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GI Unit > 3.2 Saliva And Swallowing > Flashcards

3.2 Saliva And Swallowing Flashcards

1
Q

Describe the content of saliva

A
  • Mostly water
  • Hypotonic (depending on flow rate)
  • Rich in potassium and bicarbonate (pH slightly acidic to ~8)
  • Mucins help with lubrication
  • Amylase
  • Lingual lipase
  • Contains a diversity of immune proteins (e.g. IgA, lysozyme, lactoferrin)
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2
Q

How is amylase secreted into saliva?

A

Via salivary glands

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3
Q

How are lipases secreted into the saliva?

A

Lingual glands

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4
Q

How is salivary secretion primarily regulated?

A

Autonomic nervous system
• Parasympathetic is main driver (increases production)
• Sympathetic also stimulates secretion of small amounts of less watery saliva, but also causes vasoconstriction of blood vessels supplying salivary glands

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5
Q

How is saliva modified after secretion by the acinus?

A

Initial saliva is secreted by acinus
Moved out of acinus into ducts by myoepithelial cells
Ductal cells are relatively impermeable to water
However removes Na+ and Cl-
Secrete K+ and HCO3- ion
More Na+ and Cl- removed than K+ and HCO3- ions secreted
Saliva ends up hypotonic

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6
Q

How does the rate of flow of saliva affect its composition?

A

At low flow rates, most significant modification takes place, becomes more hypotonic
At higher flow rates less modification takes place
Except for HCO3- ions which are selectively secreted at higher flow rates

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7
Q

What are the 3 stages of swallowing?

A

Oral phase
Pharyngeal phase
Oesophageal phase

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8
Q

What occurs in the oral phase of swallowing?

A
  • preparing bolus
  • Tongue pushes bolus towards oropharynx
    Bolus touches pharyngeal wall and pharyngeal phase begins
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9
Q

What occurs in the pharyngeal phase?

A
  • Soft palate elevates to seal off nasopharynx
  • Pharyngeal constrictors push bolus downwards
  • Larynx elevates, closing epiglottis
  • Vocal cords adduct (protecting airway) and breathing temporarily ceases
  • Opening of the upper oesophageal sphincter
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10
Q

Describes what happens in the oesophageal phase

A
  • Closure of the upper oesophageal sphincter

* Peristaltic wave carries bolus downwards into oesophagus

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11
Q

What is dysphagia?

A

Problems swallowing

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12
Q

How do neurological problems cause problems swallowing?

A

• Usually harder to swallow fluids (than solids) as these are more difficult to coordinate and
move as a unit into the GI tract
• Can more easily get into respiratory tract than solids

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13
Q

How does physical obstruction to lumen cause problems swallowing?

A

Makes solids harder to swallow than fluids

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14
Q

What may cause physical obstruction to the lumen?

A
  • Fibrous rings
  • Tumours
  • Achalasia-failure of LOS to relax
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15
Q

What may progressive dysphagia indicate?

A

Malignant changes - As tumour size increases it will become harder to swallow as lumen gets more obstructed

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16
Q

What are the 3 main functions of saliva?

A

Lubrication
Protection
Digestion

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17
Q

Why does saliva provide lubrication?

A

To assist in swallowing and speech

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18
Q

How does the saliva confer protection?

A

Cooling effect on hot food/drinks
Buffers acid (saliva enters mouth before vomit)
Washes away debris stuck in teeth
Antibacterial

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19
Q

How does saliva act as an antibacterial?

A

Lysozymes : attacks bacteria cell wall

Lactoferrin : collates iron, reducing iron availability for bacteria, stopping them from multiplying

20
Q

What type of glands are salivary glands?

A

Exocrine glands

21
Q

What are exocrine glands?

A

Glands that have ducts that open into an epithelial lined structure

22
Q

What are the 3 paired salivary glands?

A

Parotid
Sublingual
submandibular

23
Q

How much saliva is produced a day?

A

1500ml

24
Q

Which salivary gland produces the most saliva?

A

Submandibular

25
Q

Describe the secretions of the parotid gland?

A

25% of saliva
Serous (watery)
Lots of enzymes

26
Q

Describe the secretions of the submandibular gland

A 
70% of saliva 
Mixed secretions (mucous and serous)
27
Q

Describe the secretions from sublingual glands

A

5% of saliva
Mucous
Little enzymes

28
Q

When is secretion of HCO3- into the ductal system of the salivary glands increased?

A

During high flow rate (active saliva secretion)

29
Q

When is saliva most hypotonic?

A

At rest, when there is low flow rate. There is increased contact time with ductal cells and therefore more removal of sodium and chloride

30
Q

What innervated the parotid gland?

A

Glossopharyngeal nerve

31
Q

What innervated the submandibular and sublingual nerve?

A

Facial nerve

32
Q

What is xerostomia?

A

Xerostomia is defined as dry mouth resulting from reduced or absent saliva flow.

33
Q

What causes xerostomia?

A 
Medications
Autoimmune conditions
Dementia
Radiotherapy
Dehydration
34
Q

What can xerostomia result in?

A

Infections (bacteria multiply easier
Tooth decay
Halitosis

35
Q

What is halitosis?

A

Bad breath

36
Q

Name a viral infection of the salivary glands

A

Mumps (swollen parotid gland)

37
Q

How do we protect against mumps?

A

MMR vaccine

38
Q

What is Sjogerns syndrome?

A

Autoimmune condition. Causes dry mouth, dry eyes and painful/swollen salivary glands

39
Q

What are sialoliths?

A

Calcified salivary gland stones.

40
Q

Where is the most common place for sialoliths?

A

Wharton’s duct - where the submandibular gland drains into the mouth

41
Q

What are symptoms of a sialolith?

A

Pain in region of stone. Worsens before/during eating as producing more saliva.

42
Q

What are examples of neurological causes of dysphagia?

A

Cerebrovascular accident
Stroke
Parkinson’s disease
Multiple sclerosis

43
Q

What are symptoms of neurological dysphagia?

A

Ineffective swallow causing dribbling
Material entering respiratory tract causing coughing, choking and infections (pneumonia) if persistent.
Difficulty swallowing fluids

44
Q

What are signs of an oesophageal cancer?

A 
Progressive dysphagia (solids harder to swallow)
Weight loss
45
Q

What is achalasia?

A

Failure of the LOS to relax

GI Unit (14 decks)

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