Digestive Glands Flashcards
Components of digestive glands
- large salivary glands
- pancreas
- liver
- gall bladder
Function: salivary gland
Produce saliva
Function: pancreas
Produce digestive enzymes and hormones
Function: liver
Produce bile, metabolism, synthesize blood proteins, etc.
Function: gall bladder
Store and concentrate bile
Two parts of the exocrine glands
- Secretory part
- Duct system
Compound glands have
Branching ducts
Compound tubuloacinar glands that exist in three large pairs
Salivary glands
Three major types of salivary glands
- Parotid glands
- Submandibular glands
- Sublingual glands
Two types of secretory cells in salivary glands
- Serous
- Mucous
Function: serous cell
- Protein secreting cell (enzyme)
- secretion is washiness
- serous cells form serous acini
Function: mucous cell
- secrete mucoproteins
- secretion is viscid
- mucous cells form the mucous acini
Composed of both serous and mucous cells, mainly mucous acinus with a serous demilune
Mixed acinus
- Found within the basal lamina of secretory acini and intercalated ducts.
- Stellate or spindle in shape
- function:
1. Contraction: helping to squeeze out secretion
2. Prevention
Myoepithelial cell
Ducts involved in the duct system of salivary glands
- Intercalated duct
- Striated duct
- Interlobular duct
- Major secretory duct
Epithelium in the salivary glands duct system
- Simple cuboidal epithelium
- Flat
LM: nucleus is near the cell apex; cytoplasm is acidophilic
EM: basal striations formed by membrane infolding and mitochondria
Function: transport water and ions; reabsorbing sodium and excreting potassium
Striated duct (secretory duct)
Branched acinar gland made entirely of serous acini with longer intercalated duct and striated duct to secrete products mainly containing salivary amylase
Parotid gland
Branched tubuloacinar gland that has a mixed component (mixed gland) with more serous acini and less mixed or mucous acini
Submandibular gland
Branched tubuloacinar gland with mainly mucous acini that exist without intercalated duct
Sublingual gland
Elongated organ having a head, body and tail with a capsule and septa of connective tissues; parenchyma organ with lobules
Pancreas
Pancreas divided into two portions
- Endocrine portion
- Exocrine portion
Exocrine portion of pancreas
Contains entirely serous acini
- serous cells have basophilic basal cytoplasm
- rich in RER
- golgi complex
- zymogen granules in apical cytoplasm
Difference with pancreas and salivary glands
- no myoepithelial cells
- centroacinar cells are small, pale stained cells in the lumen of acini which are from cells of the intercalated ducts
Intralobular duct of the pancreatic gland is comprised of
Cuboidal
Interlobular duct of the pancreatic gland is comprised of
Columnar
Main pancreatic duct of the pancreatic gland is comprised of
High columnar with goblet cells
Function: exocrine portion of pancreatic gland
- Secrete pancreatic juice
When proenzymes are abnormally activated and digest the whole pancreas leading to very serious complications (not a bacterial infection; related more to alcoholism, gallstones, metabolic factors, infection, drugs)
Acute pancreatitis
Endocrine portion of the pancreas is called
Islet of Langerhans
Appears as a cluster of cells embedded within the exocrine portion and is more abundant in the tail of the pancreas
- cells are polygonal or rounded; lightly stained, arranged in cords separated by a network of fenestrated capillaries
Endocrine portion of Pancreatic Gland
Major types of cells in immunology
A cells 20%
B cells 70%
D cells 5%
Others 5%
B-cells produce the hormone
Insulin
Function: Insulin
Decrease glucose content in blood
A-cells produce the hormone
Glucagon
Function: Glucagon
Increases glucose content in blood
A-cells are located in the (Alpha cells)
Periphery
B-cells are located in the (Beta cells)
Central region
D-cells are located
Scattered
D-cells produce the hormone (Delta cells)
Somatostatin
