40 Questions
What is the primary mechanism that regulates gastric secretion?
Positive feedback mechanism
What is the role of pepsin in the stomach?
To break down proteins into smaller peptides
What is the effect of increased sympathetic action potentials on gastric secretion?
It decreases gastric secretion
What is the role of intrinsic factor in digestion?
To facilitate the absorption of vitamin B12 in the small intestine
What is the effect of cholecystokinin (CCK) on gastric secretion?
It decreases gastric secretion
What is the primary function of rennin in the stomach?
Curdles milk proteins, keeping them in the stomach longer
Which of the following hormones stimulates the pancreas to produce juice rich in digestive enzymes?
Cholecystokinin (CCK)
Why does the stomach absorb water and minerals?
To maintain the body's overall water balance
What is the role of the accessory pancreatic duct?
To allow pancreatic juice to enter the duodenum independent of bile
What is the primary function of gastric lipase?
To break down triglycerides into fatty acids and monoglycerides
Which type of cells in the gastric glands secrete hydrochloric acid and intrinsic factor?
Parietal cells
What is the primary function of the pyloric sphincter in the stomach?
To constrict and close the stomach outlet
What is the term for the semi-liquid substance formed by the action of gastric juice on food in the stomach?
Chyme
Which of the following is NOT a function of the stomach?
Absorbing vitamins and nutrients
What is the mechanism by which the stomach lining is able to stretch as it fills with food?
Gastric rugae
What is the primary function of lingual lipase in the oral cavity?
Hydrolysis of triglycerides into monoglycerides and fatty acids
What is the purpose of the lower esophageal sphincter (LES) in the digestive process?
To prevent regurgitation of stomach contents
What is the principal site of pepsin digestion in the digestive tract?
Stomach
What is the primary site of absorption for vitamin B12 in the digestive tract?
Small intestine
Which of the following hormones plays a key role in regulating gastric secretion and motility?
Gastrin
What is the primary mechanism by which gastric secretions are controlled?
Hormonal regulation through the release of gastrin and cholecystokinin
What type of digestion occurs in the stomach, where proteins are broken down into smaller peptides?
Chemical digestion via pepsin
Which of the following best describes the movement of food through the stomach during digestion?
Peristalsis, where the stomach contracts and relaxes in a wave-like manner
What is the primary site of vitamin B12 absorption in the digestive system?
Ileum
Which hormone plays a key role in regulating the digestion of proteins in the stomach?
Gastrin
What is the primary function of mechanical digestion in the digestive system?
To increase the surface area of food for chemical digestion
What is the role of digestive enzymes in the digestion process?
To speed up the breakdown of complex nutrient molecules into absorbable molecules
Which part of the digestive tract is responsible for the majority of mechanical digestion?
Mouth
What is the function of the accessory organs in the digestive system?
To aid in the digestion process through mechanical and chemical means
What is the approximate length of the digestive tract in humans?
6 m (20 ft)
What is the primary function of the muscular layer in the wall of the digestive tract?
Mixing and propulsion of luminal contents
What is the term for the ringlike contractions followed by relaxation at multiple places along the digestive tract?
Segmentation
What is the function of the cheeks in the digestive system?
Formation of facial expressions
What is the term for the movement that propels food along the digestive tract?
Peristalsis
What is the function of the lips?
Speech production
What is the inner lining of the cheeks composed of?
Nonkeratinized stratified squamous epithelium
What is the function of the palate in the mouth?
Surrounding the mouth
What is the name of the hollow space within the digestive tract through which food passes?
Lumen
How many layers make up the wall of the digestive tract?
Four
What is the function of the tongue in the mouth?
Speech production
Study Notes
Digestive System Overview
- The digestive system consists of the digestive tract and accessory organs, extending from the esophagus to the anus.
- The hollow space within the canal through which food passes is called the lumen.
- The wall of the digestive tract consists of four layers: serosa, muscular layer, submucosa, and mucosa.
Mouth Functions
- The mouth performs three main functions: intake of food (ingestion), mechanical digestion, and chemical digestion.
- The mouth is surrounded by the cheeks, palate, and tongue.
Cheeks
- The cheeks form the lateral walls of the mouth.
- The outer surfaces of the cheeks are covered with skin, and the inner surface is lined with nonkeratinized stratified squamous epithelium.
- The cheeks help hold food in the mouth, and contraction of muscles within them help produce facial expressions.
Stomach Structure and Function
- The stomach is located below the diaphragm in the left upper quadrant of the abdominopelvic cavity.
- The stomach has four subdivisions: cardia, fundus, body, and pyloric part.
- The pyloric sphincter is a thickened ring of circular smooth muscle cells that constricts to close the stomach outlet and relaxes to allow food to pass into the duodenum.
- The stomach has several specializations, including a muscular layer that allows it to mix food with gastric secretions, a thicker mucosa, and numerous gastric pits that receive secretions from gastric glands.
Gastric Juice and Gastric Glands
- Gastric juice is secreted by the gastric glands, which contain mucous neck cells, parietal cells, and chief cells.
- Mucous neck cells secrete mucus to protect the mucosa from digestive secretions.
- Parietal cells secrete hydrochloric acid (HCl) and intrinsic factor.
- Chief cells secrete digestive enzymes such as pepsinogen, gastric lipase, and rennin.
- Gastric juice converts food into chyme, a semiliquid substance, which is released intermittently into the duodenum through the pyloric sphincter.
Control of Gastric Secretion
- Gastric secretion is under neural and hormonal control.
- Parasympathetic action potentials increase with food stimuli and stimulate gastric glands to increase secretion of gastric juice.
- Gastrin, a hormone, is secreted by stomach cells and stimulates gastric gland secretion.
Pancreas
- The pancreas is located behind the pyloric part of the stomach and has both endocrine and exocrine functions.
- The pancreatic duct collects pancreatic juice, which is transported to the duodenum, where it neutralizes acidic chyme.
Control of Pancreatic Secretion
- Pancreatic secretion is controlled by both neural and hormonal mechanisms.
- Secretin, released by intestinal mucosa in response to acidic chyme, causes the pancreas to produce juice rich in bicarbonate ions.
- Cholecystokinin (CCK), secreted by intestinal mucosa in response to lipid-rich chyme, stimulates secretion of pancreatic juice rich in digestive enzymes.
Digestion by Pancreatic Enzymes
- Pancreatic amylase breaks down starch and glycogen into maltose.
- Pancreatic enzymes break down proteins into peptides and amino acids, and lipids into fatty acids and monoglycerides.
Other Organs and Processes
- The pharynx is a passageway connecting the nasal and oral cavities with the esophagus and larynx.
- The esophagus is a muscular tube that uses peristalsis to propel food toward the stomach.
- The lower esophageal sphincter (LES) guards the junction of the stomach and esophagus and relaxes to allow food into the stomach.
Learn about the mechanisms that regulate the secretion of gastric juice in the stomach, including the role of parasympathetic action potentials, food stimuli, and hormones. Test your knowledge on how the body prepares for digestion.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
