrin.
D) cholecystokinin.
D) cholecystokinin.
The endocrine cells of the duodenum produce four hormones. Gastrin and gastric inhibitory polypeptide increase gastric secretions and inhibit gastric secretions respectively. Secretin and cholecystokinin have a number of target organs, but the pancreas is stimulated by both. Secretin stimulates the cells lining the intercalated duct to secrete the aqueous component. Cholecystokinin stimulates the acinar cells to secrete the enzymatic component. Cholecystokinin is stimulated to be released by fatty acids and fat in the chyme of the small intestine.
This region of the large intestine has a simple columnar epithelium in its tunica mucosa, smooth muscle in its tunica muscularis, and epiploic appendages attach to its outer surface. This region is called the
A) cecum.
B) colon.
C) rectum.
D) anal canal.
B) colon.
The cecum, colon and rectum all have a simple columnar epithelium and smooth muscle in their tunica muscularis. The anal canal has smooth muscle but the epithelium changes from simple columnar to stratified squamous. Epiploic appendages are fat-filled connective tissue pouches unique to the colon. You can see these pouches in the below figure.
In the colon, the teniae coli are bands of __________, which contract to form ___________.
A) fat; epiploic appendages
B) longitudinal smooth muscle; haustra
C) skeletal muscle; haustra
D) smooth muscle; the internal anal sphincter
B) longitudinal smooth muscle; haustra
The epiploic appendages are fat-filled connective tissue pouches attached to the outer surface of the colon. The anal canal contains smooth muscle that forms the internal anal sphincter. There is no skeletal muscle in the wall of the colon. The teniae coli are three bands of longitudinal smooth muscle that run the length of the colon. When the teniae coli contract, pouches called haustra form along the length of the colon. You can see the teniae coli and haustra in the below figure.
This blind tube is about 9 cm long, is filled with lymph nodules and attaches to the cecum. This blind tube is called the
A) epiploic appendix.
B) haustra.
C) vermiform appendix.
D) tenia coli.
C) vermiform appendix.
Epiploic appendages are fat-filled pouches attached to the outer surface of the colon. Haustra are pouches in the colon formed by contraction of three bands of longitudinal smooth muscle called teniae coli. The cecum is the proximal end of the large intestine and forms a blind sac. Attached to the cecum is a small blind tube about 9 cm long called the vermiform appendix. The appendix contains numerous lymph nodules and can be seen in the below figure
Stimulation by the parasympathetic nervous system will cause the __________ anal sphincter to _____________.
A) external; relax
B) external; contract
C) internal; contract
D) internal; relax
D) internal; relax
There are two sphincters associated with the anal canal. The internal anal sphincter is composed of smooth muscle and is found at the superior end of the anal canal. The external anal sphincter is composed of skeletal muscle and is found at the inferior end of the anal canal. Skeletal muscle is controlled by the somatic motor nervous system, while smooth muscle is controlled by the autonomic nervous system. Stimulation of the internal anal sphincter by the parasympathetic nervous system will allow for a bowel movement. Thus parasympathetic nervous stimulation will relax the internal anal sphincter. Both sphincters can be seen in the below figure.
These contractions occur 3 to 4 times a day and involve large parts of the transverse and descending colon. These contractions are called
A) mass movements.
B) haustral churning.
C) the defecation reflex.
D) teniae coli waves.
A) mass movements.
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. This can be seen in the below figure.
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
A) stimulate the defecation reflex.
B) inhibit the defecation reflex.
C) stimulate mass movements.
D) inhibit mass movements.
B) inhibit the defecation reflex.
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. You can see a diagram of the defecation reflex in the below figure.
Glucose and galactose in the small intestine are taken into the epithelial cell by __________ and passed into the interstitial fluid by ___________.
