Digestive System Flashcards
1
Q
What is the primary function of digestive system?
A
Primary Function of Digestive System
* To break down food and/or liquids into smaller units of absorbable nutrients which are used by your body to generate energy
2
Q
On average how
long do you think it takes for the sandwich you ate at lunch to
completely pass through your digestive tract?
A
24 hours
3
Q
What is the Alimentary canal?
A
Alimentary canal
* Structures form long tube that breaks down food
* It takes approximately 24 hours from ingestion to defecation
4
Q
What are the Accessory digestive organs?
A
Accessory digestive organs
* Participate in digestive process but food does not pass through
these structures
* Examples:
- Liver
- Pancreas
- Gallbladder
- Salivary glands
5
Q
What is Ingestion?
A
Ingestion
* Put food into mouth
6
Q
What is Propulsion?
A
Propulsion
* Movement of food through canal
* Swallowing is voluntary
* Peristalsis is involuntary
7
Q
What is Mechanical digestion
A
Mechanical digestion
* Physical breakdown of food particles
* Chewing, churning, segmentation
8
Q
What is Peristalsis?
A
Peristalsis
* An organized contraction and relaxation of smooth muscle layers that propels food through the alimentary canal in one direction
- Ex. cookie dough gets squeezed out
- Allows you to eat upside down
9
Q
What is Segmentation?
A
Segmentation
* Contractions of smooth muscle move chyme (food product being digested) back and forth within canal to allow mixing and further breakdown
- mix up food particles and digestive enzymes
- homogenous mixture of food and enzymes
10
Q
What is Chemical digestion?
A
Chemical digestion
* Enzymes and chemicals break down food
11
Q
What is Absorption?
A
Absorption
* Particles (ex. Sugars, fatty acids, etc.) are
transported from canal into blood and lymph
capillaries
12
Q
What is Defecation?
A
Defecation
* Indigestible products are eliminated as feces
13
Q
What are the layers of the Alimentary Canal
A
- The inner canal = lumen
- There is a consistent layering of tissues that form most of
the alimentary canal (there are some exceptions to be noted later) - From lumen to outer layer:
- Mucosa: lines lumen
- Submucosa: support layer
- Muscularis externa: muscle layer
- Serosa: outer surface
14
Q
What are the 3 sublayers of Mucosa?
A
3 sublayers:
1. Epithelium
* Type varies by location
* Mucus production, absorption, protection, etc.
* Continuous & contains many digestive glands
2. Lamina propria (loose areolar)
* Capillary rich (absorption)
* MALT = mucosa associated lymphoid tissue
* Provides defense
3. Muscularis mucosa (thin layer smooth
muscle)
* Localized movements, helps glands expel
contents
15
Q
What are the components of submucosa?
A
Submucosa
* Similar to loose areolar CT but more collagen fibers (provide support)
* Highly vascularized
- Nutrient absorption
* Glands connecting to lumen may project to submucosa
* Submucosal nerve plexus
- Control of muscle cells, glandular secretions, etc. (more on this later…)
16
Q
What are the components of Muscularis Externa?
A
Muscularis Externa
* 2 layers smooth muscle (stomach has 3)
* Circular: inner layer, typically squeezes tube
* Longitudinal: outer layer, typically shortens tube
* Peristalsis and segmentation
* Myenteric nerve plexus
* Innervates muscularis externa and is between longitudinal and circular muscles (more on this later…)
17
Q
What is the enteric nervous system?
A
- The enteric nervous system controls smooth muscle and
glands of alimentary canal - Considered the “brain in the gut” - - Has as many neurons as the entire spinal cord
- Reflex arc exists (sensory neurons –> interneurons –> motor neurons)
- Made of two nerve plexuses within the wall of alimentary canal
- Submucosal nerve plexus
- Myenteric nerve plexus
- Is influenced by the autonomic nervous system
18
Q
What are the components of Serosa?
