35 - Salivary glands, structure, mechanism + control

Question 1

Acini

Answer 1

clusters of cells ⇢ these are basic secretory unit of salivary glands

• They secrete fluid containing ⇢ water, electrolytes, mucous + enzymes
• Flows out from acinus into collecting ducts

Acinar epithelial cells

• Serous ⇢ secrete watery fluid
• Mucous ⇢ produces mucous rich secretions

Salivary flow is directly related to size of gland

Question 2

Parotid gland

Answer 2

• Bilateral gland w/serous acini
• Located subcutaneously ⇢ in front of external ear + deepest portion lies behind ramus of mandible
• Associated w/branches of CN VII
• Receives blood supply from branches of external carotid artery

Duct/Stensen’s duct

• Runs along masseter muscle
• Turns inwards + opens at level of maxillary 2nd molars

Parotid gland secretes:

• a-Amylase + Kallikrein
• 20% of saliva in unstimulated flow
• over 50% in stimulated flow

Parotid serous fluid

• Antifungal capacity
• High content of bicarbonates

Question 3

Submandibular gland

Answer 3

• Mixed acini gland
• Located in posterior part of mouths floor + wraps around posterior border of mylohyoid muscle
• Parasympathetic innervation from branches of CN VII
• Blood supply from facial + lingual arteries

Wharton’s duct

• Runs above mylohyoid muscle
• Opens into mouth beneath the tongue

Submandibular gland produces

• a-amylase + Kallikrein
• 65% of unstimulated saliva

Question 4

Sublingual gland

Answer 4

• Smallest major salivary gland
• Possesses mucous acini
• Located in anterior part of mouth’s floor
• Parasympathetic innervation from CN VII
• Blood supply from sublingual + submental arteries

Secretions

• Enter oral cavity through small ducts opening along submental fold
• Also opens through Bartholin’s duct ⇢ opnes at sublingual carnucle

Sublingual gland produces

• Lingual lipase + Kallikrein
• 7-8% of unstimulated saliva

Question 5

Minor Salivary glands

Answer 5

• 600-1000 small aggregates of secretory tissue
• Located in submucosa of almost entire oral cavity
• NOT seen in gingiva + anterior hard palate
• Predominantly mucous except for lingual serous glands

Include

• Labial
• Lingual
• Palatal
• Buccal
• Glossopalatine
• Retromolar

Question 6

Formation + Secretion of saliva

Answer 6

1st stage

• 1° saliva ⇢ isotonic fluid containing most organic components + H2O is produced
• Via cells of ⇢ secretory end peices + intercalated ducts

2nd stage

• Modification of 1° saliva
• Passes through striated + excretory ducts ⇢ via reabsorption + secretion of its electrolytes
• Na⁺ + Cl^- exchanged for bicarbonates + K⁺
• Final saliva = hypotonic

Question 7

Control of salivary excretion

Answer 7

ANS ⇢ controls volume + type of saliva excreted

Parasympathetic innervations from brain

• Enhanced secretion + ⇡ flow to salivary glands
• Presence of smell of food = ⇡ salivation