Lessom 2: GI MOTILITY Flashcards
(101 cards)
1
Q
What are amylolytic enzymes?
A
Enzymes involved in the digestion of carbohydrates
The only amylolytic enzyme present in saliva is salivary amylase or ptyalin
2
Q
What does salivary amylase do?
A
Hydrolyzes starch into maltose and small polymers of glucose containing 3 to 9 glucose molecules
3
Q
What is the sequence of events in the act of vomiting?
A
- Antiperistalsis 2. Deep inspiration 3. Closure of glottis 4. Upward movement of larynx 5. Elevation of soft palate 6. Contraction of diaphragm and abdominal muscles 7. Compression of stomach 8. Relaxation of lower esophageal sphincter 9. Expulsion of gastric contents
4
Q
What is nausea?
A
An unpleasant sensation that induces the desire for vomiting, characterized by secretion of saliva containing more mucus
5
Q
What is retching?
A
Strong involuntary movements in the GI tract that intensify the feeling of vomiting, occurring before actual vomiting
6
Q
What is the definition of vomiting?
A
Abnormal emptying of the stomach and upper part of intestine through esophagus and mouth
7
Q
List some causes of vomiting.
A
- Irritating contents in GI tract
- Mechanical stimulation of pharynx
- Pregnancy
- Excess alcohol intake
- Nauseating sight, odor, or taste
- Motion sickness
- Drug effects
- GI disorders
- Acute infections
- Metabolic disturbances
8
Q
What is gastroparesis?
A
A chronic disorder characterized by delayed gastric emptying, often secondary to another primary cause
9
Q
What are some causes of gastroparesis?
A
- Diabetes mellitus
- Postsurgical complications
- Motility disorders
- Gastric infection
- Metabolic and endocrine disorders
10
Q
What are the symptoms of early dumping syndrome?
A
- Nausea and vomiting
- Bloating
- Diarrhea
- Sweating and weakness
- Fatigue and dizziness
- Fainting and palpitations
11
Q
What is the role of mixing movements in the small intestine?
A
Responsible for mixing chyme with digestive juices
12
Q
What types of movements occur in the small intestine?
A
- Segmentation movements
- Pendular movements
- Peristaltic movements
- Peristaltic rush
13
Q
What is peristalsis?
A
Waves of contraction that move food through the digestive tract
14
Q
What is receptive relaxation?
A
Relaxation of the upper stomach when food enters, allowing easy accommodation
15
Q
What are type III hunger contractions?
A
Severe contractions lasting 1 to 5 minutes that indicate intense hunger
16
Q
What is gastric dumping syndrome?
A
Condition characterized by rapid gastric emptying, often following gastric surgery
17
Q
What hormones inhibit gastric motility?
A
- Vasoactive intestinal peptide (VIP)
- Gastric inhibitory peptide (GIP)
- Secretin
- Cholecystokinin
- Somatostatin
- Peptide YY
18
Q
What is chyme?
A
The semisolid mass of partially digested food formed in the stomach
19
Q
What factors initiate the enterogastric reflex?
A
- Duodenal distension
- Irritation of duodenal mucosa
- Acidity of chyme
- Osmolality of chyme
- Breakdown products of proteins and fats
20
Q
Which factors affect gastric emptying?
A
- Volume of gastric content
- Consistency of gastric content
- Chemical composition of food
- pH of gastric content
- Osmolar concentration of gastric content
21
Q
What are segmentation contractions?
A
Rhythmic contractions in the small intestine that chop and mix chyme
22
Q
What is the significance of pendular movements in the intestine?
A
Helps in mixing chyme with digestive juices
23
Q
What are segmentation contractions?
A
Segmentation contractions are the mixing movements in the small intestine that chop the chyme, aiding in mixing with digestive juices.
24
Q
Describe pendular movement in the small intestine.
A
Pendular movement is the sweeping motion of small intestine loops, moving forward and backward or upward and downward, aiding in mixing of chyme.
25
What are propulsive movements?
Propulsive movements push the chyme in the aboral direction through the intestine, including peristaltic movements and peristaltic rush.
26
What is aerophagia?
Aerophagia is the swallowing of large amounts of air, often due to gulping food or drink too rapidly.
27
What is belching?
Belching is the expulsion of gas from the stomach through the mouth, also known as burping.
28
What are the two processes for evacuation of accumulated gases?
1. Belching
2. Flatulence
29
What are exogenous gases?
Exogenous gases constitute about 90% of accumulated gases, entering the GI tract from swallowed air or carbonated beverages.
30
What are endogenous gases?
Endogenous gases form about 10% of accumulated gases, produced by digestion and bacterial interaction in the intestine.
31
What activities are involved in the act of belching?
1. Closure of larynx
2. Elevation of larynx and relaxation of upper esophageal sphincter
3. Opening of lower esophageal sphincter
4. Descent of diaphragm
32
What is flatulence?
Flatulence is the production of intestinal gases, with expulsion through the anus known as farting or passing gas.
33
What are the major constituents of flatus?
