Gastrointestinal Physiology Exam Review Flashcards

This set of flashcards is designed to help students review key concepts and details from gastrointestinal physiology in preparation for exams.

What are the main components of the gastrointestinal (GI) tract?

The GI tract consists of the pharynx, esophagus, stomach, small intestine, large intestine, and anus, along with accessory organs such as salivary glands, pancreas, liver, and gall bladder.

What are the four layers of the GI tract?

The four layers of the GI tract are mucosa, submucosa, muscularis, and serosa.

What is the ENS and its function in the gut?

The enteric nervous system (ENS) is a nerve network within the GI tract that controls motility and secretory functions.

Where is the myenteric plexus located and what does it control?

The myenteric plexus (Auerbach’s plexus) is located in the muscularis externa and controls motility functions.

What is the role of the submucosal plexus?

The submucosal plexus (Meissner’s plexus) is located in the submucosa and controls glandular secretions.

How do the ANS and ENS interact in GI tract function?

The ANS stimulates (parasympathetic) or inhibits (sympathetic) GI activity, while the ENS regulates glandular secretions and motility.

What stimulates the release of digestive juices and contractions in the stomach?

Amino acids stimulate chemoreceptive cells in the ENS lining the stomach lumen, triggering glandular secretions and muscular contractions.

What are the general functions of the GI tract?

The main functions are digestion (mouth, stomach, small intestine), absorption (large intestine), and secretion (mouth, stomach, small intestine).

Describe the three general motility patterns of the GI tract.

Peristalsis (wave-like contractions in the esophagus), rhythmic segmentation (mixing in the small intestine), and tonic contractions (prolonged contractions in the esophagus and anus).

What is ingestion?

Ingestion is the conscious placement of food in the oral cavity.

What mechanical digestive processes occur in the oral cavity?

Mechanical digestion in the oral cavity involves chewing (mastication) by teeth and smashing food against the hard palate with the tongue.

Do mechanical processes in digestion break covalent bonds?

No, they do not break covalent bonds; their purpose is to increase surface area for digestive enzymes.

What are the three paired salivary glands?

The three paired salivary glands are the parotid, sublingual, and submandibular glands.

What does saliva contain?

Saliva contains water, mucus, buffers, antimicrobics, lysozymes, iodide, and enzymes.

What causes sialorrhea and how is it treated?

Sialorrhea is caused by excessive saliva production or impaired removal, often treated with ACh receptor antagonists or agents that reduce ACh release.

What is the pH optimum of the oral cavity?

The pH optimum of the oral cavity is 7.4.

What macromolecule is digested in the oral cavity and by which enzyme?

Carbohydrates are digested in the oral cavity by salivary amylase.

What is deglutition?

Deglutition is the conscious process of swallowing.

What types of things pass through the pharynx?

Food, liquid, and air pass through the pharynx.

What is the primary function of the esophagus?

The primary function of the esophagus is to move the bolus towards the stomach.

Does the esophagus secrete any chemicals?

Yes, the esophagus secretes mucus to facilitate bolus movement and reduce friction.

What are the two esophageal sphincters?

The two esophageal sphincters are the upper esophageal sphincter (UES) and lower esophageal sphincter (LES).

What is the function of the upper esophageal sphincter?

The UES prevents air from entering the stomach during inspiration.

What is gastroesophageal reflux disease (GERD)?

GERD occurs when stomach acid or content flows back into the esophagus due to an abnormally relaxed sphincter.

What are some potential treatments for GERD?

GERD can be treated with antacids, proton-pump inhibitors (PPIs), and surgical interventions like fundoplication.

What is esophagitis?

Esophagitis is inflammation of the esophageal lining, caused by factors such as GERD and certain medications.

What is Barrett’s esophagus?

Barrett’s esophagus is the transformation of esophageal lining cells to a type more prone to cancer, often due to GERD.

How common is esophageal cancer?

Esophageal cancer is the sixth most common cancer-related death with a 15% five-year survival rate.

What are the four regions of the stomach?

The regions are the cardiac region, corpus region, pyloric region, and fundic region.

What are rugae and what is their function?

Rugae are folds of the stomach that allow it to expand when food enters.

Describe mechanical digestion steps in the stomach.

Mechanical digestion in the stomach involves propulsion, grinding, and retropulsion.

When is the pyloric valve open and closed during digestion?

The pyloric valve is open during retropulsion and closed during propulsion and grinding.

What cells are found in gastric glands?

Gastric glands contain parietal cells, chief cells, and gastroendocrine cells.

What do parietal cells secrete?

Parietal cells secrete hydrochloric acid (HCl) and intrinsic factor.

What is the function of chief cells?

Chief cells secrete pepsinogen and gastric lipase to digest fats and proteins.

What does pepsinogen become in the stomach?

Pepsinogen is converted to pepsin in the acidic environment of the stomach.

Which macromolecules are digested in the stomach and by which enzymes?

Fats are digested by gastric lipase, and proteins are digested by pepsin.

