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241 Cards in this Set

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2 mechanisms by which food is digested
mechanically and chemically
In digestive tract, compact organs and the lining epithelium of tubular organs have what embryological origin?
what does the identification of a submucosa indicate?
an alimentary canal tubular organ
four layers of the alimentary canal:
mucosa, submucosa, muscularis, and adventitia
what is the mucosal layer composed of (in order)?
lining epithelium, lamina propria, and muscularis mucosae (2 layers)
lamina propria
loose c.t layer with numerous reticular fibers in mucosa layer of alimentary canal. Also has GALT and is richly vascularized
What are the two types of characteristic epithelium in the alimentary canal mucosa?
simple columnar or stratified squamous non-keratinized
What type of ct is in the submucosa?
loose to moderatly dense irregular fibroelastic ct. (allows STRETCH) and type 1 collagen predominates
Where in the alimnetary canal does the submucosa contain glands, and what kind are they?
esophagus and duodenum; simple branched tubular glands
submucosal plexus of meissner
component of the enteric nervous system that controls secretory activity of glands and has a sensory component that communicates with the myenteric plexus. Has parasympathetic synapses
myenteric plexus of Auerbach
component of enteric nervous system between circular and longitudinal layers of muscle in the muscularis externa responsible of gut motility
what is responsible for peristalsis
2 muscle layers- inner circular and outer longitudinal
what is adventitia surrounded by mesothelium called?
what is the difference between intraperitoneal and retroperitoneal in regards to the serosa?
intraperitoneal organs are covered in a fold of serosa and retroperitoneal organs are behind the serosa
what supports the nerve fibers of the enteric nervous system>
glia that resemble astrocyes that wrap entire bundles of axons
interstitial cells of Cajal (ICC)
cells in the gut that are thought to act as pacemakers, establishing the rhythm of bowel contractions through their influence on electrical slow-wave activity
what initiates the peristaltic reflex?
APUD cells and the serotonin they secrete act as a mediator to excite the mucosal afferent nerves
what neurotransmitters do the synapses proximal to the bolus use?
excitatory neurotransmitters: acetylcholine and substance P
what happens distal to the bolus?
inner circular layer of muscle relaxes by inhibitory neurotransmitters from interneurons, VIP (vasoactive intestinal peptide) and NO.
How do GVE neurons affect peristalis?
parasympathetics increase and sympathetics decrease peristalic activity
what do sensory components of the gut convey?
luminal contents (lipids v carbs, etc), muscular status (stretch) and secretory status of the gut
Parasympathetic innervation in the gut:
increases peristalis, inhibits sphincter muscles, and triggers secretory activity
From what nerve does the gu receive parasympathetic innervation?
vagus, and sacral outflow for the descending colon and rectum
Sympathetic innervation in the gut:
controls bloodflow, decreases peristalsis and activates sphincter muscles
From what nerve does the gu receive sympathetic innervation?
splanchnic nerves
what are the three types of oral mucosa?
lining mucosa, masticatory mucosa, and specialized mucosa
what type of tissue is the lining mucosa?
stratified squamous nonkeratinized
what type of tissue is the masticatory mucosa?
stratified squamous parakeratinized
what type of tissue is the specialized mucosa?
stratified squamous nonkeratinized
what makes up the masticatory mucosa?
gingiva and hard palate
what forms the posterior boundary of the oral cavity?
palatoglossal folds
vermilion border
pink translucent area of the lips separating the external and internal aspect of the lips. Lightly keratinized and free of sweat and sebaceous glands, and the greatest number of sensory endings.
sulcus terminalis
v-shaped groove that separates the body and the root
what 2 groups can the tongue muscles be divided into?
extrinsic and intrinsic
Is there a submucosa layer in the tongue?
not on the dorsum side
where are the lingual tonsils?
dorsal curface of the posterior one third of the tongue
3 types of lingual papillae
filiform, fungiform, and vallate
what type of epithelium make filiform papillae?
stratified squamous parakeratinized
function of filliform papillae
increase friction btwn tongue and food making it easier for the tongue to move food in the oral cavity
what innervates the tactile receptors of the filliform papillae?
trigeminal nerve (V)
what type of epithelium make fungiform papillae?
stratified squamous nonkeratinized
what is on the upper surface of fungiform papillae?
