During gastric emptying, chyme is released into the duodenum through the ________.
A. esophageal hiatus
B. pyloric antrum
C. pyloric canal
D. pyloric sphincter
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c) pyloric sphincter
- Correct: During gastric emptying, chyme (partially digested food) is released from the stomach into the duodenum through the pyloric sphincter. The pyloric sphincter is a muscular valve located at the junction between the stomach and the duodenum. It regulates the passage of chyme from the stomach into the small intestine, allowing for controlled release and preventing backflow of intestinal contents into the stomach.
a) pyloric antrum
- Incorrect: The pyloric antrum is the lower portion of the stomach that leads into the pyloric canal. It is involved in mixing and churning food, but it does not regulate the release of chyme into the duodenum.
b) pyloric canal
- Incorrect: The pyloric canal is the narrow portion of the stomach that connects the pyloric antrum to the pyloric sphincter. It is involved in directing chyme toward the pyloric sphincter for release into the duodenum, but it is not the site of chyme release itself.
The esophageal hiatus is an opening in the diaphragm through which the esophagus passes as it descends from the thoracic cavity into the abdominal cavity. It is not directly involved in gastric emptying.
Therefore, the Correct Answer is C.
More Questions on Digestive System Practice Exam 2
Question 1:
The graph below shows the effect of environmental temperature on a girl's skin temperature and on her internal body temperature.
Which statement best describes what happens as environmental temperature increases from 20ºC to 30ºC?
A. Both the internal and the skin temperatures reach 40ºC.
B. Both the internal and the skin temperatures increase by about 7ºC.
C. The skin temperature decreases to about 30ºC.
D. The internal temperature increases by about 1ºC.
The Correct Answer is D.D) The internal temperature increases by about 1ºC.
- Correct: As environmental temperature increases from 20ºC to 30ºC, the body's internal temperature tends to increase slightly. This is due to the body's thermoregulatory mechanisms, which work to maintain a relatively constant internal temperature (around 37ºC or 98.6ºF) despite fluctuations in environmental temperature. When the environmental temperature rises, the body responds by increasing blood flow to the skin and by initiating mechanisms such as sweating to dissipate heat and maintain thermal equilibrium. However, the increase in environmental temperature may result in a slight increase in internal temperature, typically by about 1ºC, as the body works to dissipate excess heat.
A) Both the internal and the skin temperatures reach 40ºC.
- Incorrect: A 10ºC increase in environmental temperature from 20ºC to 30ºC is not likely to cause both internal and skin temperatures to reach 40ºC. Such a significant increase would likely lead to heatstroke or hyperthermia, which can be life-threatening.
B) Both the internal and the skin temperatures increase by about 7ºC.
- Incorrect: A 10ºC increase in environmental temperature is not likely to cause both internal and skin temperatures to increase by about 7ºC. Such a large increase in temperature would be excessive and would likely lead to severe heat-related illnesses.
C) The skin temperature decreases to about 30ºC.
- Incorrect: In response to an increase in environmental temperature, the body typically increases blood flow to the skin and initiates mechanisms such as sweating to dissipate heat. This would not result in a decrease in skin temperature to match the environmental temperature of 30ºC.
Question 2:
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.
Question 3:
Which structure is located where the esophagus penetrates the diaphragm?
A. esophageal hiatus
B. cardiac orifice
C. upper esophageal sphincter
D. lower esophageal sphincter
The Correct Answer is A.a) esophageal hiatus
- Correct: The structure located where the esophagus penetrates the diaphragm is called the esophageal hiatus. The esophagus passes through an opening in the diaphragm known as the esophageal hiatus as it descends from the thoracic cavity into the abdominal cavity. This hiatus allows the esophagus to connect the pharynx to the stomach.
b) cardiac orifice
- Incorrect: The cardiac orifice is the opening of the stomach into the esophagus. It is located at the superior portion of the stomach and is surrounded by the lower esophageal sphincter. It is not located where the esophagus penetrates the diaphragm.
c) upper esophageal sphincter
- Incorrect: The upper esophageal sphincter is a muscular ring located at the upper end of the esophagus, where it meets the pharynx. It controls the passage of food from the pharynx into the esophagus but is not located where the esophagus penetrates the diaphragm.
d) lower esophageal sphincter
- Incorrect: The lower esophageal sphincter (LES), also known as the cardiac sphincter, is a muscular ring located at the lower end of the esophagus, where it meets the stomach. It controls the passage of food from the esophagus into the stomach but is not located where the esophagus penetrates the diaphragm.
Question 4:
Chemical digestion of carbohydrates begins in the
A. esophagus
B. stomach
C. duodenum
D. oral cavity
The Correct Answer is D.D. oral cavity
- Correct: Chemical digestion of carbohydrates begins in the oral cavity. Salivary glands in the mouth secrete saliva, which contains an enzyme called amylase. Amylase breaks down complex carbohydrates (such as starch) into simpler sugars (such as maltose) through hydrolysis. This process initiates the digestion of carbohydrates before the food bolus reaches the stomach or small intestine.
A. esophagus
- Incorrect: The esophagus is primarily involved in the propulsion of food from the mouth to the stomach through peristaltic contractions. It does not play a significant role in the chemical digestion of carbohydrates.
B. stomach
- Incorrect: While the stomach plays a role in the digestion of proteins through the action of gastric juices containing pepsin and hydrochloric acid, it does not contribute significantly to the digestion of carbohydrates. In fact, the acidic environment of the stomach may temporarily inhibit the activity of salivary amylase.
C. duodenum
- Incorrect: The duodenum is the first part of the small intestine where the majority of chemical digestion occurs. While the duodenum receives pancreatic enzymes and bile that aid in the digestion of carbohydrates, proteins, and fats, the initial chemical digestion of carbohydrates primarily occurs in the oral cavity with the action of salivary amylase.
