90 Questions
What is the function of the esophagus?
Passage of food and drink
Which part of the body connects the mouth to the esophagus?
Oropharynx
What causes reflux esophagitis?
Poorly protected stomach epithelium
What condition may be mistakenly thought to be a heart attack due to its intense pain posterior to the sternum?
Heartburn
Who is most likely to experience reflux esophagitis?
Overweight individuals
Which factor can exacerbate the symptoms in individuals affected by reflux esophagitis?
Eating spicy foods
What is the role of the tactile sensory receptors around the fauces during the swallowing reflex?
Stimulate nerve signals to the swallowing center
What prevents ingested material from entering the trachea during swallowing?
Elevation of the larynx
What is the function of the soft palate and uvula during the swallowing reflex?
Block the passageway between oropharynx and nasopharynx
Why is a breath not taken during swallowing?
Nerve signals prevent it at the respiratory center
What causes swallowed material to move from the pharynx into the esophagus?
Contraction of pharyngeal constrictors creating a pressure difference
What is the duration of the pharyngeal phase during swallowing?
~1 second
What is one of the most surprising changes noted following surgery?
Induction of type 2 diabetes into remission
What is the purpose of gastric folds in the stomach lining?
Allow the stomach to expand greatly when filled with food
Which structure extends inferiorly from the greater curvature of the stomach?
Greater omentum
What is the purpose of the stress-relaxation response in the stomach wall?
To accommodate varying quantities of food
Which smooth muscle response occurs after a prolonged stretch?
Relaxation after a period of time
What endorsement does the International Diabetes Foundation give regarding gastric bypass surgery?
It endorses it for treating type 2 diabetes
What is the primary function of smooth muscle activity in the stomach wall?
Mixing the bolus with gastric juice to form chyme
Which hormone enters the blood instead of the lumen of the stomach?
Gastrin
What is the consistency of chyme?
Pastelike soup
Which cells produce somatostatin, a hormone that modulates nearby cells?
Enteroendocrine cells
What occurs during gastric emptying in the stomach?
The pyloric sphincter opens to release chyme into the duodenum
How does gastric mixing contribute to digestion?
By reducing the size of swallowed particles through churning
What stimulates contraction of the pyloric sphincter to slow stomach emptying?
Gastrin
Which phase of digestion involves processes following chyme reaching the small intestine?
Intestinal phase
What hormone is released by the duodenum primarily in response to fatty chyme?
Cholecystokinin
Which reflex protects the small intestine from being overloaded with chyme?
Intestinal reflex
What causes a decrease in nerve signals relayed to the medulla oblongata in the intestinal phase?
Acidic chyme entering the duodenum
What hormone causes a decrease in stomach motility in response to fatty chyme in the small intestine?
Cholecystokinin
What initiates sensory nerve signals to the salivary nuclei when one eats spoiled food?
Bacterial toxins in the stomach
What leads to a more viscous saliva by decreasing the water content during exercise or excitement?
Sympathetic stimulation
What results in additional saliva being released into the oral cavity?
Glossopharyngeal nerve (CN IX) innervation
What is the possible cause of bad breath (halitosis) and dental problems when one has a dry mouth?
Decreased saliva production
What is another term for chewing in the oral cavity?
Mastication
What decreases the fluid added to saliva by constricting blood vessels in the salivary gland?
'Sympathetic stimulation
What is the main function of the esophagus?
Passage of food and drink
What is a characteristic feature of reflux esophagitis?
Commonly known as heartburn
Which factor is NOT associated with an increased risk of reflux esophagitis?
Having a small meal before bedtime
What type of muscle tissue makes up the wall of the esophagus?
Skeletal muscle
Why is reflux esophagitis more commonly seen in individuals with hiatal hernias?
Protrusion of part of the stomach through the diaphragm
What distinguishes the esophageal epithelium from the stomach epithelium in terms of protection against acidic contents?
Esophageal epithelium lacks adequate protection
What is one of the surprising changes noted following surgery?
Induction of type 2 diabetes into remission
What is the function of the gastric folds in the stomach lining?
To accommodate varying quantities of food
Which structure covers the anterior surface of abdominal organs like a fatty apron?
Greater omentum
What is the characteristic response of smooth muscle to a prolonged stretch in the stomach wall?
