Gastrointestinal Tract Anatomy Flashcards
1
Q
What are the regions the abdominal region is divided into?
A
- Right hypochondrium (RHC)
- Epigastric region
- Left hypochondrium (LHC)
- Right lumbar region
- Umbilical region
- Left lumbar region
- Right iliac (inguinal)
- Pubic (hypogastric) region
- Left iliac (inguinal)
2
Q
What are the major organs of the digestive tract?
A
- Oral cavity (mouth)
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
3
Q
What are the accessory organs of the digestive tract?
A
- Teeth
- Tongue
- Salivary glands
- Liver
- Gallbladder
- Pancreas
4
Q
What is the roof of the oral cavity formed by?
A
Hard palate
Soft palate
5
Q
What is the floor of the oral cavity covered by?
A
Thin & vascular layer of mucosa
- supported by geniohyoid & mylohyoid muscles
6
Q
What cells are present in the oral cavity?
A
Stratified squamous epithelial cells
- Can be keratinized/non-keratinized
7
Q
Where are keratinized stratified squamous epithelial cells found in the oral cavity?
A
Hard palate
Superior surface of the tongue
(where there is wear & tear)
8
Q
Where are non-keratanized stratified squamous epithelial cells found in the oral cavity?
A
Lining of cheek
Lining of lips
Interior surface of the tongue
9
Q
Why is the mucosa covering the floor of the oral cavity thin?
A
Enhances/accelerates absorption of particular substances
= certain meds (e.g. nitroglycerine for heart attack) placed under tongue for fast absorption
10
Q
What are the lateral walls of the oral cavity supported by?
A
Pads of fat
Buccinator muscle
(Cheek)
11
Q
What is the space between the tooth and the lip called?
A
Vestibule (Upper & Lower)
12
Q
What are the phases of swallowing?
A
- Buccal phase
- Pharyngeal phase
- Oesophageal phase
(4. Bolus enters stomach)
13
Q
What happens in the buccal phase (swallowing)?
A
- Bolus compressed against hard palate
- Retraction of tongue forces the bolus into oropharynx + assists in elevation of soft palate (seals nasopharynx)
- Once bolus enters oropharynx, reflex responses begin & bolus is moved towards stomach
Epiglottis is still in the same position (collapsed)
14
Q
What happens in the pharyngeal phase (swallowing)?
A
- begins as bolus comes into contact with palatoglossal & palatopharyngeal arches & post. pharyngeal wall
- Elevation of larynx & folding of epiglottis direct the bolus past the closed glottis (epiglottis moves down to close the trachea)
- Uvula & soft palate block passage back to nasopharynx
15
Q
What happens in the oesophageal phase (swallowing)?
A
- Begins as the contraction of pharyngeal muscles forces the bolus through the entrance to the oesophagus
- Once in oesophagus, bolus is pushed toward the stomach by peristalsis (one part contract, next part relaxes; involuntary)
16
Q
What happens for the bolus to enter the stomach (swallowing)?
A
Approach of the bolus triggers the opening of the lower oesophageal sphincter
17
Q
What are the functions of the oral cavity?
A
- Taste sensation
- Grinding food through actions of teeth, tongue, palatal surfaces
- Lubrication by mixing mucus & saliva (easier to form bolus & chew & masticate)
- Limited digestion of carbohydrates & lipids
18
Q
What accessory glands must work together with the major components of the oral cavity to achieve the functions?
A
- Salivary glands (parotid, sublingual, submandibular)
(work tgt w tongue & teeth)
19
Q
What is the pharynx?
A
- connection b/w oral cavity & oesophagus
- serves as common passageway for solid food, liquids, air
20
Q
What is the pharynx divided into?
A
- Nasopharynx
- Oropharynx
- Laryngopharynx
21
Q
What epithelial cells line the oropharynx & laryngopharynx?
A
Non-keratinized stratified squamous epithelium
22
Q
What are the four layers of the digestive tract?
A
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
23
Q
What does the mucosa comprise of?
A
- Epithelium
- Lamina propria
- Muscularis mucosae
24
Q
What does the muscularis externa comprise of?
A
- Inner circular
- Outer longitudinal
25
What is the submucosa?
Loose connective tissue space for blood supply & drainage system
26
Serosa vs Adventitia
Serosa: covers GIT parts in the peritoneal cavity
Adventitia: covers GIT parts that are not in the peritoneal cavity
Both are the outermost layer, just which organ
27
What is serosa?
- Outermost layer of gut
- Serous mbn lined by simple squamous epithelium
- covers most parts of GIT & extends over abdominal wall to form parietal peritoneum
- Large bld. vessels, lymphatics, nerve trunk run through serosa
- aka visceral peritoneum
--> stomach, intestines, liver
28
What is adventitia?
