LOWER GI TRACT PART II — CONSTIPATION, DIARRHOEA, ELECTROLYTES

Osmotic laxative examples

Lactulose, macrogols

Lactulose mechanism

Fermented to acids increasing osmotic load

Macrogols mechanism

Retain water in bowel

Stimulant laxative examples

Senna, bisacodyl

Stimulant laxative mechanism

Irritate mucosa to increase motility

Stool softener examples

Docusate, liquid paraffin

Diarrhoea causes

Infection, toxins, malabsorption

ORT components

Sodium, potassium, citrate, glucose

Loperamide mechanism

μ‑opioid agonist reducing motility

Codeine effect

Constipation and reduced motility

Vomiting electrolyte loss

H+, K+, water

Vomiting acid‑base effect

Metabolic alkalosis

Diarrhoea electrolyte loss

Sodium and water

Hyponatraemia cause

Excess water retention

Hyponatraemia danger

Cerebral oedema

Hypernatraemia cause

Water loss

Hypernatraemia danger

Brain shrinkage

Hypokalaemia symptoms

Weakness, arrhythmias

Hyperkalaemia symptoms

Arrhythmias, muscle weakness

Acidosis effect on potassium

K+ shifts out of cells

Alkalosis effect on potassium

K+ shifts into cells