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Block 1 > Physiology of Mouth, Pharynx, Oesophagus > Flashcards

Physiology of Mouth, Pharynx, Oesophagus Flashcards

1
Q

State the functions of saliva

A

Lubricates food for swallowing

Helps with taste

Begins digestion of starch and lipids

Protects oral environment - cools hot food, washes away bacteria

Maintains alkaline environment - prevents teeth damage

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2
Q

List the 6 components of saliva

A

Water

High K+, HCO3-, Ca2+

Low Na+ Cl-

Mucous

Digestive enzymes - salivary a-amylase, lingual lipase

Antibacterial agents - thiocynate ions, proteolytic enzymes

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3
Q

What is the pH of saliva?

What type of solution is it?

A

6.2-8.0

Hypotonic solution (compared to plasma)

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4
Q

What is the purpose of proteolytic enzymes and thiocynate ions?

A

Proteolytic enzymes attack bacteria and aid thiocynate ions in entering the bacteria and have bactericide effect.

They also digest food particles that would provide metabolic support for the bacteria

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5
Q

Name the 3 pairs of salivary glands

A

Parotid

Sublingual

Submandibular

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6
Q

Which glands in the tongue produce lingual lipase?

A

Von Ebner’s glands

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7
Q

What type of glands are salivary glands?

A

Exocrine glands

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8
Q

What type of secretions does the parotid gland produce?

A

Serous saliva

Watery

Rich in enzymes

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9
Q

What type of secretions does the sublingual gland produce?

A

Mucous saliva

No enzymes

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10
Q

What type of secretions does the submandibular gland produce?

A

Mixed serous and mucous

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11
Q

Where is the main site of production of salivary a-amalyse?

A

Parotid gland

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12
Q

Describe the structure of salivary glands

A

Bunch of grapes appearance

Has acinus at the end of the ducts

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13
Q

What 3 type of cells are found in a salivary gland?

Where are they found?

What is their function?

A

Acinar cells - line the acini (endpieces) and produce the initial secretion

Duct cells - line the ducts of the glands, modify the secretion

Myoepithelial cells - contract to eject saliva

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14
Q

What are the 2 steps to saliva production

A

Primary secretion

Ductal modification

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15
Q

Outline primary salivary secretion

A

Isotonic filtrate from plasma diffuses through acinar cells

Mixes with enzymes (serous cells) or mucins (mucous cells)

Secretion drains into ducts

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16
Q

Outline ductal modification

A

Net absorption of Na+ and Cl-

Net secretion of K+ and HCO3-

Absorption outweighs secretion

Water is unable to follow Na+ - cells or impermeable

End up with hypotonic solution

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17
Q

What provides the energy or electrolyte transport across the duct cells of a salivary gland?

A

Na+/K+ ATPase on the basolateral membrane

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18
Q

Draw out a salivary ductal cell with its transporters

A

Slide 14

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19
Q

Describe some differences between resting and stimulated saliva

What is the ‘exception to the rule’?

A

Rest - saliva flow rate is lower, more time for ductal modification

Stimulated - flow rate is higher, less time for ductal modification, saliva is more similar to plasma

HCO3- is selectively stimulated when saliva production is stimulated - stimulated saliva is more alkaline

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20
Q

What hormonal factors can influence salivary production?

A

Antodiuretic hormone (ADH)

Aldosterone

In dehydration Na+ and water reabsorption increases, saliva volume decreases

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21
Q

Briefly describe the neural control of saliva secretion

A

Controlled by the ANS

Parasympathetic - increases saliva secretion in response to mechanoreceptors, sigh and smell of food, conditioned reflexes

Sympathetic - initially stimulates release of preformed mucous saliva, but then saliva flow decreases

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22
Q

What is the term given for ‘dry mouth?

A

Xerostomia

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23
Q

Give some symptoms of Xerostomia

A

Burning/scalding sensation in mouth

Dry and painful throat

Dry and rough tongue

Dry and cracked lips

Problems swallowing and speaking

Altered taste

Halitosis

Dental caries and periodontal disease

Oral infections, e.g. candidiasis

Difficulty with keeping dentures in place

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24
Q

List some potential causes of xerostomia

A

Side effect of medication, e.g. tricyclic antidepressants, antimuscarinic drugs, beta-blockers etc.

Dehydration

Anxiety

Lifestyle, e.g. smoking

Radiation therapy for head and neck cancer

Damage to salivary glands or their innervation

Sjögren’s syndrome

Medical conditions, e.g. poorly controlled diabetes, Alzheimer’s disease

25
Q

What is Sjogren’s syndrome?

A

Autoimmune destruction of salivary and lacrimal glands

26
Q

What are the two most common symptoms of Sjogren’s syndrome?

A

Dry mouth

Dry eyes

27
Q

List the 4 places taste buds are found

A

Tongue

Palate

Larynx

Pharynx

28
Q

What are the 5 taste classifications?

A

Sweet

Sour

Bitter

Salty

Umani

29
Q

In what structures in the tongue are taste buds found?

A

Papillae

30
Q

What 3 types of papillae are there?

