3: Digestive System Flashcards
What are the 8 functions of the digestive system?
indigestion, mastication, secretion, absorption, waste elimination, motility, hormonal release, chemical digestion
What does the oral cavity include?
tongue, teeth, minor & major salivary glands, tonsils, lips
What is the oral cavity lined with?
oral mucosa
What are the 3 types of oral mucosa?
masticatory, lining, and specialized mucosa
What is masticatory mucosa found on?
gingiva & hard palate
What is the surface epithelium of masticatory mucosa?
keratinized (parakeratinized) stratified squamous epithelium
What do the surface cells of the parakeratinized stratifed squamous epithelium keep?
their nuclei
What is the lamina propria of the masticatory mucosa made of?
PAPILLARY LAYER: thick loose CT
- BV’s, nerves, sensory receptors, some Meissner’s corpuscles
RETICULAR LAYER: more dense CT
Where are Meissner’s corpuscles found in the oral cavity?
lamina propria of the masticatory mucosa
What is the lining mucosa of the oral cavity found on?
soft palate, underside of tongue, floor of mouth, cheeks, lips
What is the GENERAL surface epithelium of the lining mucosa of the oral cavity?
nonkeratinized stratified squamous epithelium (or -nonkeratinized)
What can OCCASIONALLY be the surface epithelium of the lining mucosa of the oral cavity?
parakeratinized stratified squamous epithelium
What kind of epithelium makes up the lips, vermillion border (reddish part)?
keratinized stratifed squamous epithelium
The areas of non-keratinized stratifed squamous epithelium are ______ than the areas of keratinized stratified squamous epithelium in the lining mucosa.
thicker
What is the lamina propria of the lining mucosa of the oral cavity made of?
loose CT w/ BV’s & nerves
What is the submucosa of the lining mucosa of the oral cavity made of?
more dense CT
Where is the submucosa of the lining mucosa found?
most places
What can the submucosa of the lining epithelium have?
minor salivary glands, sebaceous glands (mouth corners), larger BV’s amd nerves
Where is the specialized mucosa of the oral cavity found?
dorsal surface of tongue
What kind of specialized mucosa surface epithelium is found on filiform papillae?
keratinized stratified squamous
What type of specialized mucosa surface epithelium is found on all papillae except filiform papillae?
stratified squamous epithelium
What are the general functions of the specialize mucosa in the oral cavity?
move food, taste
What is the mucosa of the tongue like?
thicker dorsally; thinner and smoother posteriorly
What kind of surface epithelium is on the tongue?
specialized surface epithelium
stratified squamous epithelium (all other)
keratinized stratified squamous (filiform)
What kinds of papillae have specialized surface epitheilum?
all: filiform, fungiform, foliate, vallate (circumvallate)
What type of glands are associated with vallate papillae?
small salivary (von Ebner) glands
What is the function of von Ebner glands?
produce serous fluid to cleanse the taste buds on these papillae
Where are taste buds found?
on all papillae except FILIFORM papillae
What is the lamina propria of the tongue made of?
loose connective tissue, adipose possible
Is there submucosa of the present in the tongue?
usually yes; adipose possible
What can the submucosa of the tongue contain?
lingual salivary glands; produce serous products
What is unique about the intrinsic tongue muscles?
no external attachment
What are the 4 alternating muscles of the tongue?
superior longitudinal muscle
vertical muscles alternating w/ transverse muscles
inferior longitudinal muscle
What is the function of the intrinsic muscles?
change the tongue shape
What are the layers of the muscles outside to inside of developing teeth?
ameloblasts, enamel, dentin, predentin, odontoblast, dental papillae
What kind of cells are ameloblasts?
polarized columnar cells (secratory)
When do ameloblasts disappear?
after tooth eruption
What is the function of ameloblasts?
produce enamel
Which cells produce enamel?
ameloblasts
What substance is the hardest substance in the body?
enamel
How thick is enamel?
