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Semester 3 - Gastrointestinal > Session 2 - Saliva and the Salivary glands > Flashcards

Session 2 - Saliva and the Salivary glands Flashcards

1
Q

What structures facilitate mastication?

A
  • Teeth

* Muscles of mastication

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2
Q

What is the purpose of the teeth?

A
  • Cut (incisors)
  • Crush (molars)
  • Mix with saliva
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3
Q

What are the muscles of mastication?

A
  • Masseter

* Innervated by branch of trigeminal nerve

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4
Q

How many litres of saliva produced per day?

A

1.5

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5
Q

What are the functions of saliva?

A
  • Lubricates and wets food
  • Starts digestion of carbohydrate
  • Protects oral environment
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6
Q

Give four ways saliva protects the oral environment?

A 
• Keeps mucosa moist 
• Washes teeth
• Maintains alkaline environment
	○ Neutralises acid produced by bacteria
• High calcium concentration (?)
	○ Soluble in acidic solution, not in alkaline and thus do not degrade
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7
Q

What is the condition when you do not have enough saliva, and what occurs?

A
  • Zerostomia (stomeeyah)

* Can still eat food, but teeth and mucosa degrade very quickly

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8
Q

What is the tongue?

A

A collection of 8 muscles that work to manipulate food for mastication and form it into a bolus

Aids in swallowing

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9
Q

What are the six main constituents of saliva?

A 
• Water
• Electrolytes
• Alkali
• Bacteriostats
• Mucus
	○ Mixture of mucopolysaccharides
• Enzymes - Salivary amylase
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10
Q

What is meant by “hypotonic” water?

A

• More water in saliva than in rest of body (osmotic potential body –> saliva)

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11
Q

How does the concentration of Na+ and Cl- in the saliva compare to that in the plasma?

A

• Lower concentration in saliva

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12
Q

How does concentration of Ca2+, K+ and I- in saliva compare to plasma?

A

• High concentration in saliva as compared to plasma
○ K+ as by product from production of saliva
○ I- helps control population of bacteria

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13
Q

What makes saliva alkaline?

A

• The addition of HCO3

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14
Q

What are the three paired salivary glands?

A
  • Parotid
  • Sub Mandibular
  • Sub-lingual
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15
Q

What is the structure of the salivary glands?

A

• Ducted, exocrine glands

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16
Q

What are ducted exocrine glands made up of?

A
  • Blind ended tubes

* Connected system of ducts

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17
Q

What cells line the acini, or the blind ended part of the salivary glands?

A

• Acinar cells

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18
Q

What cells line the ducts of the salivary glands

A

• Duct cells

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19
Q

What kind of secretion is produced by the parotid?

A
  • Watery secretion rich in enzymes, but little mucus (serous)
    • 25%
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20
Q

What types of secretions are produced by the sublingual glands?

A
  • Viscous secretion
  • No enzymes
  • Lots of mucus
  • 5%
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21
Q

What secretion are produced by the sub-maxillary glands?

A
  • All components of saliva, mix serous and mucous
  • Gland made up of mixture of serous and mucous acini, leading to common ducts
  • 70% of all saliva
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22
Q

How is saliva produced to be hypotonic, despite being made form extra-cellular fluid

A

• Glands secrete more concentrated solution and remove solute

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23
Q

Why isn’t saliva secreted directly in its final state?

A

• No cellular mechanism to secrete water

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24
Q

How is saliva secreted?

