Salivation and Swallowing Flashcards Preview

ESA 3 - Gastrointestinal System > Salivation and Swallowing > Flashcards

Flashcards in Salivation and Swallowing Deck (118):
1

What is the entrace to the GI tract? 

The mouth

2

What does the mouth serve to do? 

  • Disrupts foodstuffs
  • Mix foodstuffs with saliva to form boluses

3

What can happen once food boluses have been formed?

They can be swallowed

4

What is the function of teeth? 

  • Cut
  • Crush
  • Mix food with saliva

5

Which type of teeth cut?

Incisors

6

Which type of teeth crush?

Molars

7

What generates the force behind the teeth?

The powerul muscles of mastication, the Masseter 

8

What innervates the Masseter?

A branch of the trigeminal nerve

9

What is the tongue?

A collection of 8 muscles

10

What does the tongue do?

  • Works to manipulate food for mastication and form it into a bolus
  • Aids swallowing by pushing bolus to back of mouth

11

Label this diagram 

  • A - Nasopharynx
  • B - Oropharynx
  • C - Hypopharynx
  • D - Esophagus
  • E - Sinus
  • F - Nasal cavity
  • G - Salivary glands
  • H - Oral cavity 
  • I - Trachea 

12

Where does the oropharynx lie?

Behind the oral cavity 

13

What does the oropharynx form?

The portion of the pharynx below the nasopharynx but above the laryngopharynx

14

Where does the oropharynx extend?

From the uvula (the end of the palate), to the level of the hyoid bone

15

What closes over the glottis?

A flap of tissue called the epiglottis

16

Why is the epiglottis needed?

To prevent aspiration, as both food and air pass through the oropharynx

17

What is the oesophagus?

A muscular tube

18

What is the function of the oesophagus?

It passes food from the pharynx to the stomach 

19

What is the oesophagus continuous with?

The lower part of the laryngopharynx

20

What are the layers of the oesophagus?

  • Mucosa
  • Submucosa
  • Muscularis externa 

21

What is the mucosa of the oesophagus composed of?

  • Non-keratinised stratified squamous epithelium
  • Lamina propria
  • Layer of smooth muscle (Muscularis Mucosa)

22

What does the submucosa of the oesophagus contain?

The mucous secreting glands

23

What kind of muscle is in the muscularis externa of the oesophagus?

  • Upper third is striated, skeletal muscle, under conscious control
  • Lower two-thirds are smooth muscle, under autonomic control

24

What is the function of the skeletal muscle in the upper third of the oesophagus?

For swallowing

25

What is the function of the smooth muscle in the lower two thirds of the oesophagus? 

Peristalsis 

26

How much saliva is produced each day?

1.5L

27

What are the function of saliva?

  • Lubricates and wets food
  • Starts digestion of carbohydrates 
  • Protects oral environment

28

How does saliva start the digestion of carbohydrates?  

Through the presence of amylase 

29

How does saliva protect the oral environment? 

  • Keeps mucosa moist 
  • Washes teeth
  • Maintains alkaline environment 
  • High Ca2+ environment 

30

What is the purpose of the alkaline environment maintained by saliva?

Neutralises acid produced by bacteria

31

What is zerostomia? 

Insufficient saliva production

32

Can a patient with zerostomia still eat? 

Yes, providing the food is moist, but teeth and mucosa degrade very quickly 

33

What are the constituents of saliva? 

  • Water
  • Electrolytes
  • Alkali
  • Bacteriostats
  • Mucus
  • Enzymes

34

Is saliva hypertonic or hypotonic? 

Hypotonic

35

Are the electrolytes in saliva at a higher or lower concentration than plasma? 

  • Naand Clusually at lower concentration than plasma 
  • Ca2+, K+, and Iare usually at higher concentration than plasma

36

What makes saliva alkali? 

HCO3-

37

Is HCO3- in saliva at higher or lower concentration than in plasma? 

Higher

38

What is salivary mucus? 

A mixure of mucopolysaccharides 

39

What enzymes are in saliva? 

Salivary amylase

40

Can we survive without salivary amylase?

Yes, it is relatively minor

41

How many paired salivary glands are there? 

3

42

What kind of glands are the salivary? 

Ducted, exocrine 

43

Describe the structure of salivary exocrine glands

  • Made up of acini (blind-ended tubes), lined with acinar cells. 
  • The acini are connected via a system of ducts to a single outlet, lined by duct cells

44

What does the parotid glands secrete? 

