Salivary glands Flashcards
What type of structures are salivary glands?
They are compound, tubulo-acinar structures
What are the primary functional units of the salivary glands?
They are a combination of tubules and globe-like secretory units called acini
What does the term compound refer to in salivary glands?
Refers to the fact that a salivary gland is made up of multiple secretory units with their tubules entering a main duct
What does the duct system do?
Modifies and transports the saliva to be finally secreted on to a free oral mucosal surface
Why are salivary glands describes as exocrine?
As they secrete on to a free oral mucosal surface
What does exocrine mean?
Glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood.
What are the two ways glands can be classified
Size
Secretion
How are glands classified by size?
Classification according to size divides the glands into 2 groups:
- Large discrete ‘major’ glands
- Small, less discrete ‘minor’ glands found throughout the oral mucosa
What are the 3 major glands?
- Parotid
- Submandibular
- Sublingual
Where are the minor glands found?
- Contained within the mucosa of the lip
- Cheek
- Hard and soft palate
- Tongue
How are glands classified by secretion?
Classification by types of secretion splits the glands into 3 types
- Glands producing a watery secretion are termed SEROUS
- Glands producing a more viscous secretion are termed MUCOUS
- Mixed glands produce a mixture of both (not necessarily in equal amounts)
What type of secretion is exhibited by the minor glands?
Mucosa of lips, cheeks, hard and soft palate are all mucous producing glands
Only the dorsum of the tongue beneath the circumvallate papillae (the glands of Von Ebner) are minor serous producing glands
What type of secretion is exhibited by the Parotid gland?
100% Serous
What type of secretion is exhibited by the submandibular gland?
Mixed
Ratio of serous to mucous is 10:1
What type of secretion is exhibited by the sublingual gland?
Mixed
Ratio of serous to mucous is 1:10
Why are mucous cells more viscous?
As they have mucin rich product containing proteins linked to a greater amount of carbohydrate
What are the main components of saliva?
99%= water 1%= additional organic and inorganic compounds like proteins and enzymes
What are the 6 functions of saliva?
- Digestion: Produces salivary amylase to aid digestion of food
- Antibacterial properties to combat bacterial colonisation. Saliva has lysozyme, histatins and antibodies
- Minerals to help maintain integrity of the dental enamel. Minerals aiding remineralisation (Ca and P) and buffering (HCO3)
- Important in Lubrication and protection, of the oral mucosa via the production of mucin, bolus formation, swallowing and speech
- Taste: solubilisation of food substances for transport to taste buds
- Hormone production: growth factors important in wound healing
Under what system is the control of salivary secretion under?
Autonomic nervous system
What do both parasympathetic and sympathetic fibres innervate?
The acini
What does innervate mean?
Supply a body part with nerves
The parasympathetic and sympathetic fibres collaterally work to do what?
Produce saliva during feeding
Afferent situation occurs when and does what?
Occurs during mastication at mealtimes
Leads to reflex stimulation of salivary flow involving salivary centres
Which gland is the only exception in regards to saliva secretion?
The minor glands mucous secretion is entirely mediated by parasympathetic nerve impulses
Which of the three major glands is the biggest?
The parotid gland
Give 7 features of the parotid gland
- It’s the largest of the 3 major glands
- Serous secretion
- Has intercalated ducts
- Striated ducts present
- Collecting ducts end in single main duct
- Non-spontaneous secretor
- Saliva is hypotonic
Give 7 features of the submandibular gland gland
- It’s smaller than the parotid but bigger than the sublingual
- Produces mixed secretion (10:1 ratio serous:mucous)
- Has intercalated ducts
- Striated ducts present
- Collecting ducts end in single main duct
- Non-spontaneous secretor
- Saliva is hypotonic
Give 7 features of the sublingual gland
- Is the smallest of the 3 major glands
- Produces mixed secretion (1:10 ratio serous:mucous)
- Few intercalated ducts
- No striated ducts
- Collecting ducts end in MANY main ducts
- Spontaneous secretor
- Saliva isotonic
Striated ducts are the site of what reaction?
Electrolyte resorption (especially of sodium and chloride ) And secretion of potassium and bicarbonate
Cells of the striated such are what?
Highly polarised
What is the striated ducts basal lamina adjacent to and what does it show?
Adjacent to the basal lamina separating it from the adjacent connective tissue
What does the basal lamina separating it from the adjacent connective tissue show and why?
Shows numerous striations under the light microscope due to the multiple infoldings of the plasma membrane
Resorption of salt is undertaken by which cells?
Striated duct cells