A
Serosa
* Found around organs within abdominal cavity
* Simple squamous epithelium + a thin loose areolar CT = Serous membrane
19
Q
What is esophagus lined with?
A
- The esophagus is lined with adventitia (a fibrous CT)
- The esophagus is not contained
within a body cavity lined with a
serous membrane
20
Q
What is Enteric Nervous System?
A
Enteric Nervous System
* Is located entirely within the wall of the alimentary canal
* Nerve plexuses allow for a localized response within visceral organs
* Partly independent of central nervous system
* Myenteric nerve plexus
* Submucosal nerve plexus
21
Q
What is the Myenteric nerve plexus?
A
Myenteric nerve plexus
* Controls peristalsis and segmentation
* Within muscularis externa
22
Q
What is the Submucosal nerve plexus?
A
Submucosal nerve plexus
* Controls secretions of glands & muscularis mucosa contractions
* Within submucosa
23
Q
What is the Submucosal nerve plexus?
A
Submucosal nerve plexus
* Controls secretions of glands & muscularis mucosa contractions
* Within submucosa
24
Q
What is the oral cavity?
A
Oral Cavity
* Mouth
* Ingestion of food
* Mechanical digestion
- Chewing = mastication
* Chemical digestion
- Mixed with saliva that contains amylase
– Starts chemical breakdown of carbohydrates
25
What is the Anatomy of the Mouth?
Mouth Anatomy
* Stratified squamous epithelium
* Thin submucosa layer anchored directly to underlying bone
* No muscularis externa or serosa/adventitia
* Lips
26
What is the Anatomy of the Lips?
Lips: margin between skin and oral cavity (lip proper = transition part)
* Poorly keratinized, translucent
- Red color from underlying capillaries
* No eccrine or sebaceous glands
* Lower lip 12X more likely to get nonmelanoma skin cancer
27
What is the Anatomy of the tongue?
Tongue
* Accessory digestive organ
* Superior surface (the part you see when you say “ah”) iscovered in keratinized stratified squamous epithelium
- Keratin makes it look whitish
* Moves food, helps mix to form bolus
(also involved with speech)
* Filiform papillae
- Rough surface
* Fungiform and circumvallate papillae
- Contain taste buds
28
What is the Lingual Frenulum?
Lingual Frenulum
* Lingual frenulum
* Fold of mucosa layer
* Connects tongue to floor of mouth
29
What is being “Tongue Tied”
Tongue Tie”
* If lingual frenulum extends too far forward, the tip of the tongue cannot move and speech is difficult
* Called ankyloglossia
* Makes saying sounds where the tongue touches teeth (letters such as t, z, p)
* Can be corrected surgically
30
What are the components salivary glands?
Salivary Glands
* Accessory digestive organs
* Exocrine glands
* Produce saliva
31
What are the components of salvia?
Saliva
* Moistens mouth
* Dissolves food (so can taste)
* Contains digestive enzymes
- Amylase starts breakdown of carbohydrates
- Lipase begins digestion of fats
* Contains mucus (helps swallowing)
* Neutralizes acids produced by bacteria that promote decay (has bicarbonate buffer)
* Antibacterial and antiviral components
32
What are the cell types of the Salivary Glands?
Cell types
* Serous cells secrete digestive enzymes
* Mucous cells secret mucus
33
What are the primary salivary glands?
* Parotid gland and duct
* Submandibular gland and duct
* Sublingual gland and ducts
34
What are the components of Parotid glands and ducts?
Parotid gland and duct
* Largest salivary gland
* Contains serous cells
- Produce watery enzyme-rich secretion
* Empties near 2nd upper molar
35
What is Mumps?
Mumps
* Viral infection
- Parotid glands swell; painful
36
What are the components of Submandibular gland and ducts?
Submandibular gland and duct
* Approximately equal amounts of serous and mucous cells
* Ducts open lateral to lingual frenulum
37
What are the components of Sublingual gland and ducts?
