Salivation and Esophagus Flashcards
achalasia (what is it)
neuromuscular disorder of lower 2/3 of esophagus
failure of the lower esophageal sphincter to relax, resulting in difficulty swallowing
acinus (what is it)
saclike dilation in the salivary gland where the initial saliva is formed (acinar cells)
intercalated duct (what is it)
part of salivary gland that connects to striated duct to the acinus
metaplasia (what is it)
change in type of cell tissue from normal to abnormal
primary peristaltic contraction (what is it)
first contraction of esophagus initiated by swallowing
secondary peristaltic contraction (what is it)
subsequent contractions of esophagus
initiated by presence of food
striated duct (what is it)
part of the salivary gland that opens into the mouth
this is where the ionic composition of the saliva is modified
xerostomia (what is it)
dry mouth due to lack of saliva
What are the functions of salivary secretions
digestion- starts digestion of starches and fats
lubrication- facilitates swallowing
protection- has antibacterial properties
sense of taste depends on adequate salivation
myoepithelial cells (where are they found and what do they do)
specialized contractile cells
in acinus and intercalated duct
contact when saliva production is stimulated and eject saliva into mouth
what are the three major salivary glands
parotid
submaxillary/submandibular
sublingual
rank the major salivary glands in order from greatest to least contributor to salivaton
submaxillary>parotid>sublingual
Salivation its controlled by what?
total autonomic system control
Sympathetics and parasympathetics have what effect on saliva production
both increase it (unique)
parasympathetic nerve stimulation effects salivation how (mechanisms)
increases transport processes of acinar and ductal cells
stimulates vasodilation of blood vessels
sympathetic nerve stimulation does what to salivation (mechanisms)
transiently increases production of saliva and growth of salivary glands
causes contraction of myoepithelial cells
causes constrictor of blood vessels
effect of removing parasympathetic or sympathetic innervation on salivary glands
removing parasympathetics- leads to atrophy of gland
removing sympathetics- little effect
Saliva production is increased by what?
food in mouth
smells (but not food)
conditioned reflexes
nausea
Saliva production is decreased by what?
sleep fatigue dehydration fear anticholinergic drugs
saliva is a mainly a mixture of what
water
electrolytes
some organic compounds
what proteins are found in salvia and what do they do
alpha-amylase (ptyalin)- digests starches
lingual lipase- digests fats
mucin- lubricates food and protects oral mucosa
epidermal and nerve growth factors
what is the composition of saliva (in general)
mixture of water, electrolytes and some organic compounds
proteins
bacteriocidal substances
saliva ultra filtrate of plasma is what compared to plasma (hypotonic, isotonic, hypertonic)
hypotonic
the initial fluid produced by the acinus is what compared to plasma (hypotonic, isotonic, hypertonic)
isotonic
how does the started duct modify ionic composition of saliva (what is reabsorbed and what is secreted)
Na+ and Cl- are reabsorbed
K+ and HCO3- are secreted
relatively insoluble to water so more solute than water reabsorbed making saliva hypotonic
what is the mechanism for reabsorption and secretion by the started duct (i.e. what is exchanged for what)
Cl- exchanged for HCO3-
Na+ exchanged for H+
H+ exchanged for K+
how does flow rate affect concentration of ions in saliva
at higher rates the less time for reabsorption to occur so saliva is more isotonic
HCO3- increases with increases flow rate because its secretion stimulated when salivation stimulated
As flow rate increases what happens to Na+, Cl-, K+, and HCO3- concentrations in the saliva
Na+: increases
Cl-: increases
K+: decreases then plateaus
HCO3-: increases then plateaus
What are the phases of swallowing
oral phase
pharyngeal phase
oral (voluntary) phase of swallowing (whats going on here)
swallowing is ignited by voluntary action of collecting bolus of food and forcing it into oropharynx by pushing up and back against the hard palate
what is inhibited during pharyngeal phase of swallowing
breathing
pharyngeal (involuntary) phase of swallowing (whats going on here)
nasopharynx closed off by soft palate (stops regurgitation)
laryngeal contract to close glottis and elevate larynx
peristalsis begins in pharynx to propel food toward esophagus
upper esophageal sphincter relaxes, allowing contraction of constrictor muscles in pharynx to move material into esophagus
Swallowing can be controlled who?
reflex response coordinated in swallowing center in medulla
initiated voluntarily- requires something to trigger swallowing reflex
lesions to swallowing center result in what?
loss of pharyngeal phase of swallowing
may result in aspiration
dysphagia (what is it and how is it caused)
difficulty swallowing
usually neurological disorders cause it but can be due to inflammation or cancer of mouth, throat, or esophagus
Upper Esophageal Sphincter (UES)
what is it formed from and what does it separate, what does it prevent
formed by circopharyngeal muscle
separates esophagus from oral cavity
prevents entry of air
Lower Esophageal Sphincter (LES)
what does it separate, what does it prevent
separates esophagus from stomach
prevents entry of gastric acid
not a distinct muscle
compared to rest of esophagus what is different about lower esophageal sphincter
at a higher pressure than the rest of the esophagus
what initiates primary peristaltic contraction
swallowing
during quiescent state what is the state of the muscles of the esophagus (contracted or relaxed)
LES tonically contracted
rest of smooth muscle flaccid
what initiates secondary peristaltic contraction
presence of food in the esophagus (stretching mechanical receptors)
secondary peristaltic contraction is mediated by what
enteric nervous system
vagovagal reflexes
Gastroesophageal Reflux Disease (GERD)
cause, symptoms
caused by decreased tone of LES (reflux of stomach acid)
leads to heartburn and esophagitis
other symptoms: asthma, chronic cough, chest pain, laryngitis
Hiatal Hernia
esophagus passes through opening in diaphragm called hiatus
LES and part of stomach moved up (instead of aligned with hiatus)
acid reflux carrier weakened
Barretts Esophagus (what causes it and what is it)
caused by long term exposure to acid
constant injury to esophagus causes continuous cell growth (metaplasia)
can lead to esophageal cancer if left untreated
Belching (Eructation)
what is it, what is happening
air swallowed during eating or drinking (aerophagia), or gas from heavy mea or carbonated beverage forms bubble in stomach; when LES relaxes during swallowing process, air/gas enters esophagus and is regurgitated
