41 Salivary and Exocrine pancreatic physiology Flashcards
Which 2 enzymes are involved when food is digested by salivary secretion?
- Alpha-amylase
2. Lingual lipase
List 3 functions of salivary secretion.
- Digestion
- Solubilization of food for taste bud
- Lubrication of food for swallowing
- Cleaning of buccal mucosa and teeth (Xerostomia: dry mouth)
- Protection of antibacterial actions
- Facilitation of speech
What are the 3 salivary glands? What cells do they contain respectively?
- Parotid cells (serous cells only)
- Sublingual cells (mostly mucous cells)
- Submandibular cells (mixed)
What is the functional unit of salivary glands?
Salivon
A salivon can be divided into 3 parts: the acinus, the intercalated duct and the striated duct.
What cells are present in each part and what are their respective functions?
Acinus: acinar cells, myoepithelial cells; secrete initial salivary secretion
Intercalated duct: myoepithelial cells; they are contractile cells that control saliva flow via parasympathetic nerves
Striated duct: Ductal cells; secrete and modify inorganic composition (Na+, Cl-)
Regulation of salivary secretion is exclusively under:
A. Hormonal control
B. Endocrine control
C. Neural control
C
True or False:
Sympathetic nerves exert major stimulatory effect in salivary regulation
False.
Should be parasympathetic as major,
BUT sympathetic also stimulates secretion!
In regulation of salivary secretion, aldosterone and ADH
A. do not play any role
B. Modify ionic content of saliva by decreasing Na+ and increasing K+
C. regulate secretion of saliva
B only
Which of the following is not a stimulatory factor of salivary secretion?
- Chewing
- Conditioned reflex
- Dehydration
- Nausea
- Smell
- will secrete less when there is dehydration
for nausea, saliva is secreted to dilute the gastric juice during vomiting to prevent damage to mouth and esophagus
Which of the following is/are inhibitory factor(s) of salivary secretion?
- Sleep
- Fatigue
- Fear
- Dehydration
All of the above
Which secondary messenger is activated when there is parasympathetic stimulation in salivary secretion?
What receptors is being activated?
IP3 > Ca2+
Muscarinic receptors on the salivary gland are stimulated by the glossopharyngeal nerve and facial nerve.
Which of the followings are glandular activities stimulated by parasympathetic nerves?
- Secretion of saliva
- Myoepithelial cells contraction
- Vasoconstriction
- Growth
- Metabolism
All except 3
Vasodilation is stimulated
In sympathetic stimulation in salivary secretion, what neural substance is released to activate what receptors?
Noradrenaline acts on adrenergic receptors of salivary gland.
In pancreatic exocrine secretion,
A. Acinar cells is the majority of cells compared to duct cells.
B. Acinar cell > Ductal epithelium. In which Intercellular canaliculi > Intralobular duct > Extralobular duct
C. Pancreatic duct joins with the common bile duct after entering the duodenum via relaxation of Sphincter of Oddi
A and B ony
A. Acinar cells (82%) and duct cells (3.9%)
C. Pancreatic duct joins with the common bile duct before entering the duodenum via relaxation of Sphincter of Oddi
Pancreatic exocrine secretion consists of aqueous and enzymatic component. What are they made up of respectively?
Aqueous component: by ductal epithelium with Na+HCO3-
Enzymatic component: by acinar cells
The aqueous component of pancreatic consists of the ductal epithelium with Na+ HCO3- which serves to:
(2 functions)
- Neutralize gastric chyme to prevent the injury to the duodenal mucosa
- Provide optimal pH for pancreatic digestive juices
True or false: Proteins by the acinar cells are active before being secreted into the duodenum.
False. All proteins are in precursor form unless it is released into the duodenum
Cl- release depends on _________, which is affected by ________ secreted by endocrine ___ cells, causing cAMP to increase and Cl- to come out.
CFTR Cystic fibrosis transmembrane conductance regulator
Secretin; S cells
The enzyme ________ facilitates conversion of water to OH- and H+, thus OH- can enter the lumen via Cl-/HCO3- exchanger (1 HCO3- out, 1 Cl- in)
Carbonic anhydrase
What is cystic fibrosis?
- Defective CFTR channel which cannot be opened
- Blocked acini ducts with thick and viscous mucous
- Tissue destruction/fibrosis
- Pancreatic exocrine insufficiency
What are the 3 basic factors stimulating pancreatic secretion?
What are their actions respectively?
a. Acetylcholine; stimulate acinar cells to secrete enzymatic component
b. CCK; response to fat,
stimulate acinar cells to secrete enzymatic component
c. Secretin; response to acidic food, secrete aqueous component (primary stimulus of Na+ HCO3- secretion)
What are the 3 phases of pancreatic secretion ?(different from 40 gastric!)
Briefly describe each phase.
- Cephalic phase (20%, neural only)
- Stimulus: vagus nerve and ENS
- Acetylcholine: M3 receptors on duct cells and acinar cells
- Stimulate enzymatic secretion mainly.
- Gastric phase (5%)
3. Intestinal phase (75%) Hormonal and neural; Hormonal is predominant: - Fat > I cells > CCK > Duct cells - H+ > S cells > secretin > acinar cells;
Neural is minor:
- Acetylcholine > M3 receptor > duct cells (short reflex)
- on acinar cells: long reflex
CCK and acetylcholine
A. is responsible for enzymatic secretin
B. is responsible for aqueous secretion
C. can multiply the aqueous secreting function of secretin
A and C only
B: no, only secretin does it
