Lesson 62 - Salivary glands

What are salivary glands?

exocrine glands in the mouth that produce saliva

What are the functions of salivary glands?

digestive, lubricating, protection, buffering

What are major salivary glands?

parotid, mandibular, sublingual

What are the minor salivary glands?

labial, lingual, buccal, palatine, molar, zygomatic

What species have molar salivary glands?

cats

What species have zygomatic salivary glands?

dogs

What separates the lobules of the parotid gland?

thin connective tissue septa

What is the location and shape of the parotid gland?

triangular, thin, and molded around the ventral portion of the auricular cartilage

What is important about location of the parotid in horses?

it partially overlays the lateral wall of the guttural pouch

What is related to the parotid gland rostrally?

masseter muscle

What is related to the parotid gland dorsally?

auricular cartilage

What is related to the parotid gland caudally?

wing of atlas

What is the parotid duct in close proximity with?

external carotid artery, maxillary vein, branches of the facial and trigeminal nerves

How does the parotid duct travel in carnivores and sheep?

crosses the lateral surface of the masseter muscle

How does the parotid duct travel in horse, ox, goat, pig?

medial to the angle of the jaw and travels alongs the ventral surface of the masseter muscle

What structure is at the end of the parotid duct?

papilla

Where does the parotid duct end at in dogs?

opposite premolar 4

Where does the parotid duct end at in horse, pig, and small ruminants?

3rd or 4th superior cheek teeth

Where does the parotid duct end at in the ox?

opposite the 5th superior cheek tooth

What is a fun fact about parotid duct?

can be translocated from the mouth to the eye to treat keratoconjunctivitis sicca

Where is the mandibular salivary gland located?

close to the angle of the jaw and partially covered by the parotid salivary gland

What gland is related to the mandibular salivary gland rostrally?

monostomatic salivary gland

What veins surround the mandibular salivary gland?

linguofacial and maxillary vein

What covers the mandibular salivary gland?

capsule

What is related rostrally to the mandibular salivary gland?

mandibular lymph nodes, sublingual gland, masseter and digastricus muscles

What is related medially to the mandibular salivary gland?

digastricus muscle, medial retropharyngeal lymph node, external carotid artery

What is the term for excessive salivation?

ptyalism

What is clinically important about the mandibular and monostomatic salivary glands?

they undergo cystic changes which require removal (ranula)

Where does the mandibular duct travel?

ventral to the mucous membrane of the mouth, close to the frenulum

Where does the mandibular duct open?

sublingual caruncles

What does the capsule of the mandibular gland also cover?

monostomatic portion of the sublingual salivary gland

What are the parts of the sublingual salivary gland?

monostomatic and polystomatic

Which part of the sublingual salivary gland is compact?

monostomatic

Which part of the sublingual salivary gland is diffuse?

polystomatic

Which sublingual salivary gland is more caudal?

monostomatic

How does the monostomatic gland drain?

single duct

What gland shares a common opening with the mandibular duct?

monostomatic salivary gland

How does the polystomatic gland drain?

multiple ducts

Where are the polystomatic duct openings?

on a longitudinal fold in the lateral sublingual recesses

Where are the polystomatic duct openings in cattle?

on top of the conical papillae located on the fold

What part of the sublingual salivary gland is present in the horse?

polystomatic

What makes up salivary glands?

secretory units

Where do secretory units originate from?

oral ectoderm but grow into the underlying mesoderm

What is the secretory component of the salivary glands?

parenchyma

What is the supporting component of the salivary glands?

stroma

What is the secretion of salivary glands?

serous, seromucous, mucous

What decides what type of secretion is made from the glands?

mucin content

Each salivary secretory unit is composed of what epithelial cell types?

serous cells, mucous cells, myoepithelial cells

What is the shape of the serous cells?

pyramidal

What organelles do serous cells contain?

round nucleus, apical secretory granules, and numerous rough endoplasmic reticulum

How are serous cells joined?