A) diffusion; facilitated diffusion
B) facilitated diffusion; cotransport
C) cotransport; active transport
D) cotransport; facilitated diffusion
D) cotransport; facilitated diffusion
Glucose is actively taken up by simple columnar epithelial cells lining the small intestine. Feces contains little to no glucose so virtually 100% of the glucose in the small intestine is absorbed. The absorption of glucose requires sodium ions, and the process is called cotransport or secondary active transport. Crossing the tissue side of the epithelial membrane to the interstitial fluid requires a carrier protein but goes down a concentration gradient. This crossing of the membrane into the interstitial fluid is called facilitated diffusion. The cotransport of glucose or galactose into the epithelial cell and the facilitated transport out of the epithelial cell into the interstitial fluid is shown in the below figure
The lipids that can be absorbed across the epithelial wall of the small intestine are hydrophobic and would have a difficult time in the watery lumen to come in contact with the epithelial membrane. These lipids are able to move easily in the watery lumen because of interaction with
A) bile salts.
B) lipase.
C) micelles.
D) chylomicrons.
A) bile salts.
The lipid digestion products are fatty acids, glycerol, cholesterol and phospholipids. These are nonpolar or hydrophobic molecules in a medium of water, which is polar. Bile salts have hydrophobic ends that are directed toward the lipid products and hydrophilic ends directed outward toward the water environment. The complex is called a micelle and it allows for easy movement of the complex toward the epithelial wall and subsequent diffusion of the lipid products into the epithelial cell. A micelle can be seen in the below figure.
Once absorbed into the epithelial cell of the small intestine, free fatty acids and glycerol are recombined and a protein coat is added to form a
A) chylomicron.
B) micelle.
C) lipoprotein.
D) fatty droplet.
A) chylomicron.
A micelle is the package in the lumen of the small intestine formed by lipid digestion products surrounded by bile salts. Once lipids reach the blood they combine with proteins and the complex is called a lipoprotein. Fatty droplets are smaller molecules of lipids that are produced when bile salts emulsify large lipid molecules. When the intestinal cells absorb cholesterol and fatty acids, they are recombined in the smooth ER to form fat. The protein coat is added to the fat and other lipid products in the golgi apparatus. This new package is called a chylomicron, which leaves the cell by exocytosis. See the below figure to see the relationship between micelle (1), chylomicron (3), and lipoprotein (4).
Once chylomicrons leave the simple columnar epithelium of the small intestine, they diffuse into
A) capillaries.
B) lacteals.
C) arterioles.
D) venules.
B) lacteals.
Chylomicrons are large molecules composed of phospholipids, triglycerides, and cholesterol with a protein coat. Products are taken up from the interstitial fluid around the small intestine either by capillaries or by lymphatic capillaries called lacteals. The walls of arterioles and venules are too thick to allow for any absorption. The chylomicron is too big and too polar to enter the capillary. Lacteals have large spaces between their simple squamous cells that allow for the diffusion of the chylomicrons. See the below figure for the diffusion of a chylomicron into a lacteal.
A lipoprotein has the following components: 5% tryglyceride, 20% cholesterol, 30% phospholipid, and 45% protein. This molecule would be best described as a
A) micelle.
B) chylomicron.
C) low-density lipoprotein.
D) high-density lipoprotein.
D) high-density lipoprotein.
A micelle is composed of bile salts, fatty acids, glycerol, plus other lipid products, but it contain no protein. A chylomicron is composed of only about 1% protein. The chylomicron carries the fat products to the lacteals. When the fat products are released into the blood, they are carried by proteins. Lipids that combine with proteins in the blood form lipoproteins. Lipids are less dense than water while proteins are more dense than water. A chylomicron with only 1% protein is referred to as a very low-density lipoprotein (VLDL) whereas a lipoprotein with 45% protein would be a high-density lipoprotein (HDL). You can see the ranges of densities in the below figure
Cholesterol that is required to produce steroids and bile salts is carried in
A) micelles.
B) chylomicrons.
C) low-density lipoproteins (LDL).
D) high-density lipoproteins (HDL).
C) low-density lipoproteins (LDL).
About 15% of the cholesterol in the body is ingested in the food we eat, while the remaining 85% is manufactured by cells of the body. Cells have LDL receptors on their surfaces that bind to the low-density lipoproteins (LDL). Cholesterol transported to cells must be carried by LDL to allow for absorption into cells by endocytosis. Excess lipids are packaged in HDL and transported back to the liver for recycling or disposal. See the below figure to see LDL and LDL receptors in cell membranes.
