Salivary Glands and Swallowing Flashcards
(52 cards)
Label this diagram of a basic salivon
Describe the components of saliva
- electrolytes
- proteins
- carbohydrate splitting enzyme (amylase)
- desquamated cells from mucosa
- lymphocytes
- mucin (if mucous secreting gland)
- 98-99% water
Why is bicarbonate ions important in ruminant saliva?
To buffer the ruminal acids
Where in the salivon is the primary secretion produced?
Epithelial cells within the acinus
Where is saliva modified after it is produced?
The ducts
Describe the modification of saliva in the ducts and what effects it
- Na and Cl resorbed
- HCO3 and K secreted into saliva
- osmolarity depends on flow
- faster flow = less time in ducts = less modification
- slow flow = hypotonic
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
Label the serous acini and the striated duct
Name the types of salivary cells and their secretion/role
Serous cells - watery secretion
Mucous cells - mucous secretion
Plasma cells - produce IgA (found around acini)
Myoepithelial cells - envelop each acinus
Name the different types of salivary ducts and their function
Intercalated ducts - secrete HCO3 and absorb Cl
Striated ducts - secrete K and absorb Na
Secretory ducts - convey saliva to the mouth
Label the cells and ducts of this mixed salivary gland
Name the functions of saliva (there is a lot)
- Wetting agent/lubrication, moistens food bolus to aid mastication and swallowing
- Lubricates oral mucosa
- mechanical washing of surfaces of teeth and mucosa to remove food, debris, microbes
- protective role via antimicrobial effect through enzymes, immunoglobulins
- antifungal and antiviral activity
- water solubkle food components dissolve in saliva
- enzyme action (amylase)
- buffering (in rumen and orally)
- phosphate buffer and aid to microbial growth to enable digestion
- hydroxyapatite in salive provides Ca ions to maintain enamel
- urea/ammonia in ruminants’ saliva returns to the rumen (protein recycling)
- thermoregulation in dogs and cars
- anti-foaming: salivary mucoproteins act with other agents to increase surface tension, frothy bloat can occur if absent
- peroxide-base antibacterial system: potassium thiocyanate in saliva is oxidised to form hypothiocyanate which it toxic to bacteria
What is pyalism
Hypersalivation
Describe the regulation of saliva production
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
What stimulates salivation in a ruminants diet
the presense of long fibre e.g., grass, hay, in the reticulum near the cardia
Describe the parasympathetic pathway in saliva production
Parasympathetic supply travels along the trigeminal nerves
Name the different salivary glands
Parotid
Mandibular
Sublingual (mono and polystomatic)
Zygomatic
Buccal
Palatine
Gustatory (on the tongue)
Label the salivary glands and ducts
Describe the location, shape and secretion of the parotid gland
- ventral to base of ear
- V-shaped in carnivores (fits around auricular cartilage)
- C-shaped in herbivores (fits against caudal border of mandibular vertical ramus)
- Mixed serous/mucus saliva
- single duct
Clinical relevance of the parotid gland and horses on new grass
Becomes swollen
parotiditis
Describe the route of the parotid duct
Runs from craniomedial surface of gland across the masseter muscle
Opens in the upper buccal area by the maxillary fourth premolar (upper carnassial)
When does the parotid gland secrete saliva in ruminants
spontaneously when distal oesophagus/reticulum is mechanically stimulated
Label the parotid gland histology
