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Semester 4 > PBL 1 > Flashcards

PBL 1 Flashcards

1
Q

What are the two plexuses of the ENS and where are they found?

A

Submucosal plexus (Meissner’s plexus) - lies in the submucosa layer

Myenteric plexus - lies in the muscularis externa layer

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2
Q

Describe the concept of the ‘Gut brain’

A

Neurons in the submucosal and myenteric plexuses have their own neuronal cell bodies, therefore are able to function on their own, independent of extrinsic nerve fibres from the CNS

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3
Q

What are pacesetter cells?

A

Cells found in the smooth muscle of the digestive tract, which set rhythmic cycles of activity in the muscle. They undergo spontaneous depolarisation, triggering waves of contraction that spread throughout the muscle

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4
Q

Which plexus of the ENS is responsible for controlling peristalsis waves?

A

Myenteric plexus in the muscularis externa

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5
Q

What is the difference between primary and secondary peristalsis?

A

Primary - coordinated by afferent and efferent fibres in glossopharngeal and vagus nerves

Secondary - local reflexes which are stimulated by the presence of ‘stuck bolus’ in the oesophageal walls

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6
Q

What are the various things that happen in the pharyngeal stage of swallowing?

A

Pharynx contracts
Upper oesophageal sphincter opens
Airways closes
Larynx is elevated - causes epiglottis to swing back

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7
Q

How does the type of muscle change down the oesophagus?

A

Upper 1/3rd - striated/skeletal
Middle 1/3rd - mixed skeletal and smooth
Lower 1/3rd - smooth muscle

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8
Q

What vertebral levels are the upper and lower oesophageal sphincters at?

A

UOS: C6
LOS: T11

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9
Q

What are the pressure levels at the upper and lower oesophageal sphincters?

Why are these pressures high?

A

UOS: 100mmHg
LOS: 20mmHg

Ensure that they remain closed apart from during swallowing

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10
Q

How is swallowing controlled by the brain?

A
  • Sensory receptors in the oropharynx, larynx and oesophagus detect changes and send signals back to the brainstem
  • The brainstem central program generator (CPG) in the medulla send signals through the motor neurons V, VII, XI, X, XII to control the muscles involved in swallowing
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11
Q

What are the two types of saliva and what do they contain?

A

Serous secretion - contains ptyalin (alpha amylase), good for digesting starches
Mucous secretion - contains mucin, used for lubricating

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12
Q

What are the four classes of salivary glands and what type of secretion do they have?

A

Parotid glands - serous secretion
Submandibular - serous/mucous secretion
Sublingual - mucous secretion
Buccal - mucous secretion

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13
Q

What are the two stages of saliva secretion?

A

1) Primary secretion by the acinis

2) Reabsorption on ions by the salivary ducts

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14
Q

How does the rate of saliva secretion effect the composition?

A

The faster the secretion, the more salty the secretion, as there is less time for reabsorption by the salivary ducts

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15
Q

What happens in primary secretion of saliva by acini?

A

Calcium activitied chloride channel allows Cl- efflux into the salivary duct lumen
The negative potential created by chloride causes Na+ to enter the lumen via tight junctions
Water follows via osmosis through aquaporin 5 channels

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16
Q

How is tight junction permability in epithelium determined?

A

By claudin family proteins:

  • some claudin don’t have any pores - won’t let anything through
  • some claudin have pores that are selective to sodium - will let sodium through
17
Q

What happens during reabsorption in the salivary ducts?

A

Sodium and chloride ions are reabsorbed into epithelial cells and into the blood

  • sodium enters passively through ENaC channel
  • chloride is drawn in through channel through positive potential
  • chloride is also exchanged for bicarbonate
18
Q

What happens during parasympathetic innervation of salivary glands?

A

Ach is released which binds to muscarinic receptors on acini
This produces IP3, which in turn causes calcium release in epithelial cells
Calcium activates Cl- and K+ transporters to stimulate ion release from acini

19
Q

What happens during sympathetic innervation of salivary glands?

