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Gastrointestinal Biology > GB 4. Swallowing > Flashcards

GB 4. Swallowing Flashcards

1
Q

What is the “bird beak” appearance of the esophagus?

A

It is when there is narrowing of the esophagus and so, there is difficulty for food and liquids to enter the stomach

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2
Q

What are the 3 purposes/functions of chewing?

A

[1] lubricates food
[2] mixes food with salivary amylase
[3] mechanically breaks up food

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3
Q

What is another word for chewing?

A

Mastication

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4
Q

What is Mastication?

A

another word for chewing

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5
Q

Where does most carbohydrate (sugar) digestion occur?

A

It occurs in the duodenum due to the presence of pancreatic amylase

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6
Q

What are the 3 glands that produce saliva?

A

[1] Parotid Glands
[2] Sublingual Glands
[3] Submandibular Glands

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7
Q

What type of saliva is created by the Parotid glands?

A

a serous, watery secretion containing amylase

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8
Q

What type of saliva is created by the Sublingual glands?

A

mainly mucous

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9
Q

What type of saliva is created by the Submandibular glands?

A

mixed serous and mucous, viscous secretion containing mucins

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10
Q

What is another name for the Submandibular glands?

A

Subaxillary glands

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11
Q

What is another name for the Subaxillary glands?

A

Submandibular glands

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12
Q

Describe the characteristics and composition of saliva. [6]

A

[1] Mucins (Glycoproteins) present
[2] alpha-amylase (ptyalin) and lingual lipase
[3] immunoglobulins, lysozymes
- has a protective function
[4] Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, P04 2-
- as the rate of secretion changes, the concentration of ions change
[5] pH 6 to pH 8
- pH optimum for amylase = 7
[6] Hypotonic
- it is a bit watery (compared to blood and other things)

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13
Q

What are the functions of saliva?

A

[1] facilitates swallowing and speech
[2] solubilizes food for tasting
- saliva presents the fluid to taste buds
[3] starch digestion
[4] oral hygiene (lysozyme, IgA)
[5] buffering
- bicarbonate has an important role in preventing the pH from going too low

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14
Q

What is dysphagia?

A

difficulty swallowing

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15
Q

What is Xerostomia?

A

dry mouth

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16
Q

What occurs due to xerostomia?

A
  • dental caries (breakdown of teeth)
  • mouth infection
  • difficulty with speech
  • difficulty with taste
  • difficulty swallowing (dysphagia)
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17
Q

What is the difference between efferent and afferent nerves?

A

Efferent Nerves = motor neurons

Afferent Nerves = sensory neurons

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18
Q

Does parasympathetic stimulation increase or decrease saliva production? Does sympathetic stimulation increase or decrease saliva production?

A 
Parasympathetic = increase saliva production
Sympathetic = decrease saliva production
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19
Q

What nerves are involved with parasympathetic stimulation?

A

Cranial Nerve VII (facial)

Cranial Nerve IX (glossopharyngeal)

20
Q

Under parasympathetic stimulation, what changes are involved with it?

A

[1] Increased Secretion of Amylase
[2] Increased Secretion of Mucus
[3] Increased Blood Flow
[4] Increased Growth

21
Q

Under sympathetic stimulation, what changes are involved with it?

A

[1] Increased Secretion of Amylase
[2] Increased Secretion of Mucus
[3] Decreased Blood Flow

22
Q

Why does stress cause xerostomia?

A

Under stress, the sympathetic nervous system is stimulated - this constricts blood vessels (decreasing blood flow) and leads to decreased secretion of saliva

23
Q

What is Deglutition?

A

another word for swallowing

24
Q

What are the 3 phases of swallowing?

A

[1] Oral (Voluntary)
[2] Pharyngeal (Reflex)
[3] Esophageal (Reflex)

25
Q

Name the layers of the general cross section of the gastrointestinal tract from the outside in. [6]

A 
[1] Tunica Serosa
[2] Tunica Muscularis Externa
[3] Myenteric Plexus 
[4] Tunica Submucosa
[5] Muscularis Mucosae
[6] Lamina Propria
26
Q

How many layers is the Muscularis Externa made up of what are they called?

A

[1] Longitudinal (outer)

[2] Circular (inner)

27
Q

Where is the Myenteric (Auerbach’s) Plexus located?

A

It is located between the muscularis externa layers

28
Q

Where is the Submucosal (Meissner’s) Plexus located?