5 taste buds
which is the largest ligual papillae?
vallate papilae
form an inverted v shaped row proximal to the sulcus terminalus
what washes chemical stimuli from the taste buds allowing new tastes to be sensed?
von Ebner's glands empty into the crypt of vallate papillae
where does lipid digestion begin?
on the vallate papillae in the oral cavity, by lingual lipase
Where can taste buds be found?
on some fungiform and all vallate papillae; on soft palate, pharynx and larynx; on the epiglottis of children
reduced ability to smell
type IV cells or basal cells
gustatory receptor cells that are the unipotential stem cells that regenerate the other cells of the taste buds
what is the cell surface specialization of type I, II, and III gustatory receptor cells
microvilli that extend to the taste pore
what are the five primary tastes?
salty, sour, sweet, bitter and umami (meaty or savory)
What type of receptors are on each of the primary taste modalities?
salty: Na+ ion channels; sour: H+ ion channels; sweet: sweet receptor G-protein; bitter: G-protein gustducin; umami: G-protein
which is more sensitive olfaction or taste?
what nerve innervates vallate papilla taste cells?
what nerve innervates fungiform papilla taste cells?
how many adult permanent teeth do we have and what is their breakdown based on location, shape and function?
32 secondary teeth comprise permanent dentition; 8 incisors, 4 canines; 8 premolars; and 12 molars
how many teeth are in the primary dentition?
special hard ct derived from mesenchym originating from neural crest
what is the only part of the tooth derived from ectoderm?
what is the root of a tooth covered by? And what is its embryological origin?
cementum; mesoderm
how is enamel different from dentin and cementum?
lacks collagen as its main organic component
dental pulp
soft tissue in the middle of the tooth composed of vascular loose ct and lined by odontoblasts
cells responsible of producing dentin that line the pulp cavity
peridontal ligament
dense fibrous ct with srong bundles of collagen fibers that span the gap between the cementum and the bony wall of the tooth socket. Anchors the tooth in position
what acts as a shock absorber during chewing?
peridontal ligament
bony socket in which the tooth is suspended by fibers of the PDL, continuations of the maxilla and mandible
what type of tissue is the gingiva?
stratified squamous parakeratinized
gingival sulcus
where the gingiva borders the tooth, it dips down to form this shallow ring-like groove
how does dentin grow?
produced by appositional growth mechanism of the odontoblasts on the inner border only (line the pulp cavity), and can be laid down rapidly in response to tooth decay and damage
when is enamel produced?
prior to tooth eruption by ectoderm-derived ameloblasts
ectoderm derived cells that produce the acellular enamel prior to tooth eruption, located at the periphery of the tooth
can new enamel be formed throughout life?
can new dentin be formed throughout life?
mesodermally derived cells that lie within lacunae and form the cementum that covers the dentin of the root of a tooth
what is the hard tissue into which collagen fibers of the PDL are anchored?
can new cementum be formed throughout life?
what tissue forms the ligual side of oral mucosa of the hard palate?
stratified squamous parakeratinized
what is the superior side of the hard palate?
respiratory mucosa
what is the core of the soft palate made of?
skeletal muscle
what is the lingual mucosa of the softpalate tissue?
stratified squamous nonkeratinized
what is the most posterior extension of the soft palate
what are the three cell types of the secretory units of salivary glands?
serous, mucous, and myoepithelial
what is the embryological origin of the salivary glands?
parotid: ectoderm; submandibular and sublingual: endoderm;
what type of secretory cells do the salivary glands specifically contain?
parotid: serous only; submandibular: 80% serous, 20% mucous; sublingual: 60% mucous, 40% serous
what are the gland types of the salivary glands?
parotid: branched acinar; submandibular: branched tubuloacinar; sublingual: branched tubuloalveolar
which salivary gland produces the majority of the saliva?
what is the invervation of the salivary glands?
