Salivation

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  • Created by: Becca
  • Created on: 23-12-13 21:33
What is the function of mastication?
To grind & break up food for swallowing, mix food with saliva and stimulate taste buds
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What are the salivary glands?
3 paired glands: parotid (20%, serous only), sub-mandibular (70%, mainly serous), sub-lingual (5%, mainly mucous), simple e.g. buccal (5%, mucous only)
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Which ions does saliva contain? What is the importance of these?
Lots of Na+ & Cl-, some HCO3-, small amounts of K+. Saliva is isotonic (same electrolyte composition) with plasma
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What are the two type of cells & what is their role in saliva?
Acinar cells: produce primary secretions that are isotonic with plasma & some salivary protiens. Duct cells: actively rebsorb Na+ & Cl- ion, some secretion of K+/HCO3-, impermeable to H20, excess absorption -> hypotonic saliva relative to plasma
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What happens if there is low primary secretions from acinar cells?
Saliva is in contact with duct cells for a long time, this allows duct cells to reabsorb Na+/Cl- & secrete HCO3-/K+. This leads to a much lower levels of Na+/Cl- in salvia than plasma & high levels of HCO3-/K+
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What is the result of increasing the flow rate?
Primary secretions in contact with duct cells for a short time. There is less time for reabsorb Na+ & thus the amount of Na+ in saliva will increase (same for HCO3- & Cl-, opposite for K+)
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What neural control is salivary secretion under?
Both parasympathetic & sympathetic!
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Describe the simple reflex of salivary secretion
Taste/smell/chewing -> pressure receptors & chemoreceoptors (mouth) -> salivary centre in medulla (cerebral cortex) -> autonomic nerves -> salivary glands -> salivary secretion
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What kind of saliva does parasympathetic stimulation produce? Describe the process
Produces a large volume of serous saliva that is rich in enzymes. Acinar cells releases kalikrein to produce bradykinin, causes local vasodilation & increases capillary permeability (more fluid for primary secretions)
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What kind of saliva does sympathetic stimulation produce?
Produces small volume of thick saliva rich in mucous (vasoconstriction decreases the amount of fluid available for saliva)
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What are the functions of saliva?
Amylase starts the breakdown of polysaccharides (requires neutral pH), protective (antibacterial), solvent (stimulate taste), moisture aids speech, oral hygiene, mucous facilitates swalling, bicarbonate neutralizes acid in food & decreases cavities
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What are the two stages of deglutition? (swallowing)
Oropharyngeal: bolus directed into oesophagus, sealing of nasal passages by uvula & trachea by glottis. Oesophageal: oesophagus protected by mucous secretion, movement by peristalsis
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Card 2

Front

What are the salivary glands?

Back

3 paired glands: parotid (20%, serous only), sub-mandibular (70%, mainly serous), sub-lingual (5%, mainly mucous), simple e.g. buccal (5%, mucous only)

Card 3

Front

Which ions does saliva contain? What is the importance of these?

Back

Preview of the front of card 3

Card 4

Front

What are the two type of cells & what is their role in saliva?

Back

Preview of the front of card 4

Card 5

Front

What happens if there is low primary secretions from acinar cells?

Back

Preview of the front of card 5
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