~2mm
What is enamel made of?
interlinked enamel rods
Can enamel be made after tooth eruption?
no
How hard is dentin?
harder than bone, softer than enamel
What does dentin contain?
thin dentinal tubules containing nerves & cell processes of odontoblasts
What is dentin produced by?
odontoblasts
What is predentin?
precursor to dentin before mineralization
What produces predentin?
odontoblasts
What are odontoblasts?
columnar cells lining the pulp cavity
Which cells survive into adulthood?
odontoblasts
What is the function of odontoblasts?
repair and produce dentin
What are odontoblasts precursors for?
dentin, predentin
What is the area of CT below odontoblasts?
dental papillae (dental pulp)
What does the dental papillae have in it?
many blood vessels and nerve
What is a potential problem with the dental pulp?
if there is an infection there is no room for expansion–> extensive inflammation
What are the 3 salivary gland names?
parotid, submandibular, sublingual
What is the largest salivary gland?
parotid gland
How much saliva does the parotid gland produce?
~30% of total
Which gland is most affected by mumps?
parotid gland
The facial nerve passes through which gland?
parotid gland
What happens to the parotid gland as we age?
it common becomes infiltrated with adipose
What is a potential problem with the dental pulp?
if there is an infection there is no room for expansion–> extensive inflammation
What are the 3 different kinds of serous products produced by the parotid gland?
salavary amylase (alpha amylase): starts carb breakdown
lipozyme (anti-bacterial)
secratory IgA
What is the largest salivary gland?
parotid gland
What can happen to the submandibular gland by midlife?
it can by infiltrated by fat
Which gland is most affected by mumps?
parotid gland
The facial nerve passes through which gland?
parotid gland
What does the parotid gland produce?
100% serous products
What are the 3 different kinds of serous products produced by the parotid gland?
salavary amylase (alpha amylase): starts carb breakdown
lipozyme (anti-bacterial)
secratory IgA
What percentage of the total salivary output does the submandibular gland produce?
~60% total output
What can happen to the submandibular gland by midlife?
it can by infiltrated by fat
What are the 2 mixed salivary glands?
submandibular, sublingual
Which gland lacks a separate serous acini?
sublingual gland
What does the submandibular gland contain?
serous demilunes
Which gland is mixed, many serous products?
submandibular
What is the sublingual gland?
smallest salivary gland ~5% total salivary output
What gland is mixed mainly mucus producing?
sublingual gland (~80%)
Where does all of the serous products of the sublingual gland come from?
the serous demilunes
Which gland lacks a separate serous acini?
sublingual gland
What does the mucosa of the gut include?
surface epithelium
lamina propria: loose CT
muscularis mucosa: smooth muscle (longitudinal)
What does the submucosa of the gut?
more dense CT
larger BV’s
SUBMUCOSAL (MEISSNER) PLEXUS
What is the function of the Meissner plexus?
influences mucosa
What id the adventitia of the gut wall?
connetive tissue along longitudinal organs
What is the muscularis externa of the gut made of?
myenteric (Auerbach) plexus
typically smooth muscle
typically fiber orientation = inner circular & outer longitudinal layers = normal pattern
Where is the myeteric (AUERBACH) plexus found?
btwn the circular and longitudinal muscle layer
What is the function of the Auerbach plexus?
influences ME
What special cells does the surface epithelium of the mucosa of the esophagus?
Langerhans cells
What is the serosa of the gut wall?
edge of simple squamous epithelium (can include some CT) serous producing (layer of peritonium)
What id the adventitia of the gut wall?
connetive tissue along longitudinal organs
What is the function of the esophagus?
transfer bolus to stomach from the oropharynx
What is the surface epithelium of the esophagus mucosa?
stratified squamous
What are Langerhans cells?
an APC (antigen presenting hormone) with some phagocytosis possible
What special cells does the surface epithelium of the mucosa of the esophagus?
