Salivary biology Flashcards
describe the pathway of saliva
acinus –> intercalated ducts –> striated ducts –> secretory ducts
What is the function of the acinus?
forms the primary salivary secretion
what is the function of the striated ducts?
modify the primary saliva secretion
what the shape of an acinus? How many types?
pyramidal cells around a central lumen. The cells are POLARIZED, peripheral nucleus.
Mucous, serous and serous demilunes (aka a mucous acinus with a serous cell demilune on top of it).
what is the appearance of serous acini
DARK CYTOPLASM (BASOPHILIC), DARK BASAL NUCLEUS, GANULAR.
what is the appearance of mucous acini
PALE CYTOPLASM (mucins dissolved or do not pick up stain), FLATTENED BASAL NUCLEUS, many large MUCIN GRANULES.
What is a serous demilune
Mucous acinus capped by serous cells. LIKELY AN ARTEFACT
Where do we find myoepithelial cells? what is their function?
around the acini and the intercalated ducts. They are CONTRACTILE.
Acinus: help squeeze the secretion out
Intercalated ducts: control the lumen of the duct.
HENCE HELP INCREASE SALIVA FLOW.
what is the structure of the intercalated ducts
low cuboidal cells with large central nucleus. surrounded by myoepithelial cells.
What is the structure of the striated ducts? What do they do?
large cells with BASAL nucleus and VERY FOLDED BASE MEMBRANE. Perform ACTIVE modification of saliva.
LARGE CELLS VS SMALL LUMEN
Where are striated ducts not present?
in sublingual gland.
What is the structure of the secretory ducts
LARGE LUMEN vs SMALL CELLS
pseudo-stratified, becomes stratified near termination where it merge with stratified squamous oral epithelium.
why do striated ducts appear striated
folded basal membrane
what does the sublingual gland not have
striated ducts
what are the 3 main constituents of saliva
water, electrolytes, organic components
what does the primary saliva secretion contain? what is another way to call this?
acinar secretion. Contains water and electrolytes
What happens when an acinar cell is excited
K permebaility increases, K flows out into PRIMARY SECRETION and connective tissue.
What causes the activation of the na K Cl co transporter.
active transporter, increase in connective tissue K concentration
what is the result of Na K Cl co transporter activation.
Brings all 3 ions into cell, causes NA K pumo to work harder and take Na out of the cell into connective tissue.
SOME MORE K AND ENTRANCE OF CL INTO THE SALIVARY SECRETION
what is the result of Cl- flow into the primary secretion?
there is a shift in charge, hence SODIUM from connective tissue is drawn between the cells (attracted by the chloride) to balance the charge.
what happens as a result of sodium addition to primary secretion?
osmotic gradient is present, hence water is dragged down between the cells to redress the osmotic balance
what are the 6 steps to acinar secretion (ion behaviors)
- At rest, inside cell: high K, low Na. Outside cell: high Na, low K.
- When activated, cell permeability to K increases, K flows DOWN IT CONCENTRATION GRADIENT outside the cell K GOES TO LUMEN AND HENCE TO PRIMARY SECRETION.
- Increase of K concentration in connective tissue activates NA K CL con transporter. Active transport of ions into cell.
- Causes Na K pump to work harder, takes Na out into connective tissue. Hence SOME K AND CL ENTER PRIMARY SECRETION.
- Cl causes charge imbalance hence NA DRAGGED INTO PRIMARY SECRETION
- Concentrated solution, hence water flows in.
what are 2 facts about acinar secretion
- ionic concentrations are similar to plasma
- concentrations unaffected by flow rate
what happens to saliva concentration after being modified by striated duct
goes from isotonic (same concentration as tissue fluid) to hypotonic (lower)
how do the ionic components of saliva change after striated duct modification? what does this depend on?
addition of bicarbonate and K, resorption of Na and Cl
what are the final ions (with concentration) in primary secretion
High concentration of Na and CL, low concentration of potassium
what is the result of exciting a striated cell?
INCREASED BASAL ION PUMPING. activation of Na K pumps, pump Na out and K in.
What is caused after the increase in K concentration in striated duct?
COMPENSATORY MOVEMENTS - removal of Na and CL from secretion into the cell, K into lumen. HENCE SALIVA HAS INCREASED K, DECREASED NA AND CL.
What is the function of the bicarbonate cl pump?
ACTIVELY pumps bicarbonate into the saliva and removed cl
what is the effect of low flow rates on striated duct secretion?
more time for Na reabsorption, VERY LOW NA IN SALIVA.
what is the effect of high flow rates on striated duct secretion?
less time for Na reabsorption, HIGHER NA CONCENTRATION IN SALIVA
what is the relationship between flow rate and bicarbonate concentration in saliva
AS FLOW RATE/ GLAND ACTIVITY INCREASES, BICARBONATE CONCENTRATION INCREASED.
what structure secretes the organic components into saliva
primarily acinar cells via exocytosis
where do pre ganglionic neurons in parasympathetics come from
brain stem and s2-s4
where do pre ganglionic neurons in sympathetics come from
t1 to L2
how many neurons involved in autonomic pathways? where do they synapse?
2 neurons involved.
- preganglionic (from brainstem or spinal cord)
- synapse in a GANGLION with postganglionic
- postganglionic originates in ganglion and terminates in effector
describe the length and neurotransmitter of sympathetic fibres
Short pre ganglionic, long post ganglionic.
- acetylcholine and then noaradrenaline (or acetylcholine)
describe the length and neurotransmitter of parasympathetic fibres
long pre ganglionic, short post ganglionic.
acetylcholine
what is the effect of sympathetics and parasympathetics on salivary secretion?
BOTH CAUSED AN INCREASED SECRETION.
Sympathetic: vasoconstriction, a1 and b2 adrenergic receptors
Parasympathetic: vasodilation
how does the facial nerve supply salivary glands
Facial takes fibres from facial nucleus and superior salivary nucleus and supplies the submandibular (submandibular and sublingual gland) and pterygopalatine ganglions (palatal gland).
how does the glossopharyngeal nerve supply salivary glands
Glossopharyngeal takes fibres from superior and inferior salivary nucleus and supplies the otic (parotid) and remak’s (lingual) ganglions.
what is the receptor for parasympathic salivary secretion
muscarinic
what is the receptor for sympathetic salivary secretion
a1 and b2 adrenergic receptors
are sympathetics or parasympathetics responsible for most of the increase in volume of saliva flow?
parasympathetics
what is a drug that will give patients a dry mouth?
atropine (antagonist of ach)
what type of salivary secretion does sympathetic activation result in? why?
thick due to exocytosis of organic components
what is freys syndrome (what causes it, and what does it cause)
- often after parotid surgery
- damage to auriculotermporal nerve
- regeneration of nerves mized up
GUSTATORY SWEATING
what are the initiating signals fro salivation?
REFLEX SALIVATION
gustatory afferents (sour, salt, sweet, bitter), mechanoreceptive afferenets (PDL, mucosa, joint, muscle).
what is gustation
process of detecting chemicals that leads to the sensation of taste
