1. Continence Nurse Specialist
ANATOMY & PHYSIOLOGY
OF THE BOWEL
Gill Nottidge
Continence Nurse Specialist

2. CC01 Assess bladder and bowel dysfunction
an in-depth understanding of the anatomy and physiology of the male and female lower gastro intestinal tract in relation to lower bowel function and continence status including:
a) stool production and what influences this
b) normal defaecation
c) the nervous system including autonomic dysreflexia
d) the bowel
e) the pelvic floor/complex and anal sphincter muscles
f) the endocrine system
g) reflexes

3. Digestion period Stomach: 3hours – converted to chyme Small intestine:
Large intestine:
12 – 72 hours
food goes through varying stages of digestion and takes varying lengths of time. Can you tell me how long it takes for the:
Stomach
Small intestine
Large intestine
The bowel consist of two sections:
The small intestine and large intestine
Colonic movement can be stimulated by anger, physical exercise, medications such as laxatives and the old Deli Belly, better known as gastroenteritis
Factors that alter colonic movement are sleep, anxiety, fear and in some cases change of environment

4. 5 Main functions of the bowel
Absorption – Minerals, water, fats, medicines
Secretion – Enzymes secreted by the small intestine
Mucus secreted by the colon to help lubricate the faeces
Synthesis – Synthesises some vitamins
Storage – unabsorbed food residue
Elimination – Propulsion of faecal matter and absorption of fluid
The bowel has 5 functions can you think what they are??
STORAGE: The colon stores unabsorbed food residue but within 72 hours 70% of this will have been excreted.
The other 30% can stay in the colon for a further week or more
ABSORPTION: The bowel is responsible for absorbing minerals, water and fats. Sodium, chloride
Drugs are also absorbed or metabolised through the colon
eg: aspirin, steroids. Some antimuscarinic drugs
Diazepam can also be given rectally
SECRETIONS: Mucus is secreted by the colon.
This helps to lubricate the faeces during the passing of the stool.

5. Small intestine Duodenum 12 ins Jejunum 5-8 feet Ileum 16-20 feet
Goblet cells in the mucosa produce mucus.
The duodenum is the major portion of the small intestine where enzyme secretion takes place.
The small intestine in adults is approximately 22 feet in length.
In newborn infants the small intestine is only 25% of its adult length and 13% of its diameter.
The absorptive surface in infants is 950cm whereas the average adult has about 7600cm.
So you can see the enormous growth that we have throughout our lives

6. Small intestine Absorptive surface in adults 7600cm
Lined with villi to increase surface area
90% of our daily fluid intake is absorbed in the small intestine

7. Large intestine 5-6 feet in length Caecum with appendix
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
In adults the large intestine is between 5 to 6 feet in length and varies in width from 1 to 2 1/2 inches.
There are 5 regions to the large intestine they are (what are they called):
Caecum with appendix
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Can any one tell me what the main functions of the large intestine are?
The function of the colon includes collection, absorption transportation and elimination of intestinal waste matter.
It is estimated that 2 litres of fluid is passed through the small intestine into the caecum every day.
After water, electrolytes, glucose and urea have been absorbed, there is between 100 – 150mls of fluid left to be excreted.

8. Structure of intestine
Small & large intestine has 4 layers
Peritoneal
Muscular
Submucosal
Mucosal
Both the small and large intestine have four layers. These are:
Peritoneal or serous
Muscular – which consists of longitudinal and circular fibres only
Sub mucosal and mucosal – In the small intestine the submucosal and mucosal layers are arranged in folds. This helps to significantly increase the absorptive surface

9. Peristalsis 2-3 mass peristaltic movements per day
Stimulated by consumption of food and warm drinks

10. 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
SO HOW IS THE FAECES EXCRETED:
The muscles in the colon work together to propel the waste matter through the colon. This is called peristalsis
During this process substances which cannot be utilised by the body are transformed into faeces.
Eventually the faeces arrives in the rectum to be expelled. So what happens then?

11. Sampling of bowel contents at dentate line
Internal sphincter contributes 85% of resting anal tone. Weakness of this sphincter may result in passive incontinence
External sphincter is striated muscle – contributes 15% towards resting anal tone
Responsible for voluntary contraction of sphincter. Weakness of EAS may result in urge incontinence
Rectal sampling with IAS

12. +
The rectum is S Shaped and leads outwards through the anus. The rectum has the ability to distend in order to accommodate the faeces.
The anal canal is slightly shorter in women than in men and is surrounded by the two cylinders of muscle called the internal and external sphincters
as you can see the muscle surrounding the rectum (which is part of the pelvic floor) helps to maintain a right angle between the anus and rectum.
This acts as a barrier and stops faeces from escaping
Both the internal and external sphincters are contracted.
With the rectum and anus in this position the person can remain continent

13. This picture shows what happens when we are ready to pass the stool.
The rectum begins to expand with the pressure of the faeces.
stretch receptors send signals to the brain.
In normal circumstances we can differentiate between flatus and stool.
When we have decided it is faeces the internal sphincter begins to open.If it is appropriate to carry on the external sphincter and muscular sling will also relax.
The rectum contracts and abdominal pressure increases and with a bit of luck you will be able to pass it.

14. Pelvic floor muscles Supports the pelvic organs
Contraction causes urethral compression – helps maintain continence during abdominal pressure
Collectively called “Levator Ani”
Striated muscle slow and fast
muscle fibres
(under Voluntary control)

15. 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
Normal stool output is about 200g a day.
Production affected by gender, diet and health
Movement of faeces into rectum initiates call to stool.

