消化腺（全英文）ppt課件

1、Components digestive glands found in the wall of digestive tract accessory digestive glands:salivary glands / pancreas / liver General structure* Parenchyma (functional portion of an organ, as distinguished from the supporting tissue):acini / gland cellsduct* Stroma (unfunctional portion of an organ

2、):capsule, CT inside. Salivary glands* Parotid* Submandibular G.* Sublingual G.Three types of acini* serous* mucous * seromucousFunction: * moistening food * carbohydrate digestion * Secrete IgA Pancreas positioned retroperitoneally on the posterior wall of the abdominal cavity at the level of the s

3、econd and third lumbar vertebrae. no distinct capsule, but is covered by a thin layer of LCT both an exocrine & endocrine gland. * exocrine part: produces pancreatic juice * endocrine part: produce hormonesComponents of the exocrine pancreas consists of serous glands acini filled with acidophilic zy

4、mogen granules intercalated duct extends into the centre of the acini, which is lined by centroacinar cells duct system: intercalated ducts (low columnar or cuboidal epith.) Interlobular ducts (columnar epith.) Main pancreatic ducts ( tall columanr epth.) major duodenal papillaFunction of pancreatic

5、 juice:* Trypsin, chymotrypsin & carboxypeptidase hydrolyse proteins; * ribonuclease & deoxyribonuclease split nucleic acids;* amylase hydrolyses starch & glycogen * lipase hydrolyses triglycerides into fatty acids and monoglycerides * cholesterol esterase breaks down cholesterol esters into cholest

6、erol and a fatty acid. Components of the Endocrine * Islands of Langerhans scattered throughout the exocrine pancreas. * Vascularization (many fenestrated cap.) is more extensive than that of the exocrine acini.* Three different types presentA-cells (20%): glucagon producerB-cells (75%): insulin pro

7、ducerD-cells (5%): somatostatin producerLiver* largest gland ( 2% of body weight in adult). * receives both venous & arterial blood through the portal V. (75%) & hepatic A (25%), respectively.* CT of capsule extended into the parenchyma, forming “ classical liver loblules ( basic structure units).*

8、functions as an exocrine gland (secreting bile). Structures of liver lobules* six-sided prism with a central V. at its centre* delimited by interlobular CT * portal triads in the corner of lobules (portal area)* anastomosing plates of hepatic cells extended radially from the central V.* sinusoids fo

9、rm between hepatic plates Portal areas*definition: a area found in the angles where adjacent hepatic lobules meet.* components: CT. + portal triadinterlobular Ainterlobular Vinterlobular bile ductSinusoids* dialated anastomosing venules between the hepatic plates * blood pathway: periphery central v

10、. * Kupffer cells lined in the wall of sinusoids* EM: significant gaps numerous fenestration incomplete basal laminaHepatocytes* make up about 80% of the cells in the liver.* typically large polyhedral cells with large round centrally located nuclei. * abundance of organelles related to the function

11、sMitochondria: energy providingRER: protein synthesisSER: bile formation / metabolism of lipids and hormones / detoxification.Lysosome: replacement and defenceMicrobody: detoxification.Inclusions: glcogen particles, lipid droplets and pigments.Hepatocyte function* Produce bile* mediate carbohydrate

12、reserves glycogen is degraded to glucose under regulation of hormones* Blood lipid metabolism* Synthesis of plasma proteinsalbumin: major plasma proteinfibrinogenthrombinclotting factor IIIBile CanaliculiDefinition: tubular space limited by plasma membrane of two adjacent hepatopcytes.Structure:LM:

13、network-like structures are seen by silver impregnationEM: * plasma membrane of adjacent hepatocytes form the wall of bile canaliculi* tight junctions form sealsBlie canaliculi stained by silver impregnationPerisinusoidal sapce (space of Disse) a space between the endothelium & hepatocyte be visible

14、 under EM occupied by numerous microvilli of hepatocytes filled with plasma fat-storing cells (storing fat & vitamin A) a site for exchange between the blood & hepatocytes.*cell junction surface* Perisinusoidal surface: face to perisinusoidal space * bile canalicular surface: face into the bile cana

15、liculusInterlobule A.&V.Three types of functional surface in hepatocyte Portal V interlobular V Hepatic Ainterlobular A sublobular Vsinusoids central Vhepatic VInferior vena cava(75%)(25%)Bile canaliculi periperal bile ductules ( Herings )interlobular bile duct Left & right hepatic ductsCommon hepatic ductCommon bile ductDuodenum papilla Cystic ductGall bladderClassification of LobulesClassic lobule: A hexagonal structure with the central vein at its center; at the six corners of the lubule are hepatic triads.2. Portal lobule: A trian