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What is the primary function of salivary α-amylase in saliva?
What is the primary function of salivary α-amylase in saliva?
Which glands are primarily responsible for the production of viscous mucinous secretions?
Which glands are primarily responsible for the production of viscous mucinous secretions?
Which phase of swallowing involves the propulsion of the bolus through the esophagus?
Which phase of swallowing involves the propulsion of the bolus through the esophagus?
What is the estimated daily saliva flow rate in a healthy individual?
What is the estimated daily saliva flow rate in a healthy individual?
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Which component in saliva contributes to its immune defense properties?
Which component in saliva contributes to its immune defense properties?
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What is xerostomia commonly referred to as?
What is xerostomia commonly referred to as?
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Which of the following statements about the parotid glands is incorrect?
Which of the following statements about the parotid glands is incorrect?
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What is the result of achalasia concerning the lower esophageal sphincter?
What is the result of achalasia concerning the lower esophageal sphincter?
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What main factors contribute to vomiting?
What main factors contribute to vomiting?
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What is the primary role of mucins in saliva?
What is the primary role of mucins in saliva?
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What is the first phase of swallowing known as?
What is the first phase of swallowing known as?
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During which phase of swallowing does breathing temporarily cease?
During which phase of swallowing does breathing temporarily cease?
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What initiates the muscle contractions in the pharyngeal phase of swallowing?
What initiates the muscle contractions in the pharyngeal phase of swallowing?
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What type of muscle primarily composes the upper oesophageal sphincter (UES)?
What type of muscle primarily composes the upper oesophageal sphincter (UES)?
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Which part of the pharynx is involved in both voluntary and involuntary phases of swallowing?
Which part of the pharynx is involved in both voluntary and involuntary phases of swallowing?
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Which nerve activity is primarily responsible for the tonically active state of the lower oesophageal sphincter (LES)?
Which nerve activity is primarily responsible for the tonically active state of the lower oesophageal sphincter (LES)?
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What triggers secondary peristaltic waves in the oesophagus?
What triggers secondary peristaltic waves in the oesophagus?
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Which structure closes off the trachea during the pharyngeal phase of swallowing?
Which structure closes off the trachea during the pharyngeal phase of swallowing?
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What primarily composes the secretion from the oesophagus?
What primarily composes the secretion from the oesophagus?
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In the context of swallowing, what does the term 'degultition apnea' refer to?
In the context of swallowing, what does the term 'degultition apnea' refer to?
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What specific role does salivary amylase play in digestion?
What specific role does salivary amylase play in digestion?
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Which autonomic response is primarily responsible for increasing salivary flow?
Which autonomic response is primarily responsible for increasing salivary flow?
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Which of the following best describes the relationship between salivary flow rate and electrolyte concentrations?
Which of the following best describes the relationship between salivary flow rate and electrolyte concentrations?
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What type of reflex is stimulated by food in the mouth and is controlled by chemoreceptors?
What type of reflex is stimulated by food in the mouth and is controlled by chemoreceptors?
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What is the optimal pH for salivary amylase activity?
What is the optimal pH for salivary amylase activity?
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Which cranial nerves are primarily involved in the autonomic regulation of salivary secretion?
Which cranial nerves are primarily involved in the autonomic regulation of salivary secretion?
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How does sympathetic activation affect salivary secretion?
How does sympathetic activation affect salivary secretion?
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What is the primary antibacterial action found in saliva that maintains oral health?
What is the primary antibacterial action found in saliva that maintains oral health?
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What effect does atropine, an anti-muscarinic, have on salivary secretion?
What effect does atropine, an anti-muscarinic, have on salivary secretion?
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The mechanical process of grinding food to increase surface area for enzymatic digestion is known as?
The mechanical process of grinding food to increase surface area for enzymatic digestion is known as?
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What is the primary cause of dysphagia in achalasia?
What is the primary cause of dysphagia in achalasia?
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Which of the following contributes to xerostomia?
Which of the following contributes to xerostomia?
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How does the vomiting reflex primarily increase intra-abdominal pressure?
How does the vomiting reflex primarily increase intra-abdominal pressure?
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Which phase of swallowing involves the relaxation of the upper esophageal sphincter (UES)?
Which phase of swallowing involves the relaxation of the upper esophageal sphincter (UES)?
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What condition is characterized by hypersalivation and can occur during early pregnancy?
What condition is characterized by hypersalivation and can occur during early pregnancy?
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Which neurotransmitter is primarily involved in the regulation of saliva production?
