2/19-mastication & digestion Flashcards
what are the 4 muscles of chewing and what does each one do?
- masseter- a large, strong, crushing muscles; aids in bitin down
- temporalis- also a crushing muscle, provides a different crushing angle
- buccinator- in cheeks, keeps food from pocketing pushing it midline
- pterygoid- attach in the middle to the pterygoid plates in the skull; allows for circulatory chewing and side to side grinding
what causes one to chew?
a reflex arc in the chewing center of the brain which is hooked to to the taste buds through the facial nerve (CN VII). if the taste buds sense food, it will cause you to chew.
- what happens in the act of chewing regarding receptors?
2. what type of contraction is this?
- stretch receptors information is sent via the facial nerve as the jaw relaxes; then the trigeminal nerve (V) sends a message to the muscles to contract
- rebound contraction
how is food turned into chyme:
- what does saliva do?
- what type of cells are in the salivary glands
- what does acinar do that is different from the duct cells
- glues the food into a ball while moisturizing it
- salivary glands have acinar glands (glands with ducts)
- duct cells secrete fluid; acinar glands secrete enzymes
why are glandular cells (especially carcinomas) called adeno?
because all glands embryonically come from the GI tube (even if in the lungs i.e. adenocarcinoma).
how are the taste buds set up as far as how and where information is sent:
- first 2/3 of the tongue?
- last 1/3 of the tongue?
- what branches of CNIX go where and what happens?
- first 2/3 of the tongue has taste buds that send info to the lingual nerve; which sends information to the facial nerve (CN VII) (adding sensory and motor innervation to the first 2/3 of the tongue).
- the last 1/3 sends information via the glossopharyngeal nv. (CN IX)
- one branch will go to the gustatory cortex in the parietal lobe which tells you the taste has been sensed; another branch goes to the salivation center which will send a message back down through the facial nerve.
- when the information is coming back down to the salivary glands from the salivation center, what nerve does it go down and where does it go next?
- what nerve deals with what 2 salivary glands?
- the glossopharyngeal nerve deals with the parotid glands
2. the facial nerve deals with the 2 “subs” (i.e. submandibular and sublingual).
(A & B) what is the difference between what the parotids and the “subs” secrete?
1.A) parotids secrete a watery and serous solution
B) submandibular and sublingual secrete a serous and mucous sectetion
what does the mucous from the “subs” do?
lubricate and glue; rather than have small bits falling down your throat, you have a bouls but if it has sharp potato chips in it, they will be lubricated so that it doesnt scratch your esophagus.
what else does the parotid gland secrete (besides watery and serous fluid)?
amylase; which breaks polysaccharides (starches, glucycogen) into into smaller oligosaccharides (turns “many to few”).
what do duct cells release (3 antimicrobials)
- IgA (duct cells bathe teeth with antibodies decreasing cavity causers)
- cytosome (a form of lysosome which kills bacterial cells)
- thiocyanate (a sulfer-cyanide poison that kills bacteria).
how do the duct cells keep mouth acid down?
- why does chloride leave?
- what is chloride exchanged for? what benefit does this have?
- the sodium and potassium channels bring in sodium and kick out potassium (chloride is a whore, so she goes with K+).
- in cells, if you want to bring chloride in, it must exchange for somthing, this will be bicarbonate ion- which goes out and buffers the acid biproduct of bacteria feeding on sugar.
what does amylase need to work?
K+ and Cl-
what triggers the swallowing reflex?
- what triggers the initial signal?
- what receptors sense the signal, where are they located?
- thru what nerves is this info sent, to where?
- tongue presses against hard palate
- cause stretch on endothelial swallowing stretch receptors in palatopharyngeal folds
- stretch info is sent via trigeminal and glossopharyngeal nerves to swallowing center of brain
- motor info is sent via trigeminal to pharynx and via glossopharyngeal to esophageal sphincter and pharynx; and Vagus to esophagus, stomach and small intestine.
- soft palate rises to block off nasopharynx
- palatopharyngeal folds squeeze in medially to funnel small food boluse only
- epiglottis closes off airway
- upper esophageal sphincter opens up like a funnel and rises to catch food bolus
how is the esophatus divided (as far as smooth and skeletal muscle)?
upper 1/3 is skeletal, last 2/3 is smooth
how is glanduar tissue of esophagus divided (the first 1/3 is ??? mucosa, etc…)?
upper 1/3 of submucosa is simple (only one fold), as it goes down the esophagus, it transitions to compound (branched) submucosa (looks like a hand with 20 fingers)
what does the compound mucosa do that the simple mucosa does not? why?
secretes more mucous and starts to secrete bicarbonate. because it is closer to the the acids of the stomach.