Constipation Diarrhoea and IBS Flashcards
is constipation a disease
no it is not, mainly considered a symptom
some symptoms of constipation
Fewer than three bowel movements a week
Stools that are hard, dry, or lumpy Stools that are difficult or painful to pass
A feeling that not all stool has passed
may last for a short or long time and bowel patterns may vary
people more at risk of constipation
Women approx. 4 times more likely than men,
▪ especially during pregnancy
▪ after giving birth
older adults
non-Caucasians non-Hispanic blacks were twice as likely as non-Hispanic
whites
those who eat little to no fibre
those taking certain medicines or dietary supplements
those with certain health problems, including functional gastrointestinal disorders
women more likely due to hormonal factors and fluctuations during pregnancy, menstruation cycle…etc
note that againg may reduce gut motility, thereby resulting in constipation
how many types of stools according to bristol stool chart
7
Types 1 and 2 indicate
constipation.
Types 3 and 4 are the
easiest to pass.
Types 5-6 are more
symptomatic of diarrhea.
Type 7 may be a sign of
cholera or food
poisoning, etc.
constipation complications
haemorrhoids,
faecal impaction,
faecal impaction with spurious overflow,
urinary incontinence,
bladder outlet obstruction,
urinary tract infection,
rectal bleeding,
general weakness
psychological disorders
Hemorrhoids, also known as piles, are swollen veins in the anus and rectum that can cause discomfort
Fecal impaction is the result of constant constipation when poop is stuck inside of your rectum.
the Problems associated with Persistent straining in constipation leads to
increased intrathoracic pressure
a reduction in coronary and peripheral circulation
development of hernias
worsening of gastro-oesophageal reflux
transient ischaemic attacks (mini strokes, where blood flow to brain is reduced.)
A hernia occurs when an internal part of the body pushes through a weakness in the muscle or surrounding tissue wall
causes of constipation
conditions like coeliac disease, multiple sclerosis, cystic fibrosis…etc
hypothyroidism
some medications like opiods and antacids
low fibre intake
inadequate fluid intake
pelvic floor dysfunction
physical inactivity…etc
Coeliac disease is a chronic autoimmune disorder that occurs when the body’s immune system attacks the small intestine in response to gluten
Cystic fibrosis is an inherited condition that causes sticky mucus to build up in the lungs and digestive system
fibre functions(foods high in wheat grains, oats, or fruits & vegetables)
Bulks Up Stool: Fiber adds bulk to stool, which makes it easier to pass through the intestines. This helps prevent constipation and promotes regular bowel movements.
Stimulates Bowel Movements
feedsd gut microbiome…etc
we have soluble and insoluble fibres
non- pharmacological treatments to constipation
dietary adjustments, like taking in more fibres and fluids
oral rehydration solutions
rest and stress management
using natural probiotics or probiotic supplements
avoiding foods that cause it
increasing physical activity
Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. generally safe ti consume
pharmacological treatments to constipation
Laxatives
Anti-Diarrheal Medications, like loperamide and Bismuth Subsalicylate
prucalopride
Prokinetic Secretagogues
laxatives
types?
medicines that treat constipation by making stools softer or easier to pass
osmotic
stimulant
bulk
only use laxatives after lifestyle modifications, supplements and emollients or stool softners have been tried
how bulk laxatives work
The fibers in these laxatives absorb water like a sponge. When you ingest a bulk laxative, it takes in water from the intestines, which causes it to expand. As it swells, it increases the size of the stool inside the colon.
