Microanatomy of the Endocrine System 2 PDF

So Microanatomy of the endocrine system 2 Dr Diana Bochynska, DVM, Dipl. ECVP This presentation has been developed and adapted from previous versions compiled by Dr M V...

So Microanatomy of the endocrine system 2 Dr Diana Bochynska, DVM, Dipl. ECVP This presentation has been developed and adapted from previous versions compiled by Dr M Valentine, Drs A Kessell, M Dennis, L Bogdanovic and C Fuentealba Figures and diagrams are from the sources were indicated or from the recommended texts that accompany the course This presentation is for educational purposes at Ross University School of Veterinary Medicine only  Learning objectives 1. List the primary endocrine organs. Explain the importance of the hypothalamus. Define: neurosecretory neuron, conducting neuron. Describe the origin of the two parts of the hypophysis. Name the cells of the adenohypophysis and the hormones produced by them. Name the main parts of the adenohypophysis and the neurohypophysis. Explain function of the hypothalamic-hypophyseal portal system. Give the location and function of the pineal gland. List the common types of hormones and their intracellular method of action. 2. Trace a releasing hormone from the hypothalamus to the acidophils/basophils of the adenohypophysis, then to the appropriate target organ for each, and the production of the third hormone of each (where applicable) and state the effect of the terminal hormone. 3. Trace the production of oxytocin/antidiuretic hormone (ADH) from the hypothalamus to its target cells and action on the mammary gland/kidney. 4. List the hormone-producing cells of the thyroid/parathyroid glands and their basic actions on the body. 5. List the regions of the adrenal gland, the hormones produced there, and their general action on the body. Identify in tissue sections the regions of the adrenal gland. 6. List the hormones of the pancreatic islets, kidney, and their general effects. List some hormones produced by GI tract enteroendocrine cells. 7. Be able to recognize in section: hypophysis, adenohypophysis, acidophils, basophils, chromophobes, melanotrophs, neurohypophysis, thyroid/parathyroid gland, follicular cells, parafollicular cells; adrenal gland, its zones and cell products; endocrine pancreatic cells. Thyroid and parathyroid glands both are in te tundra Parathyroid Thyroid Thyroid Endocrine 1 1 2 basophil z 3 4 Thyroid hormone synthesis Endocrine 2 Thyroglobulin is a protein made by the follicular cells of the thyroid gland. It is used by the thyroid gland to produce T3 and T4. When stimulated by thyroid stimulating hormone (TSH), the colloid is endocytosed from the follicular lumen into the surrounding thyroid follicular epithelial cells. The colloid is subsequently cleaved by proteases to release thyroglobulin from its T3 and T4 man_ The active forms of thyroid hormone: T3 and T4, are then released into circulation where they are either unbound or attached to plasma proteins, and thyroglobulin is recycled back into the follicular lumen where it can continue to serve as a substrate for thyroid hormone synthesis https://en.wikipedia.org/wiki/Thyroglobulin  T3 and T4 functions- reminder Endocrine 2 1. T3 increases the basal metabolic rate and, thus, increases the body's oxygen and energy consumption. 2. Thyroid hormones potentiate the effect of growth hormone and somatomedins to promote bone growth, epiphysial closure and bone maturation. 3. T3 increases the rate of protein synthesis. 4. T3 increases the rate of glycogen breakdown and glucose synthesis in gluconeogenesis. 5. T3 stimulates the breakdown of cholesterol and increases the number of LDL receptors, thereby increasing the rate of lipolysis. 6. T3 increases the heart rate and force of contraction, thus -adrenergic receptor levels in myocardium. 