Sublingual gland and ducts
* Mostly mucous cells (secrete
mucus)
* Several ducts empty below
tongue
38
What are the components of teeth?
Teeth
* Accessory digestive organs
* Involved in mastication (= chewing)
* Heterodont dentition
* Different shapes of teeth for different jobs
39
What are Deciduous teeth?
Deciduous teeth
* “Baby teeth”
* 20 total erupt typically between ages 6 months
to 6 years
40
What are Permanent teeth?
Permanent teeth
* 32 total that gradually replace deciduous
* “Wisdom teeth” = 3rd molars
* Emerge between 17 and 25 years old (not always
can become impacted and do not emerge, or are
sometimes missing)
41
What are the regions of a tooth?
Regions of a Tooth
* Crown
- Part above gum line
* Neck
- Narrow, contained within gum tissue
* Root
- Contained within bone
42
What is the anatomy of teeth?
* Pulp
* Dentin
* Enamel
* Cement
* Periodontal ligament
43
What is the pulp of a tooth?
Pulp
* Loose areolar CT with blood vessels and
nerves
* Provides nutrients and sensation to tooth
* Odontoblasts create dentin
44
What is the Dentin of a tooth?
Dentin
* Collagen (from odontoblasts) and
minerals
* Forms bulk of tooth; deep to enamel
* Has radial striations = dentinal tubules
* Can contribute to tooth sensitivity
* No cells or blood vessels
* Harder than bone
45
What is the Enamel of a tooth?
Enamel
* Hardest substance in body
* 99% calcium salts
(hydroxyapatite crystals)
* No cells or blood vessels
46
What is the cement of a tooth?
Cement
* Calcified CT that covers root
47
What is the Periodontal ligament of a tooth?
Periodontal ligament
* Dense CT that attaches cement
of tooth to bony socket
48
What is a cavity?
Demineralization of enamel and dentin
* Begins with dental plaque
* Biofilm of sugar, bacteria and other
debris on teeth
* Bacteria break down sugars and produce
acids
* Dissolve calcium salts of teeth
(demineralization of enamel)
* Bacteria also produce protein-digesting
enzymes that destroy organic component
of teeth
49
What is the Root Canal Procedure?
* A root canal may be required when the pulp within the canal
becomes infected
* Pulp is drilled out
- Tooth is now “dead”
- Cavity is sterilized and filled
* Tooth is capped off to help strengthen it
50
What is the Pharynx?
* Pharynx connects oral cavity to
esophagus and nasal cavity
* 2 parts
- Oropharynx
- Laryngopharynx
* Muscularis externa has skeletal
muscle for swallowing
* *Nasopharynx
51
What is the Oropharynx?
Oropharynx
* Immediately behind oral cavity
* Made of stratified squamous epithelium
52
What is Laryngopharynx?
Laryngopharynx
* Inferior to oropharynx
* Made of stratified squamous epithelium
53
What is the Esophagus?
Esophagus
* Connects pharynx to stomach
* Stratified squamous epithelium
(nonkeratinized)
* Mucous glands in submucosa
and mucosa secrete mucus
- Lubricates bolus of food as passes
through
54
What is the Muscularis externa of the Esophagus?
Muscularis externa
* Upper 1/3: skeletal muscle
* Middle 1/3: mix of skeletal and smooth
* Lower 1/3: smooth muscle
55
What is Hiatal hernia?
Hiatal hernia
* Superior part of stomach pushes through esophageal hiatus following weakening of diaphragmatic muscle fibers
- Acidic stomach juices are regurgitated, eroding wall of esophagus (= GERD, gastroesophageal reflux disease)
56
What is Barrett’s esophagus?
Barrett’s esophagus
* Due to persistent exposure of acidic stomach contents
* Causes lower esophageal ulcers and precancerous epithelium
57
What is the purpose of the stomach?
