SALIVARY GLANDS- STRUCTURE, MECHANISM AND CONTROL OF SALIVARY SECRETION
ORAL CAVITY
- Entrance of GIT and beginning of digestive function; It provides securing against food and drink
- When MOs enter the mouth, they trigger the umbrella of immune system which consists of cell-associated protection and phagocytes and lymphocytes
- Secretory immune system mainly protects the mucosa with secretory IgA
- Additional protection is provided by the taste buds, tactility and saliva
LIQUID ORAL ENVIRONMENT
- This is the liquid in the oral cavity that washes mucosa and dental enamel
- Consists of:
- Saliva
- Gingival crevicular fluid
- Peeling epithelial cells and their degradation products
- MOs and their products Microorganism
SALIVARY GLANDS
Basic secretory units of salivary glands are cells known as acini. These cells secrete a fluid that contains H₂O electrolytes, mucous and enzymes, all of which flows out from acini as collecting ducts
- Small collecting ducts within salivary ducts lead into larger ducts eventually forming single large ducts which empties into the oral cavity
- Basic types of Acinar Epithelial Cells Exist:
- Serous Cells: secretes a watery fluid which is devoid of mucous
- Mucous Cells: produces a very mucous-rich secretion
Three Major Pairs of Salivary Glands: extrinsic
- Parotid Glands: produces serous acini i.e. serous watery secretion
- Submandibular Glands: mixed acini gland producing mixed serous and mucous secretion
- Sublingual Glands: smallest of major salivary glands producing mucous secretion through mucous acini
PAROTID GLAND Stensen's duct
- Largest of the salivary glands with serous acini
- Superficial portion (upper portion) is located subcutaneously in front of external ear and its deepest portion lies behind the ramus of mandible
- Gland is associated with branches of Glossopharyngeal (CN IX) and Auriculotemporal nerve, Ganglion oticum
- Receives blood supply from branches of external carotid artery (ECA)
- Duct of parotid gland (Stensen’s duct) runs forward across the masseter muscle, turns inwards at anterior border of masseter and opens into oral cavity at a papilla opposite maxillary 2ⁿᵈ molar
- Parotid gland has a pyramidal shape, produces 20-25% of total amount of unstimulated saliva, and secretes largest amount of saliva of all glands that’s sparse and watery
- Enzyme alpha-amylase is secreted by parotid gland and kallikrein, a vasodilator
SUBMANDIBULAR GLAND Wharton's duct
- Situated in posterior part of floor of mouth, adjacent to medial aspect of mandible and wraps around posterior border of mylohyoid muscle
- Glands receive parasympathetic innervation from branches of facial nerve (CN VII) and blood supply is from facial and lingual arteries
- Nerve supply reaches the gland through the lingual and submandibular ganglion