organs of digestive tract Flashcards
(38 cards)
they glands are paired glands with long ducts that empty into the oral cavity.
major salivary glands
- consists of:
parotid
submandibular
sublingual
glands.
where are the minor salivary glands located
in the submucosa of different parts of the oral cavity.
includes:
- lingual
- labial
- buccal
- molar
- palatine
briefly explain the 3 epithelial cell types comprise the salivary secretory units
Serous cells:
are polarized protein-secreting cells.
Mucous cells:
contain apical granules with hydrophilic mucins
which after secretion provide lubricating properties.
Myoepithelial cells:
occur inside the basal lamina, and extend their
contractile processes around the secretory unit.
it is the basic secretory unit of glands, salivon, consists of the acinus, and salivary duct.
Secretory Gland Acini
salivary duct:
Intercalated duct
Striated duct
Excretory duct
what composes the
1. parotid glands
2. submandibular glands
3. sublingual glands
- pure serous acini
- large adipose tissue often occur in the parotid gland - mixed glands that are mostly serous in humans
- mixed glands that are mostly mucus secreting in humans
functions of saliva
*combined secretions of all the major and minor salivary glands
performs protective and digestive functions:
1. moisten oral mucosa = control water intake.
- lack of saliva signals thirst
2. moisten dry foods to aid chewing and swallowing
3. provide a medium for dissolved and suspended food materials tht chemically stimulate taste buds
4. buffer the contents of the oral caity bbecause of its high conc of bicarbonate ions
5. digest carbs w digestive enzyme a-amylase
- breaks 1,4 glycosidic bonds and continues to act in the esophagus and stomach
6. control bacterial flora of the oral cavity by the use of lysosomes (muramidase) an enzyme that lyses the muramic acid in the certain bacteria
briefly explain the liver physiology
- Excretion/Secretion
One of the most important functions is the processing and excretion of endogenous and exogenous substances into the bile or urine. - Metabolism
The liver has extensive capacity for metabolizing many biological compounds including carbs, lipids, and proteins. - Detoxification
Every substance that is absorbed in the GIT must pass through the liver before reaching the rest of the body. - Storage
Liver has a role as storage for different compounds, including biomolecules, vitamins, iron and copper.
what lipid-soluble vitamins does vitamin store in the liver
Vitamin A, Vitamin D, Vitamin E, and Vitamin K.
- Liver mobilizes Vitamin A from its storage sites.
- Liver metabolized Vitamin D by converting Vitamin D3 to 25-hydroxycholecalciferol.
- Vitamin E is transported to the liver in chylomicrons and is bound to a-TTP.
- Vitamin K is transported to the liver with chylomicrons, where it is absorbed, partially used, and the partially secreted with the VLDL fraction.
what does liver supply, store, metabolize and secretes
iron and copper
what are the proteins that liver synthesized involved in iron recovery from damaged or senescent RBCs.
Transferrin
Haptoglobin
Hemopexin
where does the copper uptake and secretion primarily occurs
in hepatocytes
- Ceruloplasmin
this cells are involved in the degradation of drugs, toxins, and other proteins foreign to the body.
Liver converts these substances into more soluble forms:
Phase I (oxidation)
- includes hydroxylation and carboxylation to a foreign compound.
- performed in hepatocyte sER and mitochondria
Phase II (conjugation)
- includes conjugation with glucuronic acid, glycine, or taurine.
what is bile made out of
bile acids/salts
bile pigments
cholesterol
other substances
it is the principal pigment in bile derived from the breakdown of red blood cells.
Bilirubin
what are the two sources of the liver’s blood supply?
hepatic portal vein (venous supply)
hepatic artery (arterial supply).
- blood from hepatic portal vein comes from the digestive tract and the major abdominal organs, and contains:
nutrients and toxins absorbed in intestine
blood cells and breakdown products of blood cells from spleen and endocrine secretion.
a branch of the celiac trunk, carries oxygenated blood to the liver.
hepatic artery
what are the liver made up of (anatomy)
- Parenchyma:
consisting of organized plates of hepatocytes. - Connective tissue stroma:
that is continuous with the fibrous capsule of Glisson. - Sinusoidal capillaries (sinusoids):
the vascular channels between the plates of
hepatocytes. - Perisinusoidal spaces (spaces of Disse):
which lie between the sinusoidal endothelium and
the hepatocytes.
it is the functional unit of the liver.
liver lobules
- has 3 models based on functional characteristics
- Classic hepatic lobule:
is based on the distribution of the branches of the portal vein and hepatic artery within the organ. - Portal lobule:
emphasizes the exocrine
functions of the liver, which is bile secretion. - Liver acinus
the structural unit that provides the best correlation between blood perfusion, metabolic activity, and liver pathology.
what do liver lobules consists of
stacks of anastomosing plates of hepatocytes, separated by the anastomosing system of sinusoids that perfuse the cells with the mixed portal and arterial blood.
what lines the hepatic sinusoids
thin discontinuous endothelium
- also consists of stellate sinusoidal macrophage or Kupffer cell
(which are antigen-presenting cells that are involved in the immune system response, and removing senescent RBC)
this lies between the basal surfaces of hepatocytes and the basal surface of endothelial cells and Kupffer cells, and is the site of exchange of materials between blood and liver cells.
perisinusoidal space
- also found in the perisinusoidal space is the hepatic stellate cells or Ito cells, which store vitamin A.
this make up the anastomosing cell plates of the liver lobule.
Hepatocytes
- large, polygonal cells
- constituting 80% of the cell population of the liver
- consists of numerous peroxisomes, extensive SER, and large Golgi apparatus.
- lysosomes are concentrated near the bile canaliculus and correspond to peribiliary dense bodies
these are concentrated near the bile canaliculus and correspond to peribiliary dense bodies.
lysosomes
it is the three-dimensional system of channels of increasing diameter that bile flows through from the hepatocytes to the gallbladder and then to the intestine.
biliary tree
- lined by cholangiocytes, which are ep cells that monitor bile flow and regulate its content.
