OB -Salivary glands II -cellular structure and acing secretory mech L3

Question 1

What are the constituents of salvia?

Answer 1

• water
• inorganic components
• organic components

Question 2

Name the sequence of ducts from the acinus to the mouth.

Answer 2

• Acinus
• intercalated duct
• striated duct
• secretory duct

Question 3

what cells are involved in the production of salvia?

Answer 3

cells compromising the acinus (secretory end piece)

Question 4

what are the 2 types of cells that produce salvia?

Answer 4

• serous

- mucous

Question 5

what are the shapes of salvia cells?

Answer 5

Pyramidal shaped cells which are polarised for function

Question 6

Describe the serous acinar cells.

Answer 6

• Nucleus at basal part of cell
• Basophilic RER
• Granular appearance

Question 7

where do serous acinar cells discharge their secretions?

Answer 7

into the tubular lumen via intercellular canaliculi running between the cells

Question 8

Describe mucous acinar crells.

Answer 8

• Pale cytoplasm - mucins lost or not easily stained, so cytoplasm can appear empty in a H & E stained section
• Flattened basal nucleus
• Many large mucin granules

Question 9

What are the serous demilunes that surround the mucous acinar cells?

Answer 9

-Cresent of serous cells
• Mucous acinus capped by serous cells
• Serous cells discharge via intercellular canaliculi between the mucous cells

Question 10

What is found on acini and intercalated ducts?

Answer 10

myoepithelial cells

Question 11

What is the function of myoepithelial cells?

Answer 11

• Contractile elements
• “Squeeze”acinus–may assist
secretion
• Regulate duct lumen diameter (make acinus more rigid to prevent over expansion)

Question 12

why do intercalated duct have myoepithelial cells?

Answer 12

they are fragile and prevent from damage

Question 13

Describe intercalated ducts.

Answer 13

• Low cuboidal cells
• Large central nucleus
• Difficult to see in routine wax sections

Question 14

What is function of intercalated ducts?

Answer 14

Only function is to transport salvia from acinus to striated

Question 15

Describe striated ducts.

Answer 15

• Not present in sublingual glands
• Columnar shaped cells
• Active modification of
primary saliva
• Massive basal membrane folding - suggests cells are very active (high metabolic rate)

Question 16

Describe secretory ducts.

Answer 16

• Large lumen
• Pseudostratified columnar epithelium (layers of cells)
• Stratified near termination – merges with stratified squamous oral epithelium

Question 17

what is the function of secretory ducts?

Answer 17

Only function is to transport salvia into the mouth

Question 18

where is the formation of sn isotonic solution?

Answer 18

acinus

Question 19

what is the name for the isotonic solution of salvia?

Answer 19

primary salvia

Question 20

what does the Sodium potassium pump do?

Answer 20

pump puts sodium out the cell and brings potassium in the cell

Question 21

what is stage 1 of producing primary salvia?

Answer 21

Increase in permeability to K+

encourages potassium to leave cell - one potassium in lumen and some outside the basal membrane

Question 22

what is stage 2 of producing primary salvia?

Answer 22

K+ in the extracellular fluid activates a Na+ K+ Cl- co-transporter (pumped back into the cell)

Question 23

What is stage 3 of producing primary salvia?

Answer 23

Cl- moves through the apical membrane into the lumen

Question 24

what is stage 4 of producing primary salvia?

Answer 24

• The increased concentration of Cl- in the acinar fluid drags Na+ to balance the charge
• water then follows sodium

Question 25

Name a feature of the primary salvia.

Answer 25

Concentrations of Na+, Cl-, HCO3- are similar to the plasma so therefore isotonic

Question 26

when does the composition of the primary salvia undergo further modification?

Answer 26

when it passes through the ducts

Question 27

Describe the conversion of isotonic solution to hypotonic solution.

Answer 27

• Active reabsorption of Na+ and Cl- from the lumen
• Active secretion of K+ and HCO3-into the lumen
• as the duct is impermeable to water this stays in the lumen

Question 28

what is the final concentration of Na+ in the salvia at low flow rates?

Answer 28

very low

Question 29

what is the final concentration of Na+ in the salvia at high flow rates?

Answer 29

High

Question 30

In high flow rates what pH does the salvia reach, explain why and what role does this play.

Answer 30

• Striated ducts are active so bicarbonate is a bi product of active metabolism
• The harder the cell works- the more bicarbonate is produced which raises the pH
• Normal pH of salva 6.5-7 , at high flow rate it can go up to 8
• Role : High pH in salvia means more of a buffer for acid -PROTECTION

Question 31

Describe the formation of organic constituents of salvia.

Answer 31

Most of the organic components are secreted by acinar cells

Question 32

Describe the synthesis of organic components.

Answer 32

• Formation of peptides
• Post translational glycosylation of peptides
• Processing and packing of organic components
• Formation of condensing vacuoles

Question 33

What is the main mechasnims for salvia components?

Answer 33

Exocytosis:
-Merocrine secretory mechanisms
(Migrate and merge with apex to discharge , cell remains the same shape)

Question 34

Describe apocrine secretory mechanism.

Answer 34

-Higher lipid content
-Loss of part of the cell
(Secretory products - are packaged into apical portion of the cell, when stimulus occurs, whole portion breaks away and ends up in secretory fluid of the cell)

Question 35

Describe holocrine secretory mechanism.

Answer 35

-Loss of the whole cell

whole cell is discharged into fluid - sebaceous glands only produce oil