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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