11. Secretion & Control Flashcards
Where is the sensory info detected by mechanoreceptors sent?
Medulla of the brain
Which nerves do impulses travel to?
Cranial nerves 7 & 9 of the parasympathetic to release enzymes, fluids, mucins and dilation of blood vessels
What is the pH of saliva?
6.2-8.0 depending on flow rate
Where is HCl and intrinsic factor secreted from?
Parietal cells
Where is the mucus secreted from?
Epithelial cells
Where is bicarbonate secreted from?
Surface epithelial cells
Where are pepsinogens secreted from?
Chief cells
What is the difference between endo and exopeptidases?
Endo cleave specific peptide bonds
Exo cleave terminal peptide bonds
5 functions of gastric acid
Activates pepsinogen Increases pepsin activity Disrupts connective tissue proteins Dissolves food matter Bacteriocidal
What are the 3 important factors of gastric secretion and where are they each released from?
ACh: Vagus and other intrinsic nerves
Gastrin: Antral G Cells by ACh, stretch an dietary proteins.
Circulates in bloodstream to parietal cells and other secretory cells
Histamine: Cells close to ACh and Gastrin; work in conjunction to induce a strong secretory response; synergistic
Cephalic phase
Trigger
Control
Head phase
Triggered by: sense of food
Controlled by: impulses from CNS via vagus nerve; releases acid and peosin as well as small amount of gastrin
Vagus nerve essential for ACh release
Gastric phase
Trigger
Control
Stomach phase
Triggered by: distension of stomach and food like components e.g caffein and calcium
Controlled by: hormonal mechanisms i.e gastrin (important in this step), circulating to glands in fundus/body and releases pepsin and acids and more
Intestinal phase
Trigger
Control
Triggered by: emptying of stomach contents into duodenum; low pH in gastric antrum
Controlled by: release of hormones from duodenal mucosa which inhibit gastric secretion (secretin, CKK, GIP) Short, local and long, nervous reflexes which inhibit gastric secretion and/or gastrin release
What is PUD?
Peptic ulcer disease
Failure of protective mechanisms, leading to ulceration
How is PUD caused?
H. Pylori infection
Steroidal and non-steroidal anti inflammatory drugs
Too much acid, pepsin, histamine
