Physiology -- Deglutition and Dysphagia Flashcards
1
Q
3 functional activities of the GIT
A
- Propulsion
- Secretion & digestion
- Absorption
2
Q
What do the pressure gradients of the GIT result from?
A
Coordinated contraction of muscular elements in the GI wall
3
Q
Magnitude of the pressure gradient in the GIT
A
5 - 30 mm Hg
4
Q
Stimulus to generate contractions in the GIT
A
Physiological distension
5
Q
What does physiological distension cause?
A
- Stimulation of stress muscle fibres
- Neurotransmitter release (ENS)
6
Q
What is the ENS modulated by?
A
ANS and hormones
7
Q
2 types of contraction
A
Segmentation and Peristalsis
8
Q
Define segmentation
A
Standing rings of contraction
9
Q
Define peristalsis
A
Propagated contraction
10
Q
5 sphincters in the GIT from top to bottom
A
- Upper esophageal
- Lower esophageal
- Pyloric
- Ileocecal
- Internal and external anal
11
Q
3 requirements for flow
A
- Generate pressure
- Prevent dissipation of pressure
- Decrease resistance
12
Q
3 phases of swallowing
A
- Oral
- Pharyngeal
- Esophageal
13
Q
Alteration in the phases of swallowing can result in what?
A
Dysphagia
14
Q
Define dysphagia
A
Difficulty or delay in passage of solid or liquid food bolus that is sensed by the patient within seconds of initiaiton of a swallow attempt
15
Q
Prevalence of dysphagia in people over 65
A
15%
16
Q
2 types of dysphagia
A
- Oropharyngeal
- Esophageal
17
Q
Define esophageal dysphagia
A
Food stuck in the center of the chest
18
Q
Define oropharyngeal dysphagia
A
Coughing or choking
19
Q
2 mechanisms that can result in dysphagia
A
- Mechanical obstruction and/or structural abnormality
- Neuromotor
20
Q
Type of control exhibited in the oral phase
A
Voluntary control
21
Q
2 neural components of the oral phase
A
- Ability to initiate (voluntary –> cortex)
- Coordinated movements (reflex; involuntary –> medulla)
22
Q
4 abnormalities in the oral phase
A
- Neuromuscular defect
- Congenital abnormalities
- Bucco-pharyngeal obstruction
- Trauma and inflammation
23
Q
How do neuromuscular defects cause abnormalities in the oral phase
A
Prevent generation of pressure
24
Q
How do congenital abnormalities cause abnormalities in the oral phase?
A
Promote dissipation of pressure
25
How can bucco-pharygneal obstruction cause abnormalities in the oral phase?
Increase resistance to flow
26
DIfferential diagnosis of dysphagia in the event of trauma and inflammation causing abnormalitites in the oral phase
Odynophagia
27
3 prerequisites for propulsion
* Generation of pressure
* Prevention of the dissipation of pressure
* Decrease resistance
28
Pharyngeal receptors bring afferent neurons to which part of the brain?
Deglutition center
29
Deglutition reflexes sent out from the deglutition center resulting from the information received from the pharyngeal receptors
* Protective reactions
* Deglutition apnea
* Relax UES
* Contract pharyngeal constrictors
30
Trigger areas for deglutition reflexes
* Soft palate
* Uvula
* Palatine tonsil
* Root of tongue
* Epiglottis
31
What does the deglutition center have a direct inhibitor influence on? What does this lead to?
Respiratory center --\> deglutition apnea
32
6 steps in the pharyngeal phase
1. Raise soft palate
2. Raise base of tongue
3. Vocal cords come together
4. Forward and upward movement of larynx
5. Propagated contraction of pharyngeal constrictors
6. Relaxation of UES
33
Where do the impulses for the closure of the cricopharyngeus originate?
Centraly
34
What mediates the closure of the cricopharyngeus
Vagus releasing ACh at neuromuscular junction --\> muscle contraction
35
How does the cricopharyngeus relax?
Cessation of impulses from vagus releasing ACh
36
4 characteristics of the pharyngeal phase
* Involuntary
* Rapid
* "Stereotyped"
* Temporospatial coordination
37
3 defects in the pharyngeal phase
* Failure of propulsion
* Obstruction to flow
* Psychological factors
38
2 effects caused by failure of propulsion in pharyngeal phase
* Generates less pressure
* Increases dissipation of pressure
39
4 parts that can be involved in the failure of propulsion in the pharyngeal phase
* Brain
* Cranial nerves
* Myoneural junction
* Muscle
40
Effect of obstruction to flow causing pharyngeal phase defects
Increased resistance
41
2 causes of obstruction to flow in pharyngeal phase
* Mass effect
* Incomplete sphincter relaxation
42
Psychological factor that can cause defective pharyngeal phase
Globus hystericus
43
3 esophageal forces
1. Pharyngeal momentum
2. Gravity
3. Peristalsis
44
What force is generated each time that we swallow
A single primary peristaltic wave (part of the deglutition reflexes)
45
Time of propagation of one wave of primary peristalsis along the length of the esophagus
8 - 10 seconds
46
Describe the vagal innervation from the deglutition center to generate primary peristalsis (diagram)
47
Consequence of cutting the vagal fibres high up in the neck on primary peristalsis
48
Consequence of cutting vagal fibres transthoracically on primary peristalsis
Primary peristalsis continues because the distal esophagus has the enteric circuitry necessary for the propagation of the peristaltic wave (orange fibres in diagram)
49
Define "vago-vagal reflex"
Reflex produced due to the vagal afferent nerves sending information to the brain centers, which send out efferent vagal nerves
50
What is essential for initiating peristalsis in the proximal esophagus
Vagus
51
What is required for the continuation and propagation of peristalsis in the distal esophagus
Intactness of ENS
52
Stimulus for secondary peristalsis
Local distension (i.e. food lodged in esophagus)
53
Similarities between primary and secondary peristalsis
* Upper esophagus requires vagus
* Lower esophagus requires ENS
* Pressure generated is 30 - 60 mmHg
54
Differences between primary and secondary peristalsis
* Different stimuli
* Primary = pharyngeal receptors
* Secondary = local distension
* Different frequency
* Primary = only 1 contraction per swallow
* Secondary = many contractions until bolus is displaced
55
Define deglutitive inhibition
Central inhibition of primary peristaltic wave resulting from rapid, repeated stimulation of pharyngeal receptors (i.e. sipping fluid through a straw)
56
How are liquids brought through the esophagus?