Langerhans cells
What is the lamina propria of the esophagus made of?
loose areolar CT
What kind of cells can the lamina propria also contain?
esophageal cardiac glands
What is the function of esophageal cardiac glands?
produce neutral pH mucos to protect the esophageal epithelium
What is the function on the esophageal proper glands?
produce slightly acidic mucus to lubricate the movement of food
Where were esophageal cardiac cells first found?
the last inch of the esophagus near the stomach
What is the muscularis mucosae of the esophagus?
discontinuous layer of longitudinal muscle
What is the muscularis mucosae’s pattern through the esophagus?
thinner distally (by pharynx) and thicker proximally (by stomach)
What is the submucosa of the esophagus made of?
dense fibroelastic CT
What kind of glands are scattered along the length of the submucosa of the esophagus?
esophageal proper glands
What is the function on the esophageal proper glands?
produce slightly acidic mucus to lubricate the movement of food
What is the normal pattern for the muscularis externa?
inner circular and outer longitudinal layers
What is the muscularis externa of the esophagus made of?
with normal patterns
upper 1/3: all skeletal muscle
middle 1/3: mix of smooth & skeletal muscle
lower 1/3: all smooth muscle
What is the adventitia/serosa of the esophagus like?
primarily adventitia except the last 1-2” = last 1-2” (after the diaphragm)
Does pick up serosa
What are the two physiological sphincters of the esophagus?
pharyngoesophageal sphincter
gastroesophageal sphincter
Where is the pharyngoesophogeal sphincter found?
btwn oropharynx & esophogus
Where is the gastroesophogeal sphincter found?
btwn esophagus and stomach (lower esophageal sphincter)
Which sphincter of the esophagus is prone to problems due to the abrupt tissue change?
gastroesophageal sphincter
What are the characteristics of physiological sphincters?
NO thickening of circular muscle in ME
pressure gradient aids movement
(muscle contractions & gravity help)
What are the 3 functions of the stomach?
continue digestion of carbs
storage (primary fxn)
some nutrient breakdown, mostly chemical, not physical
What are gastric pits?
tiny depressions in the stomach’s surface
1 pit leads to more than one gland
What kind of surface epithelium is in the mucosa of the stomach?
simple columnar
What are the functions of the surface mucous (lining) cells of the stomach?
produce thick visable mucus (adheres to the surface)
secretes bicarbonate ions
Where are the regenerative cells of the stomach found?
at the bases of pits
What is the lamina propria like in the stomach?
loose, vascular ct present in small amounts between glands
What makes up the muscularis mucosa of the stomach?
smooth muscle layer that is often arranged in 3 layers
THERE AND WELL FORMED
What are the 3 smooth muscle layers of the stomach arranged like?
inner circular
outer longitudinal
outermost circular/oblique
What is the submucosa of the stomach like?
highly vascular
contains: atriovenous anastomosis & Submucosal (Meissner’s) Plexus
What is the function of the AVA in the stomach?
shut down activity and secretion FAST
Where is the submucosal (Meissner’s) plexus in the stomach?
next to the inner circular layer of the muscle
What is the function of the Meissner’s Plexus?
to influence the mucosa (secretion, BF, and limited muscle contractions)
What layer of the stomach are the Meissner’s Plexus and AVA’s found?
in the submucosa
What is the muscularis externa of the stomach like?
three muscle layers are possible (especially between cardiac region and greater curvature; all smooth muscle
How are the 3 layers of the muscularis externa set up in the stomach?
innermost oblique
middle circular well developed
outer longitudinal
Can a normal muscle pattern show up in the muscularis externa of the stomach?
yes, other than in the cardiac and greater curvature
Where is the Myenteric (Auerbach’s) Plexus found in the stomach?
in the muscularis externa, between the circular and longitudinal layers of muscle
What is the function of the myeteric (Auerbach’s) plexus?
to stimulate the muscularis externa
What layers of the serosa are found in the muscularis externa of the stomach?
all
What are the three regions of the stomach?
cardiac, gastric (includes body & fundus), pyloric part
What are the pits of the cardiac glands of the stomach like?
