Glands and Accessory Organs Flashcards
What is the function of the saliva? What are the 3 glands?
Facilitate taste, swallowing, and initiate digestion
Contains proteins, enzymes, ions, mucins, etc.
3 major salivary glands are the parotid, submandibular, and sublingual
What does the parotid gland secrete?
Purely serous
What does the submandibular gland secrete?
Mainly serous with some mucous
What does the sublingual gland secrete?
Mainly mucous and some serous
What is the structure of the exocrine pancreas?
Secretes digestive enzymes - primarily serous
Secretory cells arranged into pancreatic acini - acinar cells are pyramidal and contain zymogen granules (inactive digestive enzymes)
Intercalated ducts - carry products of acini to larger interlobar ducts within pancreas. Centroacinar cells project into center of acini and ductal cells secrete water and bicarbonate
What covers the liver?
Thin yet strong connective tissue called Glisson’s capsule
Covered by liver mesothelium which is simple squamous
What are hepatic lobules?
Contain hepatocytes that have sinusoids or spaces between hepatocytes
Central vein in center of hepatic lobules
What is the hepatic lobule structure and what does it emphasize?
Traces flow of blood through the liver
Hexagonal plates of hepatocytes and sinusoids
Center contains central vein and corners contain portal canals
What is the blood supply in the hepatic lobule?
Mostly from portal vein and then some from hepatic artery
What is the path of blood through the liver?
Blood from portal vein and hepatic artery anastomose to form sinusoids
Blood flows through sinusoids where it is processes by hepatocytes
Processed blood flows into central vein
Flows into hepatic vein back to IVC
What is the portal lobule structure and what does it emphasize?
Emphasizes bile production and secretion
Triangular
Bile duct at center of lobule and central veins at corners
What is the path of bile production?
Bile produced by hepatocytes into bile canaliculi
Flow towards bile duct in portal canal
Opposite direction of blood flow
What is the hepatic acinus structure and what does it emphasize?
Describes blood perfusion and metabolic activity
Quadrangular
Long axis between central veins and short axis between portal canals
Zone 1 - closes to portal canal and hepatocytes are exposed to more oxygen, nutrients, toxins. Less CO2 and metabolic waste. Cells first to regenerate and last to die
Zone 2 - farthest from portal canals, hepatocytes exposed to blood with less oxygen, nutrients, and toxins. More CO2 and waste. First to show damage and die
What is the portal canal and what does it contain?
Region at corners of classical hepatic lobule
Loose CT continuous with Glisson’s capsule
Lymphatic vessels
Portal triad - portal vein, bile duct (simple cuboidal), and hepatic artery
Periportal space - Space of Mall. space between hepatocytes and portal canal
What are the sinusoids of the liver? What do they contain?
Formed by anastomosis of the hepatic artery and portal vein in portal canal
Sinusoidal epithelium - discontinuous simple squamous epithelium that lines sinusoids
Kupffer cell - hepatic macrophages that form part of sinusoidal lining
Perisinusoidal space - site of exchange between blood plasma and hepatocytes, microvilli of hepatocytes project in for increased exchange
Stellate cell - store vitamin A and lipids
What are the functions of hepatocytes?
Bile manufacture - water, bile salts, bilirubin, fats
Lipid metabolism and storage
Carbohydrate metabolism and storage
Protein metabolism
Vitamin storage - A, K, D, B12
Detoxification of drugs
Degradation of hormones
Immune response - kupffer cells
What is jaundice and its two types?
Elevated levels of unconjugated bilirubin in the bloodstream
Obstructive jaundice - decrease in ability of hepatocytes to conjugate bilirubin, blockage of bile ducts, so same amount of bilirubin but cannot be excreted with bile
Hemolytic jaundice - increased breakdown of red blood cells leads to increased level of bilirubin
What is the biliary tract and what does it contain?
Helps with main exocrine secretion of liver
Bile flows toward bile ducts in portal canals
Bile canaliculi - spaces between hepatocytes bounded by tight junctions
Canals of Hering - simple cuboidal epitheloum and lined with cholangiocytes
Intrahepatic bile ductules
Interlobular bile ducts - within portal canal
Hepatic ducts - simple columnar epithelium
What is the path of bile through the biliary tract?
Bile produced by hepatocytes
Bile canaliculi
Canal of Hering (simple cuboidal, cholangiocytes)
Intrahepatic bile ductules (simple cuboidal, cholangiocytes)
Interlobular bile ducts (simple cuboidal, cholangiocytes)
Hepatic ducts (simple columnar)
Gallbladder (simple columnar)
What is the function of the gallbladder?
Storage, concentration, and release of bile
What layers does the gallbladder contain?
Mucosa
Muscularis externa - disorganized
Adventitia and serosa
Lacks muscularis muscosae and submucosa
What is the structure of the mucosa of the gallbladder?
Simple columnar epithelium with microvilli present
Lamina propria
Muscularis mucosae absent
Where is adventitia and serosa present in the gallbladder?
Serosa on peritoneal surface
Adventitia on hepatic surface
What are gallstones?
Typically made of cholesterol or calcium bilirubinate
Asymptomatic unless they become lodged in cystic or common hepatic duct