1. Swallowed non-odorous gases
* Nitrogen
* Oxygen
2. Non-odorous gases produced by microbes
* Methane
* Carbon dioxide
* Hydrogen
3. Odorous materials
* Low molecular weight fatty acids
* Reduced sulfur compounds
34
What is the average volume of flatus released by humans daily?
The average flatus released is about 500 to 1500 mL per day.
35
What initiates the defecation reflex?
The defecation reflex is initiated by distension of the rectum due to the entry of feces.
36
What is the gastrocolic reflex?
The gastrocolic reflex is the contraction of the rectum followed by the desire for defecation caused by stomach distention from food.
37
What is the act of defecation?
The act of defecation is the process of expelling feces from the body through the anus.
38
What are the types of movements in the stomach?
1. Hunger contractions
2. Receptive relaxation
3. Peristalsis
39
What is the migrating motor complex?
The migrating motor complex is a type of peristaltic contraction in the stomach and small intestine during fasting.
40
What is a peristaltic rush?
A peristaltic rush is a powerful contraction in the small intestine caused by irritation or distention, moving contents rapidly into the colon.
41
What is the significance of peristalsis in fasting?
Peristalsis in fasting helps sweep excess digestive secretions into the colon and prevents their accumulation in the stomach and intestines.
42
What are hunger contractions?
Hunger contractions are movements of the empty stomach related to sensations of hunger, involving peristaltic waves.
43
What are the types of movements in the large intestine?
1. Mixing movements: Segmentation contractions
2. Propulsive movements: Mass peristalsis
44
What are the amylolytic enzymes present in the small intestine?
1. Pancreatic amylase
2. Maltase
3. Sucrase
4. Lactase
5. Dextrinase
6. Trehalase
45
What is the role of enterocytes in the small intestine?
Enterocytes contain enzymes that hydrolyze disaccharides and small glucose polymers into monosaccharides.
46
What are the four enzymes present in enterocytes that split disaccharides?
Lactase, sucrase, maltase, and a-dextrinase
## Footnote
These enzymes are crucial for the digestion of disaccharides into monosaccharides.
47
What monosaccharides result from the hydrolysis of lactose?
Galactose and glucose
## Footnote
Lactose is a disaccharide that is split into these two monosaccharides.
48
What monosaccharides result from the hydrolysis of sucrose?
Fructose and glucose
## Footnote
Sucrose is another disaccharide that is hydrolyzed into these two sugars.
49
What is the primary product of carbohydrate digestion?
Monosaccharides
## Footnote
All carbohydrates are ultimately broken down into monosaccharides for absorption.
50
What percentage of carbohydrate digestion products are glucose in an ordinary diet?
More than 80%
## Footnote
Glucose is the predominant product of carbohydrate digestion in typical diets.
51
What are the two major types of movements in the gastrointestinal tract?
Propulsive movements and mixing movements
## Footnote
These movements are essential for digestion and absorption.
52
What is peristalsis?
A contractile ring that moves forward to propel food along the gastrointestinal tract
## Footnote
Peristalsis is a key mechanism of propulsive movement.
53
What stimulates intestinal peristalsis?
Distention of the gut
## Footnote
Stretching of the gut wall initiates peristaltic contractions.
54
What is the role of the myenteric plexus in peristalsis?
It is necessary for effective peristalsis
## Footnote
Absence or paralysis of the myenteric plexus can hinder peristalsis.
55
What is the function of gastric juice in carbohydrate digestion?
Contains a weak amylase that plays a minor role
## Footnote
Salivary amylase is inactivated by gastric acid.
56
What is mastication?
The mechanical process of chewing food into smaller particles
## Footnote
This process prepares food for swallowing and digestion.
57
What are the muscles involved in mastication?
Masseter, temporal, pterygoid, and buccinator muscles
## Footnote
These muscles work together to facilitate chewing.
58
What is the primary absorption method for glucose and galactose in the small intestine?
Sodium cotransport
## Footnote
This process requires energy for transport across the epithelial cells.
59
How is fructose absorbed in the small intestine?
By facilitated diffusion
## Footnote
Fructose absorption does not require sodium cotransport.
60
What are the two types of peptidases important for protein digestion?
Aminopolypeptidase and dipeptidases
## Footnote
These enzymes further break down polypeptides into smaller units.
61
What is the primary form in which proteins are absorbed from the small intestine?
Amino acids
## Footnote
Proteins are broken down into amino acids for absorption.
62
What are triglycerides made of?
Glycerol nucleus and free fatty acids
## Footnote
Triglycerides are the main dietary fats.
63
What are the two classifications of dietary fats?
Saturated fats and unsaturated fats
## Footnote
These classifications are based on the chemical structure of the fatty acids.
64
What is the role of pepsin in protein digestion?
It initiates protein digestion in the stomach
## Footnote
Pepsin is most active in acidic conditions.
65
What is the significance of mastication?
Breakdown of food, mixing with saliva, lubrication, taste appreciation
## Footnote
Mastication is essential for effective digestion.
66
What is the deglutition reflex?
A reflex action that occurs during swallowing
## Footnote
It involves both voluntary and involuntary actions.
67
What is the role of the lower esophageal sphincter?