A

Fungiform

Foliate

Circumvallate

31
Q

What 3 cells types to taste buds contain?

A

Taste receptor cells

Supporting cells

Basal cells - replace taste receptor cells when they are sloughed off

32
Q

What type of cells are taste receptor cells?

A

Chemoreceptors - specialised epithelial cells which transduce a chemical stimuli into electrical signals

They respond to all taste types, but usually response best to one

33
Q

Where are taste signals sent to?

A

The medulla, then sensory cortex

34
Q

What is the purpose of mastication?

A

Break food up to increase the surface area for enzymes to work

35
Q

Name some important muscles of mastication

Which cranial nerve supplies them?

A

Masseter

Temporalis

Medial pterygoid

Lateral pterygoid

CN Vc

36
Q

What are the 3 portions of the pharynx?

What are their borders?

A

Nasopharynx - skull base to soft palate

Oropharynx - soft palate to epiglottis

Laryngopharynx - epiglottis to cricoid cartilage, posterior to larynx

37
Q

Name the 3 external circular muscles of the larynx

What is their purpose?

A

Superior constrictor

Middle constrictor

Inferior constrictor

Forces bolus into oesophagus by peristalsis

38
Q

What 2 categories of muscle are found in the pharynx?

A

Inner longitudinal muscles

External circular muscles

39
Q

What do the inner longitudinal muscles of the pharynx do?

A

Shortens/widens the pharynx when swallowing

Elevates larynx when swallowing

40
Q

What is the cricopharyngeus?

Why is it important?

A

The lower portion of the inferior constrictor muscle of the pharynx

It forms the upper oesophageal sphincter

41
Q

What forms the upper oesophageal sphincter?

A

The lower border of the inferior constrictor muscle

42
Q

Where does the oesophagus end?

A

The cardiac opening of the stomach?

T10

43
Q

Describe the distribution of muscle in the oesophagus and its control

A

Superior third - voluntary striated muscle (somatic control)

Middle third - voluntary striated muscle and smooth muscle

Inferior third - smooth muscle (autonomic control)

44
Q

List the 4 points of compression/narrowing of the oesophagus

A

Junction between pharynx and oesophagus

Superior mediastinum where it is crossed by the arch of the aorta

Posterior mediastinum where it is posterior to the left main bronchus

Oesophageal hiatus

45
Q

What is the function of the lower oesophageal sphincter (LOS)?

A

Prevent reflux of gastric contents into oesophagus

46
Q

What components of the LOS prevent reflux?

A

Higher resting basal tone of muscles (not a true anatomical sphincter)

Right crus of diaphragm

Acute angle of entry to the stomach

Mucosal folds at gastro-oesophageal junction

Positive intra-abdominal pressure

47
Q

List some symptoms of gastro-oesophageal reflux disease (GORD)

A

Heartburn

Acid brash

Regurgitation

Water brash

There is a poor correlation between symptoms and pathological severity

48
Q

Why does pregnancy increase the likelihood of developing GORD?

A

Higher intra-abdominal pressure forces stomach contents upwards

49
Q

What complication can occur due to GORD?

A

Reflux oesophagitis - damage to the mucosa

50
Q

What is Barrett’s oesophagus?

A

Metaplasia of squamous epithelium of oesophagus to columnar mucosa

Proximal displacement of squamocolumnar junction - difference between simple squamous and columnar epithelium caused by acid being further up the oesophagus

51
Q

What type of cells normally line the oesophagus?

What do these cells change to in Barrett’s oesophagus?

A

Simple squamous

Columnar epithelium

52
Q

List the 3 phases of swallowing

A

Oral phase

Pharyngeal phase

Oesophageal phase

53
Q

What happens during the oral phase of swallowing?

A

Tongue moves bolus to oropharynx

Sensory receptors in palate and anterior pharynx send info to swallowing centre in medulla

Swallowing reflex initiated

Voluntary

54
Q

What happens during the pharyngeal phase of swallowing?

A

Soft palate elevates and blocks nasopharynx - respiration inhibited

Glottis closes

Larynx elevates

Epiglottis tilts to cover opening of larynx

Peristaltic wave pushes food through sphincter into oesophagus

Involuntary

55
Q

What happens during the oesophageal phase of swallowing?

A

Upper oesophageal sphincter closes - prevents reflux into pharynx

Larynx falls

Glottis opens

Respiration recommences

Primary peristatic wave coordinated by swallowing reflex, propels food down oesophagus

Lower oesophageal sphincter relaxes

Secondary peristatic wave occurs mediated by the enteric nervous system

Involuntary

56
Q

What controls the primary and secondary peristatic waves in swallowing?

A

Primary - swallowing reflex

Secondary - enteric nervous system

57
Q

Where in the brainstem is swallowing coordinated?

A

Medulla

58
Q

What is achalasia?

List some symptoms

A

Loss of coordination of peristalsis of lower oesophagus and spasm of LOS

Intermittent dysphagia for both solids and liquids
Regurgitation of food
Retrosternal chest pain

Block 1 (13 decks)

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