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Questions and Answers
What triggers the primary peristalsis in the esophagus?
What triggers the primary peristalsis in the esophagus?
- Pressure from the stomach
- Initiation of swallowing (correct)
- Voluntary action
- Relaxation of the diaphragm
Secondary peristalsis occurs in response to residual food in the esophagus.
Secondary peristalsis occurs in response to residual food in the esophagus.
True (A)
What effect does swallowing have on the respiratory center of the medulla?
What effect does swallowing have on the respiratory center of the medulla?
Swallowing inhibits the respiratory center.
The esophagus is innervated by the _____ nerve and the enteric nervous system (ENS).
The esophagus is innervated by the _____ nerve and the enteric nervous system (ENS).
Match the phases or mechanisms with their respective descriptions:
Match the phases or mechanisms with their respective descriptions:
Gastrin hormone is secreted from which of the following?
Gastrin hormone is secreted from which of the following?
CCK hormone is secreted from which part of the digestive system?
CCK hormone is secreted from which part of the digestive system?
The gastrocolic reflex stimulates motility of the stomach upon meal intake.
The gastrocolic reflex stimulates motility of the stomach upon meal intake.
What is the primary action of the hormone Ghrelin?
What is the primary action of the hormone Ghrelin?
The contraction of the lower esophageal sphincter (LES) is an action of ______.
The contraction of the lower esophageal sphincter (LES) is an action of ______.
Which mechanism increases gastric secretion?
Which mechanism increases gastric secretion?
Match the following hormones with their primary actions:
Match the following hormones with their primary actions:
The enterogastric reflex controls the __________ of the stomach.
The enterogastric reflex controls the __________ of the stomach.
What is the primary action of the gastrocolic reflex?
What is the primary action of the gastrocolic reflex?
The primary secretion of salivary glands contains only mucin and no ions.
The primary secretion of salivary glands contains only mucin and no ions.
Name the reflex that stimulates gastric emptying.
Name the reflex that stimulates gastric emptying.
The salivary gland that provides serous secretion is the ______.
The salivary gland that provides serous secretion is the ______.
Which hormone stimulates the secretion of pancreatic juice rich in enzymes?
Which hormone stimulates the secretion of pancreatic juice rich in enzymes?
Aldosterone decreases potassium ion concentration in saliva.
Aldosterone decreases potassium ion concentration in saliva.
Match the salivary glands with their secretion type:
Match the salivary glands with their secretion type:
During maximal salivation, the concentration of ______ in saliva increases while the concentration of potassium decreases.
During maximal salivation, the concentration of ______ in saliva increases while the concentration of potassium decreases.
Which gland contains oxyntic cells responsible for secreting HCl?
Which gland contains oxyntic cells responsible for secreting HCl?
HCl helps in the absorption of iron and calcium.
HCl helps in the absorption of iron and calcium.
What is the term used for the phenomenon where bicarbonate is added to gastric venous blood as HCl is secreted?
What is the term used for the phenomenon where bicarbonate is added to gastric venous blood as HCl is secreted?
The primary function of HCl in the stomach includes the activation of __________ into pepsin.
The primary function of HCl in the stomach includes the activation of __________ into pepsin.
What stimulates the secretion of gastric acid?
What stimulates the secretion of gastric acid?
Match the following functions with their respective effects of HCl:
Match the following functions with their respective effects of HCl:
Proton pump inhibitors increase HCl secretion in the stomach.
Proton pump inhibitors increase HCl secretion in the stomach.
What substance is actively transported to the lumen by the proton pump (H-K ATPase)?
What substance is actively transported to the lumen by the proton pump (H-K ATPase)?
What is the primary function of the antrum and pylorus in the stomach?
What is the primary function of the antrum and pylorus in the stomach?
Liquid food is evacuated faster than solid food from the stomach.
Liquid food is evacuated faster than solid food from the stomach.
What is the main stimulus for gastric secretion?
What is the main stimulus for gastric secretion?
The protective mechanisms of the stomach are known as the gastric ______ barrier.
The protective mechanisms of the stomach are known as the gastric ______ barrier.
Match the following factors with their effects on gastric emptying:
Match the following factors with their effects on gastric emptying:
Which hormone is associated with the inhibitory phase of gastric secretion?
Which hormone is associated with the inhibitory phase of gastric secretion?
Gastroparis is commonly seen in individuals who have damage to the vagus nerve.
Gastroparis is commonly seen in individuals who have damage to the vagus nerve.
What symptoms can result from disorders of gastric emptying?
What symptoms can result from disorders of gastric emptying?
What role does the mucus-bicarbonate barrier play in protecting the gastric mucosa?
What role does the mucus-bicarbonate barrier play in protecting the gastric mucosa?
Prostaglandins increase acid secretion in the stomach.
