L21 - gi system: structure & function

network of organs and specialised cells that allows food to be converted to energy and nutrients needed for life

• mouth • oesophagus • stomach • small intestine • large intestine • rectum • anus

• salivary organs • liver • gallbladder • pancreas

• membranes tissue in stomach • surrounds organs in go tract • holds intestines in place • provides blood vessels & lymphatics

• teeth • tongue • mucous membranes

• main function is to chew • food passed to pharynx and epiglottis • prevents food travelling to lungs

• tube like structure • involuntary movement of food bolus • transports bolus to stomach

• mixing • muscular organ • protein digestion • HCl, pepsin • fat emulsion

• mucosa = mucus layer (top) • submucosa = glands and blood vessels • muscularis = smooth muscle

• mucous neck cell • parietal cell • enterochromaffin like cell • chief cells • d cells • g cells

produce mucus and bicarbonate

produces gastric acid and intrinsic factor

involved in enteric nervous system

produce enzymes (pepsin, gastric lipase)

produce peptide hormone somatostatin to inhibit acid

produce gastrin to stimulate acid

• longest part of gi tract • main sight of absorption • 3 sections (duodenum, jejunum, illeum)

• site of breakdown of carbs, proteins, fats • primary site of absorption

• increase SA • allow for better absorption

• paneth cells play role in defence and produce antimicrobial enzymes • stem cells for regeneration • goblet cells for mucus

• water and ion conservation • bulk movement of faeces • storage • defaection

• lubrication via mucus • protection • digestion (amylase & lipase)

• bile production • excretion