UNIT 6: Esophagus and Gastro Tract Flashcards
what is the goal of the digestive system
obtain nutrients to support energy needs, growth, and cell repair
what are the 5 functions of the digestive system
ingestion
propulsion
digestion
absorption
defecation
ingestion
brought into the body
propulsion
moved along the digestive tract
digestion (2 types)
broken down into simpler forms
mechanical and chemical
absorption
nutrients pass into blood stream
defecation
waste is removed from the body
6 organs of the digestive sys
mouth and pharynx
esophagus
stomach
small intestine
large intestine
anus
4 accessory organs of the digestive sys
salivary glands
liver
gallbladder
pancreas
mouth has 4 functions
ingestion - food brought into oral cavity
propulsion - tongue propels bolus into pharynx
mechanical digestion
chemical digestion
mechanical digestion in the mouth ….
mastication by teeth and mixing movements by tongue (voluntary)
chemical digestion in the mouth…
salivary amylase and lipase begins breakdown of starches and fats
parotid contributes…
the most saliva during chewing and swallowing
pharynx propulsion is….
peristaltic wave like - positive pressure on bolus tail moves bolus from pharynx to esophagus
esophagus propulsion is…
true peristaltic wave moves bolus (pos pressure on bolus tail) from pharyngoesophageal segment (PES) to the gastoesophageal junction
describe the esophagus
collapsible, muscular tube of approx 25cm in length
posterior to trachea, anterior to vert column
the esophagus runs from the _____ and passes through the _______ and pierces the _____ through the _______
laryngopharynx
mediastinum
diaphragm
esophageal hiatus
hiatal hernia
when a portion of the stomach protrudes into the thoracic cavity
the pharyngoesophageal segment (PES) contains the
upper esophageal sphincter (UES)
PES is comprised of ____ and ____ tissues, the UES is comprised of the _______ muscle
pharyngeal and esophageal tissues
cricopharyngeus muscle
UES is ______ at rest due to contraction of the CP muscle
closed
UES opens by
tissue compliance
relaxation of CP muscle
traction of the ascending larynx (hyolaryngeal complex)
traction of the ascending larynx (hyolaryngeal complex) works to open the UES by
cricoid cartilage is pulled anterosuperiorly and thus pulls the anterior esophageal wall away from the posterior esophageal wall
aka when this structure moves up when we swallow it pulls open the UES
inferior border of the esophagus forms the
lower esophageal sphincter - LES
LES is a
muscular junction bw esophagus and stomach at level of the diaphragm
how is the LES a physiological sphincter
physiological sphincter bc no sphincteric muscle present
smooth muscle of esophagus and crura of diaphragm maintain closure
prevents gastroesophageal reflux
along the length of the esophagus, transitions from ____ muscle to ____ muscle
striated to smooth
upper 1/3 of esophagus is
cervical esophagus
skeletal muscle
intermediate 1/3 of the esophagus is
skeletal and smooth muscle
lower 1/3 of esophagus is
smooth muscle
cervical esophagus is
a muscular wall comprised on 2 muscle groups w fibres perpendicular to each other
circular muscle fibres and longitudinal muscle fibres
what is primary peristalsis
muscle contraction triggered by arrival of bolus at UES; contraction wave propagates the length of the esophagus
what is secondary peristalsis
if residue remains in esophagus, second peristaltic wave is triggered
esophagus is innervated/controlled by
esophageal branch of CN X
UES =
a muscular sphincter (cricopharyngeus m) w/i the PES
tonic contraction of the CP muscle keeps the UES closed at rest …. prevents gastric contents from re-entering pharynx (i.e. prevents retrograde flow)
LES =
An anatomical sphincter (where esophagus passes thru crura of diaphragm)
resting pressure of LES is ____ of the UES resting pressure … created by….prevents…
1/3
circular muscle layer and the crura of the diaphragm
prevents gastric contents from re-entering esophagus (i.e. prevents retrograde flow)
as bolus approaches LES releases _____ posture and bolus enters stomach…. ______ on tail of bolus, brief supra-resting level of contraction
resting
closure
what are the 3 functions of the stomach
mechanical digestion and propulsion
chemical digestion
absorption
mechanical digestion and propulsion in the stomach
peristaltic waves mix food w gastric juice and propel it into the duodenum (small intestine)
chemical digestion in the stomach
pepsin in gastric acid begins digestion of proteins, produces chyme
proteins –> large polypeptides –> small polypeptides –> aminoacids
absoprtion in the stomach
few fat soluble substances absorded (ex. aspirin, alcohol, some drugs)
part of the stomach that often causes hiatal hernias
fundus
what is gastroesophageal reflux GER
spontaneous movement of gastric contents into the esophagus
what is GERD
Gastroesophageal reflux disease
chronic symptoms or mucosal damage due to the reflux of gastric contents
GER is ______ in western society …. caused by…. estimated at ___% symptoms daily, ___% symptoms monthly
extremely common
dietary habits, stress, obesity
10%, 20-30%
clinical symptoms of GER include
heart burn, regurgitation, chest pain
less typical symptoms of GER related to acid damage
sore throat, globus sensation, chronic cough, vocal changes (Hoarseness), poor dentition, persistent throat clearning, asthma, aspiration
laryngopharyngeal reflex LPR
what is the common mechanism behind GER
Transient lower esophageal sphincter relaxation (TLESR)
LES relaxes inappropriately, creating backflow into esophagus
other than the common mechanism behind GER, what are the two other mechanisms
hypotensive LES = weak tonic contractile state
hiatal hernia = stomach herniates thru diaphragmatic hiatus, LES no longer receives structural support from the diaphragm
Gastric reflux is _____ to the esophagus and other structures in the upper digestive tract because of -____
destructive
pepsin aka stomach acid
patients w GER are often prescribed …. alternatively could use ….
