Intro to GI (Exam 1) Flashcards
What are the accessory organs of the digestive tract?
liver, gallbladder, and pancreas
What is the function of rugae?
allows stomach to stretch
What does oro mean?
mouth
What type of digestion occurs in the mouth?
mechanical digestion with teeth making a bolus and it getting pushed around with saliva and tongue against hard palate
What does deglutition mean?
test q
swallow
The bolus moves from the oropharynx to the pharynx and esophagus and will interact with the epiglottis. What does this result in during deglutition?
test q
cessation of breathing
What moves the bolus in the esophagus?
involuntary peristaltic contractions
Is there peristalsis in the stomach?
yes
In the stomach, once the bolus mixes with digestive enzymes and acids it will become….
chyme
Where does most absorption occur?
SI
Is there any absorption in the stomach?
small amounts
Is there any absorption in the LI?
some, mostly water
What is the oral cavity formed by?
-cheeks
-hard and soft palate
-lips
-tongue
What is the vestibule of the oral cavity?
area between the cheeks and teeth
What is the space called that extends from the gums and teeth to the fauces, the passage between the oral cavity and the oropharynx?
oral cavity proper
What is the oral cavity lined with?
test q
stratified squamous epithelium
How many dentitions do you have in a lifetime?
2
What are deciduous teeth?
-primary/milk/baby teeth
-20 teeth that start erupting at 6 months
-1 new pair of teeth per month on average
What are the permanent teeth (adult teeth) types?
-incisors
-canines (cuspids)
-premolars and molars
What is the function of incisor teeth?
biting
What is the function of canine (cuspid) teeth?
tearing
What is the function of premolars and molars?
crushing and grinding food
What does mastication mean?
chew
What type of digestion is mastication?
chewing= mechanical digestion
When does the digestion of starches and fats begin?
test q
during mastication with the help of salivary amylase and lingual lipase produced from salivary glands (chemical digestion in the mouth is minor compared to mechanical digestion)
What is the function of saliva?
-wets food for easier swallowing, forming bolus, dissolves some food for tasting
-protects mouth from infection via rinsing action
-synthesis is controlled by parasympathetic stimulation
What is serous fluid made up of?
-low Na+ and Cl- conc.
-high conc. of K+ and bicarbonate (HCO3-)
-lysozyme is used to help destroy bacteria (the specific one is called thiocyanate)
What is salivary amylase?
test q
-also known as ptyalin
-begins starch digestion at pH 6.5-7 found in the mouth
-breaks starches into maltose and dextrin
-when bolus and enzyme hit the pH of 2.5 in gastric juices then hydrolysis ceases (this enzyme doesnt work great in the stomach)
What is mucin and what does it promote?
-made up of glycoproteins
-mucin is the main component of mucus
-promotes bacterial aggregation
What is lingual lipase secreted by and when does breakdown begin?
test q
-secreted by glands in the tongue
-begins breakdown of triglycerides into fatty acids and glycerol
There are 3 pairs of salivary glands. What are they?
test q
1) submandibular gland
2) sublingual gland
3) parotid gland
All of the salivary glands have ducts that empty into the…
oral cavity
What do the parotid glands secrete?
test q
serous fluid only
What do the submandibular and sublingual glands secrete?
test q
mucus and serous fluid
The von Ebner’s glands have circumvallate/vallate papillae. What do they secrete?
test q
lingual lipase
In what instances would salivation increase?
test q
-sight, smell, sounds, memory of food when hungry
-tongue/cheek stimulation (basically anything in mouth)
-cerebral cortex signals the salivary nuclei in brainstem
-parasympathetic ns signals to salivary glands with CN VII and IX
What cranial nerves stimulate salivary glands and salivation?
CN VII and IX
When does salivation stop?
when afraid (the mouth will become dry)
-this is bc sympathetic tone vasoconstricts arterioles serving glands
What is known as a funnel-shaped tube expanding from the internal nares to the esophagus (posteriorly) and the larynx (anteriorly)?
pharynx
The pharynx is skeletal muscle lined by ________ membrane
mucus
T/F: the pharynx is a common passageway for food and air
true
The oropharynx is from the ___________ to palatoepiglottic fold
soft palate
Fauces are an opening from the mouth into the….
oropharynx
The laryngopharynx/hypopharynx extends from the palatoepiglottic fold to the inferior end of ______________. The laryngopharynx ends at the ___________ posterioinferiorly
cricoid cartilage, esophagus
What tissue lines the pharynx?
stratified squamous epithelium
The esophagus has 3 portions of muscles. What are they?
upper 3rd portion= skeletal muscle
middle 3rd= skeletal and smooth muscle
inferior 3rd/ terminal portion near stomach= smooth muscle
T/F: the esophagus is a muscular tube
true
Where does mechanical digestion occur?