- Outermost layer of the gut
- Located in places where a peritoneal covering is absent
--> mouth, pharynx, thoracic part of oesophagus, duodenum, asc. & desc. colon, rectum
29
What is the oesophagus?
Muscular tube that descends from pharynx through the thoracic cavity to stomach
30
Where is the oesophagus located?
- Posterior to trachea (most posterior soft structure)
- Anterior to vertebral column (vertebral column is directly behind)
31
What controls the opening b/w oesophagus & stomach?
Oesophageal sphincter (aka cardiac sphincter)
32
What is the junction between the stomach and the oesophagus called?
Gastro-oesophageal junction
33
What does the omental foramen (of Winslow) connect?
Connects the lesser sac & greater sac
34
What is the clinical significance of the greater & lesser sac?
(empty spaces)
Accumulation of blood/pus means internal bleeding/infection
35
Where is the cardiac part of the stomach?
Below lower oesophageal sphincter
36
Where is the greater omentum attached?
Attached to the greater curvature of the stomach
The other sides are not attached = allow for movement of greater omentum
37
Why must the greater omentum be allowed to move?
Deals with abnormalities (e.g. infections, etc) = must be able to move to localize & isolate infection
Has lots of lymphatic tissue
38
What are the three parts of the stomach?
- Fundus: Dome shaped
- Body: Contains greater & lesser curvature
- Pylorus: Contains antrum & pyloric canal
39
What is the opening between the pyloric canal & 1st part of duodenum controlled by?
Pyloric sphincter
40
What are the folds on the stomach inner surface known as?
Rugae
41
What are the layers of the stomach wall?
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
42
What does the mucosa of the stomach wall contain?
Gastric pits
43
How many layers does the muscularis externa have in the stomach?
3 layers of muscle (instead of 2)
44
What are the layers of the muscularis externa?
- Oblique muscle layer: inner layer
- Circular muscle layer: middle layer
- Longitudinal muscle layer: outer layer
45
How does the stomach carry out mechanical digestion?
Stomach turns & contracts; mixes with stomach juice = chyme
46
What is rugae of the stomach inner surface for?
Allows for bigger elasticity & space for expansion
(rugae means folds & irregularities)
47
What are characteristic to the stomach?
- Gastric pit
- Gastric gland
48
What do chief cells produce?
Produces pepsinogen
- inactivated form of pepsin which is activated by HCl
49
What are the functions of the stomach?
1. Mechanical digestion
2. Enzymatic digestion
3. Neutralization of any bacteria by HCl
4. Absorption
5. Container & reservoir for food
50
Mechanical digestion (stomach)
Due to the presence of the 3 layers of muscle = stomach can turn & mix food into chyme
51
Enzymatic digestion (stomach)
Protein digestion by pepsin which is activated from pepsinogen (produced by Chief cells aka zymogenic cells)in acidic environment (HCl)
52
Neutralization of any bacteria by HCl (stomach)
HCl produced by parietal cells
53
Absorption (stomach)
Absorbs:
- alcohol
- sugar
- salt
- water
- drugs
54
Container & reservoir for food (stomach)
Stomach is distensible = bc of rugae
Can store food for up to 4 hours
55
What arteries supply the stomach?
- Celiac trunk
- Common hepatic Artery
- Right gastric Artery
- Left gastric artery
- Left gastro-omental arterry
- Right gastro-omental artery
56
Which arteries supply the lesser curvature of the stomach?
Left & Right gastric artery
57
Which arteries supply the greater curvature of the stomach?
Right & Left Gastro-omental artery
58
Where do these arteries come from:
Right gastric artery
Left gastric artery
Right gastric artery = branch of the common hepatic artery
Left gastric artery = directly from celiac trunk
59
Where do these arteries come from:
Right gastro-omental artery
Left gastro-omental artery
Right gastro-omental artery = branch of gastroduodenal artery from common hepatic artery
Left gastro-omental artery = branch of splenic artery from celiac trunk
60
Innervation of the stomach
Parasympathetic = vagus nerve
Sympathetic = celiac plexus
61
What are the lympahtics of the stomach?
Gastric lymph nodes
Gastro-omental lymph nodes
Found at the curvatures & drains into celiac lymph nodes
62
Which is the longest part of the GIT tract?
Small intestine (about 6.7m)
63
Where does the main part of enzymatic digestion occur?
Small intestine = due to presence of enzymes
64
Where are the enzymes in the small intestine secreted from?
Pancreas and bile (from liver)
65
Where is the majority of nutrients absorbed in?
Small intestine
66
How long does the absorption process in the small intestine take?