* Food spends ~4 hours in stomach
being churned into chyme
* Mechanical digestion (churning)
* Chemical digestion (digestive
enzymes and HCl)
* Some absorption takes place here
(most absorption occurs in the small
intestine)
- Limited to water, alcohol, and drugs
(aspirin)
58
What is the lining of the stomach?
* The lining mucosa is simple
columnar epithelium
- Made entirely of cells that produce
bicarbonate-buffered mucus
(protection)
- Lining is dotted with many gastric pits
which open into gastric glands (more
later)
59
What is the anatomy of the stomach?
* Rugae (= “wrinkles”)
Regions
* Cardia
* Fundus
* Body
* Pyloric antrum
* Pylorus (= “gatekeeper”) with pyloric sphincter
* Greater and lesser curvatures
* Sphincters
60
What is Rugae?
Rugae (= “wrinkles”)
* Folds of mucosa that increase surface area and allow stomach to expand
* Easily holds 1.5 liters of food, can hold 4 liters!
61
What are sphincters?
Sphincters
* Thickened regions of muscularis externa
* Cardiac sphincter (near heart)
- Prevents food from moving back into esophagus
* Pyloric sphincter
- Controls release of chyme intoduodenum
62
What are the muscularis layer of the stomach?
Muscularis externa has extra layer:
1. Longitudinal
2. Circular
3. Oblique →innermost
63
What is the microscopic anatomy of stomach epithelium?
* Mucosa is lined with simple columnar epithelium
* Mucous neck cells
* Gastric pits
* Gastric gland
64
What is Mucosa of stomach epithelium?
Mucosa is lined with simple columnar epithelium
* All secrete bicarbonate-buffered mucus
* Mucus protects stomach wall from acid and digestive enzymes
65
What is the Mucous neck cells?
Mucous neck cells
* Secrete mucus (different from mucus produced by epithelium [above], function unknown)
66
What are Gastric pits?
Gastric pits
* Regions where epithelium cups downward, meets with gastric gland
67
What are Gastric glands?
Gastric gland
* Connect to lumen through gastric pit
* Contain specialized cells
- Parietal cells
- Chief cells
- Enteroendocrine cells
- Undifferentiated stem cells
68
What are Parietal cells?
Parietal cells
* Produce and secrete 2 products
- HCl which destroys bacteria
- Gastric intrinsic factor (GIF) which is necessary for vitamin B12 absorption in small intestine
* Vitamin B12 is needed for production of RBCs
69
What are Chief Cells?
Chief cells
* Produce and secrete pepsinogen (in-active form)
* Also secrete gastric lipase (enzyme)
- Fat digestion
70
What is Pepsin?
Pepsin breaks down proteins in food
* It is created when pepsinogen mixes with HCl
* active version of pepsinogen
- gastrin stimulates release of HCl and pepsinogen
- Pepsinogen + HCl = pepsin
71
What are Enteroendocrine cells?
Enteroendocrine cells (= “gut endocrine”)
* Release hormones
- Ex. Gastrin stimulates parietal cells to release HCl)
72
What are Undifferentiated stem cells?
Undifferentiated stem cells
* Found at junction between gastric pits and gastric glands
* Because of harsh environment, stomach cells are replaced every 3-7 days
73
What is the purpose of the small intestine?
* Longest segment of canal at ~16 ft
- Longer in cadavers than living people
* Simple columnar epithelium
* Site of most absorption and chemical digestion
* Chyme move through via peristalsis
- Is churned via segmentation
74
What is the Duodenum
Duodenum (= “12 finger-widths long;” 5%)
* closest to stomach
* Shortest
* Receives a number of substances
- Chyme from stomach
- Digestive enzymes from pancreas
- Bile from liver/gallbladder
75
What is the Jejunum?
Jejunum (= “empty;” 40%)
* Most absorption occurs here
* second part of small intestine
76
What is the illeum?
Ileum (= “twisted intestine;” 55%)
* closest to large intestine
* Longest
* Absorption occurs here as well
77
What are the wall layers of the small intestine?