Parotid: CN IX; Submandibular and sublingual: CN VII
stenson's duct
main duct of the parotid gland
wharton's duct
main duct of the submandibular glands
ducts of rivinus
terminal ducts of the sublingual gland
what is the parasympathetic effect on saliva?
increased secretions, more watery
what is the sympathetic effect on saliva?
moderately increased viscous secretion
what is secondary saliva?
saliva that becomes hypotonic under the influence of aldosterone because Na is reabsorbed in the striated ducts
what are the 4 functions of saliva?
moistens, cleanses and lubricates the oral cavity; salivary amylase begins carb digestion; aids in taste; antibacterial activity
breaks down cell walls of bacteria
what tissue lines the oropharynx and the laryngopharynx?
stratified squamous nonkeratinized
what tissue lines the esophagus?
stratified squamous nonkeratinized
what cells are interspersed in the epithelium of the esophagus?
Langerhans cells
function of Langerhans cells
phagocytose and degrade antigens into epitopes, synthesize and attach MHCII molecules to epitopes and complex migrates to PM, then cells migrate to lymph nodes and present to lymphocytes
why is the muscularis mucosae of the esophagus unusual?
only single layer of longitudinal muscle that create permanent folds
What are the spincters of the esophagus
towo physiological sphincters, the pharyngoesophageal and gastroesophageal which prevent reflux
what is the change in epithelium between the esophagus and the stomach?
stratified squamous nonkeratinized to simple columnar
the major longitudinal folds of the stomach when the organ is contracted
does the stomach have goblet cells?
what protects the stomach from autodigestion?
neutral mucus product of the simple columnar surface lining cells (the epithelial sheet) or surface mucus epithelial cells
where are gastric glands located?
lamina propria
what are the 'ducts' of the gastric glands?
no true ducts, instead an invagination of the surface line the gastric pits with surface mucus epithelial cells
cardiac glands
coiled glands in the lamina propria of the cardiac region of the stomach that produce mucus; the length of the pit equals the length of the secretory unit
pyloric glands
coiled glands in the lamina propria of the pyloric region of the stomach that produce mucus, lysozyme and hormones; the length of the pit equals the length of the secretory unit
fundic glands
not coiled glands in the lamina propria of the body and fundus of the stomach with three regions: the isthmus, neck and base
what are the 5 cell types of fundic glands?
pluripotential stem, mucous neck, parietal, chief and DNES (APUD) cells
where are pluripotential stem cells found in the stomach?
among the mucous neck cells in the neck region of the fundic glands
what stimulate pluripotential stem cells in the stomach
APUD cell hormone gastrin and epidermal growth factor
where are parietal cells found?
predominate in the neck and base of the fundic gland of the stomach
what is the cell surface specialization of parietal cells of the stomach?
invaginations on their apical surface are lined with microvilli = intracellular secretory canaliculus
what happens to the number of microvilli and the amount of tubulovesicular system during active HCL production
microvilli increase, and amount of tubulovesicular system decreases
carbonic anhydrase
catalyes H2CO3 to dissociate into H+ and HCO3- which leads to production of H+ in the cytoplasm of parietal cells
How is HCl formed in the fundic glands of the stomach?
H+ produced from carbon dioxide by carbonic anhydrase and Cl- are both transpported or exchanged from the cytoplasm to the lumen of the canaliculus to form HCL
Function of HCl in Stomach:
breaks down food material and activates the proenzyme pepsinogen to become pepsin
what is the effect of gastrin and histamine on acid production in the stomach?
positive; gastrin and histamine from APUD cells have a positive effect- stimulate acid production and release
what is the effect of ACh and parasympathetics on acid production in the stomach?
positive effect; stimulates acid production
what is the effect of prostaglandins on acid production in the stomach?
negative; inhibit acid production to maintain homeostasis
what is the effect of somatostatin on acid production in the stomach?