3-6 hours
67
What is the point of the stomach being able to store food for up to 4 hours?
Since absorption process in the small intestine can take 3-6 hours
= stomach can hold the chyme while the small intestine is busy (digesting & absorbing)
68
What are the 3 major parts of the small intestine?
- Duodenum
- Jejunum
- Ileum
69
What can the duodenum be divided into?
1. Superior or 1st
2. Descending or 2nd
3. Inferior or 3rd
4. Ascending or 4th
70
Where do the pancreatic enzymes reach the small intestine through?
2nd part of the duodenum (C-shaped part of the duodenum)
- Duodenum also receives bile from liver & gallbladder
71
Which is the longest section of the small intestine?
ileum (3.5m long)
(jejunum = 2.5m long)
72
What is characteristic to the small intestine?
Villi
(DIFFERENT from gastric pits; villi are thinner)
73
How many layers of muscularis externa are there in the small intestine?
2 layers
(stomach needed 3 layers bc of mechanical digestion)
74
What is the function of villi?
Increase surface area for absorption of nutrients
75
What are the anatomical modifications to increase surface area of the small intestine for absorption?
1. Plica Circularis = circular folds on the inner surface
2. Villi (on plica circularis) = finger-like projections covered w simple columnar epithelium
3. Microvilli (on villi)
76
What are the functions of the small intestine?
1. Complete digestion
2. Selective absorption (what is absorbed & what is left for large intestine)
3. Secretion of some hormones
4. Delivers the chyme from stomach to large intestine
77
Steps in identifying part of small intestine based on histology
1. Identify villi = small intestine
2. Brunner's gland in submucosa (bunch of circles) = duodenum
3. Lack of distinctive features in submucosa = jejunum
4. Peyer's patch in mucosa (large circular structures) = ileum
78
What is the most distinctive feature in the duodenum?
Presence of Brunner's gland in the submucosa
A bunch of small circular structures
79
What is the function of the Brunner's gland in the submucosa of the duodenum?
Neutralise the HCl effect
80
What is the most distinctive feature in the jejunum?
- Absence of Brunner's gland in the submucosa (absence of any distinctive features)
- more tall & slender villi
81
What is the most distinctive feature in the ileum?
Presence of Peyer's patches in the MUCOSA
82
What are Peyer's patches?
Lymphatic cells aggregated together
83
What is the mesentary?
Fatty tissue that contains bld. vessels & lymphatics that supply small intestine
84
How to identify jejunum based on mesentary?
- Less arcades = curved bld. vessels that look like an arc
- Longer vasa recta = straight bld. vessels arising from the arc
85
How to identify ileum based on mesentary?
- More arcades & smaller in size = curved bld. vessels that look like an arc
- Shorter vasa recta = straight bld. vessels arising from the arc
86
What are the parts of the large intestine?
- Cecum
- Ascending colon
- Right colic (hepatic) flexure
- Transverse colon
- Left colic (splenic) flexure
- Descending colon
- Sigmoid colon
- Rectum
87
What are the characteristic features of the large intestine?
1. Haustrations = bulging & depressions throughout (like bumps)
2. Appendices epiploicae (omental appendices) = Droplets of fat
3. Taeniae coli = (big, strong) muscle = helps to push food through large intestine (need strong muscle bc food more solidified)
88
What is the large intestine lined with?
Simple columnar epithelium
Numerous goblet cells = mucus secretion = food more solid so need more mucus to move through
89
What supplies the foregut?
(blood supply)
Celiac trunk (Coeliac trunk)
90
What organs are in the foregut?
- Oesophagus
- Stomach
- Liver
- Spleen
- Gall bladder
- Pancreas
- 1st & 2nd parts of duodenum
91
What supplies the midgut?
(blood supply)
Superior mesenteric artery
92
What organs are in the midgut?
- 3rd & 4th parts of the duodenum
- Jejunum
- Ileum
- Appendix
- Caecum
- Ascending colon
- Proximal 2/3 of transverse colon
93
What supplies the hindgut?
(blood supply)
Inferior mesenteric artery
94
What organs are in the hindgut?
- Distal 1/3 of transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Upper anal canal
- Urogenital sinus
95
How to identify the large intestine based on histology?
Presence of taenia coli (big muscle)
96
Is there taenia coli present in the rectum?
no
BUT, there is a continuous coat of longitudinal muscle present
97
Does peritoneum/serosa cover the rectum?
Covers the front & sides of the upper 1/3 & front of the middle third
Rest of rectum don't have
98
Does the rectum have appendices epiploicae?
NO
99
What covering is present in the anal canal?
Stratified squamous epithelium
Starts as non-keratinized then becomes keratinized towards the anal opening bc wear & tear (contact/abrasion w stool)
100
What is the appendix?