Which neurotransmitter is primarily involved in the regulation of saliva production?
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Which factor contributes to vomiting due to irritation in the gastrointestinal tract?
Which factor contributes to vomiting due to irritation in the gastrointestinal tract?
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What is a common complication associated with xerostomia?
What is a common complication associated with xerostomia?
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Which process is primarily involved in the initial mechanical breakdown of food?
Which process is primarily involved in the initial mechanical breakdown of food?
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What role does the medulla play in the vomiting reflex?
What role does the medulla play in the vomiting reflex?
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This describes the chemical nature of mucins—they are proteins with carbohydrate (sugar) side chains attached.
This describes the chemical nature of mucins—they are proteins with carbohydrate (sugar) side chains attached.
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This describes their function—mucins act as ..........in the body, helping to protect and moisten tissues, particularly in mucus secretions.
This describes their function—mucins act as ..........in the body, helping to protect and moisten tissues, particularly in mucus secretions.
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PNS ach recptorter for slivia production is
PNS ach recptorter for slivia production is
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salivary centre in brainstem coordinates responses
salivary centre in brainstem coordinates responses
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what can cuase a dray mouth?
what can cuase a dray mouth?
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Sympathetic more complex, but limited physiological role α-AR activation what effect does it have?
Sympathetic more complex, but limited physiological role α-AR activation what effect does it have?
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The laryngopharynx extends from the hyoid bone to the larynx.coresposens to c6
The laryngopharynx extends from the hyoid bone to the larynx.coresposens to c6
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The contraction of the palatal muscle pulls the soft palate over the nasopharynx
The contraction of the palatal muscle pulls the soft palate over the nasopharynx
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Pharyngeal muscles pull the
Pharyngeal muscles pull the
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what phase prevent the inhlation of food
what phase prevent the inhlation of food
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Oesophageal Phase Controled by
Oesophageal Phase Controled by
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Secondary Peristaltic Contraction is initiated by stimulation of [blank].
Secondary Peristaltic Contraction is initiated by stimulation of [blank].
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Primary Peristaltic Contraction: Initiated by [blank].
Primary Peristaltic Contraction: Initiated by [blank].
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Two types of peristaltic contractions in the esophagus are both controlled by the [blank].
Two types of peristaltic contractions in the esophagus are both controlled by the [blank].
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The esophagus, like the rest of the GI tract, has two muscle layers—_______ and _______.
The esophagus, like the rest of the GI tract, has two muscle layers—_______ and _______.
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The two places in the gut where striated muscle occurs are the esophagus and the _______.
The two places in the gut where striated muscle occurs are the esophagus and the _______.
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Circular Muscle Layer: This layer of smooth muscle fibers runs around the circumference of the GI tract. Contraction of these fibers narrows the lumen (the interior space) of the tract, which helps in pushing the contents forward. This type of muscle is referred to as [blank].
Circular Muscle Layer: This layer of smooth muscle fibers runs around the circumference of the GI tract. Contraction of these fibers narrows the lumen (the interior space) of the tract, which helps in pushing the contents forward. This type of muscle is referred to as [blank].
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Longitudinal Muscle Layer: This layer of smooth muscle fibers runs along the length of the GI tract. Contraction of these fibers shortens the tract, aiding in moving the contents along and facilitating [blank] (the wave-like movement of food).
Longitudinal Muscle Layer: This layer of smooth muscle fibers runs along the length of the GI tract. Contraction of these fibers shortens the tract, aiding in moving the contents along and facilitating [blank] (the wave-like movement of food).
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Lower esophageal sphincter contraction. Tonically active muscle prevents reflux through [blank].
Lower esophageal sphincter contraction. Tonically active muscle prevents reflux through [blank].
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les xrelaexes preioier to food passage due to ................ that inhibit smooth muscle
les xrelaexes preioier to food passage due to ................ that inhibit smooth muscle
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_________ is a condition characterized by the increased tone and inability to relax of the lower esophageal sphincter (LES), which impairs the normal passage of food into the stomach.
_________ is a condition characterized by the increased tone and inability to relax of the lower esophageal sphincter (LES), which impairs the normal passage of food into the stomach.
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Vomiting (Emetic) Center:
Located in the __________ of the brainstem.
Vomiting (Emetic) Center: Located in the __________ of the brainstem.
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The area postrema of the brainstem contains the [blank] Trigger Zone, which detects chemical signals in the blood and CSF.
The area postrema of the brainstem contains the [blank] Trigger Zone, which detects chemical signals in the blood and CSF.