As the stool becomes bulkier, it stretches the walls of the intestines, stimulating peristalsis
works more gently compared to other 2 types.
are bulk laxatives soluble or absorbable from the intestines
are they excreted intact
no
They remain intact as they move through the digestive system, so they can directly affect stool consistency and volume
Yes, while some of the fiber may undergo fermentation by bacteria, much of the bulk-forming agent, especially the fiber like ispaghula husk, is excreted largely intact in the stool. This is actually one of the key features of how it works — it provides bulk and absorbs water in the intestines, but doesn’t get broken down, allowing it to have that beneficial effect on stool consistency.
composition of bulk laxatives
a special fibre called arabinoxylan a complex carbohydrate with a backbone made of xylose and side branches containing arabinose sugars.
these enhance it’s water absorbing properties
bulk laxatives are often referred to as mucilaginous fibres, why is this
because of their ability to form a gelatinous or gel-like mass when they absorb water. This gel further softens the stool and holds water within it, which is essential for preventing constipation and easing stool passage.
how are bulk laxatives digested
a small amount is fermented by faecal bacteria in our intestines, and the rest is excreted intact
the fermentation process can sometimes lead to flatulence and gas a by product
how do bulk laxatives affect the structure of the GI tract, consequently increasing peristalsis
Increased bulk adds extra weight to the material in the gut- generating more stretch of the gut wall
Stimulates stretch receptors
Activates ‘mechanoreceptors’
Leads to release of acetylcholine
ACh causes contraction of the intestines
Peristalsis is increased
Transit rate is increased
Transit time is reduced
The speed at which material moves through the GI tract.
The total duration it takes for material to travel through the GI tract.
describe the action of mechanoreceptors(like stretch receptors) that lead to an increase in peristalsis
they induce a neuronally mediated reflex contraction of the intestinal smooth muscle, while causing a descending relaxation of the smooth muscle.
This propulsion allows fecal matter to
move in the direction of the anus for
evacuation
surfactant laxatives and how they work
anionic detergents that lower the surface tension of stools, thereby softening the stool and enabling **water and lipid penetration into the faecal mass **
not effective for severe constipation, good for mild constipation
aka stool softners , they take 1-3 days to work
tenesmus (the feeling of needing to pass stool even though bowels are empty) is avoided when using these
is there is direct stimulation of peristalsis when using surfactant laxatives
no there is not
what is meant by straining in constipation
straining refers to the excessive effort or force applied during defecation to expel hard or compacted stool. This involves increased abdominal pressure through strong contraction of the abdominal and pelvic muscles.
in what instances should surfactant laxatives be used
They are commonly used in situations where straining should be avoided, such as:
Post-surgery
Hemorrhoids
Recovery from myocardial infarction..etc
osmotic laxatives and how they work
are a class of laxatives that promote bowel movements by drawing water into the intestines, softening the stool, and increasing its bulk to stimulate peristalsis (intestinal muscle contractions).
examples of osmotic laxatives
macrogol
lactulose
Magnesium hydroxide or magnesium sulphate
macrogol, what it is and how it works
A high molecular weight polyethylene glycol
is a non-absorbable polymer that retains water in the stool through osmotic action.
It increases stool volume and softens stool without causing significant electrolyte shifts
Treatment of chronic constipation.
aka polyethylene glycol
May take 1–2 days for effects at lower doses
lactulose, what it is and how it works
a synthetic disaccharide that is not absorbed in the small intestine.
lowers pH of the colon
increases osmotic pressure within the colon, drawing water into the colon.
increases stool water content
Useful in both constipation and hepatic encephalopathy
Can cause bloating, flatulence, and cramping due to bacterial fermentation
how is lactulose broken down in the colon
colonic bacteria breaks down lactulose into lactic acid, acetic acid and formic acid, lowering colon pH and increasing osmotic pressure in the colon
how is an acidic environment beneficial to the colon (normally alkaline)
Hepatic encephalopathy: Reduces ammonia levels by converting it to ammonium (NH4+), which is excreted in the stool. This reduces ammonia levels in the blood, protecting against neurotoxicity.
The acidic environment favors the growth of beneficial bacteria like Lactobacilli and Bifidobacteria.
Suppression of Pathogenic Bacteria
Magnesium hydroxide or magnesium sulphate, what it is and how it works
Magnesium sulfate (Epsom salt) and magnesium hydroxide (milk of magnesia) are poorly absorbed in the gut.
