digestive system Flashcards
what is the mucous membrane of the oral cavity lined by?
stratified squamous
the epithelium of the mucous membrane is keratinized on the surface of what two structures of the oral cavity?
tongue and hard palate
which papillae of the tongue is the most abundant and looks sharp?
filiform
which papillae of the tongue look like leaves?
foliate
which papillae of the tongue are the largest and located at the back?
vallate
which papillae does not have taste buds and serve as sensory function?
filiform
what is the outer layer of the teeth?
enamel
what is the inner layer of the teeth?
dentine
what is enamel secreted by?
ameloblasts
what is dentine produced by?
odontoblasts
when are the ameloblasts lost?
once the teeth erupts from the gum
what makes up the core of the teeth?
pulp cavity
what is the surface that projects from the gumline?
crown
true or false: the root has enamel
false
what is dentin gradually replaced by as teeth goes deeper?
cementum
what is the cementum the surface to that attaches the tooth to the jaw bone?
periodontal ligament
what is the unit of the salivary gland called?
acinus
what is the acinus made of?
a ball of epithelial cells surrounding a small lumen
Secretions from the lumen are transported through _____________ ducts that drain into larger striated ducts that further drain into __________ ducts.
intercalated
intralobular
Salivary gland secretions may be serous (watery) in which case the acinar cells appear to be _________
eosinophilic
a mixed salivary gland has mucous secreting acini with a serous secreting cap called what?
serous demilune
what epithelium is the pharynx lined by?
stratified squamous
When the esophagus runs through the neck and is surrounded by muscles, it is covered on the outside by what?
T. adventitia
when the esophagus runs through the thoracic cavity it is lined on the outside by what?
T. serosa
what is the epithelium of the esophagus lined by?
stratified squamous
true or false: the human stomach is glandular
true
what are the three distinct parts of the stomach?
cardia, fundus, pylorus
what part of the stomach are the gastric glands extensive?
fundic
what is the purpose of the gastric glands?
secrete the gastric juice which is rich in hydrochloric acid and enzymes that digest proteins
what is the pH of the stomach close to?
2
how does the stomach protect itself from its own secretions?
the surface of the stomach is lined by surface mucous cells that secrete a thick lining of mucous
describe parietal cells
cells responsible for secreting hydrochloric acid. They have specialized channels in their cytoplasm that help to move the hydrochloric acid out without digesting the cell.
what is the purpose of chief cells?
secrete pepsinogen that is converted to pepsin in the presence of hydrochloric acid. This enzyme digests proteins
what is the purpose of enteroendocrine cells?
secrete hormones (gastrin, cholecystokinin, somatostatin, chromogranin) that act locally on the gut to coordinate the secretion of bile and pancreatic enzymes.
what are the purpose of stem cells in the GI tract?
found at the neck of the gastric glands and help to replenish cells that line the gastric glands.
what is the T. muscularis made of in the stomach?
inner oblique followed by circular and then longitudinal layers of smooth muscle
what is the outermost layer of the stomach lining?
mesothelium or T. serosa and contains blood vessels, fat and nerves.
what are the three parts of the small intestine?
duodenum, jejunum, ileum
what are the folds of the mucous membrane of the small intestine called?
plica circulares
what are the projections into the lumen called?
villi
what epithelium is the surface of the villi covered by?
simple columnar
what are the columnar cells of the small intestine called?
enterocytes
what do enterocytes have on their apical surface to facilitate absorption?
microvilli
what are the glands of the small intestine called?
crypts of lieberkuhn
what are the crypts of lieberkuhn called?
enterocytes and goblet cells that secrete mucus
what is the lymphatic vessel in the core of the villi made of loose c.t.?
lacteal
what is the purpose of lacteal?
Fat in the gut is absorbed into the lacteals and traverses through the lymphatic system.
which part of the small intestine has submucosal glands?
duodenum
what part of the small intestine has peyer’s patches?
ileum
what part of the small intestine is the longest section of the small intestine and has occasional lymphatic nodules?
jejunum
what does the portal vein break down into in the liver?
sinusoidal capillaries
describe the hepatic portal system
the portal vein starts off as capillaries in the villi and breaks up into capillaries in the liver
what are the small ganglia between the T. muscularis layers?
myenteric plexuses
what is peristalsis
muscles help to propel the digesta forward in progressive motion
what is the tunica serosa that has fat, bvs, and nerves covered by?
mesothelium
what is the large intestines made of?
small colon, large colon and rectum
true or false: the large intestine has the Crypts of Lieberkuhn but the villi are absent
true
where is the T. adventitia?
anus
the caudal part of the rectum and anus are lined by what epithelium?
stratified squamous
what species don’t have a gallbladder?
rodents and horses
what is the liver important for?
metabolizing nutrients and drugs
what are the polyhedral cells of the liver called?
hepatocytes
where do the cords of hepatocytes arise from?
central vein
what do the sinusoidal capillaries between the cords of the liver line?
hepatic sinuses
the radiating cords from one central vein form in the liver?
hepatic lobule
what forms the portal triad?
portal vein, bile duct, and hepatic artery
in what species is the hepatic lobule is nicely delineated by a thin layer of connective tissue?
pigs
where does nutrient blood flow to the liver come from?
hepatic artery
where does the functional flow come through and exist through?
portal vein
hepatic vein
what epithelium is the gallbladder lined by?
simple columnar
what does bile contain?
bile acids, salts and pigment and it is important for emulsifying ingested fats, and coloring the feces.
where is the pancreas attached to?
duodenum
what is the exocrine part of the pancreas responsible for?
secretion of amylases, peptidases and lipases for digestion
what is the small cell in the lumen of the pancreatic acini?
centroacinar cell
how do the cytoplasm of the pancreatic cells appear in the basal compartment?
basophilic
why does the cytoplasm of the pancreatic cells appear eosinophilic in the apical compartment?
zymogen granules
The pancreas secretes the enzymes in response to gastric signals such as:
cholecystokinin, gastrin and somatostatin