A

There is a slight stimulation of salivary release, but much less so than parasympathetic stimulation

20
Q

What are the 2 types of dysphagia?

A 
Oropharyngeal dysphagia (high dysphagia) - problems with swallowing in the mouth or throat 
Oesophageal dysphagia (low dysphagia) - problems with swallowing in the oesophagus
21
Q

What are the main causes of Oropharyngeal dysphagia?

A

Zenker’s Diverticulum (Anatomical) - decreased compliance of cricopharyngeus (UOS)
Stroke (Neurological) -
Myasthenia Gravis (Muscular) - weak pharyngeal contraction

22
Q

How can stoke lead to aspiration Pneumonia?

A

Stroke can cause dysphagia
Inability to swallow food can lead to it going down wrong hole
Inhalation of stomach contents or secretions into the respiratory tract can lead to infection

23
Q

What is videofluorscopy?

A

Patient swallows barium while in a fluoroscope (x ray)

You can then determine where the bolus is going

24
Q

What is a fiberoptic endoscopic examination?

A

Where an endoscope is passed through the nose to get a view of the pharynx and larynx

Good at looking at anatomy but not for function

25
Q

What is a manometry?

A

Catheter is passed through the nose into the oesophagus and measures the pressures generated within the region of the LOS and the oesophagus

26
Q

What is the difference between parenteral nutrition and enteral nutrition?

A

Parenteral nutrition - infusion of nutrients into the bloodstream through a peripheral vein

Enteral nutrition - feeding of nutrients place through a tube into the gut

27
Q

What is PEG feeding?

A

PEG (percutaneous endoscopic gastrostomy) is an endoscopic medial procedure in which a tube is passed into a patients stomach through the abdominal wall, to provide a means of feeding when oral intake is not adequate

28
Q

What is the pathophysiology of GORD?

A

Antireflux mechanisms fail, allowing acidic gastric contents to make prolonged contact with the lower oesophageal mucosa

LOS relaxes independently of swallowing, allowing contents of stomach to reflux

29
Q

What is Barett’s oesophagus?

A

Where the normal squamous epithelium of oesophagus is replaced by metaplastic columnar mucosa

30
Q

What are the two types of oesophagus cancer and where in the oesophagus do they occur?

A

Squamous cell carcinoma - occur in the upper and middle third
Adenocarcinoma - occur in the lower third

31
Q

What type of oesophageal cancer can be caused by Barrett’s oesophagus?

A

Adenocarcinoma

32
Q

What is achalasia?

A

A rare disorder of the oesophagus where the LOS can fail to open properly, or doesn’t open at all. Food becomes stuck and is often brought back up

33
Q

What are the current management options for achalasia?

A

Botulinum toxin - inhibits LOS contraction
Pneumatic dilation - places balloon across LOS
Heller myotomy - surgical correction of LOS

34
Q

What is the difference between active and passive euthanasia?

A

Active - when a person deliberately causes a patients death (e.g, give an overdose of painkillers)
Passive - when a person doesn’t directly take the patients life, but allows them to die by withdrawing or withholding treatment

35
Q

What is the difference between voluntary and involuntary euthanasia?

A

Voluntary - occurs at the request of the person who dies
Involuntary - occurs when the person is unable to make a decision (e.g, due to being unconscious or unable to make decision)

36
Q

What is indirect euthanasia

A

This is where you provide treatment (usually to reduce pain) which has a side effect of speeding up the patients death

37
Q

What is the difference between absolute and relative poverty?

A

Absolute - poverty level relative to a fixed standard of living
Relative - being less than 60% of the median income of the whole population

38
Q

What is the inverse care law

A

The people who need healthcare the most get it the least

The people who need healthcare the least get it the most

39
Q

Where is the swallowing centre that controls the pharyngeal phase of swallowing?

A

Medulla and pons

Semester 4 (10 decks)

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