Acts as a sphincter at the distal end of the esophagus
## Footnote
It helps prevent reflux of stomach contents.
68
What is the deglutition reflex?
The deglutition reflex is the process by which food moves from the mouth into the stomach, occurring during the pharyngeal and esophageal stages.
## Footnote
It involves a series of coordinated muscle contractions and relaxations.
69
What initiates the deglutition reflex?
The deglutition reflex is initiated when the bolus enters the oropharyngeal region, stimulating receptors in that area.
70
What is the role of the lower esophageal sphincter?
The lower esophageal sphincter is constricted at rest but relaxes when the bolus enters the esophagus, allowing contents to enter the stomach.
71
What occurs after the bolus enters the stomach?
The lower esophageal sphincter constricts and closes the lower end of the esophagus.
72
What are secondary peristaltic contractions?
Secondary peristaltic contractions occur when primary contractions fail to propel the bolus into the stomach, resulting from distention of the esophagus.
73
What triggers secondary peristaltic waves?
Secondary peristaltic waves are initiated by intrinsic neural circuits in the myenteric nervous system and reflexes from the pharynx.
74
List the movements involved in mastication.
* Opening and closure of mouth
* Rotational movements of jaw
* Protraction and retraction of jaw
75
What does dysphagia mean?
Dysphagia refers to difficulty in swallowing.
76
What are some causes of dysphagia?
* Mechanical obstruction of the esophagus
* Decreased movement due to neurological disorders
* Muscular disorders affecting swallowing
77
What is esophageal achalasia?
Esophageal achalasia is a neuromuscular disease characterized by the accumulation of food in the esophagus due to failure of the lower esophageal sphincter to relax.
78
What are the features of esophageal achalasia?
* Dysphagia
* Chest pain
* Weight loss
* Cough
79
What is GERD?
Gastroesophageal Reflux Disease (GERD) is characterized by the regurgitation of acidic gastric contents into the esophagus.
80
List the features of GERD.
* Heartburn (pyrosis)
* Esophagitis
* Dysphagia
* Cough and change of voice
* Esophageal ulcers or cancer
81
What are the motor functions of the stomach?
* Storage of food
* Mixing food with gastric secretions to form chyme
* Slow emptying of chyme into the small intestine
82
What are the main anatomical parts of the stomach?
* Fundus
* Body
* Pyloric region
* Antrum
83
What is the pyloric sphincter?
The pyloric sphincter is a thick ring of smooth muscle that surrounds the pyloric opening between the stomach and the small intestine.
84
What divides the stomach physiologically?
* Orad portion (first two-thirds of the body)
* Caudad portion (remainder of the body plus the antrum)
85
What is peristalsis?
Peristalsis is a wave of contraction followed by relaxation of muscle fibers in the GI tract, propelling contents down.
86
What are the two types of peristaltic contractions in the esophagus?
* Primary peristaltic contractions
* Secondary peristaltic contractions
87
What initiates primary peristaltic contractions?
Primary peristaltic contractions are initiated when the bolus reaches the upper part of the esophagus.
88
What is the upper esophageal sphincter?
The upper esophageal sphincter is formed by the cricopharyngeal muscle and regulates the movement of the bolus from the pharynx into the esophagus.
89
What is deglutition apnea?
Deglutition apnea is the temporary arrest of breathing that occurs during the pharyngeal stage of swallowing.
90
What prevents the bolus from returning to the mouth?
* Position of the tongue against the soft palate
* High intraoral pressure developed by tongue movement
91
What actions prevent the bolus from entering the nasopharynx?
The elevation of the soft palate and the uvula prevent the bolus from entering the nasopharynx.
92
What prevents the bolus from entering the larynx?
* Approximation of the vocal cords
* Upward movement of the larynx
* Backward movement of the epiglottis
93
What is the pharyngeal stage of deglutition?
The pharyngeal stage is an involuntary stage where the bolus is pushed from the pharynx into the esophagus.
94
What is the esophageal stage of deglutition?
The esophageal stage is also involuntary and involves the movement of the bolus from the esophagus into the stomach.
95
What is the term for the temporary arrest of respiration during swallowing?
Deglutition apnea
## Footnote
This occurs for a few seconds during swallowing movements.
96
What characterizes the pharyngeal stage of swallowing?
Involuntary stage
## Footnote
This stage involves the bolus being pushed from the pharynx into the esophagus.
97
What is the role of the pharynx in the digestive and respiratory systems?
Common passage for food and air
## Footnote
It divides into the larynx and esophagus.
98
Where is the larynx located in relation to the esophagus?
Anteriorly
## Footnote
The larynx continues as a respiratory passage.
99
What lies behind the larynx?
Esophagus
## Footnote
The esophagus continues as part of the gastrointestinal tract.
100
List the four paths the bolus can enter during the pharyngeal stage.
* Back into mouth
* Upward into nasopharynx
* Forward into larynx
* Downward into esophagus
## Footnote
Various coordinated movements ensure the bolus enters only the esophagus.
101
What ensures that the bolus enters only the esophagus during deglutition?
Various coordinated movements
## Footnote
These movements prevent the bolus from entering the other paths.
