Defecation Flashcards

1
Q

Which part of the yolk sac is the primitive gut tube derived from

A

Dorsal

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2
Q

3 parts of the gut

A

Foregut
Midgut
Hindgut

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3
Q

Oesophageal atresia

A

Part of oesophagus closed or absent

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4
Q

Trachea oesophageal fistula

A

I abnormal connection between oesophagus and trachea

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5
Q

Duodenal atresia

A

Part of duodenum closed or absent

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6
Q

Meckels diverticulum

A

Vitelline duct persists

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7
Q

Vitelline duct

A

embryonic structure providing communication from the yolk sac to the midgut during fetal development

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8
Q

What causes malrotation

A

Midgut does not complete rotation before returning to abdomen

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9
Q

Mid gut volvulus

A

Volvulus around base of midgut causes bowel obstruction and mesenteric ischaemia

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10
Q

What defect predisposes a foetus to mid gut Volvos

A

Malrotation

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11
Q

What causes imperforate anus

A

Failure of rupture of anal membrane

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12
Q

What causes Hirschsprung’s disease

A

Lack of enteric neurones in distal portion of the gut

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13
Q

What organ is enlarged in Hirschsprung’s disease

A

Colon - megacolon

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14
Q

Hirschsprung’s disease symptoms

A

Failure to pass meconium within 48 hrs
Swollen belly
Vomiting bile

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15
Q

What part of the gut is abnormal in Hirschsprung’s disease

A

Distal part

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16
Q

Why does a lack of enteric neurones cause symptoms in Hirschsprung’s disease

A

Can’t relax gut muscles

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17
Q

How long does microbial colonisation of the infant gut take

A

1 year

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18
Q

What is examined in a stool sample

A

Metabolites
Microbes

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19
Q

Causes of incontinence

A

Sphincter is dysfunctiom
Impaired rectal sensorimotor function
Colonic sensorimotor dysfunction
Supra sphincteric Anatomical factors

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20
Q

What are the 2 anal sphincters

A

Internal anal sphincter
External anal sphincter

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21
Q

Which anal sphincter is voluntary muscle

A

External

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22
Q

Which anal sphincter encircles the other

A

External

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23
Q

Which anal sphincter extends further downwards

A

External

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24
Q

Which muscle group makes up the pelvic floor

A

Levator ani

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25
Q

Which muscles make up Levator ani

A

Puborectalis
Pubococcygeus
Iliococcygeus

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26
Q

What pelvic floor muscle is only present in males

A

Puboerythralis

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27
Q

What pelvic floor muscle is only present in females

A

Pubovaginalis

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28
Q

What structures does Puborectalis surround

A

Rectum
Vagina
Urethra

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29
Q

Which pelvic floor muscle forms a U shaped loop

A

Puborectalis

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30
Q

Function of Puborectalis

A

Supports EAS
Assists in creating anorectal angle

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31
Q

Which nerve roots supply the rectum, anus, bladder, and urethra

A

S2, s3, s4
S2 s3 s4 keep the 3 Ps off the floor

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32
Q

What nerve is responsible for continence

A

Pudendal nerve

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33
Q

Is the pudendal nerve sympathetic or parasympathetic

A

Parasympathetic

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34
Q

Nerve roots of pudendal nerve

A

S2-s4

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35
Q

What nerve supplies the EAS

A

inferior rectal branch of the pudendal nerve

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36
Q

Terminal branches of the pudendal nerve

A

Perineal nerve
Inferior rectal nerves
Dorsal nerve of the penis/clitoris

37
Q

Which nervous system innervates the IAS

A

Enteric nervous system

38
Q

Which nerves innervate the IAS

A

Hypogastric nerves - sympathetic + excitatory
Pelvic nerve - parasympathetic + inhibitory

39
Q

Do the pelvic nerves give excitatory or inhibitory innervation to the IAS

A

Inhibitory

40
Q

Do the hypogastric nerves supply excitatory or inhibitory innervation to the IAS

A

excitatory

41
Q

What factors effect continence

A

Anorectal angle
Stool consistency
Colonic transit time
Rectal filling sensation
Rectoanal inhibitory reflex

