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What is the primary function of the acini in salivary glands?
What is the primary function of the acini in salivary glands?
What type of cells predominates in the parotid gland?
What type of cells predominates in the parotid gland?
Which ions are actively reabsorbed by the striated cells in the salivary ducts?
Which ions are actively reabsorbed by the striated cells in the salivary ducts?
Which of the following is NOT a type of salivary gland?
Which of the following is NOT a type of salivary gland?
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What describes the final saliva produced after passing through the ducts?
What describes the final saliva produced after passing through the ducts?
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What does the term 'biorhythm' refer to in the context of saliva secretion?
What does the term 'biorhythm' refer to in the context of saliva secretion?
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What two components are primarily found in primary saliva?
What two components are primarily found in primary saliva?
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What process is regulated by aldosterone within the salivary glands?
What process is regulated by aldosterone within the salivary glands?
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What primarily stimulates the secretion of hydrochloric acid (HCl) and pepsin during the gastric phase?
What primarily stimulates the secretion of hydrochloric acid (HCl) and pepsin during the gastric phase?
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What is the role of secretin in digestion?
What is the role of secretin in digestion?
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Which mechanism accounts for the majority of gastric secretion during the gastric phase?
Which mechanism accounts for the majority of gastric secretion during the gastric phase?
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During the intestinal phase, what effect do lipids and sugars have on gastric secretion?
During the intestinal phase, what effect do lipids and sugars have on gastric secretion?
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Which statement about the actions of acetylcholine in the stomach is correct?
Which statement about the actions of acetylcholine in the stomach is correct?
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What initiates the nervous mechanism of gastric secretion during food intake?
What initiates the nervous mechanism of gastric secretion during food intake?
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What is the primary source of gastrin in the stomach?
What is the primary source of gastrin in the stomach?
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Which enzyme is stimulated alongside hydrochloric acid secretion in the stomach?
Which enzyme is stimulated alongside hydrochloric acid secretion in the stomach?
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What is the primary role of secretin in the regulation of duodenal pH?
What is the primary role of secretin in the regulation of duodenal pH?
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Which cells are responsible for the secretion of hydrochloric acid (HCl)?
Which cells are responsible for the secretion of hydrochloric acid (HCl)?
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How is bicarbonate formed in the parietal cells during HCl secretion?
How is bicarbonate formed in the parietal cells during HCl secretion?
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What role does Immunoglobulin A (IgA) play in the human body?
What role does Immunoglobulin A (IgA) play in the human body?
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What role does somatostatin play in the digestive system?
What role does somatostatin play in the digestive system?
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Which growth factor is primarily involved in wound healing?
Which growth factor is primarily involved in wound healing?
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What is the effect of parasympathetic reflexes on salivary secretion?
What is the effect of parasympathetic reflexes on salivary secretion?
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What is the pH level of hydrochloric acid in the canaliculi when secreted?
What is the pH level of hydrochloric acid in the canaliculi when secreted?
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Which of the following hormones decreases salivary secretion?
Which of the following hormones decreases salivary secretion?
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What is the function of pepsin in the stomach?
What is the function of pepsin in the stomach?
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What stimulates salivary centers in response to the thought of food?
What stimulates salivary centers in response to the thought of food?
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What is the mechanism by which H ions are secreted into the canaliculi?
What is the mechanism by which H ions are secreted into the canaliculi?
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What is the primary barrier preventing back leak of H ions into the mucosa during HCl secretion?
What is the primary barrier preventing back leak of H ions into the mucosa during HCl secretion?
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Which statement about humoral regulation of salivary secretion is true?
Which statement about humoral regulation of salivary secretion is true?
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What is a function of Nerve Growth Factor (NGF)?
What is a function of Nerve Growth Factor (NGF)?
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Which components are part of the reflex arc related to saliva regulation?
Which components are part of the reflex arc related to saliva regulation?
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What is the primary substrate that lipase acts upon?
What is the primary substrate that lipase acts upon?
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Which pancreatic duct runs the entire length of the pancreas?
Which pancreatic duct runs the entire length of the pancreas?
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What type of mechanism primarily stimulates pancreatic secretion through the vagus nerve?
What type of mechanism primarily stimulates pancreatic secretion through the vagus nerve?
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Which of the following hormones is NOT involved in the hormonal regulation of pancreatic secretion?
Which of the following hormones is NOT involved in the hormonal regulation of pancreatic secretion?
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What is the outcome of trypsinogen activation in the duodenum?
What is the outcome of trypsinogen activation in the duodenum?
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What does the accessory Santorini duct do?
What does the accessory Santorini duct do?
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Collagenase and elastase are classified as which type of enzymes?
Collagenase and elastase are classified as which type of enzymes?
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Which stimulus directly causes the secretion of pancreatic juices through the nervous system?
Which stimulus directly causes the secretion of pancreatic juices through the nervous system?
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Study Notes
Saliva Secretion
- Saliva is secreted by exocrine cells located in salivary glands.
- Salivary glands are parotid, submandibular, sublingual and smaller buccal glands.
- The secretory cells in the glands contain acini, which are clusters of cells containing both serous and mucous cells.