Serous saliva

45

What is serous saliva?

Watery secretion, rich in enzymes, but little mucus 

46

What % of saliva is secreted from the parotid glands?

25%

47

What does sub-lingual glands secrete?

Mucus saliva

48

What is mucus saliva?

Viscous secretion, no enzymes but lots of mucus 

49

What % of saliva is secreted from the sub-lingual glands?

5%

50

What does the sub-maxillary glands secrete?

All components of saliva (mixed serous and mucus)

51

Briefly describe the structure of sub-maxillary glands

Mixture of serous and mucus acini leading to a common duct

52

What % of saliva is secreted from the sub-maxillary glands?

70%

53

Label this diagram

  • A - Parotid
  • B - Sub-maxillary 
  • C - Sub-lingual 

54

What is the cellular mechanism to secrete water? 

None 

55

How is hypotonic saliva secreted?

A more concentrated solution is secreted, and solute is then reabsorbed from it to leave the final hypotonic solution 

56

What do acinar cells secrete?

An isotonic fluid containing enzymes 

57

What do duct cells do? 

Remove Na+ and Cl- from fluid secreted from acinar cells, and add HCO3-

58

How do duct cells ensure that saliva remains hypotonic? 

The gaps between duct cells are tight, and so water does not follow the osmotic gradient resulting from ion movement

59

What happens at low flow rate of saliva?

Regarding duct cells 

The duct cells have the opportunity to remove most Na+, so saliva is very hypotonic 

60

Can duct cells modify flow rate of saliva?

Yes, but their ability to do so is limited

61

What happens at high flow rate of saliva?

Regarding duct cells

A smaller fraction of Na+ is removed, and the saliva becomes less hypotonic

62

What does the stimulus for secretion promote?

Regarding ion movement

HCO3- secretion, therefore the saliva becomes more alkaline

63

How are Cl- ions secreted from acinar cells?

Actively 

64

What is the result of the active secretion of Cl- ions from acinar cells into the lumen of the duct?

Water and other ions (Na+will follow passively 

65

What transporter has a role in ductal modification? 

The Na/K-ATPase Antiporter

66

Where is the Na/K-ATPase involved in ductal modification located? 

In the basolateral membrane of duct cells 

67

What is the effect of the Na/K-ATPase antiporter in the duct cell membrane?

  • Lowers [Na+] inside the cell. This means there is a concentration gradient, where [Na+] is high in the duct lumen, and low in the duct cells. Na+ diffuses passively back into the duct cells 
  • Increases [K+] inside the cell. The resulting concentration gradient drives the expulsion of Cl- form the duct cells into the ECF. A concentration gradient is set up between the duct lumen and cells, with [Cl-] low inside, and [Cl-] high outside. This gradient drives the expulsion of HCO3- into the duct lumen. 

68

Draw a diagram illustrating ion transport between the duct and the ECF

69

What is salivary secretion controlled by?

Mostly the autonomic nervous system 

70

What is the effect of parasympathetic stimulation on the salivary gland?

  • Increases the production of primary secretion (acinar cells)
  • Increases the addition of HCO3- (duct cells)

71

What is the parasympathetic innervation of the parotid gland?

  • Glossopharyngeal nerve (9th cranial nerve)
  • Otic ganglion

72

What is the parasympathetic innervation of the submandibular and sublingual glands?

  • Facial nerve (7th cranial nerve)
  • Submandibular ganglion 

73

What kind of receptors mediate the parasympathetic innervation of salivary glands?

Muscarinic

74

What kind of drugs block the receptors responsible for parasympathetic innervation of the salivary glands?

Atropine-like drugs

75

What is the role of co-transmitters in the parasympathetic innervation of the salivary glands?

They stimulate extra blood flow 

76

What is parasympathetic outflow to the salivary glands mediated by? 

  • Centres in the medulla 
  • Afferent information from the mouth and tongue, nose, and conditioned reflexes 

77

What parts of the mouth and tongue mediate parasympathetic outflow to the salivary glands? 

Taste receptors, especially acid

78

What shows the effect of conditioned reflexes on the outflow to salivary glands? 

Pavlov's dogs

79

What is the effect of sympathetic stimulation on the salivary glands? 

Reduces blood flow, limiting salivary flow and producing the typical dry mouth of anxiety

80

What provides sympathetic innervation to the salivary glands? 

Superior cervical ganglion 

81

What increases the rate of ductal recovery of Na+?