shorter pits wich lead to cardiac glands with a coiled base
What cells are found in the cardiac region of the stomach?
primarily surface mucous, some neck mucous, a few DNES and parietal cells
NO CHEIF CELLS
Describe the cardiac region of the stomach….
smallest region & obtain much mucus
What kind of cells are found in the isthmus area of the gastric glands?
surface mucus & DNES cells
What kind of cells are found in the neck area of the gastric glands?
parietal & neck mucus cells
What kind of cells are found in the base area of the gastric glands?
cheif mucus cells
What do the surface mucus cells of the isthmus produce?
thick visable mucus that traps bicarbonate ions
What is the function of the surface mucus cells of the isthmus?
protect mucosa from auto-digestion and the rougher components of chyme
How many DNES (enteroendocrine) cells are found in the isthmus?
a few
What do the DNES type D cells produce?
somatostatin (inhibits release of hormones by near by DNES cells & HCl release)
What do the DNES type EC cells produce?
serotonin & substance P (increases gut motility)
What do the DNES type G cells produce?
gastrin
What do the DNES type G cells stimulate?
HCl adn pepsinogen secretion, gastric motility, and regenerative cells in body of the stomach
What is another name for the DNES cells of the gastric gland?
enteroendocrine
What kinds of cells are found in the neck of the gastric gland?
neck mucous cells, regenerative cells, parietal (oxyntic) cells
What do the neck mucous cells do?
produce a soluble SLIGHTLY ACIDIC mucus
fxn: lubricate gastric contents
What do the regenerative cells of the neck of the gastric glands do?
replace all cell types
What do the parietal (oxyntic) cells of the gastric glands do?
produce: very strong HCl, Gastric Intrinsic Factor (necessary for vit. B12 absorption)
How can chronic gastritis lead to pernicious anemia?
low # of parietal cells can lead to low amounts of intrinsic factor, which will decrease vit. B12 absorption which is necessary for RBC maturation
LOW # RBC’S
What DNES cells are found in the neck area of the gastric glands?
DNES: D, EC, G
What types of cells are found in the Base area of the gastric glands?
cheif (zymogenic) cells, parietal cells, DNES cells
What do the chief (zymogenic) cells produce?
Primarily pepsinogen (proenzyme breaking down protein & fat) some gastric lipase to break down fats
Are there parietal cells in the base of gastric glands?
yes, some
What DNES cells are found in the base of gastric glands?
DNES: D, EC, G
What is the pyloric region characterized by?
deeper pits, very short, twisted and branched pyloric glands
What cells are found in the pyloric region of the gastric glands?
primarily surface mucus, DNES and parietal cells; some neck mucous cells that also produce some lysozyme
What is the pyloric sphincter?
ANATOMICAL SPHINCTER between the pylorus of the stomach and the duodenum
What are characteristics of an anatomical sphincter?
1) well developed inner circular layer of muscle in the ME
2) inner circular layer in ME can be INDEPENDANTLY controlled
What are the 3 general functions of th esmall intestines?
digestion, absorption of nutrients, produce intestinal hormones (use DNES cells)
What are the 3 surface area increasers in the small intestines?
plicae circulares, villi, microvilli
What is another name for the plicae circulares?
valves of Kerckring
What are the plicae circulares?
permanent folds affecting the mucosa and submucosa; found in the duodenum, jejunum, and proximal ileum
Where are the microvilli found in the small intestine?
on the luminal cell surface
What is the surface epithelium of the intestines?
simple columnar
What cell types are found in the mucosa of the intestines?
surface absorptive cells, goblet cells, DNES cells, regenerative cells, paneth cells, M (microfold cells)
What are surface absorptive cells of the intestines?
ENTEROCYTES containing microvilli
What do surface absorptive cells of the intestines do?
absorb water and nutrients
terminal digestion in glycocalyx: cells produce the enzymes and absorb the monosaccharides and peptides created
Where are goblet cells found in the intestines?
fewest in the duodenum and most in ileum
How many types of DNES cells are found in the small intestines?