- Serous cells secrete a fluid that is not mucus, while mucous cells secrete mucus.
- The salivary glands are located in the mouth and are responsible for producing saliva.
- There are three main salivary glands: the parotid, submandibular, and sublingual glands.
- The parotid gland is the largest salivary gland and secretes a watery saliva that is rich in enzymes.
- The submandibular gland is located under the jaw and secretes a mixed saliva that is both watery and viscous.
- The sublingual gland is the smallest salivary gland and secretes a viscous saliva that is rich in mucus.
- Saliva is made up of water (99.5%), electrolytes (sodium, potassium, chloride, bicarbonate), enzymes (amylase, lipase), and other proteins (mucins, immunoglobulins, growth factors). - These components contribute to various functions of saliva, including
- Lubricating and moistening the mouth
- Digestion of carbohydrates
- Protection against bacteria
- Neutralizing acids
- Facilitating speech
- Saliva has a slightly acidic pH of 6.8-7.0.
- The secretion of saliva is regulated by both the nervous system and hormones.
- The parasympathetic nervous system stimulates the secretion of a watery saliva that is low in enzymes and mucus.
- The sympathetic nervous system stimulates the secretion of a saliva rich in mucus and ptyalin.
- Hormonal regulation of saliva secretion includes:
- Increasing secretion: Bradikynin, VIP (vasoactive intestinal polypeptide)
- Decreasing secretion: Angiotensin II, Substance P
- The salivary glands are essential for maintaining oral health and overall well-being.
Gastric Secretion
- Gastric secretion is a complex process involving multiple phases.
- It is regulated by both the nervous system and hormones.
- There are three phases of gastric secretion:
-
Cephalic Phase:
- Initiated by the sight, smell, taste, and thought of food.
- Mediated by the vagus nerve, which stimulates gastric secretion of hydrochloric acid (HCl), pepsin, histamine and gastrin.
- Accounts for approximately 20% of gastric secretion.
-
Gastric Phase:
- Triggered by the presence of food in the stomach.
- Mediated by distension receptors in the stomach wall, which send signals to the vagus nerve, further increasing HCl, pepsin, histamine and gastrin secretion.
- Accounts for 60% of gastric secretion.
-
Intestinal Phase:
- Begins when food enters the small intestine.
- Regulated by intestinal distension, hormones, and the enteric nervous system.
- Hormones like secretin, cholecystokinin (CCK), and somatostatin influence gastric secretion based on the type of food present.
- If proteins reach the duodenum, gastrin is further secreted, further promoting HCl and pepsin secretion.
- Lipids and sugars in the duodenum trigger the release of inhibitory hormones, reducing gastric secretion.
- Accounts for 20% of gastric secretion.
-
Cephalic Phase:
- Hydrochloric acid (HCl) is secreted solely by parietal cells in the stomach lining.
- HCl is essential for digesting protein by activating pepsinogen into pepsin.
- HCI is secreted extracellularly by parietal cells in a complex process involving the exchange of hydrogen ions (H+) for potassium ions (K+) and bicarbonate ions (HCO3-) for chloride ions (Cl-).
- The highly acidic environment (pH of 1-1.5) produced by HCI aids in the activation of pepsinogen and digestion of food.
- Pepsinogen is secreted by chief cells and is converted to active pepsin in the presence of HCI, enabling protein digestion.
- Gastric secretion is vital for the initial breakdown of food and its further processing in the digestive system.
Pancreatic Secretion
- Pancreatic juice is produced by the pancreas and contains enzymes and bicarbonate ions.
- It is responsible for digesting carbohydrates, proteins, and fats in the small intestine.
- The secretion of pancreatic juice is regulated by both the nervous system and hormones.
- The nervous stimulation of pancreatic secretion is primarily mediated by the vagus nerve, which releases acetylcholine.
- Hormonal regulation of pancreatic secretion involves several hormones:
- CCK (cholecystokinin)
- Secretin
- VIP (vasoactive intestinal polypeptide)
- GIP (glucose-dependent insulinotropic peptide)
- Somatostatin
- Enteroglucagon
- These hormones are secreted in response to different stimuli:
- CCK: Released by the duodenum in response to fatty acids and amino acids.
- Secretin: Released by the duodenum in response to acidic chyme from the stomach.
- VIP: Released by the small intestine in response to nutrient-rich chyme.
- GIP: Released by the small intestine in response to glucose and fatty acids.
- Somatostatin: Released by the pancreas in response to the presence of food, which inhibits the release of other hormones.
- Enteroglucagon: Released by the small intestine in response to food, which inhibits gastric emptying.
- Pancreatic juice contains:
- Enzymes: Amylase (carbohydrates), lipase (fats), trypsinogen, chymotrypsinogen, carboxypeptidase (proteins).
- Bicarbonate: Neutralizes acidic chyme from the stomach.
- The release of these enzymes is regulated by the nervous system and hormones.
- The pancreas is crucial for digestion and plays a vital role in maintaining digestive health.
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Description
This quiz explores the secretory mechanisms and functions of the different salivary glands, including parotid, submandibular, and sublingual glands. It covers the composition of saliva and the roles of serous and mucous cells in secretion. Test your knowledge of saliva secretion!