The release of aldosterone from the adrenal cortex (increase in ENaC, therefore increase in Na/K-ATPase)

82

What is the result of the increase in ductal recovery of Na+?

Makes saliva even more hypotonic

83

What must happen once food has been matiscated and mixed with saliva to form a bolus? 

It must be swallowed

84

What are the phases of swallowing? 

  1. Voluntary phase
  2. Pharyngeal phase
  3. Oesophageal phase

85

What happens during the voluntary phase of swallowing? 

Tongue moves the bolus back onto the pharynx

86

What happens during the pharyngeal phase of swallowing? 

  • Afferent information from pressure receptors in the palate and anterior pharynx reaches the swallowing centre of the brain stem 
  • A set of movements is triggered

87

What movements are inhibited in the pharyngeal phase of swallowing? 

  • Inhibition of breathing
  • Raising of the larynx
  • Closure of the glottis
  • Opening of the upper oesophageal 'sphincter'

88

What kind of muscle is found in the upper third of the oesophagus, and what kind of control is it under? 

  • Striated muscle
  • Under voluntary, somatic control

89

What kind of muscle is found in the lower two thirds of the oesophagus, and what kind of control is it under? 

  • Smooth muscle
  • Parasympathetic control

90

What happens in the oesophageal phase of swallowing? 

A wave of peristalsis sweeps down the oesophagus, propelling the bolus to the stomach

91

How long does the oesophageal phase take to propel the food bolus to the stomach? 

~9 seconds

92

What is the oesophageal phase of swallowing coordinated by?

Extrinsic nerves from the swallowing centre of the brain 

93

What happens once the food bolus has been propelled to the stomach by the oesophageal phase? 

The lower oesophageal 'sphincter' opens 

94

What is dysphagia? 

The symptom of difficulty in swallowing

95

What is odynophagia? 

The symptom of pain whilst swallowing

96

What may dysphagia be a consequence of? 

  • A primary oesophageal disorder
  • A secondary consequence of another tissue

97

Give an example of a primary oesophageal disorder causing dysphagia? 

Achalasia 

98

What is achalasia? 

Motility problems of the smooth muscle preventing peristalsis 

99

Give an example of a secondary condition that may cause dysphagia? 

Obstruction or compression of the oesophagus due to a tumour

100

Broadly speaking, what can dysphagia be split into? 

  • Dysphagia for solids
  • Dysphagia for liquids

101

What is dysphagia for solids called? 

Oesophageal dysphagia 

102

How is oesophageal dysphagia investigated? 

Barium swallow or endoscopy 

103

What is dysphagia for liquids called? 

Oropharyngeal dysphagia 

104

How is oropharyngeal dysphagia investigated? 

A flexible endoscopy evaluation of swallowing

105

What does a flexible endoscopy evaluation of swallowing allow? 

For you to view the entire trachea/oesophagus 

106

What is oropharyngeal dysphagia most commonly due to? 

Stroke 

107

What does the stomach produce to aid the digestion of food? 

  • Strong acids (HCl)
  • Enzymes (pepsin)

108

What protects the stomach from its potentially harmful products? 

The mucosa of the stomach

109

How is the oesophagus protected from the potentially harmful products of the stomach? 

By a one way valve mechanism at it's junction with the stomach

Does not have the mucosal protection that the stomach does

110

What is the one way valve protecting the oesophagus from stomach products called? 

The lower oesophageal sphincter

111

What is the lower oesophageal sphincter coupled with? 

The angle of His, which is formed at this point

112

What does the lower oesophageal sphincter and the angle of His work together to do? 

Prevent the contents of the stomach refluxing back into the oesophagus 

113

What does the crus of the diaphragm do? 

Helps with the sphincteric action 

114

What are the clinical consequences of free gastro-oesophageal reflux? 

  • Barrett's Oesophagus 
  • Gastro-oesophageal reflux disease (GORD)

115

What is Barrett's Oesophagus? 

An abnormal change in epithelial cells of the oesophagus 

116

What is the pathological process in Barrett's Oesophagus? 

This is a metaplasia from non-keratinised stratified squamous epithelia to columnar epithelium and goblet cells. 

This is an attempt to better resist the harmful contents of the stomach 

117

What is Barrett's oesophagus strongly associated with? 

Adenocarcinoma, a particularly lethal cancer

118

What happens in GORD?

The reflex of the stomach's contents into the oesophagus and pharynx causes several symptoms, including; 

  • Cough
  • Hoarseness
  • Asthma

All symptoms result from the acidic contents of the stomach refluxing back out