Nokea
The enteric plexus in the tunica submucosa is called the ______ plexus.
- A. Meissner's
- B. Auerbach's
- C. myenteric
- D. solar
Correct Answer: A
Rationale: The correct answer is A: Meissner's plexus. Meissner's plexus is located in the tunica submucosa and is responsible for controlling the movements of the muscularis mucosae. It regulates local blood flow, secretion, and absorption in the small intestine. Auerbach's plexus, located in the muscularis externa, controls the motility of the muscular layer. Myenteric plexus is another name for Auerbach's plexus. Solar plexus is a network of nerves located in the abdomen, not specifically related to the enteric plexus.
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Submucosal glands occur in the submucosa of the and they also occur in the _.
- A. Oesophagus and ileum
- B. Stomach and Duodenum
- C. Stomach and ileum
- D. Oesophagus and Duodenum
Correct Answer: B
Rationale: The correct answer is B: Stomach and Duodenum. Submucosal glands are found in the submucosa of the stomach and duodenum. In the stomach, these glands secrete mucus and bicarbonate to protect the lining from stomach acid. In the duodenum, they secrete mucus to protect the lining from the acidic chyme entering from the stomach. Choices A, C, and D are incorrect because submucosal glands are not typically found in the oesophagus or ileum. The rationale for the correct answer is based on the anatomical location and function of submucosal glands in the gastrointestinal tract.
Which of the following statements is true regarding arterioles?
- A. they are less muscular than arteries, and the principle site of blood pressure regulation
- B. they are the most muscular of the major vessels, and have low blood flow velocity
- C. they are thin walled with little innervation
- D. they have no smooth muscle or connective tissue, and relatively low rates of blood flow
Correct Answer: A
Rationale: Step 1: Arterioles are smaller branches of arteries that lead to capillaries.
Step 2: Arterioles are indeed less muscular than arteries but more muscular than capillaries.
Step 3: Arterioles play a crucial role in regulating blood pressure through vasoconstriction and vasodilation.
Step 4: Choice A is correct as it accurately describes arterioles' role in blood pressure regulation.
Summary: Choice B is incorrect as arterioles are not the most muscular of major vessels. Choice C is incorrect as arterioles have significant innervation. Choice D is incorrect as arterioles do have smooth muscle and connective tissue, and they regulate blood flow efficiently.
The pharyngeal phase of swallowing:
- A. Is partially voluntary
- B. Includes opening of the upper oesophageal sphincter
- C. Includes the peristaltic activity of the upper third of the oesophagus
- D. Is associated with the opening of the glottis
Correct Answer: C
Rationale: The correct answer is C because the pharyngeal phase of swallowing involves the peristaltic activity of the upper third of the esophagus, pushing the food bolus towards the stomach. This phase is involuntary and is controlled by the swallowing reflex. Choices A, B, and D are incorrect because the pharyngeal phase is entirely involuntary, the upper esophageal sphincter opens during the esophageal phase, and the opening of the glottis is associated with protection of the airway during swallowing, not the pharyngeal phase.
Which of the following is the most plausible explanation for the protective effect of dietary fibre against cancer of the colon?
- A. Propionic acid, formed during colonic fibre fermentation inhibits liver fatty acid synthesis
- B. Butyric acid, formed during colonic fibre fermentation stimulates 'silencing' of the SLC5A8 tumour suppressor gene
- C. None of these options are correct
- D. Butyric acid, formed during colonic fibre fermentation stimulates anti-oxidant defences in the colon
Correct Answer: D
Rationale: The correct answer is D because butyric acid, a short-chain fatty acid formed during colonic fiber fermentation, has been shown to stimulate antioxidant defenses in the colon. This helps protect against oxidative damage, a key factor in the development of cancer. Choice A is incorrect because propionic acid does not inhibit liver fatty acid synthesis in relation to colon cancer. Choice B is incorrect because butyric acid does not silence the SLC5A8 tumor suppressor gene; in fact, it has been shown to have anti-tumor effects. Choice C is incorrect as there is evidence supporting the protective effect of dietary fiber through butyric acid's stimulation of antioxidant defenses.
Which part of the digestive system is responsible for the absorption of nutrients?
- A. small intestine
- B. stomach
- C. pancreas
- D. liver
Correct Answer: A
Rationale: The correct answer is A, the small intestine, because it is the primary site for nutrient absorption in the digestive system. The small intestine is lined with villi and microvilli, increasing its surface area for efficient absorption. It contains specialized cells that transport nutrients into the bloodstream for distribution to the body. The stomach (B) primarily breaks down food using digestive enzymes and acids, while the pancreas (C) secretes digestive enzymes but does not directly absorb nutrients. The liver (D) plays a role in bile production and detoxification, but nutrient absorption occurs mainly in the small intestine.