A. haustra
B. lacteals
C. bacterial flora
D. intestinal glands
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b) lacteals
- Correct: Villi are small, finger-like projections that extend into the lumen of the small intestine, increasing its surface area for absorption. Lacteals are specialized lymphatic vessels located within the villi. They play a crucial role in the absorption of dietary fats and fat-soluble vitamins. Lacteals absorb digested fats and fat-soluble nutrients and transport them through the lymphatic system to the bloodstream.
a) haustra
- Incorrect: Haustra are pouches or sacculations formed by the longitudinal muscle of the colon. They are characteristic features of the large intestine, particularly the colon, and are not directly associated with villi.
c) bacterial flora
- Incorrect: Bacterial flora (microbiota) refers to the diverse population of microorganisms inhabiting the gastrointestinal tract. While they play important roles in digestion, nutrient absorption, and immune function, they are not specifically associated with villi. They primarily inhabit the large intestine, where they aid in the fermentation of undigested carbohydrates and the production of certain vitamins.
d) intestinal glands
- Incorrect: Intestinal glands, also known as crypts of Lieberkühn or intestinal crypts, are invaginations of the epithelium located between the villi in the mucosa of the small intestine. They contain stem cells that continuously divide to replace the epithelial cells lining the intestine. While they are anatomically close to villi, they are distinct structures responsible for epithelial cell renewal and secretion of intestinal juices, but they are not directly associated with villi.
Therefore, the Correct Answer is B.
Which part of the large intestine attaches to the appendix?
A. cecum
B. ascending colon
C. transverse colon
D. descending colon
The Correct Answer is A.Cecum attaches to the appendix
Which of the following organs is supported by a layer of adventitia rather than serosa?
A. esophagus
B. stomach
C. small intestine
D. large intestine
The Correct Answer is A.a) esophagus
- Correct: The esophagus is supported by a layer of adventitia rather than serosa. The adventitia is a connective tissue layer that covers organs and structures that are not located within the peritoneal cavity. In the case of the esophagus, it lies behind the trachea and heart and passes through the diaphragm before connecting to the stomach. Since it is located outside the peritoneal cavity, it is covered by adventitia instead of serosa, which is the visceral peritoneum that covers organs within the abdominal cavity.
b) stomach
- Incorrect: The stomach is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.
c) small intestine
- Incorrect: The small intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.
d) large intestine
- Incorrect: The large intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.
In the stomach:
A. muscles churn and mix the food with acids and enzymes
B. glands make 3 quarts of digestive juices each day
C. food leaves as a thick liquid called chyme
D. all of the above
The Correct Answer is D.d. all of the above
- Correct: All of the statements are true regarding the stomach:
a. muscles churn and mix the food with acids and enzymes: The stomach has muscular walls that contract and relax to mechanically churn and mix food with gastric juices, including hydrochloric acid and various enzymes (such as pepsin) that aid in the digestion of proteins.
b. glands make 3 quarts of digestive juices each day: The gastric glands in the lining of the stomach produce gastric juice, which contains hydrochloric acid, enzymes (such as pepsinogen), mucus, and intrinsic factor. These glands collectively secrete about 2 to 3 liters (quarts) of gastric juice per day.
c. food leaves as a thick liquid called chyme: After mixing with gastric juices and undergoing partial digestion in the stomach, food is transformed into a semi-liquid mixture called chyme. Chyme is then gradually released from the stomach into the small intestine for further digestion and absorption.
Therefore, all of the statements accurately describe processes that occur in the stomach.
Which of these statements about the pharynx is true?
A. It extends from the nasal and oral cavities superiorly to the esophagus anteriorly.
B. The oropharynx is continuous superiorly with the nasopharynx.
C. The nasopharynx is involved in digestion.
D. The laryngopharynx is composed partially of cartilage.
The Correct Answer is D.d) The laryngopharynx is composed partially of cartilage.
- True: The statement that the laryngopharynx is composed partially of cartilage is true. The pharynx, commonly known as the throat, is a muscular tube that extends from the base of the skull to the level of the sixth cervical vertebra. It serves as a passageway for both air and food. The pharynx is divided into three regions: the nasopharynx, oropharynx, and laryngopharynx.
a) It extends from the nasal and oral cavities superiorly to the esophagus anteriorly.