negative; inhibit gastrin producing cells and parietal cells as well
gastric intrinsic factor
glycoprotein secreeted by parietal cells that binds to vitamin B12 and required for absorption in small intestine
where are chief cells found?
base region of fundic glands
what is in the apical cytoplasm of chief cells?
zymogen granules that store pepsinogen
function of pepsin
break down very large proteins in the stomach and breaks down collagen
what secretes gastric lipase?
chief cells
where in fundic glands are APUD cells mainly found?
base region of fundic glands
what are the ive major gastrointestinal peptide hormones?
secretin, gastrin, cholecystokinin, gastric inhibitory peptide and motilin
functions of gastrin
stimulate: parietal cells to produce HCl, chief cells to produce pepsinogen, and smooth muscle cells to increase gastric motility
What prevents the H+ ions from destroying the lining epithelium of the stomach?
the mucus secreted; tight junctions between cells; together these form the common mucosal barrier
why is the mucus slightly alkaline?
the surface mucus cells take the bicarbonate out of the blood and put it into the mucus
helicobacter pylori
bacterium that can live in the thick mucus of the stomach which is responsible for ulceration in the stomach
what substances are absorbed by the stomach?
water, salts, sugar (especially simple), alcohol, and drugs
hormone produced in the stomach that increases with fasting and decreases with feeding; an important mediator of signaling between intestine and hypothalamus to increase metabolic efficiency when nutrients are limited
cephalic phase
phase of gastric secretion due to psychological factors through parasympathetic impulses through the vagus nerve; stimulates stomach to secrete pepsinogen, HCl, and mucus
gastric phase
phase of gastric secretion due to stretch and chemoreceptors in the stomach that recognize presence of food; parasympathetic nerve impulses cause peristalsis and stimulate gastric juice secretion; also hormonal negative feedback from gastrine and histamine now
intestinal phase
phase of gastric secretion that inhibit the exit of chyme and overloaing of the duodenum.
what triggers APUD cells to produce secretin and CCK and from where?
fatty acids and glucose levels in the small intestines; these hormones decrease gastric secretions and stomach emptying
what factors facilitate the emptying of the stomach?
degree of distention of the stomach, and action of gastrine
what effect does gastrin have on emptying of the stomach?
positive; stimulates contraction of muscularis externa of the pyloric region and relaxation of the pyloric sphincter
what factors inhibit the emptying of the stomach?
distension of the duodenum, overabundance of fat, proteins or carbs, and increased osmolarity and excessive acidity of the chyme
what kind of meals last the longest in the stomach?
fat laden meals with many triglycerides
where does most digestion and absorption occur?
small intestine
which part of the small intestine is responsible for digestion of chyme?
where does the absorption of nutrients primarily occur?
jejunum and proximal ileum
what make up the lining epithelium of intestinal villi?
goblet cells and surface absorptive cells
what is at the core of each intestinal villus?
capillary loops, a blind ending lymphatic channel, and a few smooth muscle fibers
what is the cell surface specialization on the epithelium lining the intestines?
striated border microvilli
crypts of lieberkuhn
invaginations of epithelium into the lamina propria between villi form these intestinal glands
what cells transport the bulk of the absorbed nutrients into the lamina propria for distriubution?
surface absorptive cells of the epithelium of the small intestine
what type of epithelium lines the small intestine?
simple columnar
are there more goblet cells in the duodenum or ileum?
M cell
squamous like cells in regions where lymphoid nudoules abut the epithelium. These cells sample, phagocytose and transport antigens present in the intestinal lumen
what type of capillaries are in the lamina propria of the intestines?
what are lymphatics in the small intestines called?
where are intestinal stem cells located?
crypts of lieberkuhn
Paneth cells
intestinal cells located on the surface of the crypts of lieberkuhn that manufacture lysozyme, TNF-alpha and defensins
Brunner's glands
branched tubuloalveolar glands whose secretory units resemble mucous acini in the submucosa of the duodenum only; secrete a mucous alkaline fluid in response to parasympathetic stimulation
what gland manufactures the epidermal growth factor in the uodenum?
