Ingegneria delle tecnologie per la salute

Fondamenti di anatomia e istologia

Apparato endocrino homeostasis homeostasis overview

Cellular signalling Lipid-soluble hormones Water soluble hormone overview Negative feedback Positive feedback X-RH : releasing hormones

X-SH : stimulating hormones (acting on endocrine gland)

X : Hormones (acting on target cell)

Pituitary gland-hypophysis Pituitary gland-hypophysis Pituitary gland-hypophysis

ectoderm

endoderm Pituitary gland-hypophysis

Size of a pea, 0.5 g wheigth On the basis of the hypothalamus, in the sella turcica (sphenoid bone) Strictly related with the optic chiasm (bitemporal hemianopsia in pineal adenomas Posterior pituitary gland Posterior hypophysis: hormones

ADH: peptide, anti-diuretic hormone, aka Arginine-Vasopressine (AVP). Stop water reabsorption in collector tubules of kidney. Weak vasoconstriction.

OT: oxytocin, peptide, uterine contraction in childbirth. Positive feedback Anterior pituitary gland

Portal system Anterior hypophysis: hormones

Pineal gland - epiphysis

Produces melatonin that regulates circadian rythm thyroid

Anterior to the trachea, two lobes, under the cricoid cartilage. Endodermic origin

Anterior: platisma and skin Posterior: trachea, superior and inferior laringeal nerves, parathyroids lateral: great vessel of the neck

parathyroids

Four glands, endodermic, 6x3x1mm, posterior to the thyroid. Produce parathormone (PTH) in that regulate calcium metabolism PTH: increases serum calcium levels Calcitonin: produced by parafollicolars cell of thyroid Vitamin D

Calcium reabsorption

stimulates osteoclasts

Adrenal glands

Medial to the kidney, 5x3 cm Two different components: medulla and cortex. Medulla: ectodermal origin (nervous system) Cortex: mesodermic origin Adrenal glands

Cortex: under the control of CRH and ACTH secerned by hypothalamus and hypophysis

Medulla: ddriven by autonomous nervous system, it can considered a special sympathetic ganglion Adrenal glands

Corticoids hormones: all derived from cholestherol, lipid hormones

Mineralcorticoids: Aldosterone, regulates Na reabsorption in kidneys and regulates angiotensin secretion  blood pressure

Glucocorticoids: cortisol, stress hormone, reguates glucose levels and metabolism

Androgens: dehydroepiandrosterone, androstenedione. In female they are converted into estrogens periferically.

Endocrine pancreas Pancreatic islets Pancreatic islets

About 3.000.000, 0.1 mm diameter 4.5% of the pancreatic volume Endodermic origin

Alpha cells: produce glucagon (15–20% of total islet cells). Arise serum glucose Beta cells producing insulin and amylin (65–80%): reduce serum glucose Delta cells producing somatostatin (3–10%): inhibits all secretions PP cells (gamma cells) producing pancreatic polypeptide (3–5%): inhibits pancreatic secretions Epsilon cells producing ghrelin (<1%): hunger hormone

Paracrine function: glucagon inhibits beta cell, insulin inhibits alpha cell, somatostatin inhibits alpha and beta. Enteroendocrine cells

Enteroendocrine cells are specialized endocrine cells of the gastrointestinal tract and pancreas. They produce gastrointestinal hormones or peptides in response to various stimuli and release them into the bloodstream for systemic effect, diffuse them as local messengers, or transmit them to the enteric nervous system

K cell: secrete incretin that promotes trygliceride storage I cell: secrete Cholecystokinin, secretion of bile G cell: (stomach), secrete gastrin N cell: neurotensin, smooth muscle contraction S cell: secrete secretin, stimulates exocrine pancreas secretion