- False: The pharynx extends from the nasal and oral cavities superiorly to the esophagus and larynx inferiorly, not anteriorly.
b) The oropharynx is continuous superiorly with the nasopharynx.
- False: The oropharynx is continuous inferiorly with the oral cavity, not superiorly with the nasopharynx. The nasopharynx is continuous superiorly with the nasal cavity.
c) The nasopharynx is involved in digestion.
- False: The nasopharynx is primarily involved in respiration and the passage of air. It contains the openings of the auditory tubes and tonsils but is not directly involved in digestion.
The digestive system breaks down food into:
A. nutrients
B. amylase
C. saliva
D. sphincters
The Correct Answer is A.a. nutrients
- Correct: The digestive system breaks down food into nutrients. These nutrients include carbohydrates, proteins, fats, vitamins, minerals, and water, which are essential for various physiological functions in the body. Once broken down into nutrients through mechanical and chemical digestion, these substances are absorbed by the intestines and transported via the bloodstream to cells throughout the body for energy production, growth, repair, and other metabolic processes.
b. amylase
- Incorrect: Amylase is an enzyme involved in the digestion of carbohydrates. It is produced by salivary glands in the mouth and by the pancreas and helps break down complex carbohydrates into simpler sugars. While amylase is an important component of the digestive process, it is not the end product of digestion.
c. saliva
- Incorrect: Saliva is a fluid secreted by salivary glands in the mouth. It contains water, electrolytes, mucus, and enzymes such as amylase. Saliva helps moisten food, initiate the digestion of carbohydrates, and facilitate swallowing, but it is not the end product of digestion.
d. sphincters
- Incorrect: Sphincters are ring-like muscles that control the movement of materials through various parts of the digestive tract by opening and closing. While sphincters play a crucial role in regulating the flow of food and waste through the digestive system, they are not the end products of digestion.
Which phase of deglutition involves contraction of the longitudinal muscle layer of the muscularis?
A. voluntary phase
B. buccal phase
C. pharyngeal phase
D. esophageal phase
The Correct Answer is A.a) voluntary phase
- Correct: The voluntary phase of deglutition (swallowing) involves the initial voluntary movement of food from the mouth into the pharynx. During this phase, the tongue pushes the food bolus backward toward the oropharynx. Contraction of the longitudinal muscle layer of the muscularis propels the food bolus into the pharynx, which is part of the voluntary control of swallowing.
b) buccal phase
- Incorrect: The buccal phase of deglutition involves the initial formation of the food bolus and its movement toward the oropharynx by the coordinated action of the tongue and muscles of the cheeks. It does not involve contraction of the longitudinal muscle layer of the muscularis.
c) pharyngeal phase
- Incorrect: The pharyngeal phase of deglutition is involuntary and occurs when the food bolus reaches the pharynx. It involves the sequential contraction of muscles in the pharyngeal wall to propel the food bolus downward toward the esophagus. The contraction of the longitudinal muscle layer of the muscularis is not a significant component of the pharyngeal phase.
d) esophageal phase
- Incorrect: The esophageal phase of deglutition involves the passage of the food bolus through the esophagus and into the stomach. Peristaltic waves of contraction and relaxation of the muscularis propels the food bolus along the length of the esophagus. The contraction of the longitudinal muscle layer of the muscularis primarily occurs during the voluntary phase of deglutition, not the esophageal phase.
Where does the chemical digestion of starch begin?