A

It is located below the muscularis externa.

29
Q

Name the layers of the general cross section of the GIT from inside out.

A 
[1] Mucosa
(a) Epithelium
(b) Lamina Propria
[2] Muscularis Mucosae
[3] Submucosa
[4] Muscularis Externa
(a) Circular Muscle Layer
(b) Longitudinal Muscle Layer
[5] Serosa
30
Q

Explain the intrinsic and extrinsic control in the gut wall?

A

REFER TO SLIDE 16
- there are chemo-, osmo- and mechanoreceptors in the gut wall

  • the receptors react in response to the stimulus in the lumen

INTRINSIC:

  • receptors feed into intramural plexuses
  • intramural plexuses have an effect on the smooth muscle, exocrine cells and endocrine cells

EXTRINSIC:

  • receptors send signals to CNS through the afferent nerves
  • the CNS controls the sympathetic and parasympathetic efferents to the intramural plexuses

*side note: other inputs (like stress) have an input on the CNS

31
Q

Where do the sympathetic and parasympathetic nerves typically end?

A

typically ends on the plexuses, not on the smooth muscles or the glands

32
Q

What is the pharyngeal phase? (general overview)

A
  • tongue pushes food to back of the throat

- the food enters the pharynx

33
Q

What are the afferent and efferent nerves involved in the pharyngeal phase?

A

AFFERENTS:

  • cranial nerves 5, 9 and 10
  • nerves from pharynx relay to the swallowing centre in the PONS and MEDULLA

EFFERENTS:
- 5, 7, 9, 10 and 12 nerves

34
Q

What are the events that occur in the pharyngeal phase?

A
  • soft palate is raised
  • vocal folds approximate
  • larynx is raised
  • epiglottis swings back
  • upper esophageal sphincter (UES) relaxes
  • superior pharyngeal constrictor contracts
  • initiates peristaltic wave!

side note: lasts 1 second + breathing inhibited

35
Q

What type of muscle is involved in swallowing?

A

striated muscle

36
Q

What might impair swallowing?

A

striated muscle involved in swallowing

- conditions which affect striated muscle (e.g. stroke, myasthenia gravis, parkinson’s disease, MS etc….)

37
Q

What are the events that occur in the esophageal phase?

A
  • UES contracts
  • primary peristaltic wave moves to the lES
  • secondary peristaltic waves clear the esophagus of food
  • controlled by vagal and intrinsic reflexes
38
Q

What nerves control the esophageal phase?

A
  • controlled by vagal and intrinsic reflexes
39
Q

Describe the composition of the esophageal wall.

A

First 1/3:
- striated muscle

Middle 1/3:
- striated + smooth muscle

Last 1/3:
- smooth muscle

40
Q

What is vomiting (emesis) preceded by?

A
  • nausea
  • salivation
  • sweating
  • pallor
  • mydriasis
  • irregular heart rate
41
Q

What are the nerves involved with vomiting? (the afferents and efferents)

A
  • afferents from stomach and duodenum to sympathetics and nerve 10 to VOMITING CENTRE + MEDULLA
  • efferents in 5, 7, 9, 10 and 12 nerves
42
Q

What is the cause of emesis (vomiting)?

A
  • distension of the stomach and duodenum
  • motion
  • psychic stimuli
  • pain
  • increased intracranial pressure
  • tactile stimulation of the back of the throat
  • pregnancy
43
Q

What are some emetics?

A
  • cytotoxic drugs
  • morphine
  • uraemia (build up of waste)
  • endogenous substances released from radiotherapy, infection or disease
44
Q

What are the receptors and nerve processes involved in emesis?

A
  • emetics acting on receptors in the stomach/duodenum and on the chemoreceptor trigger zone in the medulla (e.g. the area postrema, part of the circumventricular organ system)
45
Q

What are the physiological responses to vomiting (emesis)?

A
  • antiperistalsis in small intestine
  • relaxation of pylorus and stomach
  • muller’s manoeuvre
  • elevation of larynx
  • elevation of soft palate
  • contraction of abdominal muscles
  • relaxation of LES, esophagus and UES

*side note: the contraction of diaphragm and abdominal muscles squish the relaxed stomach

46
Q

What is Muller’s Manoeuvre?

A

it is forced inspiration against the closed epiglottis

- this leads to negative pressure in the body since not really breathing in

Gastrointestinal Biology (15 decks)

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