Oral & Stomach Physiology/Biochemistry - Twining Flashcards
Give the innervation for each of the following:
- Parotid salivary gland
- Submandibular salivary gland
- Sublingual salivary gland
- CN IX
- CN VII
- CN VII
Give the four major constituents of gastric juice (other than water)
- intrinsic factor
- hydrogen ions
- pepsin
- mucus
Give another name for ptyalin. What does it do?
Also known as alpha-amylase
Starts carbohydrate digestion in the mouth
As new saliva travels through the ducts of the salivary gland, which ions are reabsorbed? Which are secreted?
Reabsorbed: Na+ (active) and Cl- (passive)
Secreted: K+ (active) and HCO3- (passive)
Name the major saliva component directly involved in antibacterial and antifungal defense.
Broad spectrum or narrow spectrum?
Mechanism?
Lysozyme
‘Narrow’ spectrum - most involved in killing gram-positive bacteria
Mechanism: cleaves beta-1-4 linkages between NAM and NAG (gram positive cell wall peptidoglycans) or NAG in fungi cell wall chitodextrins
Name the saliva component responsible for each of the following bacterial defenses:
- Binds iron and prevents bacterial and some fungal growth
- Kills bacteria by producing reactive bromide and iodine molecules
- Secreted immunoglobulin that recognizes and binds bacteria in order to produce an immune reaction
- Polypeptides that form pore complexes on microbial cell membranes
- Large, highly glycosylated proteins that modulate adhesion of bacteria to oral tissues (including teeth)
- Lactoferrin
- Peroxidase
- IgA
- Defensins
- Mucins
Saliva is low in what two ions normally found in blood plasma?
Na+ and Cl-
Desribe how the following lead to xerostomia:
- Cystic fibrosis
- Sjogren’s syndrome
- Mutant chloride transporters lead to defective plasma secretions. Salivary mucus is thick and may clog salivary ducts, leading to xerostomia.
- Autoantibodies to salivary gland proteins leads to the destruction of these tissues, resulting in deficient saliva production (xerostomia)
Name and describe the three phases of gastric secretion
- Cephalic phase
- Anticipation of food leads to vagal stimulation of the stomach, increasing production of acid and pepsin
- Gastric phase
- Food in the stomach excites (1) long vasovagal reflexes to/from the brain, (2) local enteric reflexes, and (3) gastrin-histamine stimulation
- Intestinal phase
- Presence of food in the duodenum causes small amounts of continued gastric secretion. Continued stimulation ultimately leads to inhibition of gastric secretion/emptying by an enterogastric reflex
Describe the substances released by the vagus nerve that influence acid secretion
- ACh
- stimulating action -> acts on parietal cells to release acid
- stimulating action -> acts on ECL cells to release histamine
- inhibitory action -> acts on D cells to inhibit secrtion of somatostatin
- GRP
- stimulating action -> acts on G cells to release gastrin
Describe the role of D cells in gastric secretion
D cells secrete somatostatin, which inhibits secretion of:
- G cell gastrin
- ECL cell histamine
- Parietal cell HCl
D cells are acted upon by:
- Stimulation - HCl from gastric parietal cells
- Inhibition - ACh from the vagus nerve
Describe the role of G cells in gastric acid secretion
G cells release gastrin, which stimulates secretion of:
- D cell somatostatin
- ECL cell histamine
- Parietal cell HCl
G cells are acted on by:
- Stimulation - GRP from the vagus nerve
- Inhibition - somatostatin from D cells
Describe the role of ECL cells in gastric acid secretion
ECL cells secrete histamine, which stimulates parietal cell HCl release
ECL cells are acted upon by:
- Stimulation - ACh released from the vagus nerve
- Inhibition - somatostatin released from D cells
Describe the role of parietal cells in gastric acid secretion
Parietal cells secrete HCl (gastric acid)
Parietal cells are acted upon by:
- Stimulation - ACh from the vagus nerve
- Stimulation - histamine from ECL cells
- Stimulation - gastrin from G cells
- Inhibition - somatostatin from D cells
What accounts for the observed drop in gastric [H+] after ingestion of food?
Approximately how long after ingestion of food does the rate of H+ secretion sharply increase?
Food buffers preexisting H+ in the stomach
H+ secretion rises sharply approximately 1 hours after food ingestion
