APARATO DIGESTIVO III - TRABAJO PRÁCTICO
New Section
In this section, the focus is on the glands associated with the digestive system and their secretions.
Glands Associated with Digestive System
- The digestive glands are connected to the digestive tract through ducts for secretion.
- Classification of digestive glands includes salivary glands, pancreas, and liver.
- Major salivary glands include parotid, sublingual, and submaxillary glands.
- Illustration of minor salivary glands within lingual mucosa showing ducts and Von Ebner's glands.
New Section
This section discusses major salivary glands in detail.
Major Salivary Glands
- Description of parotid gland located in front of ears secreting serous fluid rich in proteins and enzymes.
- Sublingual gland found under the oral cavity floor secretes mixed saliva with a predominance of mucous content.
- Submaxillary gland situated outside the oral cavity floor secretes mainly serous secretion through Wharton's duct.
- Comparison of secretions from parotid, sublingual, and submaxillary glands based on composition.
This part delves into specific characteristics of different types of secretions from major salivary glands.
Secretion Characteristics
New Section
This section discusses the structure and function of salivary ducts and mucosa, focusing on their roles in producing mucus and facilitating secretion.
Salivary Ducts and Mucosa
- Salivary ducts are lined with flattened nuclei pushed to the periphery by mucus production.
- Exclusively striated salivary ducts are lined with tall cylindrical epithelium containing central nuclei rich in mitochondria for energy production.
- Striated duct function includes absorbing water/electrolytes and secreting potassium bicarbonate-rich secretions to prevent enzyme activation intra-glandularly.
New Section
This part delves into the anatomy and functions of the major accessory glands of the digestive system, focusing on the pancreas.
Pancreas Anatomy and Function
- The pancreas is a retroperitoneal mixed gland comprising exocrine (acini & ducts) and endocrine (Langerhans islets) components.
- It consists of distinct head, body, and tail regions, with exocrine secretions entering the duodenum via the pancreatic duct.
- Endocrine pancreatic islets stain paler than exocrine tissue due to different cellular compositions.
New Section
This section explores the significance of intercalated ducts within the pancreas in maintaining an alkaline environment crucial for enzyme activity regulation.
Importance of Intercalated Ducts
- Intercalated ducts add bicarbonate/water to pancreatic secretions, preventing premature enzyme activation within the parenchyma.
Histology of the Liver
In this section, the histology of the liver is discussed, focusing on structures like portal triads and hepatic lobules.
Portal Triads Composition
- The portal triads are found at the periphery of classic hepatic lobules. They consist of three components.
- These components include larger bile ducts with thin walls and blood vessels.
Hepatic Sinusoidal Space
- The space between the endothelium of hepatic sinusoids and hepatocyte columns is known as Disse's space.
- This space contains stellate cells responsible for storing vitamin A and responding to liver injuries.
Hepatic Lobule Variations
- Apart from classic hexagonal lobules, there are portal lobules (triangular) and acinar lobules (rhomboidal).
- Portal lobes represent exocrine liver function related to bile production.
Biliary System in Liver
- Bile produced in hepatocytes moves through intrahepatic bile ducts within the liver parenchyma.
- Bile then flows into extrahepatic bile ducts like common hepatic duct, cystic duct, forming common bile duct.
Classification of Intrahepatic Biliary System
- Intrahepatic biliary system includes intra-lobular and interlobular pathways.
- Intra-lobular bile ducts are formed by canalicular structures surrounded by hepatocyte membranes.
New Section
This section discusses the structure and function of the bile duct and gallbladder.
The Bile Duct and Gallbladder
- The first part of the bile duct is called the "ductus choledochus," located at the level of the hepatocyte limiting plate, with cuboidal epithelium.
- Branches of the bile duct give rise to the common bile duct, which stores bile in the gallbladder for fat digestion after meals.
- The gallbladder has a fundus, body, and neck. Its main function is to store and concentrate bile composed of various components like water, electrolytes, cholesterol, phospholipids, bile acids, and pigments.
- The gallbladder's inner lining consists of a simple columnar epithelium with microvilli aiding in fluid reabsorption. Surrounding it is loose connective tissue and an adventitia layer towards its outer surface covered by peritoneum.
New Section
This section covers salivary gland anatomy focusing on the parotid gland.
Salivary Gland Anatomy
- The parotid gland is a major salivary gland secreting protein-rich substances through excretory ducts lined with simple columnar epithelium.
- Salivary gland sections include centrolobular veins corresponding to lobules. Hepatocytes form cords directed radially towards centrolobular veins creating hepatic classic morphological structures.