Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
Exocrine secretion - definition
|
gland cells release the secretory products into ducts
ducts open onto an epithelial surface of the body |
|
|
Endocrine secretion - definition
|
a hormone elaborated in an endocrine cell is released into the blood stream to act at a distant target cell
|
|
|
Nuerocrine secretion - definition
|
Hormone synthesized in neuron and released into the blood stream to act on a distant target cell
|
|
|
Paracrine secretion - definition
|
hormone released from a cell diffuses short distance in interstitial fluid to nearby target cell
|
|
|
Nuerotransmitter secretion - definition
|
substance released into a synaptic cleft to act on a neary cell
|
|
|
Secretagogue
|
a substance that stimulates secretion from a cell
|
|
|
Parotid glands
|
largest of the salivary glands
entirely serous glands watery secretion containing amylase but not mucins |
|
|
submandibular and sublingual glands
|
mixed glands, secrete more viscous saliva containing mucins and amylase
structure: acinar cells (serous cells and mucus cells) secrete their products into the lumen of acini intercalated ducts drain the acini into larger striated ducts striated ducts drain into still larger excretory ducts etc. a single duct taken secretions of each gland to mouth |
|
|
Functions of saliva
|
1. lubricates food for easy swallowing
2. begins digestion of starch (amylase) 3. solubilizes material so that it can b tasted 4. Cleanses mouth and teeth (lysozyme and secretory IgA) -xerostomia (dry mouth) in people with no salivary glands -results in high incidence of dental caries and mouth infections 5. facilitates speaking 6. helps clear esophagus of refluxed gastric secretions |
|
|
salivary gland production
|
1-1.5L/day - basal rate of 0.5 ml/min (much less at night)
produced primarily during meals (or chewing) metabolism and blood flow of glands is proportional to rate of saliva formation |
|
|
salivary organic compontnets
|
-proteins from acinar cells
amylase lipase mucus glycoproteins proline-rich glycoproteins tyrosine-rich protein (statherin) histidine-rich protein peroxidase --proteins from non-acinar cells lysozyme secretory immunoglobulin A (IgA) growth factors-gastric mucosal regulatory peptides-vasodilation |
|
|
ionic composition of saliva
|
varies depending on rate of secretion and stimulus
w/ increased flow rate 1) [K+] decreases slightly (almost ind of flow rate) 2) concentrations of Na+, HCO3, and Cl- increased 3) pH increases (approaches pH 8) 4) saliva becomes less hypotonic |
|
|
two-stage model of salivary secretion
|
1) primary secretion in end-pieces is isotonic
a - levels of Na, K,and Cl close to those in plasma b - amylase concentration and rate of fluid secretion depend on type of stimulus 2) excretory ducts (probably striated ducts too) modify secretion a - remove Na and Cl b - add K and HCO3 c - saliva become more hypotonic as it moves down ducts because of greater rate of Na and Cl absorption than K and HCO3 secretion d - little H20 is absorbed in ducts because of low permeabiility of the epithelium of the ducts |
|
|
salivary organic compontnets
|
-proteins from acinar cells
amylase lipase mucus glycoproteins proline-rich glycoproteins tyrosine-rich protein (statherin) histidine-rich protein peroxidase --proteins from non-acinar cells lysozyme secretory immunoglobulin A (IgA) growth factors-gastric mucosal regulatory peptides-vasodilation |
|
|
ionic composition of saliva
|
varies depending on rate of secretion and stimulus
w/ increased flow rate 1) [K+] decreases slightly (almost ind of flow rate) 2) concentrations of Na+, HCO3, and Cl- increased 3) pH increases (approaches pH 8) 4) saliva becomes less hypotonic |
|
|
two-stage model of salivary secretion
|
1) primary secretion in end-pieces is isotonic
a - levels of Na, K,and Cl close to those in plasma b - amylase concentration and rate of fluid secretion depend on type of stimulus 2) excretory ducts (probably striated ducts too) modify secretion a - remove Na and Cl b - add K and HCO3 c - saliva become more hypotonic as it moves down ducts because of greater rate of Na and Cl absorption than K and HCO3 secretion d - little H20 is absorbed in ducts because of low permeabiility of the epithelium of the ducts |