Prostaglandins increase acid secretion in the stomach.
What is the primary mechanism of vomiting?
What is the primary mechanism of vomiting?
The buildup of waste products like urea in the blood is known as _____
The buildup of waste products like urea in the blood is known as _____
Match the pancreatic secretions with their characteristics:
Match the pancreatic secretions with their characteristics:
Which of the following is NOT a cause of vomiting?
Which of the following is NOT a cause of vomiting?
The tight junction between gastric mucosa cells prevents H+ back diffusion.
The tight junction between gastric mucosa cells prevents H+ back diffusion.
What factors stimulate pancreatic enzymatic secretion?
What factors stimulate pancreatic enzymatic secretion?
Flashcards
Swallowing and Respiration
Swallowing and Respiration
The swallowing center in the medulla oblongata temporarily inhibits the respiratory center, stopping breathing to allow safe passage of food.
Esophageal Peristalsis
Esophageal Peristalsis
The coordinated muscle contractions and relaxations that push food down the esophagus.
Primary Peristalsis
Primary Peristalsis
The initial peristaltic wave that begins from the pharynx and continues into the esophagus.
Secondary Peristalsis
Secondary Peristalsis
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Receptive Relaxation of the Stomach
Receptive Relaxation of the Stomach
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Gastrin
Gastrin
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Cholecystokinin (CCK)
Cholecystokinin (CCK)
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Secretin
Secretin
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Enteric Nervous System (ENS)
Enteric Nervous System (ENS)
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Gastrocolic Reflex
Gastrocolic Reflex
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Enterogastric Reflex
Enterogastric Reflex
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Lower Esophageal Sphincter (LES)
Lower Esophageal Sphincter (LES)
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Mastication
Mastication
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Salivary secretion mechanism
Salivary secretion mechanism
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Primary salivary secretion
Primary salivary secretion
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Secondary salivary secretion
Secondary salivary secretion
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Innervation of salivary glands
Innervation of salivary glands
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Salivary duct modification
Salivary duct modification
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Salivary glands
Salivary glands
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What is Gastrin?
What is Gastrin?
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What is the role of Histamine in gastric secretion?
What is the role of Histamine in gastric secretion?
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What is the action of CCK?
What is the action of CCK?
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What is the role of Secretin?
What is the role of Secretin?
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What is the cephalic phase of gastric secretion?
What is the cephalic phase of gastric secretion?
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What is the gastric phase of gastric secretion?
What is the gastric phase of gastric secretion?
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What is the intestinal phase of gastric secretion?
What is the intestinal phase of gastric secretion?
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What is the Enterogastric Reflex?
What is the Enterogastric Reflex?
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Mucus-Bicarbonate Barrier
Mucus-Bicarbonate Barrier
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Vomiting (Emesis)
Vomiting (Emesis)
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Vomiting Center
Vomiting Center
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Protective Prostaglandins
Protective Prostaglandins
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Peptic Ulcer
Peptic Ulcer
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Saliva Secretion
Saliva Secretion
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Pancreatic Endocrine Function
Pancreatic Endocrine Function
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Pancreatic Exocrine Function
Pancreatic Exocrine Function
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What are Oxyntic Cells?
What are Oxyntic Cells?
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What is the Alkaline Tide?
What is the Alkaline Tide?
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What is the role of Pepsinogen?
What is the role of Pepsinogen?
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How is Gastric Acid Secretion Controlled?
How is Gastric Acid Secretion Controlled?
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What are Proton Pump Inhibitors?
What are Proton Pump Inhibitors?
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Study Notes
Gastrointestinal (GI) Physiology
- The GI tract is stimulated by food, nerves, and chemical changes.
- Food stimulates the GI tract through pH changes, distension, and breakdown products.
- Regulation of the GI tract involves the enteric nervous system (ENS), sympathetic nervous system, and the parasympathetic nervous system (Vagus).
- The gastrocolic reflex controls lower GI tract motility after meals.
- The enterogastric reflex controls stomach motility and emptying.
GI Hormones
- Gastrin, secreted from the stomach, stimulates gastric secretion (HCl and enzymes), gastric motility, and mucosa growth.
- Cholecystokinin (CCK), secreted from the small intestine, contracts the gallbladder, increases pancreatic juice (enzymes), and increases small intestine motility.
- Secretin, secreted from the small intestine, increases pancreatic juice (HCO3−), and inhibits acid secretion.
Mastication (Chewing)
- Mastication is a reflex action.
- A drop in the lower jaw by food initiates the reflex.
- This leads to elevation of the jaw and crushing of food.
- This causes stretch of the masseter muscle, which results in reflex muscle contraction.
- The cycle repeats.
Salivary Secretion
- 0.5-1.5 liters of saliva are secreted daily.
