Histo Test 2- Digestive

Front 1

General structure of the digestive system

Back 1

consists of alimentary canal (tongue, teeth, salivary glands, pancreas, liver, gallbladder)
lumen is physically and functionally external part of the body

Front 2

General Function of the alimentary mucosa

Back 2

secretion
absorption
barrier
immune protection

Front 3

Extramural organs

Back 3

those organs that lie outside of the alimentary canal

Front 4

Oral cavity regions

Back 4

Vestibule: space b/t lips, cheeks, and teeth
Oral Cavity Proper: lies behind teeth

Front 5

Salivary glands of the Oral Cavity

Back 5

Parotid, submandibular, sublingual

Front 6

Mucosas of the Oral Cavity

Back 6

Masticatory mucosa: stratified squamous dry, gums and hard palate
Lining Mucosa: stratified squamous wet, lips, cheeks, floor of mouth, inferior tongue (covers muscle, bone, glands)
Specialized Mucosa: only on dorsal surface of tongue, associated w/ taste on papillae and taste buds

Front 7

Tongue Structure

Back 7

extrinsic and intrinsic striated muscle arranged in bundles that run in 3 RIGHT ANGLES
stratified squamous
divided into anterior 2/3 and posterior 1/3 by v-shaped Sulcus Terminalis

Front 8

Mucosa of the tongue

Back 8

Lingual papillae formed from mucosa on dorsal surface, composed of CT core covered by stratified squamous
4 types: filiform, fungiform, circumvallate, foliate

Front 9

Filiform Papillae

Back 9

smallest and most numerous
conical, elongated tipped backwards
NO TASTE BUDS
stratified squamous dry
Function: increase friction b/t food and tongue
Location: anterior dorsal surface in parallel arms

Front 10

Fungiform Papillae

Back 10

Mushroom shaped, found within filiform
more numerous towards tip of tongue
taste buds located on dorsal surface

Front 11

Circumvallate Papillae

Back 11

8-12, dome shaped structures surrounded by moat-like invagination
taste buds found on lateral surface of walls
anterior to sulcus terminalis
serous lingual salivary glands (von Ebner's) empty into base of moat

Front 12

Foliate Papillae

Back 12

lateral edge of tongue, in parallel ridges separated by clefts
lots of taste buds facing walls of neighboring papillae
degenerate by age 2
serous glands into clefts

Front 13

Taste Bud structure

Back 13

oval shaped, pale-staining that extend through thickness of epithelium
Taste pore opening at apex of taste bud
3 cell types: Neuroepithelial, Sustentacular (Support), Basal

Front 14

Neuroepithelial Cells

Back 14

round, pale staining
extends from basal lamina to taste pore, contains taste receptors
tight junctions w/ neighboring cells
synapse at base w/ afferent sensory neurons of CN VII, IX, and X

Front 15

Support Cells (sustentacular)

Back 15

DO NOT synapse w/ nerve cells
immature neuroepithelial cells
elongated cells, slightly darker staining

Front 16

Basal Cell

Back 16

small, round cells found near basal region of taste bud
stem cells for support and neuroepithelial cells

Front 17

Taste Detection

Back 17

chemical sensation on taste receptors--> initiates signal in neuroepithelial cells--> ion channels activate AP

Front 18

5 stimuli of taste

Back 18

sweet, salty, bitter, sour, unami (glutamate, aspartate, and MSG)
Facial Nerve (CN VII) carries all taste
Glossopharyngeal (CN IX) carries sweet and bitter

Front 19

GI tract structure

Back 19

hollow tube from esophagus to anus
4 layers:
Mucosa
Submucosa
Muscularis Externa
Serous/Adventitia

Front 20

Mucosa

Back 20

3 layers:
Epithelial lining: varies by region
Lamina Propria: found lining epithelium
Muscularis Mucosa: 2 layers SM underneath lamina propria, contracts to change surface area for secretion/absorption

Front 21

Submucosa

Back 21

dense irregular CT w/ blood vessels, lymphatics, and nerve
Glands in esophagus and small intestine (duodenum)
Name glands submucosal glands of the esophagus/small intestine

Front 22

Muscularis Externa

Back 22

2 layers Muscle (skeletal in upper 1/3 and anal sphincter)
Inner Circular Layer: contraction reduces diameter of lumen
Outer Longitudinal Layer: contraction shortens tube

Front 23

Serosa/Adventitia

Back 23

Serosa: serous membrane of simple squamous epithelium and small amount of CT
Adventitia: only CT, found where wall of tube is attached or fixed to adjoining structure

Front 24

Barrier Function of Mucosa

Back 24

separates external environment from tissue and organs of body
prevents antigen, pathogen entry