~11 types
What are the three main types of DNES cells found in the small intestines?
types I, K, S
What do the type I DNES cells of the small intestines do?
produces cholecystokinin (CCK): stimulates bile release from the gallbladder, and pancreatic secretion of enzymes from serous acini
What do the type K DNES cells of the small intestines do?
produces GIP (gastric inhibitory peptide): inhibits HCl release
What do the type S DNES cells of the small intestines do?
produces secretin: stimulates secretion of bicarbonate from the pancreatic ducts; also inhibits HCl release and the movement of chyme into the small intestines
Where are the regenerative cells found in the small intestines?
found in the crypts
Where are the paneth cells of the small intestines found?
at the bases of the crypts (intestinal glands)
What do the paneth cells of the small intestine produce?
lysozyme
Where are the M cells of the small intestine found?
aka: microfold cells
found in the ILEUM epithelium over Peyer’s Patches
What is the cell structure of the M cells of the small intestine?
large intracellular pockets; sample foreign antigens from the gut lumen & transfer antigens to lymphocytes and dendritic cells
What is the function of the M cells of the small intestines?
promote humoral immunity
results in plasma cells producing IgA which is then transferred to epithelial cells and released into gut lumen
important in maintaining appropriate gut flora
What is the lamina propria of the small intestine made of?
loose areolar CT
What is found with in the villus core of the lamina propria of the small intestine?
lacteals, vascular components, some longitudinal smooth muscle
What are lacteals?
they are lymphatic capillaries functioning in lipid absorption
What are the vascular components of the lamina propria?
smaller blood vessels
What is the importance of the longitudinal muscle?
if irritated then the muscle contracts and the villi will shorten; can lead to nutrient deficiencies if irritation is prolonged.
What is another name for the borders of the intestinal glands?
crypts of lieberkuhn
What is the muscularis mucosa of the small intestines like?
thin but present; connects to smooth muscle in villi
What is the general setup of the submucosa of the small intestine?
dense fibroelastic CT
very vascular: large blood vessels
What is special about the submucosa of the duodenum?
Duodenal (Brunner) Glands: seromucous glands
What do the duodenal (brunner) glands produce?
Primary product: alkaline mucus which importantly functions to neutralize chyme
Urogastrone: inhibits HCl secretion and increase mitosis of epithelial cells
What structures are significant in the jejunum?
no significant structures
What structures are significant in the ileum?
Peyer’s Patches: groups of regularly occurring large lymph nodules
Submucosal (Meissner’s) Plexus: parasympathetic innervation
Where is the Submucosal (Meissner’s) Plexus found?
close to circular muscle in the ME of the ileum
influences the mucosa
What is the muscularis externa of the small intestine like?
normal pattern: inner circular, outer longitudinal
What is significant in the ME of the small intestines?
Myenteric (Auerbach) Plexus: stimulates the ME for peristalsis
Where is the Myenteric (Auerbach) plexus found?
between the circular and longitudinal layers of the ME of the small intestines
Where is serosa found in the small intestines?
all of the jejunum and ileum; first and last 1-2 cm of duodenum
Where is adventitia found in the small intestines?
vertical (ascending) portion of duodenum
What type of sphincter is the ileocecal valve and where is it found?
physiological & anatomical sphincter
between the ileum & cecum of the colon
What is the appendix?