How is the parietal cell regulated?

Parietal cells are stimulated by gastrin, acetylcholine, and histamine, and inhibited by somatostatin.

What is alkaline tide?

Alkaline tide is a temporary increase in blood pH following HCl production in the stomach.

How do PPIs like Prilosec reduce heartburn?

PPIs reduce the amount of acid pumped by parietal cells, thereby decreasing stomach acidity.

What makes the gastric-mucosal barrier unique?

The gastric-mucosal barrier consists of surface lining cells and protective mucus with bicarbonate.

How does H. pylori affect the gastric-mucosal barrier?

H. pylori produces ureases that bind bicarbonate ions, reducing the barrier's buffering capacity.

How can H. pylori infections be treated?

H. pylori infections can be treated with antibiotics and probiotics.

What do G cells secrete and what stimulates their secretion?

G cells secrete gastrin, stimulated by peptides, amino acids, and distension.

What do D cells secrete and when?

D cells secrete somatostatin in response to low luminal pH.

What do Gr cells secrete and what triggers it?

Gr cells secrete ghrelin when induced by hunger.

What is the function of ghrelin?

Ghrelin increases appetite by stimulating neuropeptide Y in the hypothalamus.

What are the three phases of neuroendocrine control?

The three phases are the cephalic phase, gastric phase, and intestinal phase.

What occurs during the cephalic phase?

The brain stimulates gastric activity before food enters the stomach.

What occurs during the gastric phase?

The stomach responds to food and distention, activating glandular secretions and contractions.

What occurs during the intestinal phase?

The small intestine regulates stomach activity via negative feedback mechanisms.

What is gastritis and how is it treated?

Gastritis is inflammation of the stomach lining caused by NSAIDs or H. pylori, treated with medications.

What is peptic ulcer disease?

Peptic ulcer disease involves degradation of the gastric mucosa, treated with antacids and antibiotics.

What are the three regions of the small intestine?

The three regions are the duodenum, jejunum, and ileum.

What anatomical features increase the surface area of the small intestine?

Microvilli, villi, and plicae increase the surface area of the small intestine.

How do plicae differ from rugae?

Plicae are permanent structures, whereas rugae are transient.

Which macromolecules are digested in the small intestine?

All three macromolecules: carbohydrates, proteins, and fats are digested in the small intestine.

Where do the digestive enzymes in the small intestine come from?

Digestive enzymes are produced by the exocrine pancreas.

Which pancreatic cells produce digestive enzymes?

Pancreatic acinar cells produce digestive enzymes.

What cells produce bicarbonate in the pancreas?

Pancreatic centroacinar cells and biliary ductal cells produce bicarbonate.

Describe the pathway of digestive enzymes from the pancreas to the duodenum.

Digestive enzymes travel from acinar cells to small ducts that converge into the pancreatic duct leading to the duodenum.

What is the function of enterokinase?

Enterokinase activates trypsinogen into trypsin in the small intestine.

What maintains the pH of the duodenum?

Bicarbonate ions from the duodenum, pancreas, and biliary system help maintain duodenal pH.

Why is fat only efficiently digested in the small intestine?

Fat digestion is efficient in the small intestine due to bile from the liver and colipase from the pancreas.

What do I cells secrete and what induces their secretion?

I cells secrete cholecystokinin (CCK) when stimulated by fatty acids and peptides.

What is the incretin effect?

The incretin effect refers to glucose ingestion speeding up insulin release faster than glucose injection.

What is Byetta and where does it come from?

Byetta is a GLP-1 analogue from a lizard's saliva, stimulating insulin release.

What is Ozempic prescribed for?

Ozempic is prescribed for Type 2 Diabetes Mellitus (T2DM) and stimulates insulin secretion.

What is Wegovy and how does it work?

Wegovy is a GLP-1 receptor agonist for weight loss, reducing appetite and delaying gastric emptying.

What is celiac disease?

Celiac disease is an autoimmune disorder triggered by gluten, damaging the intestinal lining.

What is the organization of the large intestine?

The large intestine consists of the cecum, appendix, colon (ascending, transverse, descending, sigmoid), rectum, and anus.

What are the primary functions of the large intestine?

The large intestine absorbs water and ions from chyme and compacts it into feces.

What is unique about the histological organization of the large intestine?

The outer longitudinal muscle is divided into three strips called taenia coli.

What role do taenia coli play in the large intestine?

Taenia coli aid in forming haustra for feces storage and assist in fecal propulsion.

What is Crohn’s disease and how is it treated?

Crohn's disease is chronic bowel inflammation treated with anti-inflammatory medications.

What is ulcerative colitis?

Ulcerative colitis is a chronic inflammation of the bowel treated similarly to Crohn's disease.

What is diverticulitis?

Diverticulitis is the inflammation of diverticula in the intestines, treated with antibiotics or surgery.

How common is colon cancer and how is it treated?

Colon cancer has a 64% survival rate and is treated with surgery, chemotherapy, and radiation.