42
Q

What type of valve does the anorectal angle form

A

Flap valve

43
Q

How is passage of faeces prevented when intra abdominal pressure rises

A

Anterior rectal wall pushed downwards onto anal canal

44
Q

Reservoir continence

A

Ability of rectum to retain stool

45
Q

What features of the sigmoid colon slow the progression of stool

A

Lateral angulations
Valves of houston

46
Q

Rectal compliance

A

Ability of rectum to adapt to imposed stretch

47
Q

What type of receptors pick up sensation of urgency

A

Mechanoreceptors

48
Q

Which sphincter is more important for continence at rest

A

Internal anal sphincter

49
Q

What type of muscle fibre is predominant in the IAS

A

Slow twitch, fatigue resistant smooth muscle fibres

50
Q

Which anal sphincter is more important for generating squeeze pressure

A

EAS

51
Q

Rectoanal inhibitory reflex RAIR

A

anal reflex response characterized by a transient relaxation of the anal canal following distention of the rectum

52
Q

What 2 reflexes are involved in defecation

A

Voiding reflex
Closure reflex

53
Q

Voiding reflex

A

Opening of anus

54
Q

Closure reflex

A

Closing anus

55
Q

How is the anorectal angle broadened during defecation

A

Relaxation of EAS
Relaxation of puborectalis

56
Q

What manoeuvre is used to empty the anal canal

A

Valsalva manoeuvre

57
Q

What is the purpose of recto sigmoidal contractions

A

Push stool through relaxed anal canal during emptying

58
Q

What causes contraction of IAS in the closure reflex

A

Receptor adaptation of ampulla rectus removes inhibitory drive to IAS

59
Q

What causes contraction of EAS in the closure reflex

A

Voluntary contraction

60
Q

2 main categories of clinical problems in defecation

A

Constipation
Faecal incontinence

61
Q

What is the Bristol scale used for

A

Describing stool consistency

62
Q

Is constipation a symptom or a diagnosis

A

Symptom

63
Q

Constipation definition

A

<3 stools/wk or passage of hard stools or sensation of complete evacuation

64
Q

What groups is constipation more common in

A

Elderly
Children
Females more than males

65
Q

What does the Rome IV diagnostic criteria assess

A

IBS, constipation, functional defecation disorders functional abdominal bloating

66
Q

Primary constipation

A

Constipation with no identifiable cause

67
Q

Types of primary constipation

A

Normal transit constipation
Slow transit constipation
Pelvic floor dyssynergia

68
Q

Pelvic floor dyssynergia

A

Inability to coordinate sphincters, abdominal, and pelvic floor muscles

69
Q

What structural abnormalities can cause constipation

A

Rectal intussesception
Rectal prolapse

70
Q

Rectal intussesception

A

invagination of the rectal wall into the lumen of the rectum

71
Q

Secondary constipation

A

Constipation caused by neuromuscular disorders of the colom

72
Q

Faecal incontinence

A

Involuntary passage of rectal content

73
Q

External signs of faecal incontinence

A

Visible soiling
Excoriation
Scars

74
Q

2 types of faecal incontinence

A

Passive incontinence
Urge incontinence

75
Q

Which type of incontinence is caused by a lesion of the IAS

A

Passive

76
Q

What type of incontinence is caused by lesion of EAS

A

Urge incontinence

77
Q

Which type of incontinence is defecation not noticed

A

Passive

78
Q

Tests for colonic transit

A

Radio opaque markers
Colonic scintigraphy

79
Q

Evacuation tests

A

MRI proctogram
Evacuation proctogram
Balloon expulsion test

80
Q

Sphincter evaluation tests

A

Endoanal ultrasound
Endoanal MRI
Anorectal manometry

81
Q

What structural damage can cause incontinence

A

Obstetric sphincter tear
Latrogenic sphincter tear
Radiation damage
Congenital malformation

82
Q

What functional damage can cause incontinence

A

Pudendal neuropathy

83
Q

What does high resolution anorectal manometry assess

A

Resting pressure
Squeeze pressure
Endurance squeeze
RAIR
hyper/osensitivity

84
Q

Rectal hypersensitivity

A

Reduced sensory threshold to volumetric rectal distension

85
Q

Rectal hyposensitivity

A

Increased sensory threshold to volumetric rectal distension

86
Q

Is rectal hypersensitivity associated with incontinence or constipation

A

Incontinence

87
Q

Is rectal hyposensitivity associated with incontinence or constipation

A

Constipation

88
Q

presentation of constipation

A

Abdominal pain
Infrequent pass of bowel motion
Nausea
Vomiting
Bloating
Faecaloma

89
Q

How is constipation manages

A

Diet and lifestyle changes
Laxatives
Biofeedback
Intersphincteric Botox
Anal irrigation
Neuro modulation
ACE/DACE
stoma
Psychological therapy