A

• Ïn a concentrated substance, from which solute is reabsorbed

25
What do acinar cells secrete?
• An isotonic fluid containing enzymes
26
What do duct cells do to pre-saliva?
* Remove Na+ and Cl- | * Add HCO3-
27
Why does water not follow the electrolytes removed from saliva by the duct cells
• Gaps between duct cells very tight
28
Why is saliva more concentrated at a higher flow rate?
• Duct cells have a limit on how much Na+ and Cl- they can remove Smaller fraction removed
29
What happens to the pH of saliva at higher flow rates?
* Stimulus for secretion promotes HCO3- secretion | * Saliva becomes more alkaline
30
Outline the mechanism of acinar secretion
* Cl- actively secreted into lumen of cut | * Water and other ions then follow passively
31
How do the duct cells remove Na+ from the lumen of the duct?
* Na+/K+-ATPase antiporter on ECF membrane secretes Na+ out of cell * This generates conc gradient from Na+ from duct lumen to duct cell
32
How do the duct cells remove Cl- from the lumen?
* Na/K+-ATPase also increases conc of K+ within the cell * This drives expulsion of Cl- into the ECF via a K+/Cl- symport transporter * Cl- high in lumen, low in cell. Conc grad, diffusion
33
How is HCO3- secreted into the duct lumen?
* Cl-/HCO3- antiporter | * Cl- moves into cell down conc grad, HCO3- moves into lumen
34
What part of the nervous system controls salivary secretion?
• Autonomic nervous system
35
What does parasympathetic stimulation of the salivary glands do?
• Increases production of primary secretion and increases addition of HCO3
36
Outline the pathway of parasympathetic stimulation of salivary glands
o Parotid Gland  Glossopharyngeal Nerve (9th cranial nerve)  Otic ganglion o Submandibular and Sublingual Glands  Facial Nerve (7th cranial nerve)  Submandibular ganglion o Muscarinic receptors  Blocked by atropine like drugs o Co-transmitters stimulate extra blood flow
37
Outline the parasympathetic outflow surrounding saliva stimulation
``` • Afferent information from ○ Mouth and tounge - taste receptors ○ Nose ○ Conditioned reflexes • All goes to medulla ```
38
Outline sympathetic stimulation of salivary glands?
• Occurs via superior cervical ganglion ○ Reduces blood flow to the salivary glands ○ Limits salivary flow
39
Where is the oropharynx found?
* Behind the oral cavity * Below the nasopharynx * Above the laryngopharynx
40
From what structures does the oropharynx extend to and from?
• The uvula to the hyoid bone
41
What structure closes over the glottis to prevent aspiration?
• The epiglottis
42
What is the oesophagus?
* A muscular tube that passes food from the pharynx to the stomach * Continuous with the lower part of the laryngopharynx
43
Outline the tissue structure of the oesophagus
• Mucosa ○ Composed of non-keratinized stratified squamous epithelium, lamina propria and a layer of smooth muscle • Submucosa ○ Containing mucous secreting glands • Muscularis externa ○ Upper third of oesophagus has striated skeletal muscle under somatic control for swallowing ○ Lower two thirds are smooth muscle under autonomic control
44
What does the brain stem swallowing centre do when pressure felt of pharyngeal plate
* Inhibits respiration * Raises larynx * Closes the glottis * Can open upper oesophageal sphincter
45
What are the three phases of swallowing?
* Voluntary phase * Pharyngeal phase * Oesophageal phase
46
What happens in the voluntary phase of swallowing?
• Tongue moves bolus back onto the pharynx
47
What happens in the pharyngeal phase of swallowing?
* Afferent information from pressure receptors in the palate and anterior pharynx reaches the swallowing centre in the brain stem. * A set of movements is triggered * Inhibition of breathing * Raising of the larynx * Closure of the glottis * Opening of the upper oesophageal ‘sphincter’
48
What happens in the oesophageal phase of swallowing?
* The muscle in the upper third of the oesophagus is voluntary striated muscle under somatic control * The muscle of the lower two thirds is smooth muscle under control of the parasympathetic nervous system. * A wave of peristalsis sweeps down the oesophagus, propelling the bolus to the stomach in ~9 seconds. * Coordinated by extrinsic nerves from the swallowing centre of the brain * Lower oesophageal ‘sphincter’ opens
49
What is dysphagia?
• The symptom of difficulty in swallowing
50
What is odynophagia
• The symptom of pain whilst swallowing
51
What is achalasia?
* Motility problems of the smooth muscle preventing peristalsis * Caused by damage and loss of nerves in gullet wall
52
What are the two main types of dysphagia?
* Oesophageal dysphagia | * Oropharyngeal dysphagia
53
What is oesophageal dysphagia and how is it investigated?
* Dysphagia for solids | * Investigate with barium swallow/endoscopy
54
What Oropharyngeal dysphagia?
• Investigate with a flexible endoscopy evaluation of swallowing, allowing you to view entire trachea
55
What causes dysphagia?
• Obstruction or compression of oesophagus | - Tumours
56
What is Barrett's oesophagus?
* An abnormal change of the epithelial cells of the oesophagus * Metaplasia from non-keratinised stratified squamous epithelia to columnar epithelium and goblet cells * Strong association with adenocarcinoma
57
What is gastro-oesophageal reflux disease?
• Reflux of stomach's content's into the oesophagus and pharynx causes cough, hoarseness and asthma
58
Why does gastro-oesophageal reflux damage the oesophagus?
• Does not have the same protective mucosa as the stomach
59
What features protect the oesophagus from reflux?
* The lower oesophageal sphincter * Angle of his (acute angle of entry of oesophagus * Positive intra-abdominal pressure compresses the oesophagus

Semester 3 - Gastrointestinal (28 decks)

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