- Saliva glands include parotid (serous), mandibular (mixed), sublingual (mixed), and buccal (mucous).
- The first stage of salivary secretion involves acini.
- The ionic composition of saliva changes as it flows through ducts (reduced Na+ and Cl−, increased K+).
- Salivary secretion is an active process with two stages: primary (in acini, isotonic) and secondary (in ducts, hypotonic).
- Salivary gland innervation: Parasympathetic stimulation leads to profuse watery saliva secretion, whereas sympathetic stimulation results in vasoconstriction and less saliva with high organic content.
- Salivary secretion is regulated by conditional and unconditional reflexes.
- Unconditional reflex is initiated by the presence of food and taste.
- Conditional reflex is acquired through prior experience (smell, sight, hearing).
- Saliva functions include articulation, buffering oral pH, cleaning, dissolving food for digestion, lubrication for swallowing, taste, thirst sensation regulation, and protection of teeth and mucosa.
Swallowing (Deglutition)
- Swallowing is a process with three stages: oral (buccal), pharyngeal, and esophageal.
- The oral stage is voluntary, the pharyngeal and esophageal stages are involuntary.
- The buccal phase involves tongue elevation, moving the bolus of food backward, and pushing it to the pharynx via mylohyoid muscle contraction.
- In the pharyngeal phase, the soft palate and tongue elevate, the larynx elevates, vocal cords approximate, respiration is inhibited, and pharyngeal muscles contract, pushing food into the esophagus.
Esophageal Phase
- The esophageal phase involves peristaltic movement, contracting and relaxing of esophageal muscles.
- Primary peristalsis is initiated by swallowing and moves food in 10 seconds from the cervical region to the stomach.
- Secondary peristalsis is a result of esophageal dilation due to retained food.
Stomach Motility
- The stomach has proximal and distal units. Proximal units (fundus and body) are for storage and receptive relaxation, while distal units (antrum and pylorus) create and control motor activity.
- The motor functions of the stomach include storage, mixing and partial digestion of food to chyme, and slow emptying of chyme into the duodenum.
Gastric Secretion
- The stomach secretes 1500–2500 ml/day of gastric juice.
- The glands that secrete gastric juice are mucous, oxyntic, and pyloric glands.
- Hydrochloric acid (HCl) activates pepsinogen, establishes optimal pH for pepsin, starts protein digestion, initiates the enterogastric reflex, assists in iron/calcium absorption, and kills microorganisms.
- HCl in the duodenum stimulates secretin hormone release, which inhibits acid secretion.
- Gastric acid secretion is stimulated by acetylcholine, histamine, and gastrin.
- There are three phases of gastric secretion: cephalic (nervous), gastric (nervous and hormonal), and intestinal (hormonal).
Lower Esophageal Sphincter (LES)
- The lower esophageal sphincter (LES) remains tonically contracted to prevent gastric reflux into the esophagus.
- Acetylcholine and gastrin cause contraction, while fats, tea, caffeine, and chocolate relax the LES.
- Decreased resting tone of the LES can cause gastroesophageal reflux and related issues.
- Conditions like achalasia can lead to failure of the LES to relax during swallowing.
- Symptoms include heartburn, dysphagia (difficulty swallowing), and regurgitation.
Pancreatic Secretion
- Pancreas has exocrine (duct gland) and endocrine (ductless gland) functions.
- The exocrine function involves secretion of pancreatic enzymes involved in carbohydrate, protein, and fat digestion; these are inactive and activated in the small intestine.
- Aqueous pancreatic secretion is rich in bicarbonate (HCO3-), neutralizes acidity, and optimizes pH for several enzymes.
- Pancreatic enzymes (lipases, amylases, and proteases) are secreted to digest fats, carbohydrates, and proteins in food.
Liver Functions
- The liver performs several crucial roles including detoxifying blood, storing iron, vitamins (B12, A, D, and K), filtering blood, controlling metabolic processes, producing bile, and regulating blood glucose.
Bile
- Bile is produced in the liver, stored in the gallbladder, and released into the duodenum.
- Bile salts are crucial for fat digestion and absorption.
- They emulsify large fat globules into smaller droplets making them more accessible to pancreatic enzymes.
- Bile salts also absorb fat-soluble vitamins.
Disorders of the GI Tract
- Disorders of the GI tract include xerostomia (dry mouth), dysphagia (swallowing difficulties), gastroparesis (slow stomach emptying), celiac disease (immune reaction to gluten), and short bowel syndrome (altered small bowel function).
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Description
Test your knowledge about key concepts in the digestive system, including primary and secondary peristalsis, the role of hormones, and reflex actions. This quiz covers important aspects related to esophageal functions and digestive processes. Challenge yourself and see how well you understand the mechanisms of digestion!