VERMIFORM APPENDIX
blind pouch on the right, extending from the cecum
What is the surface epithelium of the appendix?
simple columnar
w/: surface absorpptive cells, goblets, regenerative cells, and DNES cells
Is there a LP in the appendix?
yes
Describe the muscularis mucosae of the appendix?
poorly developed
What other stuff is significant in the appendix?
short crypts
NO villi
NO to infrequent paneth cells
What is the submucosa like in the appendix?
thick layer with large blood vessels
What are the notable features of the submucosa of the appendix?
numerous lymph nodules
What is the patterning of the muscularis externa of the appendix?
normal patterning but THIN
Is there serosa present in the appendix?
yes
What is the function of the appendix?
humoral immunity
reservoir for good bacteria
What are the general functions of the colon (large intestine)?
primary function: absorption of water
compaction, lubrication, and elimination of feces
production of some vitamins (riboflavin, thiamin, vit. K & B12) as bacterial by-products
What is the surface epithelium of the colon?
simple columnar
w/: many goblets and surface absorptive cells (colonocytes), some regenerative cells and very few DNES cells
What is the LP of the colon like?
typical and has intestinal glands (crypts)
What is the muscularis mucosae like in the colon?
typical
What does the mucosa of the colon lack?
villi and paneth cells
What is the submucosa of the colon like?
typical
What is the patterning of the muscularis externa of the colon?
not normal: outer longitudinal muscle is gathered into bands called teniae coli and is discontinuous
What are the teniae coli of the colon made of?
longitudianl muscle bands of the ME
What are haustra?
constant tonus of teniae coli resulting in sacculations
Where is the adventitia found in the colon?
ascending and descending colon
Where is the serosa found in the colon?
transverse and sigmoid colon
What is the general function of the rectum?
store fecal matter
What is the surface epithelium of the rectum?
simple columnar
The rectum and colon are very similar in what features?
straight intestinal glands w/ goblet cells
What makes the colon and rectum different?
The rectum has:
Transverse rectal folds
No teniae coli in ME
has adventitia
What are the transverse rectal fold of the rectum?
significant luminal wall folds
What is the longitudinal wall muscle of the rectum like?
more complete (no teniae coli in ME)
What is the surface epithelium of the anal canal?
transitions from simple columnar to STRATIFIED SQUAMOUS
What glands are found in the anal canal?
anal glands and circumanal glands
What are the anal glands?
extend into the SM adn produce mucus to lubricate lumen
What are the circumanal glands?
APOCRINE glands in the skin surrounding the anus
What does the mucosa and submucosa of the anal canal have?
longitudinal folds creating ANAL COLUMNS
What makes the anal canal prone to hemoroids?
the submucosa has bloods vessels that are prone to irritation
What is significant about the muscularis mucosa in the anal canal?
it disappears
What is the internal anal sphincter?
a thick circular layer of smooth muscle w/i the ME
What is the external anal sphincter?
a striated (voluntary) muscle from the pelvic floor
What is the luminal wall covering of the anal canal?
adventitia
What are the two general causes of peptic ulcer disease?
insufficient protection from HCl and pepsin
- damaged mucus coat
- too much HCl and pepsin
Helicobacter pylori
With a decreased luminal acidity, how fast can damaged tissues repair themselves?
1-2 months
What are some factors that delay healing of peptic ulcer disease?
smoking, alcohol, caffeine, calcium, asprin
also stress and spicy foods can aggrivate an ulcer but not cause it
What causes gastroesophageal (esophageal) reflux?
stomach chyme backing up into the lower esophagus
What are possible contributing factors to gastroesophageal reflux?
chronic gastritis (inflammed stomach lining), hiatal hernia, pregnancy, incompetent lower esophageal sphincter, subluxations (problems w/ myenteric plexus?)
What are some ways to reduce reflux?
keep a food diary of food, spices and drinks with episodes
limit amount of food eaten at one time
do not eat less than 3 hours before bed
What are some problem foods with gastroesophageal reflux?
spices (pepper, garlic, onion, peppermint, cinnamon), acidic foods, acidic beverages (fruit juices, carbonated drinks, coffee, tea), fatty foods, alcohol
What is Barrett’s Esophagus?
stratifed squamous epithelium is replaced by mucus secreting simple columnar epithelium in lower (proximal esophagus)
Is Barrett’s esophagus acute or chronic?
metaplasia due to a chronic problem
PRE-CANCEROUS CONDITION
