1. saliva, swallowing and esophagus Flashcards
list the major pairs of salivary glands in dogs and cats
- parotid
- zygomatic
- mandibular
- sublingual
label the salivary glands in different species
discuss the composition of saliva
- 98-99% water
- electrolytes
- proteins
- carbohydrate splitting enzyme (amylase)
- desquamated cells from mucosa
- lymphocytes
- mucin if mucus secreting gland
primary saliva secretions are made by what cells where
epithelial cells within the acini
discuss modification of saliva
- primary secretion leaves acini
- modified in ducts
- Na and Cl gets resorbed
- HCO3 and K secreted
- osmolarity depends on flow – faster flow = less time in ducts = less modification = hypertonic vice versa
- ruminants retain a lot more bicarb to act as buffer in the rumen
this is a salivary gland. what do the arrows indicate
Describe basal striation of the striated duct and its other components in the salivary gland
- infolding of the basal cell membrane -> high surface area
- many mitochondria
- Na/K-ATPase pump
list salivon cell types and what they produce
- serous cells = watery secretion
- mucous cells - mucous secretion
- plasma cells = around the acini and produce IgA to control bacteria
- myoepithelial cells = envelop each acinus
- intercalated ducts = secrete HCO3- and absorb Cl
- striated ducts = secrete K and HCO3- and absorb Na
- secretory ducts = convey saliva to the mouth
the parotid gland produces what variation of saliva
serous in most species but mucus in dogs
the madibular gland prduces which variation of saliva
mixed serous and mucus except in rodents (serous)
the sublingual gland produces which variation of saliva
mixed except in rodents mucus only
what stimuli encourages saliva production
neural and hormonal stimuli
list functions of saliva
- wetting agent/lubricant (eases chewing and swallowing)
- lubricates oral mucosa (wash teeth remove debris, protect vfrom microbes, antifungal/viral)
- water soluble food components dissolve in saliva (enhances flavour)
- enzyme action to aid carb digestion
- buffering (bicarb regulates acidity in rumen AND keeps oral pH)
- phosphate buffer
- hydroxyapatite produces calcium ions
- urea/ammonia in ruminant for protein recycling
- anti foaming
- reoxide antibac
why is salivary bicarbonate important
- in ruminants needed to regulate rumen acidity
- keeps oral pH in dogs/cats at 7.5, if pH gets too low teeth dissolve and if too high calculus forms
discuss how saliva secretion is regulated
- Sympathetic NS: viscous, amylase, more protein, low volume
- Parasympathetic NS: water, high volume, increase flow in response to taste, visual and olfactory stimuli, continuous basal flow
in ruminants, what stimulates salivation reflex
presence of long fibre in the reticulum near the cardia
discuss ANS nerve supply of salivation
- sympathetic supply reaches the glands via the arterial supplies
- parasypathetic travels along the trigeminal nerves, even though the nuclei are linked with facial and glossopharyngeal
what are the main salivary glands
- parotid
- mandibular
- sublingual
- zygomatic
- buccal
- palatine
- gustatory (on the tongue)
what structures are the arrows pointing to
describe the parotid gland and duct
- ventral to base of ear
- V shaped in carnivores to fit arround auricular cartilage
- C shaped in herbivores and fits against caudal border of the mandibular vertical ramus
- mixed mucus/serous saliva
- single duct
- duct runs from craniomedial surface of the gland across the masseter muscle or ventral to it (cow, horse, pig)
- opens in the upper buccal area by the maxillary fourth premolar
which species have a zygomatic gland and what is it referred to in other animals
dogs and cats
- dorsal buccal gland in other mammals (horses)
describe the zygomatic gland
in rostral portion of the pterygopalatine fossa on the floor of the orbit ventral to the eye, medially to the zygomatic arch and dorsolateral to the last maxillary tooth
- duct opens in upper bucal mucosa opposite the upper first molar or caudal to it
- duct is usuallt caudal to the parotid duct opening and may have several minor openings of the same gland nearby
- often seen as a ridge with several small red dots
describe the sublingual glands
- have a polystomatic (many holes) part and a monostatic (one hole) part
- the monostatic part has a long sublingual salivary duct which runs next to the mandibular salivary duct and opens with it at the sublingual caruncle. the MS part can undergo cystic change
- in dogs, the polystomatic portion comprises 6-12 lobules with independent short salivary ducts opening sublingually near the frenulum. mucus mainly with lesser serous component
discuss the mandibular glands
- slightly cauda and medial to the angle of the mandible limited by the linguofacial vein ventrally and the maxilary vein caudally
- connective tissue capsule is shared with the monosomatic portion of the sublingual gland
- the mandibular salivary duct opens at the bulingual papilla (caruncle) at base of the lingual frenulum
- in about 30% of dogs, the madibular and sublingual ducts merge
- mixed serous and mucus but can alternate
- can undergo cyctic change (surgery)
what is the hyoid and list the bones
- supports larynx from the skull
what is prehension
ability to take food into the mouth
what nerves give sensory supply to the mouth
touch:
- lower jaw/tongue/gingiva/buccal mucosa/teeth = trigeminal (mandibular branch)
- upper jaw/gingiva/mucosa/teeth = trigeminal (maxillary)
- pharynx/larynx = glossopharyngeal and vagus
taste:
- rostral 2/3 of tongue = facial
- caudal 1/3 of tongue = glossopharyngeal
- caudal pharynx and larynx = vagus
what i the motor nerve supply to the mouth
- masticatory muscles = trigeminal (mandibular)
- jaw opening = mandibilar trigeminal and facial
- swallowing = glossopharyngeal and vagus
- intrinsic tongue = hypoglossal
why are mammals able to chew and breath at the same time
presence of hard palate
what are the 3 seals of the mouth
Lips
Tongue against soft palate
Soft palate against epiglottis
describe the 3 stages of swallowing
1st stage:
- tongue moves food around
- masticated food + saliva -> bolus
- up and back between fauces to pharynx
2nd stage:
- soft palate elevated -> closes posterior nares
- epiglottis covers larynx and trachea (breathing suspended)
3rd stage:
- oesophagus dilates
- bolus passes up and over larynx into oesophagus
- oesophagus recloses and epiglottis uncovers trachea
- bolus moves down oesophagus into stomach
Describe what is different about the mouth anatomy of chinchillas and guinea pigs and its clinical relevance`
Palatal ostium:
soft palate almost seals off the oropharynx from the naso and laryngopharynx
small hole (ostium) remains
This makes intubation almost impossible
