Secretion of ions and enzymes in the GI tract Flashcards
What does the control of salivary secretion depend on?
Nervous system
What is tastebuds and mechanoreceptors activated by?
Food
Where is sensory information sent to, what type of reflex?
Salivary nucleus in medulla of brain
Unconditional reflex
What is a conditional reflex of the salivary nucleus?
sensory input to brain e.g sight, smell of food
How does saliva secretion receive impulses?
via autonomic nerve
What autonomic nerves create saliva secretion?
parasympathetic, cranial nerves 7 & 9
Where does impulses for saliva secretion go to?
salivary glands
What does the salivary glands do?
Increase secretion of fluid/enzymes/mucins and dilate blood vessels
What is the PH of saliva? (low flow rate)
6.2
What is the PH of saliva, high flow rate?
8.0
Where does secretions of primary saliva occur?
In acinus of a salivary gland
Where does secondary modification of saliva occur?
in the duct
Where does mucus in the stomach occur from?
Surface epithelial and mucus neck cells - glycoprotein forms gel with water - protective layer over epithelium
Where does the bicarbonate secretions arise from in the stomach?
surface epithelial cells - trapped in mucus layer, protective against acid
Where does hydrochloric acid arise from in the stomach?
Parietal cells
What is the intrinsic factors of gastric secretions occur from?
parietal cells - protection of vitamin b12
Where do pepsinogens arise from?
Chief cells - commences protein digestion