Salivary Secretions

Question 1

How do salivary secretions protect the body?

Answer 1

they include buffers to neutralize acidic materialswash out any unwanted materialshave ABX capability via lysosome and lactoferrin

Question 2

How do salivary secretions aid in digestion?

Answer 2

it includes a-amylase which contributes to 70% ofhydrolysis of starch to produce maltose via breaking a1,4-glucosdase bondsand contains lingual lipase (which starts lipid digestion)

Question 3

What are the three main salivary glands?

Answer 3

parotid (serous cells)submandibular andsublingual (serous and mucus cells)

Question 4

What is the difference beween serous and mucus cells?

Answer 4

serous fluid only contains electrolytes and protein while mucus fluid contains mucus

Question 5

Acinar cells secrete the electrolytes, water, and proteins (initial saliva- similar to plasma)which are propelled via the myoepithelial cells into the intercalated ducts. The cuboidal cells of the intercalated cells also propell the initial saliva into the striated ducts.Striated ducts are lined by columnar cells, the composition of the saliva changes

Question 6

What is the vasculature to the salivary glands?

Answer 6

Very high blood flow from branches from the external carotid a., which flows opposite to salivary flow and capillaries, surround acini and non-acinar regions

Question 7

What is the innervation to salivary glands?

Answer 7

parasym via the facial glosspharyngeal nn. and autonomic ganglia and sympathetics via the superior cervical ganglion both contribute to gland secretions

Question 8

Note that the osmolarity, composition, and pH vary with flow rate

Answer 8

WIth lower flow rates, there is more time for NaCl to be absorbed into the striated ducts as it passed through the acinar system and it becomes more hypotonic. With higher flow rates, the composition of the saliva is similar to whats produced in the acinus

Question 9

Describe electrolyte exchange from the acinus to the striated duct openings

Answer 9

Initially, I-, Na+, Cl- and HCO3- are secreted into the acinus (so that its composition is similar to plasma) and as it enter the striated ducts K+(active)and more HCO3- is added and Na+ (active), Cl-, and H2O are lost (absorbed)

Question 10

Why does the osmolarity of fluid decrease along the length of the striated ducts?

Answer 10

the water re-asborption is very slow and cannot match the Na and Cl reabsorption

Question 11

What other products are secreted in the acinus into saliva?

Answer 11

amylase, lipasemucuslysozyme and lactoferrinKallikreinEGFblood group substances

Question 12

What part of saliva secretions is active?

Answer 12

Cl- into the acinus lumen because it is coupled to a K/Na ATPase on the basolateral membrane. So blocking this ATPase will cause Cl- to not be secreted and reduce saliva.

Question 13

How does Cl- enter the acinus epithelium to produce the gradient that drives movement into the lumen passively?

Answer 13

a Na/K/2Cl transporter on the basolateral membrane ANDa basolateral Cl/HCO3- exchangerBOTH of these require a Na gradient so Cl- is linked to Na/KTPase

Question 14

How does Na+ enter the acinus lumen to enter intiial saliva?

Answer 14

paracellular mechanisms via tight-junctions andCldn2

Question 15

How does water enter the acinus lumen to enter intiial saliva?

Answer 15

Aquaporin 5

Question 16

How is Na+ reabsorbed from the acinus lumen in the striated ducts?

Answer 16

There is a much higher conc. of Na+ in the lumen leading to passive reabsorption of Na+ which is then returned to blood via a NaKATPase pump on the basolateral side. The K that then enters the acinus epithelium passively diffuses into the lumen via gradient

Question 17

How is Cl- reabsorbed from the acinus lumen in the striated ducts?

Answer 17

it passively diffuses to maintain theelectrochemical gradient after Na leaves the lumen or via exchange with HCO3- on the luminal membrane and passively into blood on the basolateral side.The HCO3- needed for this enters the acinus epithelium via a co-transport mechanism with Na+

Question 18

T or F. There is no known hormonal regulation of saliva

Answer 18

T. Only para- and sympathetic stimulation

Question 19

How does the parasym system regulate saliva secretions?

Answer 19

mainly by increasing blood flow and production of kallikrein and thus bradykinin (a vasodilator)

Question 20

Saliva output in terms of sympathetic inputThe dip is due to transient vasocontriction (via a receptors) and the longterm increase is due to constriction of the myoepithelial cells via B receptors

Question 21

How else can salivary secretion be mediated?

Answer 21

centrally via inputs such as smell, taste, nausea which stimulate the salivary nucleus of the medulla to signal via CN IX and X to release Ach to cause increased secretion via a Gq mechanism as well as sympathetics from T1-T3

Question 22

What things inhibit the salivary nucleus of the medulla?

Answer 22

fatigue, sleep, fear, dehydration

Question 23

What are the main salivary gland tumors?

Answer 23

-Pleomorphic adenoma (50%) (mixed benign tumor)-Mucoepidermoid carcinoma (15%)-Warthin tumor (5-10%) (benign)

Question 24

What are these?

Answer 24

Pleomorphic adenomas, which show great histologic variation. These are most commonly found in middle aged females

Question 25

How do pleomorphic adenomas present?

Answer 25

typically as slow growing, painless, movable, firm masses. Rarely, carcinomas can arise in longstanding pleomorphic adenomas, which is marked by sudden rapid growth

Question 26

Histological variation of pleomorphic adenomas

Answer 26

•benign tumors that consist of a mixture of ductal (epithelial) and myoepithelial cells, and therefore they show both epithelial and mesenchymal differentiation.•They reveal epithelial elements dispersed throughout the matrix along with varying degrees of myxoid, hyaline, chondroid (cartilaginous), and even osseous tissue.

Question 27

What is this?

Answer 27

A warthin tumor

Question 28

Describe warthin tumors

Answer 28

These are benign salivary tumors common in middle-aged males and especially SMOKERS. They are found almost exclusively in the parotid glands, can be bilateral, and are painless

Question 29

How do Warthin tumors appear histologically?

Answer 29

They are marked by epithelial and lymphoid elements•Note the follicular germinal center beneath the epitheliumCystic spaces separate lobules of neoplastic epithelium consisting of a double layer of eosinophilic epithelial cells based on a reactive lymphoid stroma

Question 30

What is this?

Answer 30

AMucoepidermoid carcinoma

Question 31

What pt. pop areMucoepidermoid carcinomas common in?

Answer 31

can present at ANY age (even kids)

Question 32

Where areMucoepidermoid carcinomas most commonly found?

Answer 32

parotids

Question 33

DescribeMucoepidermoid carcinomas

Answer 33

These MALIGNANTneoplasms are composed of variable mixtures of squamous cells, mucus-secreting cells, and intermediate cells.•They represent about 15% of all salivary gland tumors, and while they occur mainly (60% to 70%) in the parotids.

Question 34

What is probably the most important determinant of the prognosis ofmucoepidermoid carcinomas?

Answer 34

gradeGrade 5-year survivalLow: 90%High: 50%