Digestion Secretion and Absorption Flashcards
What is digestion
Complex molecules undergo enzymatic degradation to absorbable forms
What is absorption
Process by which molecules transported through epithelium to enter blood
Where does the secretion of saliva occur?
Parotid
Sublingual
Submandibular
Buccal
Where does primary secretion occcur?
acinar cells
What is aqueous secretion
similar compostition to ECF
where does serous secretion occur and what does it contain
Parotid
contains ptyalin and lysozyme
Where does modification of the saliva of the occur
Ductal epithelium
What does modification of saliva consist of
Na+ Cl- absorption
K+ HC03- secretion
What is salivary secretion stimulated by and what does this cause?
Chemoreceptors/mechanoreceptors
higher centres CNS
Causes an increase in parasympathetic activity
Where does gastric secretion occur?
Columnar epithelial cells Oxyntic glands -mucous neck cells - parietal cells -Enterochromaffin- like cells - chief cells pyloric cells
what do the columnar epithelial cells secrete
Mucous , HC03 - for protection
What do the oxyntic cells secrete
HCl
pepsinogen
intrinsic fx
What do the pyloric glands secrete
Gastrin and mucous
What mediates slow waves in GI smooth msucle
intersitial cells of cajal
What do segmentation contractions involve
Stretch
localised concentric segmentation and mixing of chyme
How does emptying of the small intestine occur
through the ileocecal valve- prevents backflow
mixing movements
propulsive movements
defecation reflex
large intestine movements
movement of sigmoid colon and defecation
what promotes opening of the small intestine
local peristalsis and gastroileal reflex regulated by pressure and chemical irritation
What are the function of the colon
absorption of water and electrolytes
storage of faecal matter
What are haustations
Sustained segmentation contractions/ mixing contractions
