Digestive System Quiz: Peristalsis and Hormones
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Questions and Answers

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.

    True

    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).

    <p>vagus</p> Signup and view all the answers

    Match the phases or mechanisms with their respective descriptions:

    <p>Primary peristalsis = Triggered by swallowing Secondary peristalsis = Triggered by esophageal distension Receptive relaxation = Preparation of the stomach for incoming food Vagus nerve = Controls involuntary esophageal contractions</p> Signup and view all the answers

    Gastrin hormone is secreted from which of the following?

    <p>Stomach</p> Signup and view all the answers

    CCK hormone is secreted from which part of the digestive system?

    <p>Small intestine</p> Signup and view all the answers

    The gastrocolic reflex stimulates motility of the stomach upon meal intake.

    <p>False</p> Signup and view all the answers

    What is the primary action of the hormone Ghrelin?

    <p>Increases appetite</p> Signup and view all the answers

    The contraction of the lower esophageal sphincter (LES) is an action of ______.

    <p>Gastrin</p> Signup and view all the answers

    Which mechanism increases gastric secretion?

    <p>Vagal stimulation</p> Signup and view all the answers

    Match the following hormones with their primary actions:

    <p>Gastrin = Stimulates gastric secretion and motility Cholecystokinin (CCK) = Stimulates gallbladder contraction Secretin = Inhibits gastric acid secretion Ghrelin = Increases appetite</p> Signup and view all the answers

    The enterogastric reflex controls the __________ of the stomach.

    <p>motility and emptying</p> Signup and view all the answers

    What is the primary action of the gastrocolic reflex?

    <p>Stimulates evacuation of colon</p> Signup and view all the answers

    The primary secretion of salivary glands contains only mucin and no ions.

    <p>False</p> Signup and view all the answers

    Name the reflex that stimulates gastric emptying.

    <p>Gastrocolic reflex</p> Signup and view all the answers

    The salivary gland that provides serous secretion is the ______.

    <p>Parotid</p> Signup and view all the answers

    Which hormone stimulates the secretion of pancreatic juice rich in enzymes?

    <p>CCK</p> Signup and view all the answers

    Aldosterone decreases potassium ion concentration in saliva.

    <p>False</p> Signup and view all the answers

    Match the salivary glands with their secretion type:

    <p>Parotid = Serous secretion Mandibular = Mixed secretion Sublingual = Mixed secretion seromucous Buccal = Mucous secretion</p> Signup and view all the answers

    During maximal salivation, the concentration of ______ in saliva increases while the concentration of potassium decreases.

    <p>Na+, Cl-, and HCO3-</p> Signup and view all the answers

    Which gland contains oxyntic cells responsible for secreting HCl?

    <p>Oxyntic glands</p> Signup and view all the answers

    HCl helps in the absorption of iron and calcium.

    <p>True</p> Signup and view all the answers

    What is the term used for the phenomenon where bicarbonate is added to gastric venous blood as HCl is secreted?

    <p>Alkaline Tide</p> Signup and view all the answers

    The primary function of HCl in the stomach includes the activation of __________ into pepsin.

    <p>pepsinogen</p> Signup and view all the answers

    What stimulates the secretion of gastric acid?

    <p>Protein in the stomach</p> Signup and view all the answers

    Match the following functions with their respective effects of HCl:

    <p>Activation of pepsinogen = Begins protein digestion Provides optimum pH = Facilitates enzymatic action Kills microorganisms = Protects the digestive tract Initiates enterogastric reflex = Regulates gastric secretion</p> Signup and view all the answers

    Proton pump inhibitors increase HCl secretion in the stomach.

    <p>False</p> Signup and view all the answers

    What substance is actively transported to the lumen by the proton pump (H-K ATPase)?

    <p>H+ ions</p> Signup and view all the answers

    What is the primary function of the antrum and pylorus in the stomach?

    <p>Motor functions</p> Signup and view all the answers

    Liquid food is evacuated faster than solid food from the stomach.

    <p>True</p> Signup and view all the answers

    What is the main stimulus for gastric secretion?

    <p>GIT hormones (CCK &amp; secretin)</p> Signup and view all the answers

    The protective mechanisms of the stomach are known as the gastric ______ barrier.

    <p>mucosal</p> Signup and view all the answers

    Match the following factors with their effects on gastric emptying:

    <p>Liquid food = Faster gastric emptying Pain = Inhibition of gastric emptying Distension = Increased gastric emptying GIT hormones = Slow gastric emptying</p> Signup and view all the answers

    Which hormone is associated with the inhibitory phase of gastric secretion?

    <p>Secretin</p> Signup and view all the answers

    Gastroparis is commonly seen in individuals who have damage to the vagus nerve.

    <p>True</p> Signup and view all the answers

    What symptoms can result from disorders of gastric emptying?

    <p>Heartburn, nausea, and vomiting</p> Signup and view all the answers

    What role does the mucus-bicarbonate barrier play in protecting the gastric mucosa?

    <p>It neutralizes acids and prevents H+ ions from reaching the mucosa.</p> Signup and view all the answers

    Prostaglandins increase acid secretion in the stomach.

    <p>False</p> Signup and view all the answers

    What is the primary mechanism of vomiting?

    <p>Forceful evacuation of stomach contents through the mouth</p> Signup and view all the answers

    The buildup of waste products like urea in the blood is known as _____

    <p>uremia</p> Signup and view all the answers

    Match the pancreatic secretions with their characteristics:

    <p>CCK = Stimulates pancreatic enzyme secretion Endocrine = Ductless gland function Exocrine = Duct gland involvement Inactive form = Prevents autodigestion of pancreas</p> Signup and view all the answers

    Which of the following is NOT a cause of vomiting?

    <p>Ingestion of protein-rich food</p> Signup and view all the answers

    The tight junction between gastric mucosa cells prevents H+ back diffusion.

    <p>True</p> Signup and view all the answers

    What factors stimulate pancreatic enzymatic secretion?

    <p>Cholecystokinin (CCK)</p> Signup and view all the answers

    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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    GIT Physiology PDF

    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!

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