50) Which of the following nutrients must be digested in order to be absorbed? A
ID: 3484175 • Letter: 5
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50) Which of the following nutrients must be digested in order to be absorbed? A. Water B. Vitamins C. Proteins D. Minerals E. Cholesterol 51) Theregulates digestive tract motility, secretion, and blood flow. Its neurons are found in the di A. autonomic nervous system; serosa B. centra I nervous system; muscularis externa and muscularis mucosae C. enteric nervous system; submucosa and muscularis externa D. visceral sensory division; muscularis externa and submucosa E. visceral motor division; mucosa and submucosa 52) Which of the following is not normally found in saliva? A. Mucus B. Lysozyme C. Amylase D. Lipase E. Protcase 53) Acid reflux into the esophagus ("heartburn") is normally prevented by A. pharyngeal constrictors C. the lower esophageal sphincter (LES) E. pharyngeal and buccal sphincters B. the upper esophageal sphincter D. esophageal glands is/are secreted by cells. 54) Necessary for Vitamin B12 absorption A. intrinsic factor; parietal D, hydrochloric acid; parietal E. enterokinase; mucous B. bile salts; chief C. lecithin; hepatic 55) Pepsinogen is produced by and is activated by , which is secreted by A. chief cells; carbonic anhydrase (CAH); parietal cells B. chief cells; hydrochloric acid (HCI); parietal cells C. parietal cells; hydrochloric acid (HCI); chief cells D. parietal cells; carbonic anhydrase (CAH); chief cells E. enteroendocrine cells; carbonic anhydrase (CAH); parietal cells 56) Several digestive enzymes are secreted as zymogens because A. it saves one step in their synthesis B. gastric cells do not have the necessary enzymes for their synthesis C. they start digesting intracellular proteins of the gastric cells more quickly D. they act only in the stomach lumen and do not digest intracellular proteins E. they can start digesting dietary proteins more quickly is a hormone, whereas is an enzyme. 57) A. Enterokinase; pepsin B. Gastrin; secretin D. Gastric lipase; histamine 58) C. Gastrin; cholecystokinin (CCK) E. Secretin; pepsin The _phase is associated with food stretching the stomach and activating myenteric and vagovagal reflexes, which in turn stimulate gastric secretions. A. cephalic B. gastric D. gastrointestinal E. mesenteric C. intestinalExplanation / Answer
50. Water, minerals, and some vitamins are directly absorbed by the body. Most vitamins are synthesized by the body. Cholesterol is synthesized by the body from acetylcholine. However, proteins cannot be absorbed directly. The body only has transporter protein for small peptides and amino acids. Proteins are first broken down to peptides and amino acids in stomach by digestive enzymes and then absorbed by the small intestine.
Option is C.
51. The enteric nervous system is the local nervous system that regulates digestive tract processes such as ion transport and secretion and GI blood flow. This nervous system along with sympathetic and parasympathetic nervous system constitutes the autonomous nervous system. It has the myenteric plexus and the submucous plexus. The muscularis externa is the outer covering of the submucosa and has two muscle layer. It regulates gut movement during peristalsis. Submucosa is a layer of connective tissue that supplied blood vessels and lymphatics to the mucosa and muscularis propria. The neurons of enteric nervous system are present in these layers.
Option is C.
52. Saliva has amylase, proteases, lipase to break down food. Lysozyme is also present in abundance for destruction of bacteria that enter the oral cavity. However, it lacks mucus. Mucus enters the saliva from the mucous membranes of oral cavity.
Option is A.
53. Lower esophageal sphincter is the muscle ring present at the bottom of esophagus. This sphincter is controlled by neural input and forms an anti-reflux barrier along with the flap valve (GEj) between stomach and esophagus. When food moved down, the esophagus shortens and GEj moves up. When food reaches the stomach, the GEj closes to prevent return of gastric fluid to the esophagus. This is possible due to contraction of lower esophageal sphincter and closing of GEj.
Option is C.
54. Intrinsic factor is a proteins secreted by parietal cells of gastric mucosa. It is involved in absorption of Vitamin B12. Dietary Vitamin B12 is bound by gastric proteins after release and hence is not absorbed. In small intestine, these gastric binding proteins are degraded by enzymes, and Vit B12 is bound by the intrinsic factors. The intrinsic factor binds to the receptors on ilieal mucosa, allowing absorption of Vit B12 in blood.
Option is A.
As per Chegg’s rule, only one question is to be answered.
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