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Systems 1 > Mastication, Esophagus and Salivation > Flashcards

Mastication, Esophagus and Salivation Flashcards

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1
Q

Primary oral cavity effects

A

Interaction of mandible and maxilla triturates food into smaller particles. Enhances efficiency of digestive process

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2
Q

Secondary effects of oral cavity

A
  • Protection for dentition
  • Starch and lipid digestion
  • Lubricated food bolus for swallowing
  • Forms alternate airway and functions in verbal communications
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3
Q

Bite force depends on

A

muscle volume, jaw muscle activity and the coordination between the various chewing muscles

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4
Q

Myotatic reflex

A

Resting tone of skeletal muscle in jaw to keep mouth closed

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5
Q

Inverse myotatic reflex (Golgi tendon)

A

Pressure on TMJ and periodontal ligament inhibits jaw closing and stimulates jaw opening muscles

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6
Q

Low threshold mechanoreceptor reflex

A

Pressure or touch on dorsum of tongue stimulates jaw closing. This is activated during swallowing

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7
Q

High threshold mechanoreceptor reflex

A

Nociceptive stimuli result in rapid jaw opening. Rids the oral cavity of harmful substances

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8
Q

In the myotatic reflex, what opens the jaw?

A

Gravity- which then stretches spindles in the jaw closing muscles to stimulate the reflex

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9
Q

Muscle spindles for myotatic reflex are only in

A

jaw closing muscles

(not needed in opening muscles)

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10
Q

Inverse myotatic reflex- Stimulation of

A

Golgi tendon, such as PDL or TMJ

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11
Q

Inverse myotatic reflex will do 3 things

A
  • Stimulate jaw opening muscles
  • Inhibit jaw closing muscles
  • Modulate pressure on dentition
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12
Q

Low threshold mechanoreceptors activation reflex purpose is to

A

seal oral cavity in prep for swallowing

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13
Q

Low threshold mechanoreceptors activation reflex: Pressure on dorsum of tongue results in

A
  • Stimulation of jaw closing muscles
  • There is No reciprocoal innervation apthway to jaw opening muscles
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14
Q

High Threshold receptor activation receptors

A
  • Golgi tendon like organs in gingiva and periodntal ligament
  • Pain receptors in gingiva, PDL and in peri-oral mucosa
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15
Q

High Threshold receptor activation: Adequate noxious stimulation results in

A
  • Stimulation of motor nerves to jaw opening muscles
  • Reciprocoal inhibition of jaw muscle closing motor nerves
  • Rapid opening of oral cavity
  • Expulsion of offending stimulus
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16
Q

At rest, gamma efferents are

A

quiet

(enough to keep jaw closed)

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17
Q

At rest, TMJ afferents from pressure and rotation are

A

quiet

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18
Q

At rest, 1A afferents from muscle spindles are

A

at a low level of activity

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19
Q

At rest, PDL receptors (pressure, pain) have what level of activity?

A

a low level of activity

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20
Q

To start chewing cycle, how is command started?

A

Command given by CNS to a motor nerve to contract

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21
Q

During chewing, as the jaw closing muscle contract, what happens to the gamma efferents?

A

They are stimulated in proportion to feedback from muscle spindles

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22
Q

As pressure increases during chewing, what happens to the TMJ and PDL?

A

TMJ and PDL pressure receptors increase their firing rate

Sends data back to CNS to reset gamma effects to maintain optimal force and achieve optimal efficiency

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23
Q

When the mandible is rotated, what happens to receptors?

A

TMJ receptors that detect roation begin to fire at a high rate as the mandible is rotated

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24
Q

In the example of chewing a peanut, what happens when the peanut is split?

