Please enable JavaScript.
Coggle requires JavaScript to display documents.
Digestive System - Coggle Diagram
Digestive System
Clinical Correlation
Barrett's esophagus
reflux at GE junction allows acid
epithelium undergoes metaplasia
converts to columnar mucus-secreting
high risk of developing dysplasia and
invasive adenocarcinoma
Esophageal Varices
dilates submucosal veins in lower
1/3 of esophagus
usually by portal hypertension
in front of a vein and ruptures, BLOOD
causes cirrhosis
Gastric Ulcers
painful erosive lesions of mucosa
Helicobacter pylori infection, NSAID
overproduction of Hal or pepsin
Sleeve Gastrectomy
bariatric surgery, weight loss
Celiac Disease
immune response to gluten, blunted villi
lot of immune cells in lamina propia
Hemorrhoids
if anal venous plexuses become dilated
increased pressure, form engorged areas
internal and external
(pregnancy, low fiber, persistent diarrhea ...)
prolonged sitting on toilet
Toxic Megacolon
C diff infection, inflammation, nitric oxide
dilation, fecal transplant can help
inflammatory cells and volcanic area
with debris (grossly, white regions)
Cirrhosis
too much regeneration, scarring (collagenous tissue)
portal hypertension
-
-
Pancreatic Cancer
adenocarcinoma most common
usually near duodenum, Whipple
Pancreatitis
pancreatic enzymes become active
within acinar cells, dangerous
RF: alcohol, gallstones, infection
Diabetes
disruption of insulin signaling
high glucose, type 1 loss of beta
type 2 failure to respond to insulin
Alimentary Canal
Enteric Nervous System
- kinda functions independently
- input from sympathetic and
parasympathetic
Meissner's Plexus submucosa
innervates glands in mucosa and sub
and smooth muscle of muscularis mucosa
Auerbach's Plexus
between the 2 layers of smooth muscle
in muscularis externi
- both respond to local stimuli, para and symp
- functions even when CNS input is cut
GALT
- scattered cells in lamina propia and
epithelium
- along length of alimentary canal
Esophagus
- pharynx to stomach
- deliver food and liquid
Mucosa
- non-keratinized strat squamous
- lamina propia of CT
- longitudinal smooth muscle (in muscularis
mucosa) thickest of alimentary canal
Submucosa
- loose/areolar CT with mucous glands
(esophageal glands)
Muscularis Externi
- upper 1/3 skeletal (proximal)
- middle 1/3 smooth and skeletal
- lower 1/3 smooth (distal)
Adventitia or serosa (has mesothelium)
- thoracic portion adeventitia
- short abdominal portion has serosa
Esophagogastric Junction
- Z-line, abrupt change
- strat squamous to simple columnar
- Glands move from the submucosa (eso gl)
to lamina propia (cardiac/gastric)
- third layer of smooth muscle (inner oblique)
added to muscularis externe
Stomach
- between esophagus and duodenum
- cardiac and pyloric sphincters
- bolus, the goes to small intestine
as pulpy fluid (chyme)
- longitudinal folds (rugae),
flatten/stretch with food
- simple columnar epithelium
- deep invaginations form millions
of gastric pits, lined by surface
mucous cells (also line lumen)
Cardiac Region
- narrow transitional, mucus production
-
Muscularis Externi
- 3 layers of smooth muscle
Mucosa
- lamina propia CT with cardiac glands
(mostly mucous, simple coiled tubular)
- muscularis mucosa
-
Fundus and Body
- identical microscopically
- gastric glands relating acid juice
Muscularis Externi
- 3 layers of smooth muscle
(inner oblique, middle circular, outer longitudinal)
-
-
Mucosa
- mucous cells line surface and gastric pits
- mucous secretions protect stomach
- lamina propia gastric glands, sparse CT
- gastric glands secrete gastric juice
- short pits long glands
- muscularis mucosa
-
Pylorus
- funnel-shaped,
mucus production
-
Mucosa
- epithelium primarily mucous cells
- gastric pits
- lamina propia gastric glands, mainlu
mucous secreting cells and sparse CT
- long pits short glands