All typical layers of the alimentary canal
occur in the small intestine
* Mucosa
* Submucosa
* External muscularis
* Serosa
78
What is the total surface area of the small intestine?
200 m2
- large surface area = more absorption
79
What gives the Small intestine a large surface area?
Has a very large internal surface area to increase absorption:
1. Length (approx. 16 feet)
2. Circular folds
- contain villi, which contain microvilli
80
What are Circular folds?
Circular folds
* 1 cm tall
* Increase surface area and forces chyme
to spiral through small intestine
- This slowing allows for increased
absorption of nutrients
81
What is villi?
Villi
* 1 mm tall
* Made of absorptive cells (= enterocytes)
* Have blood capillaries and a lymphatic
capillary called a lacteal
82
What is Microvilli on enterocytes?
Microvilli on enterocytes
* 1 um tall
* Called brush border as well
83
What are the features of the villi?
Associated features
* Lamina propria is highly vascular
* Allows for increased absorption
- Capillaries - Absorb proteins and carbs
- Lacteals
- Absorb fats (which are too large
to enter capillaries)
* Muscularis mucosa
- Moves villi within lumen to increase contact with nutrients
84
What are the specialized cells of the small intestine?
* Absorptive enterocytes
* Goblet cells
* Enteroendocrine cells
*Intestinal crypts
- Undifferentiated epithelial cells
- Paneth cells
* Duodenal glands
85
What are Absorptive enterocytes?
Absorptive enterocytes
* Found in mucosa
* Majority of epithelial cells
* Lots of mitochondria
- Absorption of nutrients requires energy
* Abundant ER
- Assemble absorbed lipids into chylomicrons
- Lipid-protein complexes
- This structure allows lipids to enter lacteals
86
What are Goblet cells?
Goblet cells
* Found in mucosa
* Secrete mucus
- Protects surface cells and lubricates chyme
87
What are Enteroendocrine cells ?
Enteroendocrine cells
* Secrete hormones to control
the release of other substances (ex. CCK and secretin)
88
What are Intestinal crypts?
Intestinal crypts
* Invaginations of mucosa, between villi
* Epithelial cells produce intestinal juice
- A watery liquid that mixes with chyme
89
What are Undifferentiated epithelial cells (stem
cells)?
Undifferentiated epithelial cells (stem
cells)
* Intestinal crypts
* Rapid replacement of cells
* New lining every 3-6 days
90
What are Paneth cells?
Paneth cells
* Intestinal crypts
* At base of crypt
* Secrete enzymes that selectively destroy
unwanted bacteria
* Help maintain healthy microbiota
* Role in protecting stem cells
91
What are Duodenal Glands?
* Duodenal glands have ducts
that open into intestinal crypts
* Found in submucosa of duodenum only
* Secrete alkalinic mucus to neutralize acidic chyme
92
What are the Lymphoid Tissue in Small Intestine?
* The small intestine has many areas of lymphoid tissue
* MALT = mucosa associated lymphoid tissue
- In mucosal layer of small intestine
* Aggregated lymphoid nodules (Peyer’s patches)
- Located in submucosa of ileum
93
What is the structure of the Duodenum?
Inputs to duodenum:
* Stomach contributes chyme
* Gallbladder adds bile
- Breaks down fats
- Bile duct and sphincter control release
* Pancreas contributes
- Digestive enzymes
- Pancreatic juice (bicarbonate) that neutralizes chyme
- Main pancreatic duct and sphincter control release
* Hepatopancreatic sphincter is the final control “valve”
94
What happens when Chyme enters duodenum from stomach
and activates enteroendocrine cells?
* Presence of fats
stimulates release of.
- Cholecystokinin (CCK) Signals release of stored bile
- Breaks down fats for better absorption
* Presence of acids stimulates release of...
- Secretin Signals release of pancreatic juice
- Neutralizes acids
95
What is the anatomy of the Large Intestine?
