MCAT Biology : Excretory and Digestive Systems
Study concepts, example questions & explanations for MCAT Biology
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Example Questions
Example Question #612 : Biology
If a person has their gallbladder removed, what must they attempt to exclude from their diet?
Proteins
Polysaccharides
Lactose
Triglycerides
Triglycerides
The gallbladder stores and concentrates bile from the liver. Bile is used to emulsify fats, assisting digestion in the small intestine. A person whose gallbladder has been removed should restrict fat consumption, as they will have a limited ability to digest fatty compounds. Triglycerides are a form of fat.
Example Question #613 : Biology
Generally, nutrients absorbed during digestion enter the blood stream through the vena cavae. Which of the following enters the lymphatic system before entering venous circulation?
Peptides and amino acids
Carbohydrates
Ethanol
Triglycerides and cholesterol
Triglycerides and cholesterol
Triglycerides and cholesterol do not go straight into the venous circulation. These fats are made into structures called chylomicrons and are processed through lacteals into the lymphatic system.
Example Question #31 : Other Digestive Physiology
An athlete is trying to prepare for a long day of physical activity and eats a high-protein meal in the morning. During their exercise, which of the following is most likely true?
Their heart rate will decrease as the day goes on
Their body does not fully digest the protein until later in the day
The athlete will require more oxygen inhalation to digest the meal
Their muscles will fatigue after metabolizing the protein diet
They will not get as much energy as if they had consumed a beverage with electrolytes
Their body does not fully digest the protein until later in the day
Exercise can induce the release of corticoids which stimulate the sympathetic nervous system. This initiation will divert the body's resources and blood flow away from the digestive system, and toward the muscles that the athlete is engaging. As such, the meal will take a long period of time to digest.
Example Question #615 : Biology
Which of the following is true of intestinal function?
Dehydration can occur if resorbtion of fluid is inhibited in the small intestine
Water taken into the upper digestive tract is added to undigested food particles and other waste in the large intestine
Fluid from the pancreas delivered to the upper digestive tract is resorbed in the large intestine
Feces is hydrated in the descending colon in preparation for elimination
Fluid from the pancreas delivered to the upper digestive tract is resorbed in the large intestine
The most important function of the large intestine is the resorption of water that comes from intake or the pancreas. Waste is still hydrated while in the small intestine.
Example Question #110 : Digestive System
Passage:
In a fictional universe, a new life form is discovered that appears to have a number of similarities to humans. Since its discovery by humans, it has been studied with x-ray imaging, magnetic resonance imaging (MRI), computed tomography imaging (CT), as well as with blood chemistries and laboratory studies. Based upon such analyses, scientists have found that both structurally and functionally, this fictional species, called Lorempis marengis, is highly similar to humans. It has structures that appear similar to lungs that are active during respiration. It has a structure that is highly active at all times, especially so in different parts during different activities (similar to the human brain). It also appears to have a digestive tract with a mouth, esophagus, stomach, small intestine, large intestine, and anus that is assumed to carry out the same functions at the cellular level as the parts of the human digestive tract. Scientists are now hoping to continue studying the organism at the cellular level to confirm their assumption that the cellular functions are indeed similar to those of human tissues.
Based upon the above passage, which of the following cell types, if found in Lorempis marengis, would be most likely to be directly responsible for stomach acid production?
Chief cells
Parietal cells
Foveolar cells
G cells
Enteroendocrine cells
Parietal cells
The cell type that would be most likely to be directly responsible for producing stomach acid in Lorempis marengis is parietal cells. In humans, parietal cells, when stimulated by gastrin (produced by G cells), produce stomach acid. In the fictional organism, Lorempis marengis, we are told within the passage a great deal of information related to the structural and functional similarities between Lorempis marengis and humans in studies performed. The passage describes that the digestive tract of the fictional organism and humans is extremely similar based upon studies, and that it is assumed that at the cellular level they are similar as well. This question asks us to determine what cell type in the fictional organism would be most likely to be directly responsible for stomach acid production. As such, since we are told to assume that they are similar to humans at the cellular level, this question is really asking us what cell type in humans is most directly responsible for stomach acid production. The cell type most directly responsible for that in humans is the parietal cell, and therefore we can assume that that is true of Lorempis marengis as well.
While G cells produce gastrin, which stimulates acid production, the G cells do not directly produce the acid, so this is an incorrect answer choice.
Chief cells produce pepsinogen, a precursor enzyme to pepsin. They do not produce stomach acid.
Foveolar cells produce a mucus layer for the stomach. They do not produce stomach acid.
Enteroendocrine cells secrete a number of substances, including gastrin, histamine, endorphins, CCK, and somatostatin, but they do not directly produce stomach acid.
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