7. T3 affects the lungs and influences the postnatal growth of the central nervous system. It stimulates the production of myelin, the production of neurotransmitters, and the growth of axons. It is also important in the linear growth of bones. https://www.idexx.com/en/veterinary/analyzers/catalyst- one-chemistry-analyzer/catalyst-total-t4-test/  Thyroid gland o Regulated by TSH secretion o FOLLICLES (F) Thyroid o Cuboidal follicular cells secrete THYROGLOBULIN o Stored in follicle lumen (COLLOID) and combined with IODINE o Cuboidal follicular cells convert colloid to active THYROXINE increases basal metabolic rate, thermogenesis, gluconeogenesis o PARAFOLLICULAR 'C' cells (C) o Large pale, round o Secrete CALCITONIN (in response to increased plasma calcium) o Decreases plasma calcium o Decreased osteoclast activity--> calcium stored in bone o Increased renal excretion Follicular cells Colloid inside the follicles (ingredients for T3, T4 = thyroxin) C cell (parafollicular cell): produces Calcitonin Demo 1000x Thyroid Follicles: Less Active vs. Active Parafollicular cells aka C (clear) cells Less active thyroid follicle More active thyroid follicle Notpull paler and have vaccules Parathyroid gland Adjacent to thyroid gland 1 internal embedded within thyroid Thyroid 1 external away from thyroid CHIEF CELLS secrete PARATHORMONE Fab (PTH) in response to decreased plasma calcium PTH increases plasma calcium Chief cells Parathyroid Stimulates osteoclasts --> bone (internal) resorption and calcium release Increases intestinal uptake Increases renal resorption Thyroid  Endocrine 2 Parathyroid  Endocrine 2 https://www.dreamstime.com/stock-illustration-calcitonin-agonist-to- pth-parathormone-hormonal-regulation-blood-calcium-levels- regulation-calcium-levels-image59085590 what C cells cues towardleads Erasing Incrace calcium is Chief cells put Adrenal gland Endocrine 2 “ K hat at the kid Middle line topof mys  Endocrine 2 Adrenal glands The adrenal glands are composed of an outer cortex, derived from intermediate mesoderm, and an inner medulla, derived from neural crest ectoderm. The tissue architecture and staining affinities of the adrenal cortical parenchyma give rise to a pattern of zonation (from the outermost to innermost): 1. zona glomerulosa constitutes the outer cortex; 2. zona fasciculata inner cortex. 3. and zona reticularis. At the interface of the outer and inner cortices, there is a narrow band, the zona intermedia, of small, undifferentiated cells that make up the blastemic stem cells, which generate replacement parenchyma for both the inner and outer cortex. https://www.yourhormones.info/glands/adrenal-glands/ Histology of adrenal cortex Endocrine 2 Zona glomerulosa Endocrine 2 Arranged as tufts of epithelial cells (zona glomerulosa in ruminants and humans) or as arches of columnar cells (zona arcuata in horses, pigs, and carnivores) the outer cortex is the source of mineralocorticoids (aldosterone and corticosterone). Aldosterone- sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a central role in the homeostatic regulation of blood pressure, plasma sodium (Na+), and potassium (K+) levels. (Aldosterone is part of the renin–angiotensin–aldosterone system). Zona Fasciculata Endocrine 2 The zona fasciculata is composed of radiating columns (cords) of spherical cells, separated by sinusoids and bundled as fascicles; these cells produce glucocorticoids (cortisol and cortisone) Glucocorticoid's function – reminder Decreased sensitivity to Memory and pain attention Heart disease High blood High blood pressure sugar Suppression of Digestive issues immune system Zona Reticularis Endocrine 2 The zona reticularis is formed by polyhedral cells, arranged as a network of anastomosing cords and plates, separated by large sinusoids. These cells synthesize small amounts of androgens.  Stimulus Effect Na/K ATPase expression in distal tubule increased blood Low blood pressure / renin system volume Angiotensin II Cortisol release Gluconeogenesis in liver, decrease glucose use by muscle and fat, skeletal muscle break Stress signal perceived by down (amino acid use), immunosuppression. hypothalamus ACTH Immediate “flight or fight” response Fear / stress Sympathetic Gartner’s Histology  Adrenal cortex o Zona glomerulosa o Mineralocorticoid (ALDOSTERONE Na+/H2O resorption and K+secretion at distal convoluted tubule increase blood pressure) o Zona fasciculata o Glucocorticoid (CORTISOL liver, skeletal muscle, adipose, immune cells) o Zona reticularis o Sex steroids (WEAK ANDROGENS male characteristics)  GPCR- G protein coupled receptor basophil  Adrenal medulla Large sympathetic ganglia cells Vascular sinusoids Chromaffin (phaeochromocytes) cells secrete EPINEPHRINE and NOREPINEPHRINE EM H&E Pale, foamy cells (ADRENALINE and NORADRENALINE) Cortex Fight and flight