A
  • Jaw closure rate accelerates
  • Alpha and gamma motor neurons continue to fire
  • TMJ pressure nerves go silent. Detection of a rapid fall in pressure
  • PDL pressure receptors go silent
  • TMJ rotation receptors increase
  • 1A spindle input to CNS rapidly goes silent
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25
To prevent cracked dentition, afferent input is alters and cause what?
The CNS to rapidly inhibit motor nerves to jaw closing muscles
26
As chewing is a repetitive process, much of the CNS circuitry is found in what part of the brainstem?
Central pattern generators (CPGs) And can be influenced by higher centers, such as the basal ganglia
27
Masticatory system is mainly
closed loop controlled
28
How does saliva protect dentition and esophagus?
- Neutralize acids from foods or from any gastric reflux - Provides immunoglobulins for cario-static effect - Allows for adhesion of proteins to enamel to provide a protective pellicle
29
Saliva secretes hormones from blood which is useful in what?
Stress and avoids venipuncture
30
Parotid gland is composed of
serous cells
31
Parotid gland secretes
aqueous fluid consisting of water, ions and enzymes
32
Submandibular gland consists of
mix of serous and mucus cells
33
Sublingual gland contains
mix of serous and mucus cells
34
What drugs are the biggest offenders to causing dry mouth?
Anticholinergic
35
What cells produce the initial saliva?
Acinar cells
36
Myoepithelial cells are stimulated by neural input and allow
the saliva to be ejected intot he duct and mouth
37
Ductal cells modify the saliva by
reabsorbing Na, Cl and secreting K and HCO3
38
What is saliva from parasympathetics like?
More watery and has high flow and volume rate
39
Wha is the saliva from sympathetic like?
Protein enriched and low flow rate and volume
40
Once saliva leaves the duct, it is
hypotonic
41
Why is saliva hypotonic when it leaves the duct?
Because the ductal cells are impermeable to water
42
At high salivary flow rates, the saliva closely resembles the plasma, but will still be _____
hypotonic
43
HCO3- secretion is selectively stimulated when _________ system is turned on
Parasympathetics
44
Saliva secretion is mediated by what?
Both parasymp and symp
45
Aldosterone can alter the
salivary ionic composititon
46
Beta-adrenergics will increase cAMP and
slightly increase volume and significant increase enzyme/protein content (very viscous)
47
Alpha adrenergic agonists can do what to blood flow?
Vasoconstrict and therefore decrease volume and enzyme content of saliva
48
What is the cephalic phase of salivation mediated by?
Sight, aroma or though of meal
49
What is the oral phase of salivation?
Mechanical stimulation of the oral cavity from food, gum Largest volume
50
What is the esophageal (gastric) phase of salivation?
Distension of food in esophagus and stomach helps to clean dentition and oral cavity
51
Oral phase of deglutition is
voluntary
52
Pharyngeal and esophageal phases of deglutition are
involuntary
53
Pharyngeal phase of deglutition allows
food to pass from pharynx to the esophagus
54
What is the pharyngeal phase of deglutition mediated by?
CN IX (glossopharyngeal) and X (vagus)
55
Swallong center in the brain is where?
Medulla oblongata
56
What are the 4 phases of pharyngeal phase of deglutition?
- Soft palate pulled upward creating narrow passage for food to move into pharynx without entering nasopharynx - Epiglottis moves to cover opening of larynx and larynx moves upward against epiglottis - Upper esophageal sphincter relaxes allowing food to move from pharynx to esophagus - Peristaltic wave of contraction is intitiated in pharynx to propel food through opened UES
57
Pharyngeal phase is rapid due to
skeletal muscle contraction
58
Between swallows, is UES open or closed?
Closed
59
Esophageal phase is much slower due to
smooth muscle contraction
60
Esophageal phase is controlled by what?
Swallowing reflex and ENS
61
Serotonin (5-hydroxytryptamine, 5-HT) is a key
ENS transmitter for peristalsis
62
Serotonin release is stimulated by
stretch receptors and/or efferent vagal stimulation.
63
In front of (anad side of) bolus serotonin will:
* Stimulate longitudinal muscle contraction circuits (Ach, Substance P) to shorten and widen the lumen. * Inhibits circular muscle contraction circuits (nitric oxide (NO), VIP, Adenosine) and also widens the lumen
64
Behind (orad side of) bolus, serotonin will:
* Inhibit longitudinal muscle contraction circuits to lengthen and narrow the lumen. * Stimulates circular muscle contraction and contraction behind the bolus. * Both actions push bolus anad.
65
Between swallows, LES smooth muscle are normally contracted. Smooth muscle tension is
myogenic and generated through the opening of L-type calcium channels
66
Efferent vagal innervation to LES is
inhibitory
67
Relaxation of LES made possible through release of
nitric oxide (NO) and vasoactive intestinal peptide (VIP).
68
The inhibition of the LES and lowering of tension during swallowing is known as
Receptive relaxation
69
Because the lower portion of the esophagus is within the thoracic cavity, pressures will be
negative
70
What is achalasia?
Swallowing disorder where LES failts to relax. There is impaired peristalsis in lower 2/3s of esophagus, causes for dilation to occur above the LES
71
Once LES relaxes, food will move into the stomach which will
Relax in order to receive the food bolus (receptive relaxation)
72
Wet swallows generate
Secondary peristaltic contractions and more pronounced LES inhibition
73
Dry swallow generates
weaker secondary peristaltic contractions as the distending air in bolus leaks out
74
What is hiatal hernia?
LES is detached from diaphragm, so LES rises up into the thoracic cavity and is pulled opened by the negative intrapleural pressure

Systems 1 (33 decks)

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