Initial contraction followed by relaxation
What endorsement does the International Diabetes Foundation give regarding gastric bypass surgery?
Endorsement for treating type 2 diabetes
What is a function of the serous membrane known as the lesser omentum?
To connect the stomach to other abdominal organs
What is the primary function of parietal cells in the stomach?
Creating a low pH environment
Which cells in the stomach produce gastric lipase?
Chief cells
What is the role of chief cells in the stomach?
Releasing pepsinogen
What is the primary function of gastric emptying?
Moving chyme from stomach to duodenum
What facilitates the movement of chyme through the pyloric sphincter into the duodenum?
Wave of peristaltic muscular contraction
How does the pyloric sphincter prevent chyme from moving back into the stomach after gastric emptying?
By exerting higher pressure than the contents
What is the primary function of the mucus layer produced by mucous cells in the stomach?
Preventing ulceration of the stomach lining
Why is pepsinogen activated into pepsin in the stomach?
To prevent the destruction of chief cell proteins
Where are mucous neck cells located in relation to the gastric pit?
Deep to the base of the gastric pit
Which type of cells release an alkaline mucin to coat the epithelial lining in the stomach?
Mucous neck cells
What is the main function of chief cells in the stomach glands?
Secrete pepsinogen granules
How do mucous neck cells differ from surface mucous cells in terms of mucus production?
Mucous neck cells release alkaline mucin
What enzyme in saliva initiates the chemical digestion of starch?
Salivary amylase
Which structure provides lubrication to facilitate swallowing by secreting mucus in the superior part of the pharynx?
Soft palate
What is the term for the wet mass formed when saliva mixes with ingested materials in the oral cavity?
Bolus
In which part of the upper gastrointestinal tract is the bolus mixed with gastric secretions?
Stomach
Which organ transports the bolus from the pharynx through itself into the stomach?
Esophagus
What initiates mastication, the process of mechanical digestion, in the oral cavity?
Tongue movement
What is the primary effect of secretin on the stomach?
Inhibition of secretory activity
Which hormone primarily regulates the release of insulin in response to increased glucose concentration in the small intestine?
Glucose-dependent insulinotropic peptide (GIP)
What is the revised name for the hormone initially believed to regulate stomach activity but is now thought to primarily regulate insulin release?
Glucose-dependent insulinotropic peptide (GIP)
What do both secretin and cholecystokinin (CCK) inhibit?
Release of gastrin
In what specific section are the details about gastrin, secretin, and cholecystokinin (CCK) hormones discussed?
26.3c
What was the initial belief about the hormone released from the small intestine called gastric inhibitory peptide?
It primarily regulated stomach activity
What type of epithelium is found in the stomach mucosa?
Simple columnar epithelium
Which cells in the stomach mucosa are often replaced within a week?
Surface mucous cells
What structures extend deep into the mucosa from the base of each gastric pit?
Gastric glands
Which part of the stomach lining is indented by numerous depressions called gastric pits?
Mucosa
What surrounds the gastric glands and helps expel their secretions when it contracts?
Muscularis mucosae
Which characteristic feature of the stomach wall contributes to digestion by containing invaginations within the mucosa?
Gastric pits
What physiological responses occur prior to vomiting?
Increase in heart rate and sweating, feeling nauseous, increase in saliva production
What is the primary force for the expulsion of digestive tract contents during vomiting?
Skeletal muscle contraction
Why is it critical for individuals undergoing surgical procedures to have an empty stomach and small intestine?
To avoid inducing nausea and vomiting under general anesthesia
What can extensive vomiting lead to?
Metabolic alkalosis
What happens as pressure increases in the stomach during vomiting?
Gastric contents move up the digestive tract and are expelled through the mouth
What region of the brain controls the vomiting reflex?
Vomiting center in the medulla oblongata
What allows the stomach to expand greatly when filled with food and drink?
Gastric rugae
Which smooth muscle response is a characteristic response of the stomach wall to a prolonged stretch?
Contraction then relaxation
What is the term for the structure extending inferiorly from the greater curvature of the stomach?
Greater omentum
Which organization now endorses gastric bypass surgery for treatment of type 2 diabetes?
International Diabetes Foundation
What is an additional term for the serous membrane that forms a fatty apron over abdominal organs?
