BIO198 S225 Chapter 17 Digestion II 2-28-25

Salivary Amylase

An enzyme that digests starch, functioning optimally at a pH of 6.5-7.0.

Lingual Lipase

An enzyme that breaks down triglycerides in the mouth.

Lysozyme

An antibacterial enzyme found in saliva that helps inhibit bacterial growth.

Gastric Juice

A digestive fluid secreted by the stomach containing water, hydrochloric acid (HCl), and digestive enzymes like pepsin.

Pepsinogen

A precursor enzyme that is activated to pepsin in the presence of hydrochloric acid, beginning protein digestion.

Mumps

A viral infection affecting the parotid salivary glands characterized by fever and gland swelling.

Deglutition

The process of swallowing, involving complex muscle movements in the mouth, pharynx, and esophagus.

GERD (Gastroesophageal Reflux Disease)

A condition where the lower esophageal sphincter does not close fully, leading to heartburn and acid reflux.

Acid Resistance

The ability of certain bacteria, such as Heliobacter pylori, to survive in the acidic environment of the stomach.

Pancreatic Juice

Digestive fluid secreted by the pancreas, containing enzymes like amylase, lipase, and nucleases to aid in digestion.

Esophageal Sphincters

Muscular rings at the upper and lower ends of the esophagus that control the passage of food to and from the stomach.

Chyme

The semi-fluid mass of partially digested food that moves from the stomach to the duodenum.

Bolus

A round mass of chewed food formed in the mouth before swallowing.

Intrinsic Factor

A protein secreted by parietal cells in the stomach, essential for the absorption of vitamin B12 in the small intestine.

Gastritis

Inflammation of the stomach lining, often caused by infection or irritation that may lead to ulcers.

What is the nasopharynx?

The nasopharynx is the upper part of the pharynx located behind the nose, serving as a passageway for air from the nasal cavity to the larynx and for the drainage of the Eustachian tubes.

What is the oropharynx?

The oropharynx is the middle portion of the pharynx located behind the mouth, serving as a passageway for both air and food.

What is the laryngopharynx?

The laryngopharynx is the lower part of the pharynx that connects to the larynx and esophagus, serving as a passageway for both air and food.

Peristalsis

A series of wave-like muscle contractions that move food through the digestive tract, starting from the esophagus and continuing through the intestines.

What are the phases of deglutition?

Deglutition occurs in three phases: the oral phase (voluntary), the pharyngeal phase (involuntary), and the esophageal phase (involuntary), each involving specific muscle movements.

Swallowing Center

The swallowing center is located in the brainstem and coordinates the complex series of muscle contractions involved in the process of swallowing (deglutition).

What are the four regions of the stomach?

The four regions of the stomach are the cardia, fundus, body, and pylorus, each having distinct functions in the digestion process.

What is the function of the cardia?

The cardia is the region of the stomach where the esophagus connects, facilitating the passage of food and preventing reflux back into the esophagus.

What is the function of the fundus?

The fundus is the uppermost region of the stomach that stores undigested food and gas, allowing for the initial processing of food before it moves into the body of the stomach.

What is the function of the body of the stomach?

The body of the stomach is the central region where the majority of digestion occurs, mixing food with gastric juices to create a semi-liquid substance called chyme.

What is the function of the pylorus?

The pylorus is the narrow outlet of the stomach that connects to the duodenum, regulating the passage of chyme into the small intestine and preventing backflow into the stomach.

What are gastric pits?

Gastric pits are small, deep invaginations in the stomach lining that lead to gastric glands; these glands secrete gastric juice, including hydrochloric acid and digestive enzymes, playing a crucial role in the digestive process.

Goblet Cells

Goblet cells are specialized epithelial cells found in the respiratory and gastrointestinal tracts that secrete mucus, providing lubrication and a protective barrier.

Chief Cells

Chief cells are specialized cells in the gastric glands of the stomach that secrete pepsinogen, the inactive precursor to pepsin, and gastric lipase, contributing to the digestive process.

Parietal Cells

Parietal cells are specialized cells in the gastric glands of the stomach that secrete hydrochloric acid (HCl) and intrinsic factor, playing a crucial role in digestion and vitamin B12 absorption.

What are the protections of the stomach?

The stomach has several protective mechanisms, including mucous secretion from goblet cells that coat the stomach lining, a strong layer of epithelial cells that resist damage, the secretion of bicarbonate to neutralize gastric acid, and the release of prostaglandins that promote mucus production and maintain the integrity of the gastric mucosa.

Vomiting

The involuntary expulsion of the contents of the stomach through the mouth, often triggered by various factors such as illness, irritation, or psychological aspects.

Ulcers

Ulcers are open sores that develop on the lining of the stomach or intestines, often caused by the erosion from stomach acid, infection (such as Heliobacter pylori), or the use of nonsteroidal anti-inflammatory drugs (NSAIDs). Symptoms may include abdominal pain, bloating, and indigestion.

What is the spongy retroperitoneal gland?

The spongy retroperitoneal gland is commonly referred to as the pancreas, which is located behind the stomach and serves both exocrine functions (such as producing digestive enzymes) and endocrine functions (such as regulating blood sugar levels by secreting insulin and glucagon).

Pancreatic Duct

The pancreatic duct is a tube that carries digestive enzymes produced by the pancreas to the duodenum; it merges with the common bile duct to deliver bile and pancreatic juices for digestion.

Accessory Ducts

Accessory ducts are additional ducts that transport pancreatic juices in the pancreas, providing an alternative pathway for digestive enzymes to reach the duodenum.

What is pancreatic juice?

Pancreatic juice is a digestive fluid produced by the pancreas, containing enzymes such as amylase, lipase, and proteases that help digest carbohydrates, fats, and proteins in the small intestine.

What is the hepatopancreatic ampulla and sphincter?

The hepatopancreatic ampulla is a structure where the bile duct and pancreatic duct merge and empty into the duodenum. The sphincter of Oddi, which surrounds the ampulla, regulates the flow of bile and pancreatic juices into the small intestine.

What are acini?

Acini are small, grape-like clusters of cells in exocrine glands, such as the pancreas and salivary glands, that secrete digestive enzymes or saliva.