* Epiploic (= “membrane-covered”) appendages
* Teniae coli (= “ribbons of the colon”)
* Haustra (= “to draw up”)
* Ileocecal valve
* Cecum (= “blind pouch”)
* Colon (4 parts)
96
What is the Epiploic?
* Epiploic (= “membrane-covered”) appendages
- Fat-filled pouches on outside
97
What is the Teniae coli?
Teniae coli (= “ribbons of the colon”)
* Longitudinal strips of smooth muscle
* Cause puckering into sacs = haustra
98
What are the Haustra?
Haustra (= “to draw up”)
* Saclike structures
99
What is the Ileocecal valve?
Ileocecal valve
* Connects ileum to cecum
100
What is the cecum?
Cecum (= “blind pouch”)
* Vermiform appendix (off of
cecum)
- Stores beneficial bacteria
101
What are the four parts of the colon?
Colon (4 parts)
* Ascending
* Transverse
* Descending
* Sigmoid
102
What type of epithelium would you expect to find lining the large
intestine?
Simple columnar
103
What is the anatomy of Microanatomy of Large Intestine?
* No circular folds
* No villi
* Absorptive cells = colonocytes
absorb primarily
water/electrolytes
* Lots of goblet cells (mucus)
- Reduce friction of fecal movement
* Intestinal crypts with stem cells
- Epithelium is replaced every 7 days
104
What is the rectum?
* Connects sigmoid colon to anal canal
* Has rectal valves
- Transverse folds that prevent feces being
passed with flatus (gas)
105
What is the Anal Canal?
Anal Canal
* Epithelium transitions into
stratified squamous
* External anal sphincter
- Skeletal muscle, voluntary
control
* Internal anal sphincter
- Smooth muscle, involuntary
control
106
What are Hemorrhoids?
Hemorrhoids
* Hemorrhoids = varicose veins
of the hemorrhoidal veins in
anal canal
- External and/or internal
hemorrhoidal vein swelling
* Caused by excessive straining
(baby or defecating)
107
What are the Accessory Digestive Organs of Abdominal
Cavity?
* Liver
* Gallbladder
* Pancreas
108
What is the purpose of the liver?
The liver is a chemical processing plant
1. Digestive function: produces bile
2. Metabolic functions: processes blood
coming from stomach and intestines
109
What is the digestive function of the liver?
1. Digestive function: produces bile
* Bile salts break emulsify fats in small
intestine
* Bile is stored in gallbladder until released
into duodenum
110
What is the Metabolic functions of the liver?
2. Metabolic functions: processes blood
coming from stomach and intestines
* Stores some vitamins
* Processes fats and amino acids
* Inactivates drugs and toxins
* Stores glucose as glycogen
* Makes blood proteins
111
What are the four lobes of the liver?
Has 4 lobes
* Right
* Left
* Quadrate
* Caudate
112
What is the hepatic portal vein?
Hepatic portal vein
* Gathers blood from
digestive organs and
transports it to the liver
113
What is the blood supply to the liver?
Blood supply
* Hepatic artery proper
* Hepatic portal vein
* Inferior vena cava
114
What is the purpose of the Hepatic artery proper?
Hepatic artery proper
* Provides oxygen-rich blood to
liver
115
What is the purpose of the Hepatic portal vein?
Hepatic portal vein
* Transports nutrient-rich blood
from stomach and intestines to
liver
116
What is the purpose of the Inferior vena cava?
Inferior vena cava
* Removes blood from liver after
it has been processed
117
What is Bile?
* Bile, which is produced
in liver, is transported
through ducts to the
gallbladder for storage
118
How is the anatomy of liver organized?
* Cells of the liver are organized into 50,000-100,000 hexagonally-shaped lobules
119
How are blood vessels organized in the liver?
* Blood vessels & ducts are organized into
portal triads at corners of lobules
120
What is in each triad?