- Extension from the cecum
- function unknown
101
Where does the appendix receive blood supply from?
Appendicular artery & vein
102
What is appendicectomy?
Removal of appendix in case of its inflammation
103
How to identify appendix from histology?
- Presence of a lumen
- Absence of villi
- Presence of many lymphatic follicles (if have villi = ileum; no villi = appendix)
104
What is appendicitis?
Acute inflammation of appendix = acute, severe abdominal pain
105
How to confirm apendicitis?
- Put pressure at McBurney's point (about 2/3 from umbilicus towards anterior superior iliac spine) for 10 sec = no pain felt (bc pressure prevents substances released from inflammation from entering bld stream so nerves X triggered = no pain)
- Once pressure removed = SEVERE pain (bc pressure released = all inflammation substances collected is released & flushed into system at once - high nerve stimulation = severe pain)
106
What happens if appendix is not removed?
Rupture resulting in peritonitis
107
How many deciduous and permanent teeth are there?
Deciduous = 20
Normal = 32
108
What is the alveolar ridge?
Elevated part of bones at the upper & lower jaw --> where teeth are inserted
109
What is gingivitis?
Inflammation of the gingiva
- Caused by calculus = cause pressure on gingiva = irritation = become inflammed + bleeding gums
110
What nerve innervates the tongue & controls tongue movement?
Hypoglossal nerve (cranial nerve 12)
111
What kind of projections are present on the tongue?
1. Fungiform papillae (closer to the tip of the tongue)
2. Filiform papillae (around mid tongue)
3. Vallate papillae (back of the tongue)
112
What are the functions of the tongue?
1. Mechanical processing
2. Manipulation of food (e.g. food stuck b/w lip & teeth = tongue can bring it in)
3. Sensory analysis by touch, temperature & taste receptors
4. Secretion of mucins and the enzyme lingual lipase
113
What do mucins do (secreted by tongue)?
Lubricate the food so that it can become a bolus & move smoothly down the oesophagus
114
What does the enzyme lingual lipase do (secreted by the tongue)
Partial digestion of triglycerides & other types of fat
Note: SPECIAL bc works in wide range of acidity (pH 3-6) = can keep working even when it reaches the stomach
115
What are some problems that may occur with the tongue?
1. Ankyloglossia
2. Tongue ulcers
3. Tongue Lesions
4. White discolouration of the tongue
116
What is ankyloglossia?
Lingual frenulum cut off/healed improperly with scar/short from birth
= restrict tongue, cannot move properly
117
What are tongue ulcuers & lesions due to?
- Can be due to bad hygiene
- Can be related to other diseases = e.g. dec. salivary secretion
- Can be a direct indication of serious systemic disorder
118
Where does the parotid duct run?
- Crosses over the masseter muscle
- Pierces the buccinator muscle
- Opens into oral cavity opposite 2nd upper molar
119
Where does the sublingual salivary gland open?
Opens on either side of the lingual frenulum (multiple small ducts)
120
Where does the submandibular salivary gland open?
- Opens in the floor of the mouth, opposite the junction where the front of tongue meets floor of the mouth
- Through submandibular duct (AKA Wharton's duct)
121
Where does the parotid salivary gland open?
Opens in the oral cavity opposite to 2nd upper molar
122
Which is the biggest salivary gland?
Parotid salivary glands
123
Which salivary glands produce the most saliva?
Submandibular salivary gland (~70%)
124
What does the parotid salivary gland produce?
Serous secretion containing large amts of salivary amylase = break down starch
125
What does the sublingual salivary glands produce?
Mucous secretion that acts as a buffer & lubricant
126
What are the sublingual salivary glands covered in?
Covered by mucous membrane of the floor of the mouth
127
What does the submandibular salivary glands secrete?
Mixed salivary gland (bc secrete mixture = serous & mucous)
- Buffers
- Glycoproteins called mucins
- Salivary amylase
128
What is saliva?
- Water (99.4%)
0.6%:
- Electrolytes: Na+, Cl-, HCO3
- buffers
- glycoproteins
- antibodies
- enzymes
- waste products
1-1.5 L produced per day
129
What are the functions of saliva?
1. Lubricating & moistening food in mouth & oral cavity
2. Dissolve chemicals that can stimulate taste buds & provide sensory information about food
3. Begins the digestion of complex carbs before food is swallowed (salivary amylase)
130
What happens if there is no proper saliva secretion?
dry mouth (xerostomia)
- problem with oral flora = ulceration & lesions
131
What is oral flora?
Different organisms in the oral cavity (e.g. normal bacteria) in a particular order & quantity (if there is less/more = problem)
