Endocrine system http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_mckinley/f20-2a_negative_feedbac_c.jpg http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_mckinley/f20-2b_positive_feedbac_c.jpg Hormonal regulation Endocrine glands •Glands w/o ducts •Secretory cells release their products, hormones, into the extracellular space and blood stream •Alternatively, the hormones may affect neighbor cells (paracrine) •Structure: •c.t. – capsule + septs •irregular clumps or cords of the cells •network of capillaries •fenestrated capillaries •sinusoids http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_mckinley/f20-1_endocrine_system_c.jpg Hypophysis – pituitary gland HypDevAni fig1 f20-4_pituitary_gland_c Pituitary gland – anterior pituitary lChromophil cells l- Acidophilic cells (produce proteins) lsomatotrophs lmammotrophs (or lactotrophs) l- Basophilic cells (produce glycoproteins) lthyrotrophs produce thyroid stimulating hormone (TSH or thyrotropin). lgonadotrophs produce follicle stimulating hormone (FSH) and luteinizing hormone (LH) lcorticotrophs (or adrenocorticolipotrophs) l lChromophobe cells hya40he Pituitary gland – anterior pituitary Adenohypophysis adenoh Adenohypophysis adeno - oranž G+PAS oranž G + PAS Neurohypophysis x Adenohypophysis adenohypofýza - přechod Neurohypophysis - structure lStructure lunmyelinated nerve fibres derived from neurosecretory cells of the supraoptic and paraventricular hypothalamic nuclei lpituicytes /neuroglia/ l lFunction lTwo hormones are oxytocin, which stimulates the contraction of smooth muscle cell in the uterus and participates in the milk ejection reflex, and antidiuretic hormone (ADH or vasopressin), which facilitates the concentration of urine in the kidneys and, thereby, the retention of water. l lUsually only the oval or round nuclei of the pituicytes are visible. Hypothalamic nerve fibres typically terminate close to capillaries. Scattered, large masses represent dilations of these nerve fibres - Herring bodies - are filled by small vesicles which contain the neurosecretory products of the hypothalamic cells. Neurohypophysis Neurohypophysis neurohypofýza Herring bodies pineal+gland+et+on+earth Pineal body (epiphysis cerebri) Pineal body lis surrounded by pia mater, which functions as its capsule and which sends c.t. septa into the pineal body, subdividing it into lobules ltwo cell types and unmyelinated nerve fibers lpinealocytes (about 95% of the cells; large, light and round nuclei) lastrocytes (glial cells; dark, elongated nuclei) lboth pinealocytes and astrocytes have long processes which give the tissue between the nuclei its "stringy" appearance lthe most prominent secretory product of the pineal body is melatonin - decrease secretory activity in most other endocrine glands and may "delay" puberty through antigonadotrophic effects. lsecretory activity in the pineal gland is stimulated by darkness and inhibited by light pin42he Pineal body HP_img6-17-4 brain sand (or acervulus cerebri or corpora arenacea) - calcium-containing concretions which increase in size and number with age /are radioopaque/ Thyroid gland lThyroid hormones (T3, T4) increase metabolic activity in almost all tissues and organs. Many of the other effects of the hormones are secondary to an increased oxygen consumption of the affected cells. lC cells produce the hormone calcitonin, which decreases blood calcium concentration thyr lobes→lobules - follicles 20 g 8966 Thyroid gland HP_img6-17-5 Follicles /50 µm to about 1 mm/, which are separated by scant interfollicular c.t. It consists of a simple cuboidal epithelium which surrounds a lumen filled with a viscous substance, colloid. Thyroid gland - follicles HP_img6-17-6 C cells (or parafollicular cells) are only few of them, typically situated basally in the epithelium, without direct contact with the follicular lumen. They are always situated within the basement membrane, which surrounds the entire follicle. thyroglobulin, consists of triiodothyronine T3 and tetraiodothyronine (thyroxine) T4 C-cells Glandula thyreoidea Image_000198A Parathyroid gland thyroid+parathyroid HP_img6-17-7 c.t. /capsule+septs/ network of the capillaries cords or clumps of the cells 6 mm, 130 mg /total weight/ Parathyroid gland lChief cells are the most numerous type. They are small cells /7-10 µm/ with round, big and centrally placed nucleus and a small amounts of cytoplasm /very weakly acidophilic/. lOxyphilic cells l less frequent (occurring first in children 6-7 years old and increasing with age), larger - their cytoplasm is strongly acidophilic, the nucleus is round. They contain large amounts of mitochondria and glycogen. lFat cells (adipocytes) pty20he Glandula parathyreoidea parathyroid Parathyroid gland Synthesise parathyroid hormone (PTH or parathormone) which is of pivotal importance for normal calcium concentrations in the fluids and tissues of the body. The effect is mediated by a stimulation of osteoclastic bone resorption, intestinal calcium uptake and calcium resorption in the kidneys nm0800_860_F1 Suprarenal gland c.t. : capsule+septs network of capillaries cords of the cells Illu_adrenal_gland Suprarenal gland - cortex Zona glomerulosa (1/10) Zona fasciculata (6/10) Zona reticularis (3/10) 400px-Adrenal-core Glandula suprarenalis adrenalcortex2 Suprarenal gland - function lHormones produced in the cortex are all steroids - cortical cells contain large amounts of AER, lipid droplets and mitochondria with tubules. Since the hormones are synthesised in the cortex they are more termed corticosteroids. l mineralocorticoids l glucocorticoids lThe most important mineralocorticoid is aldosterone, which regulates the resorption of sodium and excretion of potassium in the tubules of the kidney – zona glomerulosa. lThe most important glucocorticoids is cortisol, which has a wide range of effects on most cells of the body. Cortisol effects protein catabolism in almost all cells aside from liver cells, gluconeogenesis, glycogen storage, mobilisation of fat from adipocytes, anti-inflammatory effects, inhibition of allergic reactions – zona fasciculata. lSmall amounts of androgens, oestrogens and progesterone are also produced – zona reticularis. lBoth the zona fasciculata and zona reticularis depend on ACTH. Suprarenal gland - medulla lCells are arranged in strands or small clusters in reticular c.t. - chromaffin cells because the granules of these cells can be stained with potassium bichromate and also some ganglion cells. lChromaffin cells correspond to the adrenaline - (80%) and noradrenaline - producing cells of the medulla. The two groups cannot be distinguished using routine histology. lChromaffin cells are innervated by preganglionic sympathetic fibres and correspond functionally to postganglionic neurones. The correspondence is not only functional - chromaffin cells are, like ganglion cells of the PNS, derived from neural crest cells. HP_img6-17-11 Islets of Langerhans lGroups of pale cells lcca 1,5 ´ 106 lThin c.t. capsula lEpithelial-like cords of cells lSinusoids lCell types: A, B, D, PP 0194_0001 0195_0001 A cells: 20%, glukagon B cells: 60-70%, insulin D cells: minor, somatostatin PP cells: minor, pancreatic polypeptide Islets of Langerhans List of slides l52. Hypophysis cerebri l53. Epiphysis l54. Glandula thyreoidea l55. Glandula parathyroidea l56. Corpus suprarenale l23. Pancreas – islets of Langerhans