A. mouth
B. esophagus
C. stomach
D. small intestine
The Correct Answer is A.a) mouth
- Correct: The chemical digestion of starch begins in the mouth. Salivary amylase, an enzyme secreted by the salivary glands, initiates the breakdown of starch molecules into maltose and other smaller carbohydrate molecules. This process begins as soon as food enters the mouth and continues as it is mixed with saliva during chewing and swallowing.
b) esophagus
- Incorrect: The esophagus is not directly involved in the chemical digestion of starch. It serves primarily as a conduit for the passage of food from the mouth to the stomach via peristaltic contractions.
c) stomach
- Incorrect: While some minor digestion may occur in the stomach due to the presence of salivary amylase from swallowed saliva, the stomach is not the primary site of starch digestion. Its acidic environment inhibits the activity of salivary amylase, so significant starch digestion does not occur there.
d) small intestine
- Incorrect: Starch digestion continues in the small intestine, primarily in the duodenum, but it does not begin there. Enzymes such as pancreatic amylase and brush border enzymes further break down starch into simpler sugars in the small intestine.
Which human excretory organ breaks down red blood cells and synthesizes urea?
A. lung
B. kidney
C. skin
D. liver
The Correct Answer is D.D) liver
- Correct: The liver is the human excretory organ that breaks down red blood cells and synthesizes urea. Red blood cells have a finite lifespan and are continually replaced by new cells produced in the bone marrow. When old or damaged red blood cells are removed from circulation, their components are broken down by macrophages, primarily in the spleen and liver. The liver plays a crucial role in this process by breaking down hemoglobin, the oxygen-carrying protein in red blood cells, into heme and globin. Heme is further broken down into bilirubin, which is excreted in bile and eventually eliminated from the body in feces. Additionally, the liver synthesizes urea as a waste product of protein metabolism, which is excreted by the kidneys in urine.
A) lung
- Incorrect: While the lungs play a role in the excretion of carbon dioxide during respiration, they are not involved in breaking down red blood cells or synthesizing urea.
B) kidney
- Incorrect: The kidneys are responsible for filtering blood to remove waste products and excess substances, such as urea, creatinine, and electrolytes, to produce urine. While the kidneys excrete urea synthesized by the liver, they do not break down red blood cells.
C) skin
- Incorrect: The skin is involved in excreting certain waste products, such as sweat (containing water, electrolytes, and small amounts of urea and other metabolic waste), but it does not break down red blood cells or synthesize urea.
Which of the following organs has 3 layers of smooth muscle in its muscularis externa?
A. small intestine
B. esophagus
C. stomach
D. large intestine
The Correct Answer is C.C. stomach
- Correct: The stomach has three layers of smooth muscle in its muscularis externa, which is the muscular layer of the gastrointestinal tract responsible for peristalsis and mixing of food. These muscle layers are arranged in longitudinal, circular, and oblique orientations, allowing for the mechanical processing of ingested food and the propulsion of food through the digestive tract. This muscular arrangement contributes to the stomach's ability to churn and mix food with gastric juices during digestion.
A. small intestine
- Incorrect: While the small intestine does have smooth muscle in its muscularis externa, it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.
B. esophagus
- Incorrect: The esophagus also has smooth muscle in its muscularis externa, but it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.
D. large intestine
- Incorrect: The large intestine, like the small intestine, typically has two layers of smooth muscle in its muscularis externa: an inner circular layer and an outer longitudinal layer.
Which of the following stimuli activates sensors in the walls of digestive organs?
A. breakdown products of digestion
B. distension
C. pH of chyme
D. all of the above
The Correct Answer is D.d) all of the above
- Correct: All of the listed stimuli activate sensors in the walls of digestive organs:
a) Breakdown products of digestion: The presence of breakdown products, such as nutrients and smaller molecules resulting from digestion, can activate sensors in the walls of digestive organs. These sensors help regulate various digestive processes and signal the release of digestive enzymes and hormones.
b) Distension: Distension, or stretching of the walls of the digestive organs, is a stimulus that activates sensors. It occurs as the volume of the digestive tract increases due to the presence of ingested food, and it triggers reflexes that coordinate muscular contractions for propulsion and mixing.
c) pH of chyme: The pH of the chyme (the semi-liquid mixture of food and digestive juices in the stomach and small intestine) is another stimulus that activates sensors. Changes in pH can signal the need for adjustments in the secretion of digestive enzymes and the regulation of gastric and intestinal functions.
Therefore, all of the mentioned stimuli play a role in activating sensors and regulating digestive processes in response to the specific conditions within the digestive organs.