Digestive Glands - Cole Flashcards
Functions of digestive glands?
Lubricative, protective, digestive and absorptive functions
3 major glands
Salivary
Exocrine pancreas
Liver (gallbladder)
4 ways exocrine glands are classified
- Structure of duct - simple and branched
- Structure of secretory units - tubular or alveolar (acinar)
- Secretory product - mucus or serous
- Secretory mechanism - merocrine, holocrine, apocrine
3 Major salivary glands
- Parotid - 25% of saliva - amylase rich
- Submandibular - 70% of saliva
- Sublingual
Saliva
.5 liters a day
Contains proteins, glycoproteins (mucus), ions, water and IgA
Under the control of the ANS
Functions: lubricate, protect, digestive
Parotid gland
Serous acinus
Secretes zymogen
Clears bacteria before the bastids get in the body
On teeth
Submandibular gland
Mixed acinus - serous and mucus
Serous demilunes
Secrete mucin that protects and lubricates
Sublingual gland
Mucous acinus
Mixed mucus and serous
Mucus acini predominate
No long ducts, multiple small
What makes IgA in saliva?
Plasma cells
Enzymes of the parotid gland?
Amylase, peroxidase, lysozyme
Clinical significance of mumps, rabies and tumors
Parotid gland is primary target for all 3
Mumps - transient swelling
Most frequent site of slow-growing benign salivary glands
Surgery - protect facial nerve
Exocrine Pancreas
Pancreas is combined endocrine and exocrine
Functional unit - acinus
Centroacinar cells - low cuboidal epithelial lining the intercalated duct
Endocrine Pancreas
Islet of Langerhans - 2% of pancreas volume
Main function - regulation of glucose metabolism by hormones secreted into the bloodstream
Centroacinar cells
Pancreas
Secretin controls
Secrete mucin
Pancreatic secretions
Cholecysokinin (CCK) and secretin increase flow of pancreatic fluid
CCK stimulates release of zymogen
Diet affects what is secreted - ex. if eat pale - proteases
Secretin
Can act on cells in duct to get them to secrete bicarbonate and water
If you eat a paleo diet high in protein, pancreas will secrete mainly?
Proteases
If you eat a shit ton of carbs, pancreas will secrete
Amylase - breaks down starch
Acute pancreatitis
Premature activation of pancreatic enzymes that start to digest the pancreas
Can be caused by heavy meals and excessive alcohol
Liver
Largest gland in body
Blood supplied by: Portal v. (75%) and Hepatic a. (25%)
What is the structural and functional unit of liver?
Hepatic lobule (Cole's favorite - not classic lobule or portal lobule) (Portal triad)
Portal triad
Hepatic artery branch
Bile duct
Hepatic portal vein branch
Blood flow in the liver
Blood goes from portal triad to central venule
Bile goes from central venule to the portal triad
Kupffer cells
Macrophages in the lobule
-break down old RBCs (normally mostly in spleen)
Space of Disse
Space between discontinuous cap and hepatocytes
Cap is so leaky that blood goes into the space of disse and is immediately available to hepatocytes and it can absorb what ever it wants
Bile canaliculus
Between hepatocytes
-secrete bile
Ito cells
Located at intervals within space of Disse
Storage sites for fat and vitamin A
Hepatocytes
Functional endocrine and exocrine cell of the liver
Has basolateral domain with abundant microvilli extending into space of Disse
Contain SER
Functions of smooth endoplasmic reticulum
- Synthesis of cholesterol and bile salts
- Glucuronide conjugation of bilirubin, steroids and drugs
- Breakdown of glycogen into glucose
- The detoxification of lipid-soluble drugs
Bile
Fat absorption
Transports IgA to the intestinal mucosa
Metabolism of bilirubin
85% originates from senescent RBCs destroyed in spleen by macrophages
Bilirubin forms a complex with albumin
Albumin detaches and bilirubin is internalized by the hepatocyte
Fatty liver
Long term consumption of ethanol
Can reverse
Cirrhosis - collagen proliferation of fibrosis of the liver
Gallbladder
Storage, concentration and release of bile
