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Gastric dysmotility at the organ level in gastroparesis

Introduction Gastric motor functions represent a complex series of regional relaxations (e.g., fundus and pylorus) and contractions (gastric body and antrum) that are regulated by circulating blood glucose and hormones such as incretins, extrinsic sympathetic and parasympathetic neural control from the brain and spinal cord, the enteric nervous system (ENS), the interstitial cells of Cajal and other excitatory cells (PDGFRα positive cells), smooth muscle cells, and…

Natural history of patients with gastroparesis

Introduction Gastroparesis is defined as slow emptying of the stomach with associated symptoms thereof in the absence of mechanical obstruction . Symptoms can vary but are focused on the postprandial time period and include fullness, bloating, early satiety, nausea, epigastric abdominal pain and sometimes vomiting which occurs >1 hour after a meal. The most common subsets of gastroparesis are idiopathic, diabetic, and post-surgical with idiopathic being…

Clinical presentations of gastroparesis

Introduction Gastroparesis is a chronic gastric motility disorder, characterized by delays in the emptying of food contents from the stomach into the small bowel in the absence of a mechanical obstruction . The most frequently reported symptoms of gastroparesis include early satiety, nausea, vomiting, bloating, abdominal discomfort, and postprandial fullness . However, these symptoms of gastroparesis can also be seen when gastric emptying is even normal…

Epidemiology of gastroparesis

Introduction – the challenge Gastroparesis is commonly defined on the basis of the combination of symptoms and delayed gastric emptying, in the absence of mechanical obstruction. Therein lies a major challenge to attempts to provide accurate data on the incidence or prevalence of this disorder which must include (i) a definition of what symptoms are to be regarded as relevant, (ii) an accurate measurement of gastric…

Historical perspectives on gastric motility and gastroparesis

Introduction Remarkable progress has been made in the study of gastrointestinal (GI) motility, particularly gastric motility, in the last century. This progress in GI motility has proceeded from contributions of a wide range of disciplines with advances in smooth-muscle physiology, electrophysiology, neurohormonal regulation of the GI tract, anatomic/mechanical factors, flow dynamics, as well as basic molecular and cellular biology. Increasingly sophisticated instrumentation, biomedical engineering, and pharmaceutical…

Answers to Self-Study Problems

Chapter 1 1. Each of the three agents acts only on cells having receptors for that agent. Because hormones travel through the general circulation, receptors are responsible for specificity. In the case of paracrines, the cells containing a specific receptor must also be located in near proximity to the site of release in order for the agent to reach them by diffusion. Target cells for neurocrines…

Regulation of Food Intake

Objectives Understand the importance of food intake to clinical medicine. Discuss the role of the nervous system in the regulation of food intake. Explain the role of the endocrine system in the regulation of metabolism and food intake. Discuss the role of the gastrointestinal (GI) system in the regulation food intake. Understand how input from the nervous, endocrine, and GI systems is integrated to regulate food…

Fluid and Electrolyte Absorption

Objectives Indicate the sources of fluid and electrolytes in the gastrointestinal (GI) tract and their sites of absorption. Describe the mechanisms involved in and the location of the sites for the absorption of sodium, potassium, chloride, bicarbonate, and water. Understand the mechanism and significance of the intestinal secretion of fluid and electrolytes. Explain the difference between osmotic and secretory diarrheas and discuss the disorders that may…

Digestion and Absorption of Nutrients

Objectives Indicate the sources, types, and functions of the primary digestive enzymes. Explain the transport processes and the pathways involved in the absorption of nutrients. Describe the processes involved in the digestion and absorption of carbohydrates. Indicate problems that may result in the malabsorption of carbohydrates. Describe the digestion and absorption of proteins. Explain the role of trypsin in protein digestion and how it may be…

Bile Secretion and Gallbladder Function

Objectives Describe the constituents of bile and their functions. Understand the solubility of the bile acids and bile salts and how it affects their reabsorption in the small bowel. Describe enterohepatic circulation and its role in bile acid synthesis and the secretion of bile. Understand the process involved in the excretion of bile pigments and its relationship with jaundice. Explain the function of the gallbladder. Describe…

Pancreatic Secretion

Objectives Describe the two components of pancreatic exocrine secretion, their cells of origin, and their functions. Understand the mechanisms involved in the formation of both the electrolyte (aqueous) and enzymatic components of pancreatic secretion. Explain the hormonal and neural regulation of both the aqueous and enzymatic components of pancreatic secretion. Discuss the cellular basis for potentiation and its importance in the pancreatic response to a meal.…

Gastric Secretion

Objectives Identify the secretory products of the stomach, their cells of origin, and their functions. Understand the mechanisms making it possible for the stomach to secrete 150 mN hydrochloric acid. Describe the electrolyte composition of gastric secretion and how it varies with the rate of secretion. Identify the major stimulants of the parietal cell and explain their interactions. Discuss the phases involved in the stimulation of…

Salivary Secretion

Objectives Discuss the constituents and various functions of saliva. Understand the mechanisms leading to the formation of saliva. Explain the processes resulting in the tonicity of saliva and concentrations of its various ions. Describe the regulation of salivary secretion. Although the salivary glands are not essential to life, their secretions are important for the hygiene and comfort of the mouth and teeth. The functions of saliva…

Motility of the Large Intestine

Objectives Describe the anatomy of the large intestine. Explain the function of the ileocecal reflex. Define a mass movement. Understand the motility of defecation and the rectosphincteric reflex. Discuss the control of defecation and explain the loss of control that occurs with some spinal cord injuries. Contractions of the large intestine are organized to allow for optimal absorption of water and electrolytes, net aboral movement of…

Motility of the Small Intestine

Objectives Compare the motility patterns of the small intestine during feeding and fasting. Describe the functions of slow waves and spike potentials in regulating contractions of the small intestine. Describe the functions and control of the migrating motility complex. Explain the peristaltic reflex and the intestino-intestinal reflex. Describe the motility changes that result in vomiting, and discuss the primary factors controlling it. Motility of the small…

Gastric Emptying

Objectives Describe the contractions of the orad and caudad regions of the stomach. Explain the regulation of the contractile activity of the stomach, including the role of slow waves. List the components of the gastric contents that affect the rate of gastric emptying. Understand the role of duodenal receptors in the regulation of gastric emptying. Describe the changes in motility that regulate gastric emptying. Describe the…

Swallowing

Objectives Describe the oral and pharyngeal events taking place during a swallow. Describe the pressures within the esophagus and oral stomach at rest and during a swallow. Explain the regulation involved during a swallow, including its initiation and peristalsis through the esophagus. Understand the process of receptive relaxation of the oral stomach, its function, and regulation. Understand gastric esophageal reflux disease (GERD) and its causes. Swallowing…

Regulation: Nerves and Smooth Muscle

Objectives Understand the anatomy and functions of the enteric nervous system and its relationship with the parasympathetic and sympathetic systems. Describe the anatomy and types of contractions of smooth muscle cells. Explain the role of calcium ion in the contraction and relaxation of smooth muscle cells. Understand the roles of the interstitial cells of Cajal and slow waves in the contraction of smooth muscle cells. Secretory,…

Regulation: Peptides of the Gastrointestinal Tract

Objectives Describe the four major functions of the gastrointestinal (GI) tract. Understand the differences between and significance of endocrine, paracrine, and neurocrine agents. Identify the major GI hormones, their functions, sites of release, and stimuli for release. Identify the important neurocrines and their functions in the GI tract. Identify the important paracrines and their functions in the GI tract. Understand the causes and resulting physiology of…