proton pump inhibitors - typically proton pump (in stomach) pulls protons into cells to create HCI - PPIs inhibit creation of HCI
H2 blockers, histamine 2 receptor agonists, gastric acids suppressors raises pH of stomach after acid has already been produced
3 parts of small intestine and the order of them
duodenum
jejunum
ileum
mechanical digestion and propulsion in the small intestine
smooth muscle segmentation mixes contents w digestive juices, produces short distance peristaltic waves
chemical digestion in small intestine
enzymes delivered from pancreas and gallbladder complete digestion of all food classes
absorption in small intestine
products of carbohydrate, protein, fat, and nuclei acid digestions, plus vitamins, electrolytes, and water are absorbed
segmentation vs peristalsis
peristalsis = adjacent segments of alimentary tract organs alternately contract an relax which move food along the tract distally
segmentation = nonadjacent segments of alimentary tract organs alternately contract and relax, moving the food forward then backward - food mixing and slow food propulsion occurs
chemical digestion in large intestine
remaining food residues digested by enteric bacteria
absorption in large intestine
remaining water, electrolytes (NaCl), and vitamins produced by bacteria (organic compounds)
propulsion in the large intestine
feces propelled toward rectum by haustral churning and mass movements
defecation of large intestine
reflex triggered by rectal distension; eliminates feces from body
2 functions of swallowing
supportive function = transports ingested material from mouth to stomach
protective function = protects respiratory sys from entry of foreign material
why is swallowing necessary: in the adult human the upper respiratory and digestive paths are _____, crossroads is called the _____
crossed
upper aerodigestive tract
4 phases of swallowing
oral preparatory
oral (transport)
pharyngeal
esophageal
describe the oral preparatory phase of swallowing… voluntary or involuntary?
ingested material is broken down mechanically and chemically, forming a bolus
a voluntary phase - actions vary w the properties of the food/liquid
describe the oral (transport) phase of swallowing
bolus is moved posteriorly over the tongue surface
describe the pharyngeal phase of swallowing… voluntary or involuntary?
phase is triggered when a moving bolus excites oropharyngeal sensory receptors
bolus transported from mouth to esophagus
involuntary -patterned motor response
describe the esophageal phase of swallowing
bolus is transported to stomach
swallowing events tend to occur in a _____ patter, although there is _____ subject and ____ subject variability
predictable
intra
inter
how is the epiglottis deflecting during swallowing?
in 2 stages
first = upright, once the bolus comes along the hyolaryngeal complex moves up, base of epi comes up becoming a horizontal structure
second = to get it to tip the rest of the way the tongue base, pharyngeal wall, and bolus itself push the epi down to flip it the rest of the way
describe the path of the bolus
bolus flows lateral to the larynx w/i the pyriform sinuses
1 pyriform sinus on each side - bw larynx and the pharyngeal wall
during the esophageal phase, the ____ of the esophagus is relaxed in basal state; ____ and ____ are normally contracted, _____ on demand
body
UES and LES
Relaxed
UES opens during the esophageal phase bc of
CP m relaxes, traction from HLAE, compliant segment, intrabolus pressure
describe the peristalsis of the esophagus
progressive, normal/constant amplitude, non-repetitive, non-spontaneous = motility
3 parts of esophagus contraction
primary peristalsis = distally progressive wave initiated by the act of swallowing
secondary peristalsis = distally progressive wave initiated by esophageal distension
tertiary contraction = non peristaltic (non-progressive) contraction of the body of the esophagus
what causes residue/material in the pharynx?
weakness in pharyngeal constrictor muscles
inability to open UES sufficiently
gastroesophaeal reflux - incomplete closure of LES/UES at rest
cervical osteophytes is….
bone spurs that grow on the cervical spine
narrow the pharynx and esophagus making it more difficult to get a bolus through
leads to residue
what is hypertonicity in inferior pharyngeal constrictor
incomplete/inadequate relaxation during swallowing
leads to herniation of pharyngeal wall - at level of UES, this is called a zenker’s diverticulum … at triangle of killian
what is triangle of killian …. what is pharyngoesophageal diverticulum … what does it result from?
triangle of killian = area of weakness bw oblique fibres of thyropharyngeus m and transverse fibres of CP
posterior hypopharyngeal mucosa protrudes bw two components of inferior pharyngeal constrictor
results from repetitive high hypopharyngeal pressures due to poor compliance of the UES
clinical symptoms of zenker’s diverticulum
dysphagia with both solids and liquids
reguritation of undigested foods
coughing/aspiration
halitosis (bad breath bc of food stuck)
how is zenker’s diverticulum diagnosed
use barium swallow
can use endoscopy but risk a perforation of the esophagus
treatment of zenker’s diverticulum
diverticulectomy and or CP myotomy