Deglutitive inhibition --\> cessation of stimulation of pharyngeal receptors --\> single peristaltic wave sweeps over esophagus --\> empty contents
57
3 facotrs influencing esophageal transport
* Viscosity of bolus
* Temperature of bolus
* Posture of subject
58
What type of control is exhibited in the closure of the LES
Myogenic
59
What type of control is exhibited in the relaxation of the LES?
Neurogenic --\> local release of NANC
60
Compare the characteristics of the upper esophageal sphincter vs. the lower esophageal sphincter
61
When closed, what is the magnitude of the resistance to flow provided by the lower esophageal sphincter?
10 - 30 mm Hg
62
6 characteristics of the LES musculature (in vitro)
1. More collagen fibres
2. Lower RMP; partially contracted at RMP
3. More resistant to stretch
4. Sensitive to hypoxia
5. Ca++ dependent
6. More sensitive to transmitters and hormones
63
Does gastrin provide modulation of the LES?
ONLY in large (pharmacologic) doses!!
64
3 gut hormones that have an effect on LES
* Gastrin (increase tone)
* Secretin (decrease tone)
* CCK (decrease tone)
65
Special hormone that decreases LES tone and the specific period when it has an effect
Progesterone decreases sphincter tone during the last trimester of pregnancy (reason for reflux during this period)
66
6 external influences on the LES and their effects
* Cigarette smoking
* Alcohol (high doses)
* Morphine, valium
* Fat
* Chocolate
* Carminatives
All decrease LES tone
67
Factors that affect the LES (Venn diagram)
68
Define pyrosis
Heartburn: retrosternal burning sensation, radiating upwards from the xiphoid towards the neck
69
Rate of occurrence of reflux in healthy individuals + duration
1 - 4 instances per hour (usually \<30 sec)
70
Define transient LES relaxation (TLESr)
Reflux occurring in healthy individuals
71
3 disordered functions associated with GERD
* Ineffective esophageal clearance of refluxate
* Less effective secondary peristalsis
* Defective epithelial resistance to damage by refluxate
72
Why does an increase in intraabdominal pressure cause a greater than expected increasei in LES pressure?
Reflex tightening of the LES (vago-vagal reflex)
73
3 ways to examine the esophagus
* Radiology
* Endoscope
* Intraluminal pressure recording (manometry)
74
Esophageal resting pressure
-5 mm Hg
75
UES resting pressure
+80 mm Hg
76
LES resting pressure
+20 mm Hg
77
Pharyngeal resting pressure
0 mm Hg
78
Stomach resting pressure
+5 mm Hg
79
Describe the normal manometric recordings in response to swallowing
* 8 - 10 sec for wave to reach distal esophagus
* Pressure complex = 30 - 80 mm Hg
* LES relaxes early
80
Describe the manometric findings of a patient with achalasia
* LES does not relax with wet swallows
* Wet swallows do not produce peristaltic pressure waves in the esophagus
* Instead, there are low-amplitude, simultaneous P waves with a nearly identical configuration (not sequential)
81
Define achalasia
Failure to relax:
* Aperistalsis
* Incomplete relaxation of LES with swallowing
* Increased resting tone of LES
82
Potential cause for achalasia
Dysfunction of inhibitory neurons in distal esophagus:
* NO
* VIP
83
3 categories of oropharyngeal dysphagia
* Structural
* Myogenic
* Nervous system
84
3 types of structural oropharyngeal dysphagia
* Poor dentition, xerostomia
* Intraluminal
* Extraluminal
85
3 intraluminal causes of oropharyngeal dysphagia
* Diverticulae
* Webs
* Oropharyngeal tumors
86
3 extraluminal causes for structural oropharyngeal dysphagia
* Osteophytes
* Thyromegaly
* Lymphadenopathy
87
5 causes for nervous system-related oropharyngeal dysphagia
* Head injury
* Brainstem tumors
* Stroke
* MS
* Parkinson's
88
2 types of esophageal dysphagia
* Structural
* Motility abnormalities
89
4 intraluminal causes for esophageal dysphagia
* Stricture
* Schatzki's ring
* Cancer
* Eosinophilic esophagitis
90
Extraluminal cause for esophageal dysphagia
Mediastinal tumors (lymphoma, lung cancer)
91
5 motility abnormalities that may cause esophageal dysphagia
* Achalasia
* Esophageal spasm
* Secondary achalasia from tumor infiltration
* Diabetes
* Collagen vascular disorders