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In the context of vomiting, peripheral nerves transmit signals from the gastrointestinal tract via afferent nerves to the [blank].
In the context of vomiting, peripheral nerves transmit signals from the gastrointestinal tract via afferent nerves to the [blank].
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Emotional and sensory inputs processed by the [blank] influence the vomiting center. This includes memory and anticipatory responses.
Emotional and sensory inputs processed by the [blank] influence the vomiting center. This includes memory and anticipatory responses.
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The inner ear's vestibular apparatus sends motion-related signals to the brain when there's a discrepancy in sensory information regarding [blank].
The inner ear's vestibular apparatus sends motion-related signals to the brain when there's a discrepancy in sensory information regarding [blank].
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What is the role of the salivary center in the brainstem during the vomiting reflex, and why is increased salivation important?
What is the role of the salivary center in the brainstem during the vomiting reflex, and why is increased salivation important?
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The emetic center is located in the [blank] and its primary function is to coordinate the [blank] reflex.
The emetic center is located in the [blank] and its primary function is to coordinate the [blank] reflex.
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During vomiting, the respiratory center interacts with the emetic center to typically [blank] breathing patterns.
During vomiting, the respiratory center interacts with the emetic center to typically [blank] breathing patterns.
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The [blank] reflex involves deep inspiration, closure of the glottis, relaxation of the stomach, LES, oesophagus, and UES, along with contraction of abdominal muscles and diaphragm to force gastric contents upwards.
The [blank] reflex involves deep inspiration, closure of the glottis, relaxation of the stomach, LES, oesophagus, and UES, along with contraction of abdominal muscles and diaphragm to force gastric contents upwards.
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Vomiting Reflex
• Deep inspiration and closure of _______
– elevation of soft palate and uvula • Relaxation of stomach, LES, oesophagus and UES • Contraction of abdominal muscles and diaphragm • Increases intra-abdominal pressure forcing gastric contents upwards
– against gravity
Vomiting Reflex • Deep inspiration and closure of _______ – elevation of soft palate and uvula • Relaxation of stomach, LES, oesophagus and UES • Contraction of abdominal muscles and diaphragm • Increases intra-abdominal pressure forcing gastric contents upwards – against gravity
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Vomiting Reflex: Deep inspiration and closure of the glottis – elevation of soft palate and uvula; Relaxation of stomach, LES, oesophagus and UES; __________; Increases intra-abdominal pressure forcing gastric contents upwards against gravity.
Vomiting Reflex: Deep inspiration and closure of the glottis – elevation of soft palate and uvula; Relaxation of stomach, LES, oesophagus and UES; __________; Increases intra-abdominal pressure forcing gastric contents upwards against gravity.
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The vomiting reflex involves deep inspiration and closure of the glottis, elevation of the soft palate and uvula, relaxation of the stomach, LES, oesophagus, and UES, contraction of abdominal muscles and diaphragm, and increases in [blank].
The vomiting reflex involves deep inspiration and closure of the glottis, elevation of the soft palate and uvula, relaxation of the stomach, LES, oesophagus, and UES, contraction of abdominal muscles and diaphragm, and increases in [blank].
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Study Notes
Saliva
- Major salivary glands: Parotid (~20-25%), Submandibular (~70-75%), and Sublingual (~3-5%).
- Parotid glands produce serous watery secretions rich in amylase; located anterior to the ear.
- Submandibular glands are major glands producing a mix of serous (watery) and mucous (thicker) secretions, resulting in intermediate secretion.
- Sublingual glands mainly produce viscous mucinous secretions; smallest and located under the tongue.hick mucinous fluid
Composition of Saliva
- Typical saliva production: 1-2 L/day, varies with stimuli; basal flow ~0.5 ml/min, max ~5 ml/min.
- Composition: ~99.5% water, ~0.5% electrolytes (Na+, K+, HCO3-, Cl-) and proteins (α-amylase, lingual lipase, mucins, IgA, lysozyme).
- Saliva is hypotonic to plasma, with lower sodium and chloride, but higher potassium and bicarbonate concentrations.in have a ph range of 6-8
Regulation of Salivation
-
Salivation controlled by autonomic nervous system; parasympathetic activation (ACh) increases salivation.
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Simple reflex triggered by food in the mouth via chemoreceptors and pressure receptors.
-
Conditioned reflex occurs from learned experiences (thinking/smelling food).
-
Salivary centre in brainstem coordinates responses via cranial nerves VII, IX, and V.
