L3 Salivat and swall

Question 1

LO2: compns of saliva from each pair gls.

Answer 1

gen composit: hypotonic watery. 99.5% water. mucus maj constit some types. 0.5% solid. var amnts Ab, electrolyte, enz, bact flora, lymphoc/neut, epith. 3 types:

• serous- thin watery. v little mucus. parotid maj. lingual gls of van ebner. lot enz and Ab. faint nuc HE.
• mucous- thick muscinous/viscid. palatine, post ling, labial buccal gl. maj subling. muc acini large round.
• mixed- subling most mucus, submandib mostly serous, ant ling mixed. sep or same acini, if muc predom= serous demilune.
• parotid- largest, ant ear. thick, cont in fib thick caps=parotid fascia- gives shape, inexpansible. prod 20-30%. serous only, lot amylase. deep portions behind mandib ramus. stensons duct opens adjac to 2nd molar of maxilla. mix water, electrolytes, enzs.
• submandib- 2nd largest. 65-75%. floor of mouth. mostly serous. whartons duct emerge floor mouth either side lingual frenulum. PNS supp.
• subling- smallest. less than 5%. largely PNS. mostly mucinous.

Question 2

LO3: desc mechs of sec serous saliva.

Answer 2

-sec unit- termin branched tubulo-acinar. acinus comp of serous and/or mucus sec cells. myoepith surr, contrac aids expuls. termin units merge= intercal ducts lined by sec cells=large striated ducts=excret ducts.
prim serous prod- acinus sec fluid isotonic with plasma, cont enzs.
secondary- modif. ion reabs in striated ducts=hypotonic less Na and Cl, more K and HCO3 than plasma. tight gaps in duct cells means water not foll=rems hypertonic.
at low flow rate duct cells rem most Na=hypotonic. high flow less hypertonic though stim to sec prom HCO3 sec by duct cells=alk.
- 2 modes prod-
contin sec by minor, baseline, ANS contr, maint hydrat, coat surfs mucus, decr friction, prev bact. fail=dry mouth, halitosis, dent hyg.
mass ejec by major- intermitt, large amnt, trigg by thought/sight/smell/taste food.

Question 3

LO4: desc contr of saliv sec.

Answer 3

• mostly ANS. parasym nerves from otic ganglion stim acinar cells prod prim sec and duct cells to add HCO3. vol deps on ANS. auton outflow coord from brain stem in resp to afferent stim eg smell/taste/condit reflxes. sympath activ decr blood to saliv gls=decr flow=dry mouth.
  rate of ductal recov of Na incr by aldosterone from adren cortex.

Question 4

LO5: desc the procs of swall/deglutition.

Answer 4

series ordely procs by which subst avail to mouth passed to pharynx then oesoph.
-oral/buccal phase:
prep part- ant to ATPillar in mouth proper. volunt. chew and mix=bolus. ends when bolus on tongue for transp, push ag hard palate, tongue sloping=hit ATPillars.
transit part- tongue pushes bolus up and post. shape of super tongue critic. bolus activs sensory Rs of ATPillars, pharyng part of tongue. =reflex activ of pharyng phase.
- pharyng phase- trigg by food tough ATPillars. soft pal raised to close opening btw naso and oropharynx. hyoid bone and larynx raised= epig seal airw. tongue up and post forces food to oesoph. relexive no contr. reqs musc and nerve coord.
- oesoph phase- main contr by swall centres. bolus ent upper sphinct=constric reflex- init prim peristaltic wave below, 10s length of oesoph. lower sphinct relaxes early and remains til food pushed through. distend if some left=secodary wave above it. inputs from oesoph sensory fibs in cent and enteric NS modul peristalsis.

Question 5

LO6: desc struc of oesoph and outl func.

Answer 5

• 25cm then wall tube, musc. upper 1/3 volunt striated, somat nerve contr. lower smooth PNS.
  upper sphinct 2-3cm zone incr press byw pharynx and oesoph attend by cricopharyngeus musc of inter constrictor musc. trigg by pharyng swall.
  lower btw oesoph and stom. t10. not anat. ANS partic vagus nerve. tone aff by horms and indiv var.

Question 6

LO7: categ diff typs dysphagia based on pathology.

Answer 6

• congenit abnorm mouth eg cleft pal/uvula.
• stroke/brain injury, paral soft pal nerves. also drugs dep NS.
• hypertrophy of pharyngeal tonsils, pain dur swall.
• achalasia- prev lower oesoph relaxat, disord peristalsis.

Question 7

LO8: desc anat mechs that prev gastro oesoph reflux and outl clinic conseqs of free reflux.

Answer 7

-part oesoph goes through diaph=sling, diaph pulls up and clamps oesoph.
oblique angle=physic barr.
mucosal folds act as valve.
press in chest const change, never pos. abdo more const and higher press. abdo press clamps tip of oesoph closed.
- can cause barretts oesoph.

Question 8

LO9: outl anat rel of oesoph and how disord swall may occ as conseq of prim oesoph disord or a cond in a closely rel struc.

Answer 8

• hiatus hernia- diaph open of oesoph not tight enough=parts stom ent thoracic cav.
• or defec lower sphinct (diags).

Question 9

LO1: desc funcs of saliva.

Answer 9

• moisten food by electrolytes, serous mainly, soften decr epith dam.
• lubric food bolus, mucus mainly.
• taste- due to chem breakd.
• soft tiss rep.
• maint tooth integ.
• dilut and clear sug.
• init ling phase dig of carb by amylase, lipase, protease.
• detox by antibact peroxidase, mucin, histatin, amylase, cystatins, lysos. antifung histatin. antivir cystatin, mucin.
• buffering
• mineralisation
• tiss coatings.