Front 25

Absorption Function of Mucosa

Back 25

happens thru projections of mucosa/submucosa into GI lumen
Plicae: submucosal folds in small intestine
Villi: mucosal projections over entire surface area of small intestine, principal site of absorption
MV: intestinal absorptive cells coated by Glycocalyx--> localization of enzymes for final step of digestion

Front 26

Secretion Function of Mucosa

Back 26

Mucus secretion: lubrication, buffering of tract lining
Digestive aids: enzymes, HCL, peptide hormones
Antibodies: from underlying CT

Front 27

Glands of GI tract

Back 27

Mucosal: extend into lamina propria
Submucosal: deliver secretions directly into lumen of mucosal glands or ducts that pass to surface
Extramural: outside of digestive tract and deliver secretions via ducts that pass through intestine to enter lumen (liver, pancreas)

Front 28

Lamina Propria Glands

Back 28

Mucosal glands extend into lamina propria throughout length of alimentary canal
Esophagus and anal canal contain mucus-secreting cells

Front 29

Lamina Propria Vessels

Back 29

products of digestion diffuse into blood and are absorbed
Blood vessels are fenestrated and absorb most metabolites
Lymphatic vessels collect absorbed lipids and proteins

Front 30

Lamina Propria Lymphatic Tissue

Back 30

Immunological barrier
Diffuse Lymphatic Tissue
Nodules (Peter's patches in Ilium)
Eosinophils, Macrophages, and neurtrophils

Front 31

Muscularis Mucosa

Back 31

2 layers of SM, inner circular and outer longitudinal
contraction facilitates absorption and secretion
occurs independently of peristaltic movement of GI

Front 32

Submucosa

Back 32

dense irregular CT
Meissner's Plexus-regulates secretion and blood flow
Glands present in esophagus and Duodenum

Front 33

Meissner's Plexus

Back 33

visceral sensory fibers (sympathetic)
parasympathetic ganglia- excitatory on GI functions

Front 34

Enteric nervous system

Back 34

preganglionic and postganglionic parasympathetic fibers
responsible for innervating SM
function independent of CNS

Front 35

Muscularis Externa

Back 35

2 thick layers of SM
Inner Circular: contraction compresses and mixes luminal contents, forms sphincters
Outer Longitudinal: contraction propels luminal contents by shortening tube

Front 36

Pharyngoesophageal Sphincter

Back 36

prevents entry of air, prevents gastric reflux by creating pressure difference b/t esophagus and stomach

Front 37

Pyloric Sphincter

Back 37

b/t pylorus and duodenum, controls release of chime into duodenum

Front 38

Ileocecal Sphincter

Back 38

b/t small and large intestine, prevents reflux of colon (helpful due to large amount of bacteria there)

Front 39

Internal Anal Sphincter

Back 39

surrounds anal canal, prevents feces movement from anal canal to undestended rectum

Front 40

Myenteric (Auerbach's) plexus

Back 40

found b/t muscularis mucosa SM layers, contains ganglia of parasympathetic neurons and enteric system neurons
control motility of GI SM

Front 41

Peristalsis

Back 41

Waves of contraction that constrict and shorten tube, moving contents through
controlled by enteric system

Front 42

Muscularis Mucosa Variations

Back 42

proximal esophagus and anal sphincter contain Striated Muscle
Stomach: 3 obliquely oriented layer of SM deep to circular layer
Large Intestine: longitudinal SM thickened to form 3 longitudinal bands called "teniae coli"

Front 43

Serosa

Back 43

equivalent to visceral peritoneum
continuous w/ mesentery, abdominal cavity lining
contains large blood and lymphatic vessels

Front 44

Adventitia

Back 44

CT
thoracic esophagus, duodenum, ascending/descending colon, rectum, anal canal

Front 45

Esophagus

Back 45

fixed muscular tube, delivers food and liquids from pharynx to stomach
LM: lumen normally collapsed w/ a branched appearance due to longitudinal folds

Front 46

Esophagus Mucosa

Back 46

stratified squamous wet (protection)
normal lamina propria, except esophageal cardiac glands secrete neutral mucus to lubricate/protect walls

Front 47

Submucosa of Esophagus

Back 47

dense irregular CT
Meissner's Plexus present
Submucosal glands of esophagus
Diffuse lymphatic tissue and lymphatic nodules present

Front 48

Muscularis Externa of Esophagus

Back 48

Unique parts:
upper 1/3: striated muscle
middle 1/3: mix of striated and SM
lower 1/3: contains only SM

Front 49

Innervation of Esophagus

Back 49

Striated muscle of upper 1/3 innervated by vagus (CN X)
SM innervated by visceral motor neurons of vagus that synapse w/ postsynaptic neurons