Function: somatostatin
Prevents (inhibits) the release of pancreatic hormones including insulin, glucagon and gastrin and pancreatic enzymes that aid in digestion
A disease in which the body’s production and use of insulin is impaired
As a result, the level of blood glucose is too high (hyperglycemia)
Diabetes Mellitus
Most common types of diabetes
- Type I diabetes
- Type II diabetes
- Gestational diabetes
Insulin- dependent and results from partial or total destruction of B-cells due to autoimmune disease. It occurs more in children (juvenile diabetes)
Type I diabetes
Insulin-independent diabetes and is frequently associated with obesity. It occurs at a later stage in life
Type II diabetes
Parenchymal organ having the Glission’s capsule and a hilum
Liver
Parts of the liver lobule
- central vein
- liver plates formed by hepatocyte
- liver sinusoid
- others
Basic structural unit of the portal area of liver
- Interlobular arteries
- Interlobular veins
- Interlobular bile duct
Function: liver
- Produce bile
- Lipid, carbohydrate and protein metabolism
- Inactivate and metabolize toxic substances and drugs
- Iron metabolites and synthesis of plasma proteins (albumin, fibrinogen)
Basic structural unit of the liver that is a polygon shaped mass of tissue
Hepatic lobule
Composition of liver lobule
- Central vein
- Liver plates
- Liver sinusoids
- Perisinusoidal space (space of Disse)
- Bile canaliculi
Occupies the center of the liver lobule, lined by endothelium and a few connective tissues.
- receive blood drainage directly from the sinusoid
Central vein
Composed of a single row of hepatocytes
Liver plates
- Form liver plates or liver cords
- Polyhedral shape
- Eosinophilic cytoplasm
- 1 or 2 lathe rounded nuclei with 1 or 2 nucleoli
LM: Hepatocytes
Probably the most versatile cell
Hepatocyte
Function: hepatocytes (mitochondria)
Provide the energy
Function: hepatocytes (RER)
Synthesize plasma proteins
Function: hepatocytes (golgi complex)
Formation of bile and lipoprotein
Function: hepatocytes (SER)
- synthesize bile, triglyceride
Function: hepatocytes (lysosomes)
- Metabolism of hepatocytes and renewal of organelles
- transport of bilirubin
- storage of iron
Under LM: Liver sinusoid is situated between the hepatic plates and is composed solely of
Endothelial cells
Under EM: endothelial cells of liver sinusoid are
- Thin
- Discontinuous
- Fenestrated
- No basal lamina
Located in the lumen of liver sinusoid which belong to mononuclear phagocytic system.
- irregular, phagocytic and contain a number of lysosomes
Kupffer cells
Function: kupffer cells
- Recognize and phagocytose aged erythrocytes, freeing heme and iron for reuse or storage in ferritin complexes.
- Antigen-presenting cells
- Remove any bacteria or debris present in the portal blood
Space between endothelial cells and hepatocytes containing fluid similar to plasma, microvilli from the hepatocytes, reticular fibers and fat-storing cells
Space of Disse
Function: space of Disse
Site of materials exchange between blood and hepatocytes
Fat-storing cells are also called
Ito’s cells
In chronically diseased liver, fat-storing cells are activated by factors released by hepatocytes and kupffer cells. The activated fat-storing cells proliferate and can produce many collagenous fibers and cause fibrosis and
Hepatic cirrhosis
- Formed by indented plasma membranes of opposing hepatocytes
- Microvilli extend into canalicular lumen which contains bile (secretion of liver)
Bile canaliculi
Common symptom of liver disease
Jaundice
Interlobular veins are branches of the
Portal vein
Interlobular arteries are branches of the
Hepatic artery
Blood drains from the peripheral regions of the liver to the
Central part of the liver
Discharge way of bile
Bile canaliculi —> Hering’s canals —> Interlobular bile ducts —> Hepatic duct —> common bile duct —> duodenum
*common bile duct —> gall bladder
Three functional surfaces of hepatocyte
- Bile canaliculi
- Plasma
- Intercellular