Gastrointestinal system Flashcards
week 21
what are the functions of the digestive system? (4)
secretion
digestion
absorption
elimination
what is secretion for? (3)
lubrication
liquification
digestion
what is digestion for?
breakdown of molecules into their constituent parts
define absorption
movement of molecules into cells and circulation
define elimination
removal of waste products
what are the 2 types of digestion?
mechanical and chemical
define mechanical digestion
physical disruption of food into smaller parts
define chemical digestion
breakdown into small soluble constituents
reliant on enzymatic action
example of mechanical digestion in the mouth/ oral cavity
chewing/ mastication
example of chemical digestion in the mouth/ oral cavity
saliva from salivary glands
what produces enzymes? (2)
the body and bacteria
define fermentation
digestion carried out by commensal bacteria
what are the 4 layers of the tract?
mucosa
submucosa
tunica muscularis
serosa/ adventitia
what are the 3 sets of salivary glands?
parotid
sublingual
submandibular
what is the function of the oesophagus?
transport of food from pharynx to the stomach
example of mechanical digestion in the stomach
churning and mixing of food
increases contact between enzymes and digesta
example of chemical digestion in the stomach
pepsinogen
hydrochloric acid
rennin/ chymosin
what are the 3 muscle layers of the stomach?
outer - longitudinal
middle - circular
inner - oblique
define rugae
temporary folds in the mucosa lining of the stomach that allow for distension to accommodate a meal and increase the surface area of the epithelium
when are rugae present?
in an empty stomach and disappear when distended
describe mucosa
simple columnar epithelium with gastric pits
what do chief cells secrete?
pepsinogen and rennin/ chymosin
