213 practice - vyuka-data.lf3.cuni.czvyuka-data.lf3.cuni.cz/cvse1m0001/213 endocrine glands and...
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Endocrine glands and liver213 Practice
Endocrine glands – cells producing signal molecules
• Arrangement:
• discrete organs – (thyroid gland) • clusters of cells (gonads, pancreas)• singly distributed cells: DNES in GIT
• endocrine tissue, endocrine glands = epithelial tissue (glandular form)
• fenestrated capillaries
Hormones– chemical structure – 4 classes. Corresponding cell morphology
● Small peptides, proteins, glycoproteinyhypothalamus, hypophysis, thyroid gland, parathyroid
gland, pancreas, DNES● Amino acid derivates or analogues
hypothalamus (dopamin), medulla of adrenal gland, DNES (serotonin)
● Steroids: ovaries, testes, cortex of adrenal gland● T3/T4 (thyroxine) - thyroid gland
DNES(diffuse neuroendocrinne system)
• Regulation of GIT secretion, motility and water and electrolyte metabolism (gastrin, secretin, GIP, cholecystokinin, motilin, VIP, serotonin, somatostatin, glucagon, substance P, ghrelin)
Neuroendocrine cells in smal intestine
Thyroid gland
Thyroid gland
• Follicles - content of colloid (thyroglobulin) – structural unit of the thyroid gland
• Cubic cells -follicular – thyroxine (T4) and tri-iodotyrosine (T3)
• Function: T3/T4 stimulates the oxidative phosphorylation within mitochondria ( resorption in gut, lipid metabolism, growth of the body, development of CNS
• Parafollicular cells– calcitonin –decrease of Ca level in blood –storage into bone and release into urine.
Follicular and parafollicular cells (C)
Secretion of thyroxine
• Thyroglobulin synthesis (RER, Gc)• Absorption of iodide from blood – active
transport• Iodide activation and its bound to AA tyrosine
on thyroglobulin (within colloide)• Thyroglobulin resorption and its break-up
within lysosomes. Release of T3 and T4
Thyroid gland
Suprarenal glands
Suprarenal gland
Suprarenal gland
• Medulla:
• Epinephrin (80%)• Norepinephrin (20%)
• Reaction to stress – Increase of blood pressure, frequency of heart
Cells of cortex
• SER• Lipids droplets• Mito with tubular cristae• No secretory granules• Function – transcriptional
factors – receptor in cytoplasma – transported into the nucleus
Suprarenal gland - medulla
Pancreas
• Exocrine gland (serous) with endocrine gland (islets of Langerhans)
• Difference from parotid gland: no striated ducts, intercalated ducts are longer, presence of intraacinar cells
• Presence of islets of Langerhans
Pancreas
• Exocrine gland – acinar– enzymes for digestion
• Endocrine gland – islets of Langerhans – cords of cells- controls of glucose level in blood and function of GIT
Pankreas
● A-cells – glucagon● B-cells – insulin● D-cells –
somatostatin● F-cells –
pancreatic polypeptide
● D-cells – somatostatin
F-cells – pancreatic polypeptideB-cells – insulinD-cells – somatostatinF-cells – pancreatic polypeptide
Islet of Langerhans - insulin
Islet of Langerhans – B cell
Islet of Langerhans - glucagon
Islet of Langerhans - somatostatin
Liver
Hepatic lobule - polygonal mass of hepatocytes, separated by connective tissue. Central vein in the centre of lobule Portal lobule – portal
trias in the centre(bile duct, vein, and artery)
Hepatic acinus: Heterogenity in the
enzyme content It depends on
oxygen saturation and concentration of nutriens in the blood
Structure
Plates formed from hepatocytes – radial disposition – spongy-like structure
Limiting plate – on the lobular periphery Hepatic sinusoids – discontinuous capillaries Kupffer cells (phagocytes)
Hepatocytes
Vascular space (baso-lateral) – brush border, space of Disse between hepatocyte and endothelial cell
Bile canaliculus – apical surface – microvilli and tight junctions – between two hepatocytes – prevent the return of bile back to blood
Hepatocyte function
Proteosynthesis – blood proteins (except for immunoglobulins): RER, GA
Metabolism of glucose: Glycogen (SER) Metabolism of lipids: SER and RER, GA Metabolism of xenobiotics: SER (microsomal
fraction) - cytochrome P450, peroxisomes (peroxidase)
Bile ducts
Bile canaliculus Bile ductiles (Hering´s) bile ducts – simple cuboidal
epithelium Interlobular bile ducts and wider – simple columnar
epithelium
Liver• Hepatocytes - histochemical
demonstration of ceruloplasmin • Hepatocytes: PAS
reaction - glycogen