Podcast
Questions and Answers
Which region of the stomach is responsible for absorbing water and ions from chyme?
Which region of the stomach is responsible for absorbing water and ions from chyme?
Which salivary gland secretes saliva located beneath the tongue on either side?
Which salivary gland secretes saliva located beneath the tongue on either side?
Which enzyme found in saliva breaks down starch and glycogen?
Which enzyme found in saliva breaks down starch and glycogen?
What is the function of the Ascending Colon in the digestive system?
What is the function of the Ascending Colon in the digestive system?
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Which segment of the colon acts as a storage depot for remaining material after absorption?
Which segment of the colon acts as a storage depot for remaining material after absorption?
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What is a significant function of the liver in the digestive system?
What is a significant function of the liver in the digestive system?
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What is the function of the peritoneum?
What is the function of the peritoneum?
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Where does the mechanical breakdown and digestion of food begin?
Where does the mechanical breakdown and digestion of food begin?
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Which enzyme found in saliva helps in the digestion of carbohydrates?
Which enzyme found in saliva helps in the digestion of carbohydrates?
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What is the function of the esophagus in the digestive system?
What is the function of the esophagus in the digestive system?
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How does the esophagus accommodate food when it is swallowed?
How does the esophagus accommodate food when it is swallowed?
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Which region of the stomach extends above the lower esophageal sphincter and easily expands to accommodate food?
Which region of the stomach extends above the lower esophageal sphincter and easily expands to accommodate food?
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Which type of cells secrete pepsinogen, the precursor for the proteolytic enzyme pepsin, into the lumen of the stomach?
Which type of cells secrete pepsinogen, the precursor for the proteolytic enzyme pepsin, into the lumen of the stomach?
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What is the function of parietal cells in the stomach?
What is the function of parietal cells in the stomach?
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Which part of the stomach produces the strong contractions responsible for gastric mixing and emptying?
Which part of the stomach produces the strong contractions responsible for gastric mixing and emptying?
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Where are neck cells located in the stomach?
Where are neck cells located in the stomach?
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Which region of the stomach accounts for the bulk of its volume?
Which region of the stomach accounts for the bulk of its volume?
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Study Notes
The Esophagus
- Contains both skeletal and smooth muscle
- Upper Esophageal Sphincter: a ring of skeletal muscle surrounding the esophagus at its upper end
- Lower Esophageal Sphincter: a ring of smooth muscle at the lower end of the esophagus, regulating the flow of food from the esophagus to the stomach
The Stomach
- A J-shaped sac beneath the diaphragm that stores food after it is swallowed and releases it into the small intestine
- Gastric Glands: secrete a watery fluid called gastric juice into the lumen
- Chyme: a mixture in the stomach’s wall that pulverizes food into smaller particles and mixes it with gastric juice
- Divided into three anatomical regions: Fundus, Body, and Antrum
- Fundus: extends above the lower esophageal sphincter; the wall is thin and easily expands to accommodate food
- Body: the middle region which accounts for the bulk of the stomach’s volume
- Antrum: the lower region which is narrow and small in volume; has the thickest muscle layer and produces strong contractions responsible for gastric mixing and emptying
- Gastric glands include:
- Neck Cells: secrete mucus
- Chief Cells: secrete pepsinogen, the precursor for a proteolytic enzyme called pepsin
- Parietal Cells: secrete hydrogen ions to acidify the stomach contents and intrinsic factor, necessary for the absorption of vitamin B12
- G Cells: secrete the hormone gastrin
The Small Intestine
- A coiled tube about 2–3 cm in diameter and 2.5–3 meters long, responsible for digestion of nutrients in food
- Divided into three regions: Duodenum, Jejunum, and Ileum
- Duodenum: the initial short region that begins at the pylorus and extends about 30cm
- Jejunum: the middle portion that extends about 1m
- Ileum: the last, terminal portion that extends approximately 1.5m and joins the colon
The Colon
- Composed of four regions: Ascending Colon, Transverse Colon, Descending Colon, and Sigmoid Colon
- Ascending Colon: runs upward on the right side of the body from the end of the small intestine toward the diaphragm
- Transverse Colon: runs across the abdominal cavity
- Descending Colon: runs downward on the left side
- Sigmoid Colon: an S-shaped segment that leads to the rectum, acts as a storage depot for whatever remains in the lumen after absorption
The Rectum and Anus
- The colons contracts and pushes feces into the rectum
- Movement through the anus is controlled by two sphincters: Internal Anal Sphincter and External Anal Sphincter
- Relaxation of both sphincters allows fecal material to be eliminated from the body, which is called defecation
The Accessory Glands
- The Salivary Glands: secrete saliva
- Three major salivary glands: Parotid Glands, Sublingual Glands, and Submandibular Glands
- Saliva consists of:
- Bicarbonate that makes the saliva alkaline and neutralizes acid
- Mucus that lubricates the food and protects the lining of the mouth from abrasion
- Salivary amylase, a digestive enzyme that breaks down starch and glycogen
- Lysozyme, an enzyme that destroys certain bacteria and prevents tooth decay
The Pancreas
- Located beneath the stomach and secretes pancreatic juice
- Exocrine organ and endocrine gland
- Gland secretes hormones important to regulation of metabolism
- Pancreatic juice contains:
- Bicarbonate
- Several digestive enzymes, including:
- Pancreatic amylase, which breaks down starch and glycogen
- Pancreatic lipases, which break down fats
- Proteases, which break down proteins
- Nucleases, which break down nucleic acids
The Liver
- The largest organ in the abdominal cavity
- Functions include:
- Secretion of bile
- Metabolic processing of nutrients
- Removal of aged blood cells from the blood
- Liver secretes bile which contains:
- Bicarbonate
- Phospholipids
- Inorganic ions
- Bile salts
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Description
Test your knowledge of the esophagus anatomy and function, including details about the upper and lower esophageal sphincters. Learn about how these muscles work to regulate the flow of food from the esophagus to the stomach and prevent heartburn.
