Pancreas and Liver Flashcards
Endocrine
Secretion into blood
Can be performed by both epithelial and non-epithelial cells
Exocrine
Secretion onto a free surface, usually via a duct
Performed by epithelial cells
Can be merocrine, holocrine or apocrine
Merocrine
Exocytosis of vesicles and membrane transport of salts and water
Sweat and Salivary Glands
Holocrine
Entire cell ruptures
Sebaceous glands
Apocrine
Apical portion of cell pinches off
Mammary Gland
Capsule
Connective tissue that encloses larger glands
Septa separate glands into lobules
Tubular glands
Short, long or coiled tubes of secretory cells
Can be simple, branched or compound
Acinar/Alveolar glands
Rounded, sac-like glands
Can be simple, branched or compound
Compound glands
Branching ducts with multiple tubular, acing or tubuloacinar secretory portions
Zymogen
Proenzyme, inactive precursor. Stored in pancreas so pancreas isn’t damaged by active enzymes
Pancreas
Mixed exocrine-endocrine gland, produces digestive enzymes and hormones
Exocrine pancreas products
1.5L per day of products
Lipases
Protease zymogens - trypsinogen, chymotrypsin
Enterokinase
Activates trypsinogen into trypsin.
Trypsin activates the other proteases
Path of exocrine
Acing cells > Intercalated ducts > Intralobular duct > Interlobular ducts
Secretin
Causes centroacinar cells to secrete HCO3-
Intercalated ducts
Simple squamous epithelium
Intralobular ducts
Simple cuboidal
Interlobular ducts
Simple columnar
Endocrine pancreas products
Islets of Langerhans
Alpha cells - Glucagon - 30% - raises blood sugar, glycogen breakdown
Beta cells - Insulin - 65% - lowers blood sugar
Gamma cells - Somatostatin - 4% - inhibits alpha and beta cells
Acute Pancreatitis
Zymogens activated, causing autodigestion of pancreas, inflammation, lots of pain
Associated with gall stones and alcohol abuse
Pancreatic carcinomas
3% of cancers, mostly in females, poor prognosis
Diabetes mellitus
Disruption of insulin signaling by loss or malfunction of beta cells
Liver endocrine secretion and synthesis
Albumin, fibrinogen, prothrombin, angiotensin, cholesterol, VLDL, LDL
Liver storage
Glucose - glycogen
Lipids - fat droplets
Fat soluble vitamins
Iron
Oxidation and Reduction in Liver
Cytochrome P450
Conduction reactions in Liver
Bilirubin from hemoglobin breakdown converted to glucuronide
Kupffer cells
Liver macrophages
Liver exocrine activity
Bile salt excretion
Hepatic lobules
Portal triad, sinusoid surrounded by hepatocytes, and terminal hepatic vein
Liver blood supply
75% from portal triad
25% from hepatic artery
Hepatic Lobule Model
Basic structure-function
Endocrine function of hepatocytes as blood flows toward terminal hepatic vein
Hepatic Acinus Model
Emphasizes different O2 and nutrient content along sinusoid
Zone 1
Freshest blood closest to portal Biggest mitochondria Most active in glucuronidation Most active in endocytosis, most lysosomes Highest regenerative activity
Zone 3
Highest cytochrome P450, oxidation and reduction
Fat deposited here
Hepatocyte
Large cuboidal, lots of mitochondria, often have double nuclei
Sinusoids
Thin fenestrated endothelium, contain Kupffer cells
Space of Disse
Plasma filled perisinusoidal space between sinusoids and hepatocyte microvilli
Contains Stellate Cells
Stellate Cells
Store fat and fat soluble vitamins
Store 80-90% of body’s retinoids (Vitamin A)
Can transform into myofibroblasts to synthesize collagen in response to damage - cause of cirrhosis
Hepatic Portal Model
Emphasizes exocrine function
Flow of bile from lobules toward bile duct in the center
Flow of bile
Hepatocytes > Bile canaliculi > Canals of Hering > Bile duct > Left and right hepatic ducts > Common hepatic duct > Cystic Duct > Gallbladder > Cystic duct > Common bile duct > Hepatopancreatic ampulla > Duodenum
Cholangiocytes
Cuboidal/Columnar cells that line Canals of Hering and bile duct
Gallbladder
Epithelium has basolateral Na/K-ATPase pump for sodium and water recovery/bile concentration
Enterohepatic recirculation
Recycling of bile
Drugs and toxins released from liver though bile can be recycled too
CCK
Stimulates bile flow by inducing contraction of gallbadder smooth muscle
Cholestasis
Blockage of bile flow
Jaundice
Yellow discoloration of skin and eye sclera from bile leaking into the blood
Cholecystitis
Inflammation of gallbladder, causes upper right epigastic pain
Hepatitis
Inflammation of liver
Fibrosis
Excess collagen deposition in the liver
Cirrhosis
Extensive fibrosis in the liver
Leads to portal hypertension
Causes confused thinking and other mental changes - hepatic encephalopathy