Each triad contains
* Bile duct (transports bile out of lobule)
* Portal venule (transports nutrient-rich blood
into lobule)
* Portal arteriole (transports oxygen-rich blood
into the lobule)
121
What are Hepatocytes?
Hepatocytes are the primary
cell of the liver
* Arranged into plates within
lobules
* Many functions
- Produce bile which is removed
via bile canaliculi
- Metabolize and store
substances from blood
* Great ability to regenerate
122
What are Liver sinusoids?
Liver sinusoids
* Large capillaries between
plates of hepatocytes
* Site where arterial and
venous blood mix →blood is
carried to central vein
123
What is the Central veins?
Central veins
* Drains blood from sinusoids out of liver
124
What are Stellate macrophages?
Stellate macrophages = hepatic macrophages
* Move through sinusoids
* Destroy microorganisms that have made it through intestine and worn out blood cells
125
How does bile move?
Bile moves from hepatocytes →bile canaliculus →bile duct
126
What are the anatomical structures of the liver?
* Hepatocytes
* Liver sinusoids
* Central veins
*Stellate macrophages
127
How does blood travel through the liver?
* Blood in portal arteriole and Blood in portal venule (mix)
- Blood mixes within sinusoid Gives hepatocytes access to oxygen, nutrients, etc
- Blood leaves the lobules through the central veins
on its way to the heart
128
How do the liver and the gallbladder connect?
* A series of ducts connect liver to gallbladder and duodenum
129
What is the purpose of the gallbladder?
* Gallbladder stores and concentrates bile
- Bile = cholesterol, bile acids, salts, and bilirubin
130
What are gallstones?
Gallstones
* Usually formed of cholesterol that precipitates out of bile while stored in gallbladder
131
how is bile released?
* A sphincter at the duodenum controls the release of bile into the duodenum
132
What is the purpose of the pancreas?
* Exocrine (digestive) function:
- Acinar cells produce and secrete
pancreatic enzymes/juices
-- Breakdown different food types
-- Neutralizes chyme (bicarbonate)
* Pancreatic juices transported in
main pancreatic duct and released
by sphincter
* Hormone controlling the release?
- Secretin (produced by the small
intestine)
133
Endocrine function of the pancreas?
Pancreas also has endocrine function
* Different cells produce different hormones
- Beta cells produce insulin
- Alpha cells produce glucagon
134
What is the Mesentery?
* Mesentery: double-
sided serous
membrane that
suspends organs
within cavity
- Contains blood
vessels, nerves, fat
135
What are the disorder of the GI tract?
* Ulcers
* Inflammatory Bowl Disease
* Irritable bowel syndrome
* Celiac disease
136
What are ulcers?
Ulcers
* Crater-like erosions of the mucosa
* Most occur in pyloric region of stomach or
duodenum
* Used to think ulcers were caused by stress
* Now know they are due to bacterium:
Helicobacter pylori
- Binds to gastric epithelium →induces over-secretion
of acid and inflammation →ulcer
* Treatment: antibiotics
137
What is the Inflammatory Bowl Disease?
Inflammatory Bowl Disease
* Two types
- Crohn’s Disease (more severe)
-- Along entire intestine; primarily in terminal ileum
- Ulcerative colitis (less severe)
-- Shallow inflammation large intestine; primarily in rectum
* General characteristics:
- Cramping, diarrhea, weight loss, intestinal bleeding
- Abnormal immune and inflammatory response to bacterial
antigens that normally occur in the intestine
* Can be treated with diet
138
What is Irritable bowel syndrome?
Irritable bowel syndrome
* Affects large intestine
* Causes unknown (smooth muscle, nervous
system, inflammation...)
* Symptoms: abdominal pain, excess gas,
diarrhea, constipation, mucus in stool
139
What is Celiac disease?
Celiac disease
* Autoimmune
* Gluten triggers and immune response, damages
villi of small intestine
* Treatment: gluten free diet