Peritoneum
What is one of the most surprising changes noted following surgery as mentioned in the text?
Induction of type 2 diabetes into remission
Study Notes
Pharynx and Esophagus
- The pharynx connects the mouth to the esophagus, and the esophagus is a muscular tube that extends from the pharynx to the stomach.
- The esophagus is normally collapsed and functions in the passage of food and drink.
- The esophagus has three tunics in its wall.
Reflux Esophagitis and Gastroesophageal Reflux Disease (GERD)
- Reflux esophagitis is an inflammation of the esophagus caused by backflow of acidic stomach contents into the esophagus.
- It is commonly known as heartburn and is more frequent in overweight individuals, smokers, and people with hiatal hernias.
- Eating spicy foods or ingesting too much caffeine can exacerbate the symptoms.
Swallowing Reflex
- The swallowing reflex is initiated by the arrival of the bolus at the entryway to the oropharynx.
- The bolus stimulates tactile sensory receptors around the fauces, which initiate nerve signals to the swallowing center in the medulla oblongata.
- The response includes elevation of the soft palate and uvula, elevation of the larynx, and sequential contraction of the pharyngeal constrictors.
Stomach Structure
- The internal stomach lining is composed of numerous gastric folds, or rugae, which allow the stomach to expand greatly when filling with food and drink.
- The stomach is able to accommodate varying quantities of food due to the stress-relax response of the smooth muscle in the stomach wall.
Gastric Secretions
- The stomach has two serous membrane structures: the greater omentum and the lesser omentum.
- The stomach lining has a simple columnar epithelium supported by lamina propria, with numerous gastric pits and gastric glands.
- The gastric glands produce and secrete various substances, including pepsinogen, gastric lipase, and intrinsic factor.
Gastric Emptying
- Gastric emptying is the movement of acidic chyme from the stomach into the duodenum of the small intestine.
- The process is facilitated by the progressive thickening of the muscularis layer in the pyloric region.
- The pyloric sphincter closes after the peristaltic wave has moved past, and the process is repeated to empty the chyme into the duodenum.
Hormonal Regulation
- Gastrin, secretin, and cholecystokinin (CCK) are hormones that regulate the digestive process.
- Gastrin stimulates the release of gastric acid and pepsin.
- Secretin and CCK inhibit the release of gastrin and decrease stomach motility.
- Secretin causes the release of bicarbonate-rich pancreatic juices and stimulates the release of bile from the gallbladder.
Intestinal Phase
-
The intestinal phase involves the processes following the chyme reaching the small intestine.
-
The intestinal reflex opposes the other two reflexes (cephalic and gastric reflexes) and protects the small intestine from being overloaded with chyme.
-
The release of cholecystokinin and secretin is stimulated by the entry of acidic chyme into the duodenum.### Vomiting Reflex
-
The vomiting reflex is controlled by the vomiting center in the medulla oblongata.
-
It responds to head injury, motion sickness, infection, toxicity, or food irritation in the stomach and intestines.
Physiological Changes Prior to Vomiting
- Heart rate and sweating increase, nausea is felt, and saliva production increases.
Vomiting Mechanism
- Vomiting is initiated following a deep inspiration and the closure of nasal cavities.
- Skeletal muscle contraction (abdominal muscles and diaphragm) increases pressure within the stomach.
- The acidic gastric contents are forced into and through the esophagus and out of the oral cavity.
Complications of Vomiting
- Aspiration of vomit into the respiratory tract is a risk for semiconscious or unconscious individuals.
- Vomiting causes increased formation of HCl, leading to increased HCO3− in the blood, raising blood pH.
- Extensive vomiting can lead to metabolic alkalosis.
Gastric Anatomy
- The internal stomach lining is composed of numerous gastric folds, or rugae, which allow the stomach to expand greatly when it fills with food and drink.
- The stomach is able to accommodate varying quantities of food due to the stress-relax response exhibited by the smooth muscle within the stomach wall.
Associated Structures
- Two serous membranes structures are associated with the stomach: the greater omentum and the lesser omentum.
- The greater omentum extends inferiorly from the greater curvature of the stomach, forming the fatty apron that covers the anterior surface of abdominal organs.
Learn about the structure and function of the esophagus, including its connection to the mouth and stomach. Explore the layers of the esophageal wall through a photomicrograph of a transverse section.
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