They create an osmotic gradient in the intestines, pulling water from the surrounding tissues into the intestinal lumen.
This increases the volume and water content of the stool, softening it and making it easier to pass.
The increased stool volume stretches the intestinal walls, triggering mechanoreceptors.
This stimulates peristalsis (rhythmic contractions of the intestinal muscles), propelling the stool forward.
it’s Magnesium ions may stimulate the release of the hormone cholecystokinin (CCK)
it also increases osmotic pressure of the stool
CCK is a hormone
some CCK functions in the gut essential to it’s function as a laxative
Enhances intestinal motility.
Increases fluid and electrolyte secretion, further aiding in bowel movements.
the inactive susbtance in senna(a stimulant laxative)
they are metabolised into an active metabolite known as ? by what?
sennosides
rheinanthrone , by gut bacteria
how does rheinanthrone act on the myeintric plexus
by;
stimulating peristalsis, increases force and rate of contractions
inhibiting local contractions within the colon, (haustrations)
these actions together reduce fluid absorption from the stool.
describe the mechanism by which senna reduce water reabsorption within the colon
what is another way that senna can increase water content in the lumen of the large intestine
increases
cyclooxygenase 2 (COX2)
expression in macrophage cells, leading to;
an increase in prostaglandin E2.
this causes a decrease in aquaporin 3 expression in mucosal epithelial cells of the large intestine
results in a reduction of the water reabsorption within the colon, thereby an increase in stool water content
by rheinanthrone acting on submucosal cholinergic neurons, resulting in increased chloride
secretion in the large intestines. This draws water into the large intestines(osmosis)
name some prokinetic secretagogues
Lubiprostone
Linaclotide
Plecanatide
linaclotide mechanism of action
Binds to Guanylate Cyclase-C (GC-C) Receptors
Increases cGMP(secreted extracellularly)
Intracellular cGMP stimulates the cystic fibrosis transmembrane conductance regulator (CFTR) channel.
increased Cl- and HCO3- secretion
The secretion of chloride and bicarbonate creates an osmotic gradient, drawing water into the intestinal lumen.
This softens stool and increases stool volume, promoting easier bowel movements.
it is a Guanylate cyclase C (GC-C) agonist
Lubiprostone mechanism of action
it activates Chloride channels in the intestines, which leads to efflux of Cl- into the lumen(primary effect of the drug)
efflux of Na+ ions, following the chloride efflux
increased salt concentration
water secretion into the lumen of the large intestines, due to the osmotic gradient created
Results in softening the stools
it is classed as a Locally acting Cl- channel activator
prucalopride, what it is, and
it’s mechanism of action
Highly selective and potent 5HT4 receptor agonist
it is absorbed into the systemic circulation, where it stimulates gut motility.
Acts on presynaptic 5HT4 receptors on myenteric cholinergic nerve terminals
▪ enhances the fast excitatory synaptic signals
▪ increase the parasympathetic system induced contractions of the
intestine.
▪ enhances the occurrence of mass movements
▪ accelerates propulsion of material in the colon.
it basically enhances gut movement
Examples of bulk laxatives
Methylcellulose
Ispaghula husk
Psyllium
Bran
Sterculia
Examples of osmotic laxatives
Polyethylene glycol (PEG): Also known by the brand names Movicol, Laxido, Molaxole, and Macrolief
Magnesium hydroxide: Also known by the brand names Dulcolax, Ex-Lax, and Phillips’ Milk of Magnesia
Glycerin: Also known by the brand names Colace Glycerin and Fleet Pedia-Lax
Lactulose: Also known by the brand names Duphalac or Laxose
Sorbitol: An osmotic laxative
Sodium sulfate, potassium sulfate, and magnesium sulfate: An osmotic laxative
Examples of stimulant laxatives
Bisacodyl: Also known by the brand name Dulcolax
Senna: Also known by the brand name Senokot
Sodium picosulfate: Also known by the brand name Dulcolax Pico
Castor oil: A vegetable oil derived from the seeds of the Ricinus communis plant