- mucous secretion to protect from acid
- muscularis mucosa
Muscularis Externi
- 3 layers of smooth muscle
- middle layer thickened (pyloric sphincter)
-
Small Intestine
- principal site for absorption
- length, place circulars, villi,
microvilli increase surface area
Plicae circularis
big folds in mucosa and submucosa
Crypts of Lieberkühn
openings of short tubular glands
between villi
Submucosa
- loose CT and Brunner's Glands
mucous glands (neutralize acid)
Muscularis Externi
- inner circular and outer
longitudinal layers
Mucosa
- enterocytes and goblet cells
- occasional lymphatic nodules
- muscularis mucosa
-
-
Ileum
peritoneal, serosa
-
-
Mucosa
- same a jejunum but with
Peyer's patches
-
Cells
Enterocytes
- tall columnar cells
- basally located nucleus
- striated (brush border), microvilli
Goblet cells
- throughout
- secrete mucus to lubricate
and protect
Paneth cells
- bright pink, eosinophilic
- basal most portion of the crypts
- exocrine cells, secretory granules
- play role in immunity
- break down membranes of microorganisms
Enteroendocrine cells
many types, have chemoreceptors
like taste buds, sample nutrient levels
and detect them (esp sugars) and regulate
hormone release
-
Rectum
- same as colon
- even more goblet cells
- no tenure coli
- lower rectum adventitia
Anal Canal
- Recto-anal junction (pectinate line)
- non-keratinized strat squamous with
hair follicles, sebaceous glands,
and sweat glands
- submucosa, numeral rectal veins
- internal anal sphincter, smooth muscle
- voluntary skeletal muscle (external)
- goes from non-keratinized to
keratinized squamous once hits skin
Gastroduodenal Junction
- massive area
- pyloric sphincter and gastric mucosa
- intestine mucosa (villi) stomach (pits)
- Brunner's glands in duodenum
- no glands in sphincter
Liver
Structure
- in Glisson's Capsule
- covered with visceral peritoneum
- hepatocytes parenchymal cells
- hepatic sinusoids capillaries
- reticulin
Hepatic Lobules
- thousands, small
- arranged radially around central vein
-3 to 6 portal areas (portal triad)
Portal Triad
- hepatic portal venule
- hepatic arteriole
- bile duct (cuboidal), nerve
and lymphatics
- dense CT
Space of Disse
- narrow space between hepatocytes and sinusoids
- have microvilli projections, contain hepatic stellate cells
-
-
-
Bile Production
by hepatocytes
- travels through caniculi to ducts
- then larger ducts, then right
and left hepatic ducts
then common hepatic duct
Function
- produce bile, carbs, proteins, lipids
- filter toxins
Components
Hepatocytes
- filter blood, remove toxins synthesize
Proteins, carbs, and lipids
- polyhedral, round nuclei
- might be multinucleated
- large cells, abundant RER and SER
- eosinophilic
- anastomosing plates (1-2 cells)
- microvilli on surface
Central vein
in middle, merges to form larger
hepatic vein
Hepatic Sinusoids
large, highly permeable sinusoidal
- between plates of hepatocytes
-
Stellate cells
- space of Disse
- store fat and fat-soluble vit A
Bile Canaliculi
- network of anastomosing channels
within hepatocyte plates
- created by space between occluding junctions
- drain into bile ducts in portal triads
Flow
Blood flows from periphery to
center of each lobule
Bile flows in opposite direction
- hepatocytes near portal more
active in protein synthesis
- centrolobule hepatocytes exposed
to less O2 and nutrients, more detox
and glycogen metabolism
-
GI Tract
hollow tube
Submucosa
connective tissue with larger
blood and lymph vessels and
Meissner plexus of autonomic nerves
Muscularis
smooth muscle cells organized
as 2 or more layers, contains
Auerbach nerve plexus
Mucosa
epithelial lining and underlying
lamina propia, thin layer of smooth
muscle, muscularis mucosa
Serosa
thin layer of loose connective tissue
with simple squamous covering
(mesothelium)
serosa vs adventitia