Autonomic Control of Secretion
• Parasympathetic (ACh) is dominant response
– hence dry mouth with anti-muscarinics such as atropine • Increases salivary flow rate
– increased flow rate decreases electrolyte reabsorption along the duct so salivary
electrolyte concentrations increase – and blood flow via vasodilatation
• Sympathetic more complex, but limited physiological role
– α-AR activation seems to increase flow (may be related to resistance in duct)
– β-AR activation increases amylase content
Functions of Saliva
- Initiates digestion, principally of starches, but minimal digestion occurs.
- Lubricates food aiding in swallowing and taste bud stimulation.
- Contributes to oral hygiene through buffering (bicarbonate) and antibacterial actions (IgA, lysozyme).
Mastication
- Begins mechanical breakdown of food, increasing surface area for salivary enzymes.
- Saliva mixes with food to form a bolus, facilitating swallowing.
- Taste stimulation leads to reflex increase in gastric and salivary secretions in preparation for food.
Phases of Swallowing (Deglutition)
- Three phases: oral (voluntary), pharyngeal (reflex), and esophageal (reflex).
- Oral phase involves rolling bolus from mouth to pharynx.
- Pharyngeal phase triggers pressure receptors, activating swallowing reflex; epiglottis closes off the trachea.
- Esophageal phase features peristaltic waves moving bolus from UES to LES.
The pharynx serves as a common pathway for the respiratory and gastrointestinal tracts and consists of three regions.
- The nasopharynx conditions inspired air and houses lymphoid tissue (adenoid tonsils) and openings to the eustachian tubes.
- The oropharynx directs food to the esophagus and contains palatine tonsils.
- The laryngopharynx extends from the hyoid bone to the larynx.coresposens to c6
Pharyngeal Phase Control:
As the bolus enters the pharynx, it triggers involuntary pressure receptors that send afferent signals to the deglutition center in the medulla oblongata and pons, initiating muscular contractions.
The contraction of the palatal muscle pulls the soft palate over the nasopharynx. Pharyngeal muscles pull the epiglottis to close off the trachea while moving the bolus downwards, lasting approximately 1 second during which breathing is inhibited (deglutition apnea).
Oesophageal Phase Control: The upper oesophageal sphincter (UES) contracts and primary peristaltic waves push the bolus through the esophagus. Secondary waves help clear any lodged bolus. Oesophageal muscle layers consist of circular and longitudinal muscles with variations along its length, and UES and LES are formed by thickened striated or circular smooth muscle. Controlled by vagal and intrinsic reflexes, peristaltic contractions facilitate swallowing.
Lower Esophageal Sphincter (LES)
- Tonically active muscle prevents reflux through vagal cholinergic activity.
- relaexes preioier to food passage due to vip and no by vagle that inhipite smooth muscle
- decartion is entrily mucse amiing to lubrcat and prtect from acide ensymes
Swallowing Complications
- Conditions affecting striated muscles (e.g., stroke, muscular diseases) can impair swallowing.
- Dysphagia (difficulty swallowing) frequently occurs in the elderly and is exacerbated in achalasia due to excessive LES tone.
Xerostomia and Ptyalism
- Xerostomia (dry mouth) can stem from medical conditions like Sjögren Syndrome, dehydration, anxiety, or medications.
- Associated issues include speech difficulties, dental problems, and increased risk of oral infections.
- Ptyalism (hypersalivation) may be caused by infections, pregnancy, or associated with nausea and emesis.
Vomiting (Emesis)
- A defense mechanism to expel harmful substances; involves complex pathways activating the vomiting centre in the medulla.
- Common triggers include irritation, motion sickness, raised intracranial pressure, and psychological factors.
- Vomiting involves deep inspiration, gastric relaxation, and abdominal contraction leading to expulsion of contents.
Summary Insights
- Saliva production primarily regulated by PNS; has low Na+ and Cl- and high K+ and HCO3- concentrations.
- Swallowing process is a highly coordinated reflex involving muscular contractions and relaxation.
- Vomiting reflex includes GI tract relaxation and an increase in intra-abdominal pressure, forcing expulsion.
Additional Study Resources
- Textbooks on gastrointestinal physiology for further reading.
- Educational videos on swallowing mechanisms may provide illustrative understanding.
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Description
Test your knowledge on the composition and functions of saliva with this quiz. Explore the roles of salivary α-amylase, glands responsible for mucinous secretions, and phases of swallowing. Additionally, learn about saliva flow rates and its immune defense properties.