response stimulate sympathetic Medulla nervous system  Endocrine 2 Adrenal gland medulla The adrenal medullary parenchymal cells are modified sympathetic neurons, constituting a large sympathetic ganglion. They synthesize epinephrine and norepinephrine and store these neurotransmitters as secretory granules. When exposed to chromium salts, the cells containing the granules stain boldly brown; accordingly, these and other similarly staining cells are referred to as chromaffin cells. At the periphery of the medulla and adjacent to medullary sinusoids, columnar cells (in horses, ruminants, and pigs) produce epinephrine; Rounded, epithelioid cells of the medulla produce norepinephrine. Epinephrine is formed by the columnar cells from norepinephrine by the action of a methyltransferase; Connective tissue trabeculae extend from the capsule, bearing arterioles and preganglionic, sympathetic axons that synapse with multiple medullary cells. Epinephrine and norepinephrine are the molecular mediators of the “fight or flight mechanism,” the immediate physiologic response to fear and stress, resulting in increased heart rate and the breakdown of glycogen in skeletal muscle and liver. Endocrine Organs Hypothalamus Secondary organs Pancreas Primary organs Testes 1. Pituitary gland (Hypophysis Ovaries cerebri) Kidneys Stomach 2. Pineal gland (Epiphysis Intestines cerebri) Thymus 3. Thyroid gland Heart Placenta 4. Parathyroid glands Adipose tissue 5. Adrenal glands  Endocrine 2 Endocrine pancreas "secondary endocrine organ" 2% endocrine I Islets of Langerhans (I) 98% exocrine Digestive enzymes I I  Pancreatic Islets of Langerhan o Alpha cells o GLUCAGON Glucagon o Cholecystokinin o Gastrointestinal peptide (mediating absorption, digestion and the disposal of ingested nutrients into tissues) o Beta cells o INSULIN o Delta cells o Somatostatin ( prevents the production of other hormones in your endocrine system and certain secretions in your exocrine system) Insulin o F cells ????? Immunohistochemistry using antibodies that stain hormones  -cells sense changes in plasma glucose concentration and response by releasing corresponding amounts of insulin https://www.ncbi.nlm.nih.gov/books/NBK279127/ Endocrine 2 “ Glucagon  Endocrine 2 “ Insulin https://www.google.com/search?q=insulin+functions+in+the+bodychart&tbm=isch&ved=2ahUKEwj Gv6eiuoSAAxWYFN4AHfqcCS0Q2- cCegQIABAA&oq=insulin+functions+in+the+bodychart&gs_lcp=CgNpbWcQA1CSB1j8F2D7GmgAc AB4AIABkAGIAdkMkgEEMC4xM5gBAKABAaoBC2d3cy13aXotaW1nwAEB&sclient=img&ei=vCOs ZMbxGZip-LYP-rmm6AI&bih=932&biw=1351#imgrc=ZQyjavwBesBBpM  Endocrine 2 Enteroendocrine cells Groups or individual hormone producing cells that act in the digestive system Gastrin (stimulates secretion of gastric juice ) Cholecystokinin Ghrelin (hunger hormone) Known by many names previously Diffuse neuroendocrine cells Enterochromaffin cells Enterochromaffin-like cells Amine precursor uptake and decarboxylation cells (APUD)  Endocrine 2 Unilocular (white) adipocytes secrete leptin -signal to the hypothalamus, regulating energy homeostasis for the organism. Leptin is one of the inputs to the hypothalamic “ “lipostat,” the output of which affects feeding behavior. Leptin binds to its cytokine receptor on neurons of the hypothalamus and inhibits food intake, for example, by inhibiting the release of the food intake–stimulating (orexigenic) hormones neuropeptide Y and agouti-related peptide (AgRP). Adipocytes HEART as secondary endocrine organ Atrial myocardial cells Secrete Atrial Natriuretic Peptide (ANP) ANP promotes Na+ and water loss, decreases blood pressure ANP Target: Distal convoluted tubules of kidneys KIDNEY and Endocrine System Kidneys produce 2 hormones: Renin - produced by juxtaglomerular cells - Part of Renin-Angiotensin-Aldosterone System (RAAS) - Involved in control of blood pressure Erythropoietin: - Controls erythropoiesis (red blood cell production) - It is a cytokine for red blood cells precursors Endocrine diseases usually result in excessive or insufficient production of HORMONES Hyperadrenocorticism (pituitary, adrenal) and Cushing’s disease Hypoadrenocorticism (pituitary, adrenal) and Addison’s disease Hyperthyroidism Hypothyroidism Hypoinsulinaemia and type 1 diabetes mellitus (pancreas) Diabetes insipidus (pituitary) Endocrine gland tumours (neoplasia)