- serosa has mesothelium, freely moving
intraperitoneal organs
- adventitia lacks mesothelium just
loose CT, fixed organs
Function
ingestion, mastication, motility,
secretion, hormone release, chemical
digestion, absorption, elimination
Salivary Glands
-
General
- produce saliva, start digestion
- protect from bacteria
- 1.5L saliva daily
serous cells acini and demilunes
mucous cells tubules
- also have minor
Organization
- branched compound acinar or tubuloacinar glands
acini= serous cells
tubules=mucous cells
-
Myoepithelial cells
between epi and basal lamina
of secretory unit, helps propel secretions
-
Secretory Lobule
serous acini, mucinous acini
intralobular ducts
Serous Acini
clusters of glandular cells, dark
color and round nuclei, enzyme rich fluid
Mucinous acini
clusters of glandular cells, pale
flat blue nuclei at bottom
Ducts
Interlobular
columnar/strat cuboidal,
surrounded by CT
Main excretory duct
- massive, strat cuboidal/pseudostrat
- in interlobular CT
Intralobular ducts
Intercalated
secretory acini, cuboidal
Striated
merging of intercalated,
near blood vessels, resorb NaCl,
low columnar
Oral Cavity
- vestibule
- oral cavity proper
Tongue
General
- muscular structure
- covered by oral mucosa specialized
for food and sensory reception
- sulcus terminalis divides
tongue into anterior 2/3 (papillae) and
posterior 1/3 (V-shaped)
- body is skeletal muscle
-
Taste Buds
Types
- sweet (tip)
- salty (tip C shape)
- sour (sides)
- bitter (back)
- unami (all)
Structure onion-shaped
- 50-100 cells
- afferent nerve, little nerve fibers
Mucosa
Masticatory Mucosa 25%
- gingiva, hard palate
- rigid, tough, tightly bound
- keratinized strat squamous
Lining Mucosa 60%
- lips, cheeks, floor, ventral
surface of tongue and soft palate
- mobile surfaces
- loosely bound, soft and pliable
- non-keratinized strat squamous
Specialized Mucosa 15%
- dorsal surface of the tongue, taste
- non-keratinized strat squamous with
taste buds and papillae
- plays role in regenerating papillary
architecture of lingual epithelium
Teeth
- 16 in each arc (32)
- crown (projects) and roots
- sits in socket (alveolus)
- CT, harder than bone
- hydroxyapatite
Cementum
- bone like covering dentin of root
- Sharpey's fibers, bundles of collagen
extend from cementum to connect to bony socket
Dentin
- bulk of tooth
- calcified tissue, harder
than bone
Enamel
- covers crown, mineralized material
- saliva maintains it, acid by bacteria destroys
Pancreas
- thin connective tissue capsule
Exocrine
-
Regulation
- Cholecystokinin for acinar cells
- Secretin for centroacinar cells
- both secreted by enteroendocrine
cells in duodenum and jejunum
- parasympathetic stimulation too
Structure
- compound tubuloacinar glands
- empties into duodenum at
hepatopancreatic ampulla
acinus
- 45-50 pyramidal shaped epithelial cells
- oriented around central lumen
- surrounded by basal lamina
Acinar Cells (zymogen)
- protein secretin cells
- extensive RER, round nucleu basally
prominent Golgi and lots of granules
- drained by intercalated duct
Centroacinar cells
- initial cells of intercalated duct
- penetrate into lumen of acinus
- distinguishing feature
Endocrine
- Islets of Langerhans scattered
- cells separated by fenestrated capillaries
Beta
insulin, amylin (slow gastric emptying)
-
Alpha
glucagon, glyco to gluco
-
Epsilon
ghrelin, stimulates hunger
Gallbladder
under liver, stores bile
cystic duct+ hepatic duct
= common bile duct
- hepatopancreatic sphincter
Structure
-
-
Mucosa
- tall simple columnar
- apical microvilli
- lamina propia
- highly absorptive capacity
to concentrate bile
Pharynx
- common for air and food
- naso/oro/hydropharynx then larynx
and esophagus
- Abrasion = non-keratinized strat squamous (oro)
- no abrasion= pseudostrat ciliated epithelium
(naso)
- palatine, pharyngeal and lingual tonsils