1) mouth during chewing
2) stomach churning
3) SI segmentation
Where does propulsion occur?
1) oropharynx during swallowing
2) esophagus, stomach, SI, and LI during peristalsis
Which part of the digestive tract is collapsed at rest, flat in upper 2/3 and rounded in lower 1/3?
esophagus
Where does the esophagus begin?
at the lower border of the cricoid cartilage (approx. C6)
Which part of the digestive tract descends along the front of the spine, through the posterior mediastinum, passes through the diaphragm at the cardiac hiatus?
esophagus
Which part of the digestive tract enters the abdomen and terminates at the cardiac office of the stomach?
esophagus
The esophagus secretes ________ and transports ingested food to the stomach
mucus
The mucosal layer of the esophagus contains what type of epithelium?
test q
stratified squamous epithelium
The submucosal layer of the esophagus and stomach is made up of what tissue?
test q
areolar connective tissue
The muscularis externa of the esophagus has 2 layers. What are they?
test q
longitudinal (outer) and circular (inner) layer
The adventitia layer of the esophagus is made up of what tissue?
test q
fibrous connective tissue
The submucosa of the esophagus has large ________ glands
test q
mucous
The muscularis of the esophagus has 3 types of muscle. What are they and where?
test q
top 1/3 is skeletal muscle
middle 1/3 is skeletal+ smooth muscle
bottom 1/3 is smooth muscle
The upper and lower esophageal sphincters are prominent _________ muscle (of the muscularis layer)
circular
What are the other names for mechanoreceptors?
pressure receptors/sensors and baroreceptors
What stage of deglutition is this?
-begins when the bolus gets pushed against the hard palate with the tongue and is forced into the oropharynx
-pressure receptors in the oropharynx stimulate the deglutition center in the medulla
voluntary stage
What stage of deglutition is this?
-moves food from the pharynx to the esophagus
-breathing stops and airways are closed
-soft palate and uvula are lifted to close off nasopharynx
-epiglottis is bent over airway as larynx is lifted
test q
pharyngeal stage
What stage of deglutition is this?
-begins when the bolus enters the esophagus
-peristalsis moves the bolus from the esophagus to the stomach
esophageal stage
During swallowing, the upper esophageal sphincter relaxes when the __________ is lifted
larynx
During swallowing, the primary peristalsis wave pushes the food down. The ___________ fibers are behind the bolus, and the ___________________ fibers are in front of the bolus to shorten the distance of travel
test q
circular, longitudinal
What travels down the esophagus faster- solids or liquids?
liquids
When does the lower esophageal sphincter relax?
when the food approaches
define dysphagia
difficulty swallowing
Steps of deglutition:
1) The upper esophageal sphincter is contracted. During the buccal phase, the tongue presses against the _____________, forcing the food bolus into the oropharynx where the involuntary phase begins
2) The uvula and __________ rise to prevent food from entering respiratory passageways. The tongue blocks off the mouth. The upper esophageal sphincter relaxes, allowing food to enter the esophagus
3) The constrictor muscles of the pharynx contract, forcing food into the esophagus inferiorly. The upper esophageal sphincter contracts (closes) after entry
4) Food is moved through the esophagus to the stomach by peristalsis
5) The gastroesophageal sphincter opens and food enters the stomach
hard palate, larynx
Peristalsis is ____________ mixing
propulsive
What is the stimulus for peristalsis of the esophagus?
test q
distension
What type of irritation in the esophagus can turn on peristalsis?
test q
chemical or physical irritation
Name these stages:
A) _______________- chyme is pushed toward the closed pylorus
B) _____________- the antrum churns the trapped material
C) ______________- chyme is pushed back into the proximal stomach
Test q
A) propulsion
B) grinding
C) retropulsion
If the lower esophageal sphincter fails to open, then the…..
distention of the esophagus will start to feel like chest pain/heart attack
If the lower esophageal sphincter fails to close, the stomach acids will enter the esophagus and cause heart burn. Laying down after eating or eating a big meal will weaken the sphincter. Smoking, alcohol, and mint oil can cause the sphincter to relax, worsening the situation. What disease is this?
gastroesophageal reflux disease (GERD)
What is lamina propria?
cell glue, next to all epithelial tissue
What are the 3 parts of the small intestine?
duodenum, jejunum, ilium
What does the submucosal gland of the submucosa secrete?
mucus
What is another name for the meissner nerve plexus?
submucosal nerve plexus
What is another name for the auerbach nerve plexus?
myenteric nerve plexus
