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What governs the control mechanisms of the gastrointestinal system according to the text?
What governs the control mechanisms of the gastrointestinal system according to the text?
What factor leads to an increase in the force of antral smooth muscle contractions in the stomach?
What factor leads to an increase in the force of antral smooth muscle contractions in the stomach?
Which substance is mentioned in the text as influencing the force of initial stomach contraction after a large meal?
Which substance is mentioned in the text as influencing the force of initial stomach contraction after a large meal?
What is meant by 'luminal contents' in the context of gastrointestinal control mechanisms?
What is meant by 'luminal contents' in the context of gastrointestinal control mechanisms?
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How does the body respond to nutrients ingested even when it may not need them according to the text?
How does the body respond to nutrients ingested even when it may not need them according to the text?
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What conditions inhibit gastric emptying in the duodenum?
What conditions inhibit gastric emptying in the duodenum?
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Which segment of the small intestine is approximately 25 cm (10 in.) long?
Which segment of the small intestine is approximately 25 cm (10 in.) long?
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Where does 90% of absorption occur in the digestive system?
Where does 90% of absorption occur in the digestive system?
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What anatomical structures in the small intestine favor absorption and digestion?
What anatomical structures in the small intestine favor absorption and digestion?
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Which part of the pancreas secretes pancreatic juice into the small intestine?
Which part of the pancreas secretes pancreatic juice into the small intestine?
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Which of the following is NOT a function of the pharynx and esophagus during swallowing?
Which of the following is NOT a function of the pharynx and esophagus during swallowing?
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Which of the following statements about the stomach is FALSE?
Which of the following statements about the stomach is FALSE?
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Which of the following statements about gastric glands is CORRECT?
Which of the following statements about gastric glands is CORRECT?
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Which of the following chemical messengers stimulates the production of hydrochloric acid (HCl) in the stomach?
Which of the following chemical messengers stimulates the production of hydrochloric acid (HCl) in the stomach?
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Which of the following is NOT a function of the stomach?
Which of the following is NOT a function of the stomach?
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What triggers reflex relaxation of the external anal sphincter to allow feces expulsion?
What triggers reflex relaxation of the external anal sphincter to allow feces expulsion?
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What is the most common location for peptic ulcers?
What is the most common location for peptic ulcers?
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Which enzyme and acid combination is typically responsible for causing ulcers?
Which enzyme and acid combination is typically responsible for causing ulcers?
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What symptom is characteristic of peptic ulcers?
What symptom is characteristic of peptic ulcers?
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What serious condition can result from a perforated ulcer?
What serious condition can result from a perforated ulcer?
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What is the primary function of the pharynx and esophagus?
What is the primary function of the pharynx and esophagus?
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Which of the following is NOT a type of gastric gland found in the stomach?
Which of the following is NOT a type of gastric gland found in the stomach?
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Which hormone plays a key role in regulating the production of hydrochloric acid (HCl) in the stomach?
Which hormone plays a key role in regulating the production of hydrochloric acid (HCl) in the stomach?
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What is the primary function of the stomach?
What is the primary function of the stomach?
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Which part of the stomach is responsible for storing and concentrating bile prior to excretion into the small intestine?
Which part of the stomach is responsible for storing and concentrating bile prior to excretion into the small intestine?
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What is the primary function of the pancreatic enzyme amylase?
What is the primary function of the pancreatic enzyme amylase?
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Which of the following is NOT a component of bile secreted by the liver?
Which of the following is NOT a component of bile secreted by the liver?
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What is the primary function of the hepatic portal system?
What is the primary function of the hepatic portal system?
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Which of the following is NOT a function of bile secreted by the liver?
Which of the following is NOT a function of bile secreted by the liver?
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What is the primary function of the pancreatic enzyme lipase?
What is the primary function of the pancreatic enzyme lipase?
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What is the primary function of the pharynx?
What is the primary function of the pharynx?
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Which of the following is NOT a function of the esophagus?
Which of the following is NOT a function of the esophagus?
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Which type of gastric gland is responsible for the production of hydrochloric acid (HCl) in the stomach?
Which type of gastric gland is responsible for the production of hydrochloric acid (HCl) in the stomach?
