30. GI Secretions Flashcards
How do exocrine glands vary from endocrine glands?
Exocrine secrete substances onto an epithelial surface via a duct
Endocrine secretes directly into the blood
What are the three pairs of major salivary glands?
Parotid, sublingual, submandibular
Where are the minor salivary glands located?
ON the mucosal lining of the oral cavity, eg lips, cheeks, palate
What are the main components of saliva?
Water, mucins (lubrication), electrolytes, antibodies, enzymes
What types of cells are present in salivary ducts?
Serous cells - secrete watery fluid
Mixed acinus cells - secrete mucous and serous
Mucous cells - secrete viscous saliva with mucins
How is salivation regulated by the NS?
Sympathetic NS modulate composition of saliva
PS NS modulate volume of fluid secreted
What is required for the absorption of B12?
Intrinsic factor
Secreted by parietal cells
What is secreted by chief cells?
Pepsinogen, gastric lipase, leptin
How is mucus in the stomach affected by prostaglandins and ACh?
Induce release of mucus to increase protective barrier thickness
What is the function of the pancreatic duct cells?
Secrete NaHCO3 to neutralise acid from stomach
What is the function of acinar cells?
Secrete digestive enzymes to digest various components of food
What is the endocrine function of the pancreas?
Alpha cells secrete glucagon when blood glucose falls
Beta cells secrete insulin when blood glucose rises
Delta cells secrete somatostatin which inhibits gastrin release
What triggers biliary secretions?
CCK
What are enteroendocrine cells?
Gastrointestinal chemoreceptors
Where does chemical digestion occur in the SI?
On the brush border. Epithelial cells with microvilli