brunners glands; EGF inhibits HCl production
where are peyer's patches found?
lamina propria and submucosa of the ileum
intestinal enterokinase
cleaves and activates the trypsinogen from the pancreas in the glycocalyx of the absorptive cells
where do absorbed nutrients go once they enter the capillaries of the small intestine?
directly to the liver via the hepatic portal system
What hydrolyzes lipids in the small intestine and where are they absorbed?
pancreatic lipase and they're absorbed into the glycocalyx of the striated border microvilli
where are chylomicrons formed
in the golgi of the surface absorptive cells of the small intestines
lipid-rich substance that filles the lacteals; fluid consisting of lymph and emulsified fats (chylomicrons)
What is the local influence via the Meissner's and Auerbach's plexuses on the small intestines?
positive influence on the activity of the cells; Ach and VIP
what 2 neurotransmitters are used my the interneurons of the ENS in the small intestines?
ACh and Vasoactive intestinal peptide (VIP)
How do sympathetics affect the small intestines?
inhibition of the VIP interneurons only
peyer's patches
permanent clusters of lymphoid nodules found in the mucosa and submucosa of the ileum
follicle-associated epithelium (FAE)
surface epithelium covering the lymphoid nodules.
what 2 cells are found within FAE
intraepithelial lymphocytes and M Cells
What do M cells border on each side?
the lumen of the gut and lymphocytes
where do activated lymphocytes in the ileum migrate?
to the mesenteric lymph nodes where they form germinal centers
what happens to most of the IgA produced in the lamina propria?
enters the circulatory system, transported to liver, complexed with secretory component and released into bile
what is the function of the large intestine?
to convert undigested material received from the small intestine into feces by removing water and adding mucus
plicae semilunares
folds of the colon's lining
taeniae coli
the three strips formed by the robust outer longitudinal layer of the muscularis externa in the large intestine
haustra coli
sacculations of the large intestines formed by the constant tonus of the taeniae coli
which part of the large intestine is intraperitoneal?
cecum, transverse and sigmoid
which part of the large intestine is retroperitoneal?
ascending and descending
epiploicae appendices
teardrop shaped adipose filled outpockets of the colon
feces are composed of:
water (75%), dead bacteria(7%), roughage (7%), fat (5%), inorganic substances (5%) and undigested protein, dead cells and bile pigment (1%)
what is the function of mucus in the colon
protects the mucosa of the colon and facilitates the compaction of feces
how is the appendix different from the rest of the large intestine?
smaller lumen, fewer shorter crypts, more lymphoid nodule and no taenia coli
what type of gland is the exocrine part of the pancreas?
purely serous, compound tubuloacinar
from what is the exocrine pancrease derived?
are there myoepithelial cells in the pancreas?
what proenzymes do the acinar cells of the pancreas secrete?
trypsinogen, chymotrypsinogen, procarboxypeptidase and proelastase
what combines with trypsin formed accidentally in the pancreas to block its activity?
trypsin inhibitor
activating striated-border enzyme in the small intestine that activates trypsinogen to trypsin
what does active trypsin activate?
chymotrypsinogen, procarboxypeptidase, and proelastase
what clogs the lumen of a pancreas acinus?
3 o4 centroacinar cells which are the beginning of the duct system
ampulla of vater
the duct formed by the main pancreatic duct joining the common bile duct and enters the duodenum at the duodenal papilla
what do the intercalated ducts of the exocrine pancreas produce and why?
seous, bicarbonate-rich alkaline fluid to neutralize the acid chyme in the small intestines
carbonic anhydrase in the pancreas
catalyzes the formation of carbonic acid from water and CO2, the H+ the goes to the surrounding connective tissue and the HCO3- goes to the lumen
what is the effect of the vagus nerve on the exocrine pancreas?