tight junctions and adherent junctions to form an acinus

What is the shape of the mucous cells?

columnar shaped cells with more compressed basal nuclei

What do the mucous cell apical granules contain?

hydrophilic mucins that provide lubricating properties in saliva

How are mucous cells organized?

can be in acini but often found in cylindrical tubules

What type of cells predominantly make up the parotid salivary gland?

serous cells

What is the cellular structure of the parotid salivary gland?

compound acinar gland

What cells are located between the secretory cells and the basement membrane of the parotid gland?

myoepithelial cells

What does the acinus of the parotid gland open into?

intercalated duct

What cells line the parotid intercalated duct?

simple cuboidal epithelium

What does the parotid intercalated duct join into?

larger striated duct

What ducts are intralobar in the parotid gland?

intercalated and striated duct

What does the striated ducts of the parotid gland join into?

interlobular ducts located in the connective tissue septa

What lines the interlobular ducts of the parotid gland?

simple columnar epithelium which becomes stratified as it becomes larger

What do the interlobular ducts of the parotid gland join to form?

parotid ducts

What gland produces 2/3 of all saliva?

mandibular salivary gland

What kind of gland is the mandibular gland?

seromucous compound tubuloacinar gland

How are the serous and mucous cells oriented?

may be separate or the serous cells may form a halfmoon shaped cap on one side of the mucous unit called a serous demilune

What kind of gland is the sublingual gland?

seromucous compound tubuloacinar gland

What is important about the sublingual gland in cattle, sheep, and pigs?

almost entirely mucous with relatively few serous demilunes

What do dogs and cats contain in the sublingual gland?

clusters of serous acini

What do the mucous cells of the sublingual gland form?

tubular secretory units that connect the serous acini with the intercalated ducts

Where are the lingual glands located?

submucosa between the intrinsic muscles of the tongue

Where are the gustatory glands located and what is secretes?

associated with vallate and foliate papillae and are entirely serous

What minor glands are seromucous?

labial, palatine, buccal, pharyngeal

What ions are highly concentrated in the saliva?

bicarbonate ions

How does the saliva help with digesting carbohydrates?

with the enzyme alpha amylase

What helps the saliva control the bacterial flora?

lysosomes

How does saliva help with normal tooth development?

because of calcium and phosphate ions present

What nervous system controls saliva production?

autonomic nervous system

What cranial nerves provide parasympathetic innervation to salivary glands?

VII and IX

Where do the parasympathetic fibers originate?

two salivatory nuclei in the brainstem

What glands does the CN VII supply?

mandibular and sublingual

What glands does the CN IX supply?

parotid

Where do the sympathetic fibers originate?

caudal thoracic segment of the spinal cord from synapses in the cranial cervical ganglion

What is acini?

secretory unit of salivary glands

What is mucocele?

accumulation of saliva producing a swelling of subcutaneous tissue following injury to the salivary gland or duct

What is rumination?

regurgitation of fibrous digesta from the rumen to the mouth, remastication, and reinsalivation, followed by swallowing and returning of the material to the rumen

What is sialolith?

concretions that may develop in any salivary gland and its duct

What is sialadenitis?

inflammation of the salivary gland

What method is used to study the structure and function of entire nucleotide sequences from all organisms in a sample?

metagenomics

What is microbiota?

all living microbial organisms constituting the microbiome

What is microbiome?

sum of microbes, their genetic information, metabolites, and the environment in which they interact

What is biome?

large geographical area with a distinct climate, vegetation, and animal life

What is niche?

function or role played by an organism in a habitat

What is symbiosis?

two or more spaces living closely together in a long-term relationship

What is dysbiosis?

condition in which the normal microbiome population structure is disturbed by external burdens such as disease states or medications

What are DNA based approaches to study microbiomes?

metagenomics

What are RNA based approaches to study microbiomes?

metatranscriptomics

What are protein-based approaches to study microbiomes?

metaproteomics

What are metabolite-based approaches to study microbiomes?

metabolomics