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Which hormone is primarily responsible for stimulating the production of hydrochloric acid (HCl) in the stomach?
Which hormone is primarily responsible for stimulating the production of hydrochloric acid (HCl) in the stomach?
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Which part of the stomach is primarily responsible for the mechanical breakdown of food?
Which part of the stomach is primarily responsible for the mechanical breakdown of food?
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Which of the following is NOT a function of the stomach?
Which of the following is NOT a function of the stomach?
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Which part of the stomach is primarily responsible for the temporary storage of ingested food?
Which part of the stomach is primarily responsible for the temporary storage of ingested food?
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Which of the following cells in the gastric glands are responsible for the production of pepsinogen?
Which of the following cells in the gastric glands are responsible for the production of pepsinogen?
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What is the primary function of the pyloric sphincter in the stomach?
What is the primary function of the pyloric sphincter in the stomach?
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Which part of the stomach is responsible for the production of intrinsic factor, necessary for vitamin B12 absorption?
Which part of the stomach is responsible for the production of intrinsic factor, necessary for vitamin B12 absorption?
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Study Notes
Gastrointestinal System
- The body absorbs all nutrients ingested, regardless of whether they are needed or not.
- Control mechanisms of the gastrointestinal system are governed by the volume and composition of the luminal contents.
Stomach
- Gastric motility is increased by the concentration of gastrin and distension of the stomach.
- The force of initial stomach contractions is greater after a large meal, resulting in a greater emptying per contraction.
- Gastric emptying is inhibited by distension, presence of fat, high acidity, and hypertonic solutions in the duodenum.
Small Intestine
- 90% of absorption occurs in the small intestine.
- The small intestine is divided into three segments: duodenum, jejunum, and ileum.
- It is composed of fingerlike villi and microvilli structures, which increase the surface area for absorption and digestion.
Absorption in the Small Intestine
- The small intestine is anatomically arranged for a large surface area, enhancing absorption of nutrients.
- Villi increase surface area and contain blood vessels and lacteal, which play a role in absorption.
- Microvilli increase surface area and form the brush border.
Pancreas
- The pancreas has both exocrine and endocrine functions.
- The exocrine portion secretes pancreatic juice into the small intestine, which is rich in bicarbonate and digesting enzymes.
- Pancreatic secretions break down triglycerides into monoglycerides and 2 fatty acids.
Regulation of HCl Production
- Parietal cells in the stomach secrete about 2L of HCl per day.
- The acid secretion is regulated by four chemical messengers: gastrin, acetylcholine, histamine, and somatostatin.
- Somatostatin inhibits acid secretion, while the other three stimulate it.
Pathophysiology of the Gastrointestinal Tract
- Ulcers affect approximately 10% of the population in the USA.
- Ulcers are an erosion of the lining of the GI wall, usually due to pepsin and acid.
- Symptoms include a chronic rhythmic and periodic gnawing or burning pain.
Liver and Gall Bladder
- The liver serves as a secretory organ, secreting bile.
- Bile is a yellow-brownish liquid that contains bile salts, bicarbonate, lecithin, cholesterol, bilirubin, and other ions.
- Functions of bile include emulsifying large lipid molecules and neutralizing acidic chyme.
Hepatic Portal System
- The Hepatic Portal System is a specialized vasculature that delivers absorbed nutrients to the liver for processing.
- It is responsible for the synthesis of plasma proteins, processing and storing nutrients, and removal of old red blood cells.
Large Intestine
- The large intestine consists of the cecum, colon, and rectum.
- Functions of the large intestine include absorption of salt and water, mixing and propulsion of contents, storage and concentration of undigested matter, and defecation.
Motility of the Large Intestine and Defecation
- Contractions of the circular smooth muscle in the large intestine produce a segmentation motion.
- Three to four times a day, a wave of intense contraction known as a mass movement spreads rapidly over the transverse segment of the large intestine toward the rectum.
- The sudden distension of the walls of the rectum initiates the defecation reflex.
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Description
Learn about the breakdown process of triglycerides by lipase, the movement of food through the pharynx and esophagus, and the key functions of the stomach in the digestive system.