16. Correct position

17. Bristol Stool Chart
Bristol Stool chart useful tool when assessing bowels for both patient and nurse

18. What affects the bowel? Poor diet Lack of fluid Mobility Medications
Surgery
Diet plays a key role in the healthy bowel. It important to get a good balance of both fruit and fibre
However it is equally important to have an adequate fluid supply. If you have too much fibre without sufficient fluid that can cause constipation
Lack of mobility or exercise can cause the body to become sluggish causing the transit times to be decreased which in turn can cause increased bulking in the bowel. If the rectum becomes impacted it loses the S shape therefore making it more difficult for the rectum to contract
Certain medications can cause constipation can you tell me what these are
Surgery can also cause the body to become sluggish which is due to a number of factors such as the general anaesthetic, lack of mobility and poor diet and fluid

19. 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

20. Effect of endocrine system
Pancreas – Diabetes
Adrenal glands – fight/flight
Corticotrophin-releasing factor (CRF) – (Stress hormone) eg. IBS
The adrenal medulla produces adrenaline and noradrenaline, substances that increase the heart rate and blood pressure during times of stress. Their action is referred to as the "fight-or-flight" response.
Hydrocortisone reduces the amount of glucose absorbed by muscles and adipose tissue. Another function of cortisol is to protect the body from the adverse affects of stress, including emotional and physical trauma.
GH), has a central role in controlling the growth and development of the body and its components, including organs, tissue, and muscle. It also affects the metabolism of carbohydrates,
protein, and fat. For example, GH increases glucose levels in the blood by reducing the amount of glucose used by muscle cells and adipose tissue and by promoting glucose production from certain liver molecules.
CRF is the brain’s “stress hormone.” When stimulated, it
interacts with many systems within the body.
These interactions include those between the brain and the
digestive tract. They effect whether or not we feel discomfort or
pain, and the way our bowels move.
In some people, the stress response is overactive. When the
stress response is out of balance, unwanted symptoms can
result.

21. Nervous system Vagus nerves – stimulate acid secretion
Intestine – sympathetic and parasympathetic nerve supply - sub mucosa
Internal sphincter – autonomic (smooth muscle)
External sphincter – under voluntary control (striated muscle)
Between the two muscle layers the blood vessels, lymph
vessels and the major nerve supply to the GI tract can be
found. The nerve supply is called the mesenteric or Auerbach’s
plexus, and it consists of both sympathetic and parasympathetic
nerves. It is mostly responsible for GI motility, which is
the ability of the GI tract to move spontaneously (Tucker 2002;
Martini 2004).
Submucosa
The submucous layer is highly vascular as it houses plexuses
of blood vessels, nerves and lymph vessels, and tissue. It consists
of connective tissue and elastic fibres. It also contains the
submucosal or Meissner’s plexus, which is important in controlling
the secretions in the GI tract (Martini 2004).
Mucosa

22. Reflexes Anal wink Anal reflex Perineal reflex
Reflexive contraction of external anal sphincter on touching/stimulation
A noxious or tactile stimulus will cause a wink contraction of the anal sphincter muscles and also flexion. The stimulus is detected by the nociceptors in the perineal skin to the pudendal nerve, where a response is integrated by the spinal cord sacral segments S1-S3.
The absence of this reflex indicates that there is an interruption of the reflex arc, which may be in the sensory afferent limb or the motor efferent limb. The synapse between the afferent and efferent limbs occurs in the lowest sacral segments of the spinal cord.

23. WHAT IS AUTONOMIC DYSREFLEXIA?
It develops after spinal cord injury/ lesion at or above T6
Exaggerated response of nervous system to localised trigger below level of spinal cord injury
This causes an sudden extreme rise in blood pressure
It can occur without warning and is a medical emergency

24. Autonomic Dysreflexia
Normally a harmful stimulus causes the autonomic nervous system to respond resulting in a rise in blood pressure.
If T6 lesion or above present, stimulus below the injury causes BP to rise, but autonomic nervous system does not act to lower it below the lesion.
Therefore BP continues to rise until stimulus is removed
Autonomic nervous system attempts to lower BP above lesion: this causes the symptoms that aid the diagnosis of AD

25. Signs and symptoms Stuffy nose / nasal obstruction
Severe pounding headache, usually frontal
Raised BP (by 20mm/hg) / bradycardia
Cutis anserina (goose bumps) above and possibly below level of SCI and shivering
Flushing above level of lesion due to vasodilatation
Reduced urine output
Blurring vision – spots before eyes
Increased spasms

26. 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)

27. 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

28. Facts
Annual spend on laxatives in the UK is £50 million per year. (DH 2001)
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 affect 1:250 people in the UK (National association for colitis and crohn’s disease 2010)
Just a few facts
The UK is the most constipated nation in the world. Why do you think that is?
The UK has the highest incidence of bowel cancer in the world. Not a nice statistic to have.
Can anyone tell me the causes of bowel cancer.
Diet
Long term conditions
Inactive lifestyles
Family history
Old age
1 in 3 need to see the GP with a bowel problem, that’s a lot of people
Bowel disorder are now widespread do you think this is due to the same reason as with bowel cancer

29. Constipation!

30. Thank you for your attention.
Any questions?
Gill Nottidge
Tel: