GIT Flashcards
Lip structure
Vermilion border- cont w chin skin, ET
Blood vessels
Inner mucosal border- cont w vermilion border
Minor salivary glands
Gingiva- cont w mucosal border
Minor salivary glands use what secretion
Constitutive
PDL
Cementum to bone
Enamel
Dentin
Cementum
Made by?
Derived from?
Enamel made by ameloblasts from ectoderm
Derived from oral epithelium
Dentin made by odontoblasts
Derived from neural crest cells
Cementum is secreted by cementocytes, that resemble osteocytes
A vascular
Bottle mouth syndrome
When baby teeth decay before they even erupt due to excess sugar consumption
Where does digestion begin
Oral cavity w salivary amylase
Oral cavity structure
- Strat squamous ET for abrasion
- Lamina propria w salivary glands
- Skeletal muscle
- Lymph tissue- diffuse tissue, nodes, and tonsils
Salivary glands are
Exocrine glands
Unit: salivon = acinus + intercalated duct + excretory duct
Acinus shapes
Sac of cells that make secretory portion of gland
Tubular- tube like
Alveolar- sac like
Intermediate- tubuloalveolar- mix of the two
Gland development
- Glands arise from epithelium into mesenchyme below
- Mesenchyme Cells dediff and proliferate
- Epithelial cells grow down into modified mesen cells
- Epithelial cells diff into duct and secretory cells
- These cells can become mucus, serous, or zero mucous
Three types of cells
Mucous
Serous SAC- protein
*serious about protein
Seromucous
Alveolar glands have what cells
Tubular glands have what cells
Alveolar= serous SAC—-> wide base small apex
Tubular= mucous —-> cuboidal
Serous demilune
Found in tubular glands
Half moon shaped serous cell that secretes lysozyme to breakdown bacterial cell walls
Myoepithelial cells
Contractile
Between epith cell and SM cell
Contract to expel products of acinus into duct
Order of ducts leaving acinus and tissue
Acinus Intercalated duct -sim squamous Striated duct- cuboidal or columnar, has striations Lobar duct- Stat columnar Main duct
*aisle M
Grapes comparison
Bunch of grapes lobule
One grape- acinus
Minor vs major salivary glands
Minor- constitutive secretion
Housed in lamina propria
Major- regulated secretion
Major salivary secretion
ACINUS:
Nerve causes ACTIVE NaCl import
Water follows Passively
IgA, lysozyme, amylase are added to saliva
Intercalated duct: saliva is Isotonic
Striated duct: hypotonic saliva bc NaCl is actively pumped out
Bicarbonate buffer added
3 major salivary glands
Parotid
Submandibular
Sublingual
Parotid salivary gland
PROTEIN
Serous glands *serious about protein SAC Stain dark Many intercalated Some Striated ducts
Submandibular salivary gland
Mostly serous protein secreting, but mucus also
Serous demilunes visible on mucous cells
Some Intercalated ducts
Many striated ducts
Sublingual salivary gland
Mixed but mostly mucous secreting, stains lighter
Not many intercalated or striated ducts
How does saliva keep tooth integrity?
Slatherin and pellicle
Slatherin- calcium bind protein that prevent calcium precip, so it can be used to remineralize enamel
Pellicle - thing glycoproteins film that forms on enamel to prevent calcium deposition
Mumps
Sialolithiasis
Sialadentitis
M- virus, swollen salivary glands
Lith- stones from calcium deposits
Dent- inflamm of glands, in sjogrens disease
Papillae types
Circumvallate- posterior, very large, contain most of taste buds, glands of von ebner
Filiform- finger like, keratinized
Fungiform- mushroom shaped, rare in humans
Glands of von ebner
Located on circumvallate papillae
Serous/protein secreting salivary glands to break down food
3 types of taste buds in a taste pore
Sustentacular- Support and nourish “nurse cell”
Neuroepithelial- taste receptor cell, covered in microville and project out of taste pore to take in info
Basal cells- adult stem cells
Taste is a chemical sensation:
- Taste receptor cells at apex binds to tastant molecules
- Activates G protein—-> lipase C ——>IP3—-> activates Na+ channels
* GCIPNA - Na+ influx causes depolarization
- calcium channels open for calcium to enter
- Neurotransmitter release into synapse to meet gustatory nerve fiber
Tonsils
First organ of immune defense
Strat squamous et is highly folded
Palatine- active in youth, atrophy in adult
Lingual
Palate
Hard vs soft
Hard- strat squamous for abrasion, keratinized
Seromucous glands, spicules of bone
Soft- talking, breathing, swallowing, lymph tissue, seromucous glands
Lower=oral cavity- sset
Upper= nasal cavity- respiratory epith pseudo w cilia and goblet cells
Pharynx
Naso
Oro
Lower
Strat squamous w mixed glands
Made of muscle and elastic tissue
Basic structure of GIT
Lumen
Mucosa- squamous or columnar, LP, muscularis mucosa w longitudinal layout
Submucosa- DIRCT, loose Ct makes folds, meissner plexus
Muscularis externa- inner circular, Auerbach plexus, outer long
Serosa- CT and outer simple squamous et
Meissners vs Auerbach plexus
Innervation
Nerves
M- after submucosa,
A- between muscularis externa layers
Esophagus
Lumen- Strat squamous for abrasion
LP has thin walled veins
Sub has seromucous glands
Stomach
Epithelium CHANGES TO SIMPLE COLUMNAR!!! Metaplasia
Sub has NO glands
Metaplasia
When lining of et changes from Strat squamous to simple columnar!
BAD when the esophagus changes bc of acid, these cells become more prone to cancer
Parts of stomach
Cardiac
Fundic
Body
Pyloric- h pylori here that causes ulcers
Stomach function
Turns food into chyme Produces hormones and dig enzymes Produces acid HCl Tight junctions to protect from acid Mucus to protect
Little absorption of water, asp, caffeine, alcohol
Mucinogen granules
Secrete mucus in the epithelium of sim columnar
Protects cells from stomach acid
Gastric pits and glands order
pit Gland made of 3 parts Isthmus Neck Base
Isthmus
Neck
Base
Isthmus:
parietal cells- secrete HCl
Secrete GIT which tells cells to uptake vitamin B12
inhibits HCl w somatostatin and secretin to stop H+ pumping
Neck:
Parietal
Stem cells- regen of gastric cells w mitotic activity
Mucous
Base: Parietal Mucous Chief cell- pepsinogen to pepsin and lipase Neuroendocrine
Parietal cells secrete
HCl
Gastric Intrinsic Factor- tells cells to uptake B12
Acidophilic BASIC PINK
*parietal is basic pink
B12 deficiency
Pernicious anemia
Chief cells secrete
Chief cell- pepsinogen to pepsin and lipase
Base
Basophilic ACIDIC BLUE
*baso blue
Neuroendocrine cells
Base
Produce hormones and coordinate GI activity
Look like triangle
Lengths of gastric pits
Cardiac= lengths are equal
Fundic and body= short pits, long glands bc this is where gland secretion is most needed
Pyloric= large PITS, short coiled glands
*pyloric pits
Gastric artery enters
Through serosa
In mucosa vessels are
Fenestrated capillaries w sinusoids
Adjacent to gastric glands
H pylori steps
Pyloric location
Activation: Ammonia produced to increase pH
Stationary: attach to mucous cells and initiate inflam response
Colonization: detach from receptor and replicate, attach to acid containing proteins in mucous blanket of columnar cells
Regeneration of gastric cells
High acidity means a high turnover rate
Stem cells in the neck of gastric glands, constantly replace mucous cells at the surface
During injury, stem cells prolif into epithelial cells
Invaginate and form pits/glands and mucous/parietal/chief cells
Small intestine
DJI
Absorbs nutrients
Continues digestion
Intestinal structural specializations
1 degree= plicae circularis, large lump
2 degree= villi, many on one plicae
3 degree= crypts of lebrocomb, invaginations between villi
4 degree= microvilli that line villi and COL, ‘ACTIN
Small intestine cells : Goblet Enterocytes Lacteal Enteroendocrine Paneth cell
Columnar ET
Goblet cells- create glycocalyx for protection and digestive enzymes
Enterocytes= absorptive cells
Lacteal= in microvilli, absorbs lipids
Enteroendocrine- aka APUD, only acts on Ps!! To regulate pH
in duodenum chyme stimulates secretion of
1) secretin and 2)CCK
These can:
A) go to pancreases to secrete PES/bicarbonate into duodenum OR
B)stim gall bladder contraction which secrete bile into the duodenum for excretion
Paneth cell: base of crypts, defensins like lysozyme and tumor necrosis factor
Protect and nourish, RED in color
CCK vs Secretin
CCK slows down emptying by acting on pyloric sphincter
Stim bile release from gall bladder and pancreatic enzymes
Secretin stim pancreatic bicarbonate release
Enhances insulin secretion
How does digested material get to BV in lamina propria?
2 pathways
Transcellular: goes through enterocytes, USUAL
Paracellular- goes between enterocytes which requires a breach of tight junctions so they are more RARE
All digestive cellls are located at ___ of enterocytes
Apical surface
Where does most digestion occur
Lumen of small intestine
Duodenum
Jejunum
Ileum
D- brunners glands in prominent submucosa
Short/broad villi
J- nothing special, long linger like villi with lacteals, NO brunners/peyers
I- peyers patches
Short villi
Brunners glands
Duodenum submucosa
Secrete bicarbonate to neutralize chyme
Activated by parasympathetic for rest and digest
Peyers patches
Ileum submucosa
Part of GALT (GI Lymph Tissue)
Large lymphatic nodules in LP/sub mucosa
Have a germinal center w B/T cells and APC
Lined by enterocytes and M cells
M cell function
Line peyers patches around germinal center. In ILEUM
- Sample antigens by transporting antigens to the LP for APC to uptake and present
APC migrates to lymph node and present antigen to tH cells (activate B cells for AB)
Antibodies secreted into lumen - Work w plasma cells to phagocytize bacteria w IgA
GIT innervation
Extrinsic vs intrinsic
Extrinsic- CNS, controls SM contraction, segmentation, and peristalsis
1) Auerbach plexus> between circ and long layers of musc externa
PARA and SYMP
2) meissner plexus> between submucosa and and circ layer of musc externa
PARA ONLY- rest and digest
Intrinsic- AKA enteric nervous system
nerves within mucosa and musc externa!
Formed from neural crest cells
Controls digestion by changing the motility and secretion
Segmentation vs peristalsis
Both work by plexus, extrinsic innervation
Segmentation- discoordinated contractions to MIX
Peristalsis- coordinated contractions to MOVE
Large intestine aka
Colon
NO VILLI
Columnar epithelial tissue
COL
Same cell types
Musc externa has inner circ, 3 outer long ribbons of SM >TENIA COLI, suppress colon into haustra coli when contracted
HAUSTRA COLI are segments of large intestine that contract independently
Colon functions
Extract water and salts
Fecal compaction bc water goes out
Peristalsis to the rectum
Controlled by intrinsic (enteric nervous system)
Hirschprungs disease
Mutation in 2 genes causing defective migration of neural crest cells during embryogenesis
Which means ABSENCE OF MEISSNERS AND AURBACHS PLEXUS
And colon cannot innervate= mega colon
collection of fecal material means you feel like you have to poop but you can’t
Appendix
Extension of cecum first part of large intestine
Has lymph tissue in submucosa
NO villi in lumen
Filled with scar tissue and can become obstructed> appendicitis
Rectum
Thick mucosa w goblet cells Prom veins No villi Long COL Columnar
Has sphincter muscle at the end to control pooping
Anal canal
ET changes from simple columnar to STRAT SQUAMOUS for abrasion
Other than that sim to rectum
