Test 4 - Digestive Flashcards
Generally, what tissue types can be found in the main layers?
- mucosa: stratified squamous epithelium with goblet cells, lamina propria (loose and dense irr. CT), muscularis mucosa (smooth muscle)
- submucosa: dense irregular CT
- muscularis externa: smooth muscle (2 layers: circular muscle and longitudinal muscle)
- adventitia: serous membrane + CT (more adipose/touches organ)
- serosa: serous membrane + CT (touches body cavity/thinner)
What is a specialization located in the tonsils?
lymph nodules
What is the function of the tonsils?
initial response to protect against pathogens
What is parakeratinized epithelium?
cells filled with keratin but don’t lose nucleus and are incompletely keratinized (doesn’t stain as intensely with eosin)
Where is parakeratinized epithelium found?
in the masticatory mucosa lining of the oral cavity
How is the lining of the oral cavity different than integument when it comes to histology?
- it has parakeratinized epithelium
- only has 3 layers (stratum basale/stratum spinosum/stratum superficial)
How would you describe the lips on the facial region versus inside the mouth?
the lips closer to the facial region have more keratinization, which decreases as it goes further inside the mouth
from outside:
keratinized -> parakeratinized -> no keratinization
What is specialized about the mucosal layer of the tongue?
specializations are only on the dorsal surface and has papillae in different area of the tongue
What are the 4 types of papillae?
- circumvallate (back)
- foliate (side)
- fungiform (middle)
- filiform (texture & friction)
Do all papillae on the tongue have taste buds?
No, only the foliate and circumvallate have taste buds
Is taste perception specific to certain regions of the tongue?
No, taste perception is not just for specific regions of the tongue. Papillae have taste buds which contain multiple TRCs that are specific to a certain taste. In other words, taste perception is specific to gustatory cells/TRCs of taste buds and not regions of the tongue
Describe histological and/or physiological features of the tongue, mouth, etc. that assist with taste perception.
The papillae (circumvallate and foliate) have taste buds, which contain taste receptor cells. Moats around circumvallate papillae help trap in tastants from saliva where they enter into the taste bud via microvilli at the taste pore. There are 2 different types of gustatory cells: GPCRS (bitter, sweet, umami) and ion channels (sour, salty).
Which cell secretes enamel?
ameloblasts
What is enamel made up of?
hydroxyapatite (hardest substance in the body)(ectodermal epithelium)
What is the function of enamel?
protect tooth from wear and tear
Which cell secretes cementum?
cementocytes
What is cementum made up of?
bone-like, but avascular (has lacunae and canaliculi)
What is the function of cementum?
helps root tooth into jawbone
Which cell secretes dentin?
odontoblasts
What is dentin made up of?
calcified & hydroxyapatite (mesodermal epithelium)
What is the function of dentin?
hard bulk of tooth
What is gingiva?
masticatory mucosa surrounding neck of tooth (gums)
What is the periodontium?
all tissues attaching tooth to jaw bone
What is the function of the periodontium (4)
- tooth attachment
- tooth support
- bone remodeling
- nutrition of adjacent structures
What issues might arise if someone did not secrete much saliva?
- trouble swallowing
- dental caries
- trouble breaking down carbohydrates
Compare and contrast the secretions of the 3 major salivary glands?
- parotid (all serous)
- submandibular - mixed (mostly serous)
- sublingual - mixed (mostly mucous)
In a mixed gland, describe the setup of the serous and mucous cells.
The mucous doesn’t stain well since it is made up of sugars, but serous secretion will stain darker.
Describe the flow of saliva from the secreting cells to the mouth cavity with changes in epithelium
acinus (simple cuboidal) -> intercalated duct (tall simple cuboidal) -> striated duct (simple columnar) -> excretory duct (stratified cuboidal)
Describe a sphincter
specialization of the muscularis externa that close lumen so things don’t go backwards in the alimentary canal
What type of tissue makes up a sphincter?
smooth muscle tissue
What are the 4 sphincters and their functions?
- pharyngoesophageal: prevents entry of air into esophagus
- pyloric: controls release of chime
- ileocecal valve: prevents reflex of colon contents into small intestine
- internal anal: prevents passage of feces into anal canal
What type of epithelium is in the mucosa of the esophagus?
stratified squamous epithelium (has glands)