stimulation will produce secretion
CCK's effect on the exocrine pancrease
stimulates acinar cells to synthesize and release digestive enzymes
Secretin's effect on the exocrine pancreas
promotes water and ion transport by stimulating the intercalated duct cells; this secretion neutralizes the acid chyme in the intestine
what is the largest gland in the body?
glisson's capsule
the capsule of the liver
what divides the liver into the right and left lobes?
falciform liver
what is the parenchymal cell of the liver?
what enters and exits via the porta hepatis?
hepatic portal vein, hepatic artery proper, autonomic nerves; exits: right and left hepatic ducts and efferent lymphatics
limiting plate
continuous wall of hepatocytes that surounds the interlobular septum (including the portal areas)
what is the space between the ct and limiting plate called?
periportal tissue space of mall, and it contains tissue fluid
what are the central veins in liver?
thin walled veins without valves that hepatocytes radiate out from
what is the blood vessel that runs between the hepatocyte cords?
what is the pattern of blood flow in the liver?
from the periphery of lubules (portal areas) to sinusoids to the central v.
what do central veins join to form?
hepatic vein which joins the vena cava
what are blood vessels in the liver lined by?
endothelial cells and fixed macrophages (Kupffer cells)
what is the space between sinusoids and plates of hepatocytes called? And what does it contain?
perisinusoidal space of Disse; tissue floid, nerve fibers, fibroblasts, reticular fibers and hepatic stellate cells
hepatic stellate cells
cells in the space of Disse that accummulate lipid and are involved in storage and metabolism of vitamin A; mesenchymal origin; can produces collagen, laminin, proteoglycans and GFs
What is the deposit of collagen and ECM components in a particular organ of the digestive system typical of?
fibrosis of the liver; cirrhosis
what stimulates collagen production by hepatic stellate cells?
cytokines produced by Kupffer cells
where does lymphatic drainage of the liver begin?
why does bile not leak into the sinusoids?
the bile canaliculi are sealed around the periphery with continuous occluding juncs
preductile portal of hering
first true bile duct that forms near and passes through the limiting plate to join the bile ductule in the portal area
what are the 3 surfaces or domains of hepatocytes
bordering other hepatocytes, intercellular canaliculi, or the space of Disse
what liver cells are responsible for filtering the blood?
kupffer cells that line the sinusoids
what are the endocrine functions of hepatocytes?
production and release of most plasma proteins (α and β globulins, albumin, prothrombin, and fibrinogen), glucose, lipoproteins, IGF-1 and angiotensinogen
what does the liver store?
vitamins, minerals, glycogen and some triglycerides
what tissues can synthesize the active form of vitamin D?
skin, liver and kidney
what is the function of the gallbladder
stores and concentrates bile secreted by the liver
what is the lining epithelium of the gallbladder?
simple columnar cells with numerous microvilli
how does the gallbladder concentrate bile?
the mucosa reabsorbs water and ions from the bile
rokitansky-aschoff crypts
epithelial clefts or diverticul in the gallbladder that extend into the lamina propria
sphincter of Oddi
complex of spincter muscles that controls the opening of the common bile duct and the pancreatic duct
what effect does parasympathetics have on the liver?
increases bile production
CCK's effect on the bile secretion
binds to smooth muscle of the gallbladder and causes them to contract. Also binds to smooth muscle of sphincter of oddi causing it to relax
ACh's effect on bile secretion
stimulates contraction of the gallbladder
where in the GI tube is there an abrupt transition between stratified squamous nonkeratinized epithelium and simple columnar epithelium?
gastroesophageal junction
What do all surface cells of the stomach secrete?
are junctional complexes found in the surface epithelial cells of the lower anal canal?
paneth cells are associated with hich gland?
crypts of Lieberkuhn
what part of the digestive tract has M cells?
a smooth surfaced system of tubules and vesicles is associated with what cell type in the stomach?
detoxification of drugs in hepatocytes is associated w/ what organelle
smooth endoplasmic reticulum
what is the function of paneth cells?
provide protection from bacteria
how is glucose transported into epithelial cells of the villi?
secondary active transport coupled to active transport of sodium ions