Anatomy and physiology of the bowel

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ANATOMY PHYSIOLOGY OF THE BOWEL Gill
Nottidge Continence Nurse Specialist
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5 Main functions of the bowel

• Storage unabsorbed food residue
• Absorption Minerals, water, fats
• Secretion Mucus secreted by the colon to help
  lubricate the faeces

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5 Main functions of the bowel

• Synthesis Synthesises some vitamins
• Elimination Propulsion of faecal matter and
  absorption of fluid

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Digestion period

• Stomach
• 3hours
• Small intestine
• 4 6 hours
• Large intestine
• 12 72 hours

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Small intestine

• Duodenum
• 25-30cm
• Jejunum
• 2 metres
• Ileum
• 3 metres

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Small intestine
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Large intestine

• Caecum with appendix
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

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Structure of intestine

• Small large intestine has 4 layers
• Peritoneal
• Muscular
• Submucosal
• Mucosal

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Excretion

• How does it work?
• Muscles work together to propel waste matter
• (Peristalsis)
• During process substances not absorbed by the
  body becomes faeces
• Faeces arrives in rectum to be expelled

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Normal Defaecation

• Full rectum
• Adopt correct posture
• Raise intra-abdominal pressure
• Internal and external anal sphincters relax
• Rectum contracts to expel stool
• Should pass soft formed stool with minimal
  effort
• Sphincter snaps shut after completion
• Normal 3 times / day to 3 times / week

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Normal Defaecation
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Bristol Stool Chart
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What affects the bowel?

• Poor diet
• Lack of fluid
• Mobility
• Medications
• Surgery

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• Continence is Complex

• Anal sphincters (structural integrity, residual
  function if damaged)
• Internal anal sphincter - passive stool retention
• External anal sphincter- control of urge to stool
• Pelvic floor and mucosal seal
• Sensory function and co-ordination
• Stool consistency (e.g. diet)
• Gut motility
• Emotional factors
• Lifestyle and toilet access

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• What Goes Wrong?

• Anal sphincter (childbirth, injury, iatrogenic
  damage, degeneration)
• Internal - passive soiling External - urge
  incontinence
• Gut motility (infection, inflammation, radiation,
  hypermotility, emotions)
• Stool consistency (diet, motility, anxiety

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What Goes Wrong?

• Local pathology (prolapse, piles, fistula)
• Neurological damage (motor or sensory)
• Lifestyle, toilets, drugs,immobility, frailty
• Impaction with overflow diarrhoea most
• common in frail dependent individuals

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Facts

• The UK is the most constipated nation in the
  world
• The UK has the highest incidence of bowel cancer
  in the world with 20,000 new cases per year
• One in three people consulting GPs have a bowel
  problem
• Bowel disorders such as irritable bowel syndrome,
  colitis, crohns disease and diverticulitus are
  now widespread

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Severe Constipation
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Thank you for your attention. Any
questions? Gill Nottidge Tel 01274
322210 Gillian.nottidge_at_bradford.nhs.uk