GI-Part 2 Flashcards
Jaw closing muscles include the: (3)
Masseter, Medial Pterygoid, Temporalis Muscle
Jaw opening muscles are the: (2)
Lateral Pterygoid, Digastric Muscles
What innervates the jaw muscles?
Trigeminal Nerve (V)
The chewing rhythm is generated by … to the chewing center from the pressure receptors.
afferent stimuli
The chewing rhythm cycle of about … duration is repeated until the colts of food is swallowed.
1 second
The Chewing Reflex occurs when (initiated by) a … touches the lining of the mouth
blows of food
What mediates the Chewing Reflex?
monosynaptic stretch reflexes are activated
Deglutition (Swallowing) may be initiated … but after oral phase swallowing becomes exclusively …
voluntarily; reflexive
Deglutition (Swallowing) is mediated through the…
Swallowing Center in the Medulla
Buccal (Oral) phase of swallowing is initiated by …
Tactile Receptors in the back of the Mouth
What are the Afferents Tactile/Pressure Receptors associated with the Buccal (Oral) Phase of Swallowing (4)?
V-Trigeminal Nerve
VII-Facial Nerve
IX-Glossopharyngral Nerve
X-Vagus Nerve
What is the added (5th) Efferent nerve associated with the Buccal (Oral) Phase of Swallowing?
XII-Hypoglossal Nerve
In the Pharyngeal Phase of Swallowing the Soft Palate and Uvula are pulled up and the … close to prevent …
Palatopharyngeal Folds close to prevent nasal reflux
In the Pharyngeal Phase of Swallowing what accommodates around the bolus of food to squeeze it into the Esophageal Phase?
Pharyngeal Muscles (striated)
What action in the Pharyngeal Phase of Swallowing inhibits respiration?
Vocal Cords contract to close the Glottis and Epiglottis covers the trachea
The Esophageal Phase of Swallowing is through …
Primary Peristalsis
In Primary Peristalsis the … contracts behind the bolus of food, beginning to propel the bolus of food down the Esophagus.
UES
In the Primary Peristalsis the … relaxes independent of and prior to the arrival o the Peristaltic Wave.
LES
In the Secondary Peristalsis what is not involved?
Pharyngeal Phase
Usually caused by the LES not maintaining complete closure.
Dysphagia (difficulty swallowing)
Occurs when the LES fails to relax (open)
Achalasia
Achalasia is usually due to problems with the …
myenteric plexus
In Achalasia food accumulates in the esophagus (instead of the stomach) and causes …
secondary peristalsis
What NT is impaired in pts with Achalasia?
NO levels are decreased
Is a potent constrictor of the LES, and levels of it may be increased in pts with Achalasia.
Acetylcholine
Gastric Reflux during pregnancy and in infants since … is not complete at birth.
Peristalsis circuitry
The fundus and body of the stomach are very distensible (volumes may change from … to … with little change in internal pressure)
50 - 1500 mL
What occurs upon swallowing allowing food to remain virtually unmixed for up to an hour, and allowing fats to flow to the top of the stomach for digestion by lingual lipase.
Receptive Relaxation
What is the last to be digested in the stomach?
fats
Receptive Relaxation is diminished by …
vagotomy
Antrum of the Stomach has strong contractions; function is to mix chyme with gastric secretions, most mixing is due to retropulsion.
Astral-Pyloric Systole
Is Gastric Emptying occurring faster or slower with a larger volume (meal)?
faster
The rate of Gastric Emptying is slowed by …
high fat and protein concentrations
In Gastric Emptying usually only particles smaller than … are emptied
0.2 mm
Gastric Motility is decreased by: (3)
GIP, CCK, and SNS
Gastric Motility is increased by: (3)
- Distention (increase release of Gastrin from G-cells)
- Closed Pyloric Sphincter
- PSNS via Vagovagal Reflexes
Where are the signals coming from that influence the Vagus Nerve during Cephalic Phase?
“above the chin” like conditioned reflex, smell, taste, sight
In the Cephalic Phase of Digestion the efferent limb of regulation is the Vagus Nerve which can directly increase Stomach Motility by releasing …
Acetylcholine
In the Cephalic Phase the Vagus Nerve can stimulate the release of … from cells located within the Antrum.
Gastrin Releasing Peptide (GRP)
In the Cephalic Phase of Digestion the released GRP acts on nearby G-cells of the Antrum/Pylorus Region that release Gastrin, which then has what effect?
Gastrin is circulated through the stomach increasing motility at its target tissue the visceral smooth muscle
The Gastric Phase of Digestion is similar to the Cephalic Phase except that the stimulus comes from …
Mechanoreceptors and Chemoreceptors within the Mucosal Lining of the Stomach (ENT)
The neural stimuli of the Gastric Phase of Digestion is …
distention
In the Intestinal Phase gastric emptying is decreased primarily through modification of …
decreasing the stomach SV
In the Intestinal Phase chemoreceptors for … and … and to a lesser extent MechanoReceptors are stimulated in the Mucosal Lining of the Duodenum as Chyme enters from the Pylorus.
duodenal pH and osmolarity (decrease gastric emptying)
The stimulatory effects of the Cephalic and Gastric Phases are significantly reduced through a series of neural reflexes
Enterogastric Reflex
The Intestinal Phase is controlled by … and … which act to inhibit the release of GRP.
Secretin and GIP (and CCK)
Stomach pain is mediated by …
SNS afferents in the mucosa
Dumping Syndrome is the composite of dumping large bouts of osmotically active particles into the intestine thereby …
drawing water out of the blood, decreasing overall blood volume and pressure