Question 5:
Most of the nutrient absorption along the alimentary canal occurs in the
A. ascending colon
B. stomach
C. jejunum
D. ileum
The Correct Answer is C.C. jejunum
- Correct: Most of the nutrient absorption along the alimentary canal occurs in the jejunum, which is the middle segment of the small intestine. The jejunum has a highly folded inner surface covered with finger-like projections called villi and even smaller microvilli. These structures greatly increase the surface area available for absorption. The epithelial cells lining the villi contain numerous transport proteins and enzymes responsible for absorbing nutrients such as carbohydrates, proteins, fats, vitamins, and minerals into the bloodstream for distribution to the body's cells.
A. ascending colon
- Incorrect: The ascending colon is part of the large intestine (colon) where water and electrolytes are primarily absorbed, but it is not a major site of nutrient absorption.
B. stomach
- Incorrect: While some substances, such as water, electrolytes, alcohol, and certain drugs, can be absorbed in small amounts in the stomach, the stomach is not a major site of nutrient absorption. Its main function is to begin the digestion of proteins and store food temporarily.
D. ileum
- Incorrect: The ileum is the final segment of the small intestine, and while it does participate in nutrient absorption, the majority of nutrient absorption occurs in the jejunum, which precedes the ileum along the alimentary canal. The ileum primarily absorbs bile salts, vitamin B12, and some remaining nutrients not absorbed in the jejunum.
Question 6:
In which organ of the human body is urea produced as a result of the breakdown of amino acids?
A. liver
B. pancreas
C. stomach
D. small intestine
The Correct Answer is A.A) liver
- Correct: Urea is produced in the liver as a result of the breakdown of amino acids. Amino acids are the building blocks of proteins, and when proteins are metabolized for energy or other purposes, their constituent amino acids are broken down in a process called deamination. During deamination, the amino groups (-NH2) are removed from the amino acids, forming ammonia (NH3). The liver converts ammonia into urea through a series of biochemical reactions known as the urea cycle. Urea is then excreted by the kidneys in the urine, helping to remove nitrogenous waste from the body.
B) pancreas
- Incorrect: The pancreas is an organ involved in the production of digestive enzymes and hormones such as insulin and glucagon. It is not primarily responsible for the production of urea from the breakdown of amino acids.
C) stomach
- Incorrect: The stomach is primarily involved in the mechanical and chemical digestion of food, particularly proteins. While protein digestion begins in the stomach with the action of gastric juices containing enzymes such as pepsin, urea production from the breakdown of amino acids occurs mainly in the liver.
D) small intestine
- Incorrect: The small intestine is primarily involved in the absorption of nutrients from digested food, rather than the production of urea from the breakdown of amino acids. While some amino acids may be absorbed in the small intestine, urea production primarily occurs in the liver.
Question 7:
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.
Question 8:
Where does the majority of chemical digestion in the stomach occur?
A. fundus and body
B. cardia and fundus
C. body and pylorus
D. body
The Correct Answer is A.a) fundus and body
- Correct: The majority of chemical digestion in the stomach occurs in the fundus and body regions. These regions contain gastric glands that secrete hydrochloric acid (HCl), pepsinogen, and mucus. Hydrochloric acid creates an acidic environment necessary for the activation of pepsinogen to pepsin, which is responsible for the digestion of proteins. Additionally, the stomach churns and mixes food with gastric juices in the fundus and body, facilitating the breakdown of food particles and the mixing of digestive enzymes with the food bolus.
b) cardia and fundus
- Incorrect: While the fundus region is involved in chemical digestion due to the presence of gastric glands, the cardia region primarily serves as the entry point of the esophagus into the stomach and does not significantly contribute to chemical digestion.
c) body and pylorus
- Incorrect: While the body region of the stomach is involved in chemical digestion, the pylorus region is primarily responsible for regulating the passage of partially digested food (chyme) into the small intestine through the pyloric sphincter. The pylorus region does not contribute significantly to chemical digestion.
d) body
- Incorrect: While the body region of the stomach is involved in chemical digestion, the majority of chemical digestion occurs in both the fundus and body regions. The body region alone does not represent the entirety of where chemical digestion occurs in the stomach.
Question 9:
During the process of absorption, nutrients from food go from:
A. the intestines into the bladder
B. the blood into the organs
C. the intestines into the bloodstream
D. the mouth into the stomach
The Correct Answer is C.c. the intestines into the bloodstream
- Correct: During the process of absorption, nutrients from food pass from the intestines into the bloodstream. After food is broken down into its constituent nutrients through digestion in the stomach and small intestine, these nutrients are absorbed across the lining of the small intestine into the bloodstream. The small intestine is highly specialized for absorption, with villi and microvilli increasing the surface area available for nutrient absorption. Once absorbed into the bloodstream, nutrients are transported to various organs and tissues throughout the body to provide energy, support growth and repair, and maintain overall health.
a. the intestines into the bladder
- Incorrect: The bladder is part of the urinary system and is responsible for storing urine produced by the kidneys. Absorption of nutrients does not involve passage into the bladder.
b. the blood into the organs
- Incorrect: While nutrients absorbed into the bloodstream are indeed transported to various organs and tissues throughout the body, absorption itself occurs in the intestines, not directly from the blood into the organs.
d. the mouth into the stomach
- Incorrect: The mouth and stomach are primarily involved in the initial stages of digestion, including mechanical breakdown of food and the initiation of chemical digestion of carbohydrates and proteins. Absorption of nutrients occurs primarily in the small intestine, not from the mouth into the stomach.
Question 10:
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.