Lecture 9 Flashcards
3 pairs of salivary glands?
parotid (watery), submandibular (watery), sublingual (thick)
What does saliva contain?
Mucous (lubricates food), amylase (breaks down carbohydrate-starch), lysozyme (antibacterial actions)
How is saliva formed?
Isotonic fluid is produced by acinar cells (secrete electrolytes/water), fluid is modified as it flows along salivary duct according to signals received, final composition depends on flow rate + neuronal input
Parasympathetic input for saliva secretions?
Watery + rich in amylase + mucous, increased blood flow to glands (rest/digest - about to eat tasty food -> mouth watering)
Sympathetic input for saliva secretions?
Promotes increased output of thicker mucous, reduces blood flow to glands, reduction in secretion of watery saliva (fight/flight - anxious -> mouth dry)
Deglutition?
Swallowing process
Stages of deglutition?
Voluntary stage, pharyngeal stage
Voluntary stage of swallowing?
Tongue pushes bolus (chewed food) backwards to orthopharynx (middle part of throat)
Pharyngeal stage of swallowing?
Is a reflex action: soft palate and uvula move up -> seals off nasopharynx, larynx raised, glottis (valve between mouth/lungs) sealed, epiglottis covers glottis -> breathing suspended for 1-2 seconds (prevents food going down trachea into lungs)
Role of segmentation?
Facilitates mixing of food - contract/relax, occurs largely in small intestine (circular muscle)
Role of peristalsis?
Propels food along tract (longitudinal muscle)
Why absorption through mouth results in rapid action?
Drug must cross epithelium (oral mucosa), enters bloodstream directly -> greater bioavailability, no need to go through digestive system (avoids first pass metabolism: drug absorbed via gut wall)
Problems with absorption through mouth?
Solubility in saliva (hydrophobicity is an issue), only small lipophilic molecules well absorbed (will drug diffuse passively?), barrier to absorption which are hard to overcome
Important features of oral mucosa?
Limited SA for absorption, rich blood supply leading to rapid onset
Barriers to oral delivery?
Drug must diffuse across lipophilic cell membrane and hydrophilic interior of cell
Enzymatic barrier (aminopeptidase) in buccal tissue - causes rapid breakdown of peptides/proteins -> limits transport across epithelium, may degrade the drug
Challenges for buccal delivery?
Drug must be kept in place (excess saliva reduces this)
SA limited
Taste of drug must be bland
Drug must be non-irritant to mouth/teeth
Xerostomia?
Dry mouth
About xerostomia?
Leads to ulcers which affects digestion/drug absorption, can be side effect of certain drugs, trated with artificial saliva preparations (spray)
About oral ulcers?
Usually clear up without treatment, but can require anti-inflammatory (corticosteroid) + anti-microbial mouthwash (prevent infection)
About oral thrush (yeast infection)?
Caused by antibiotic overuse/poor immune system/smoking/dentures…, treated with oral anti-fungal gel (e.g. miconazole) - reduces fungal infection
Meds that may cause tooth decay?
Antacids - can contain sugar/artificial sweeteners, get stuck in teeth
Pain meds - opioids cause dry mouth -> erosion of tooth enamel
Antihistamines - block release of saliva -> dry mouth
Inhalers - contain beta-adrenergic agonist (slightly acidic) -> harmful to tooth enamel
Advice to maintain good dental hygiene?
Drink plenty water
Brush teeth twice day
No smoking
Reduce coffee, tea, alcohol: cause dehydration
Hydrate mouth - use mouth spray/rinse
