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Endocrine systemBasics
The regulating systems of the body are:
► Nervous System electrochemical impulses rapid control
► Endocrine System hormones
slow control
Endocrine System => maintains the body in balance
Hormones
= substances secreted by endocrine tissue into the blood
act on the target tissue
produce a
specific response
http://antranik.org/the-endocrine-system/
http://www.ksshopfitters.co.za/hypothalamus-definition&page=3
CNS control via Hypothalamo – Pituitary axis
Hypothalamus• location -lines the walls of 3rd ventricle - above the pituitary gland
www.truthonthenet.com
Hypothalamic nuclei
Paraventricular NucleusContains 2 types of cells:
– Parvocells ► Medial - neurons secrete
hypothalamic releasing hormones
► Dorsal and ventral - some neurons secrete oxytocin and vasopressin
– Magnocells ► Neurons control endocrine
function by secreting oxytocin and vasopressin directly into the posterior pituitary gland.
Hypothalamo – pituitary axis
http://www.bio.miami.edu/tom/courses/protected/ECK/CH09/figure-09-15.jpg
Hypophyseal (pituitary) hormones
Released hormones from the anterior pituitary :• Thyroid-stimulating hormone (TSH): stimulates the thyroid gland;• Adrenocorticotrophic hormone (ACTH): stimulates the adrenal glands;• Follicle-stimulating hormone (FSH): promotes development of eggs within the ovaries
stimulates the secretion of estrogen
stimulates the sperm production in the testes;• Luteinizing hormone (LH): causes ovulation in women and prepares the uterus
for pregnancy;• Prolactin (PRL): causes the development of breast tissue and the production of milk;• Growth hormone (GH): causes growth in almost all tissues in the body
promotes increase in cell size and cell number.
The posterior pituitary hormones :• Anti-diuretic hormone (ADH): causes the kidneys to keep more water in the body;• Oxytocin: causes contractions in the uterus of a pregnant woman
causes the release of milk from the breast.
The paraintermedia hormone:• Melanocyte – stimulating hormone: stimulates melanogenesis
Thyroid gland
www.vcahospitals.com
two major hormones: Thyroxine (T4) Triiodothyronine (T3)
Calcitonin - keeps normal calcium levels
+
Thyroid hormones - metabolic actions
• regulate Basal Metabolic Rate • ↑ oxygen consumption in most target tissues• ↑ sensitivity of target tissues to catecholamines
→ by elevating lipolysis
glycogenolysis
gluconeogenesis
Thyroid hormones - development actions
• critical for normal development of the skeletal system and musculature
• essential for normal brain development• regulates synaptogenesis
neuronal integration
myelination
cell migration
=> neonatal hypothyroidism → Cretinism
Parathyroid glandsPTH - parathormone
blogs.scientificamerican.com
↓increases blood calcium
Adrenal Gland- located above the upper pole of the kidney
- consists of the adrenal cortex and adrenal medulla
Þregulation of fluid volume
Þ stress response http://physicianjobster.com/physician-guidelines/pathophysiology/the-anatomy-and-physiology-of-adrenal-gland/
HPA axis
http://kcampbell.bio.umb.edu
• Mineralocorticoids • Glucocorticoids• Sexosteroids
cholesterol–steroid ring
Adrenal Cortex Steroid Hormone Production
Steroidogenesis in the human adult adrenal cortex
Keegan CE, Hammer GD - Recent insights into organogenesis of the adrenal cortex, Trends in endocrinology, Vol 13, issue 5, 2002, pag: 200-208
Mineralocorticoids ↓ aldosterone
Adrenal cortex - hormones
hydro-electolitic balance
Glucocorticoids ↓
cortisolhydrocortisone
Adrenal cortex - hormones
http://www.wardelab.com
stim. gluconeogenesis & h blood glucoseanti-inflammatoryanti-immunityanti- allergy
Neuroendocrine regulation of adrenal glucocorticoid (GC) and its physiological roles
Hoon SG et al. - The adrenal peripheral clock: Glucocorticoid and the circadian timing system, Front in Neuroendo, 2011, Vol 32, issue 4, pag: 451-465
Multiple mechanisms underlying the circadian regulation of glucocorticoid (GC) biosynthesis and secretion
Hoon SG et al. - The adrenal peripheral clock: Glucocorticoid and the circadian timing system, Front in Neuroendo, 2011, Vol 32, issue 4, pag: 451-465
Sexosteroids (small amounts)
↓ ↓testosterone DHEA
(dehydroepiandrosterone)
Adrenal cortex - hormones
development of secondary sexual characteristics
Kennedy, MJ - Hormonal Regulation of Hepatic Drug-Metabolizing Enzyme Activity During Adolescence; Clinical Pharmacology & Therapeutics 84, 662-673 (December 2008) | doi:10.1038/clpt.2008.202
Developmental ontogeny of the hypothalamic–pituitary–gonadal (HPG) axis and adrenal androgen secretion. GnRH, gonadotropin hormone–releasing hormone; LH, luteinizing hormone.
Kennedy, MJ - Hormonal Regulation of Hepatic Drug-Metabolizing Enzyme Activity During Adolescence; Clinical Pharmacology & Therapeutics 84, 662-673 (December 2008) | doi:10.1038/clpt.2008.202
Adrenal medulla (modified sympathetic ganglion)
http://faculty.pasadena.edu
Adrenal medulla - hormones
Catecholamines
↓ adrenaline
(epinephrine)
noradrenaline (norepinephrine)
E – major determinant of response to metabolic or global challengesNE - response to reflexive changes in cardiovascular tone
http://www.angelfire.com/sc3/toxchick/endocrinology/endocrinology03.html
Adrenoceptor-Signal transduction
php.med.unsw.edu.au
http://encyclopedia.lubopitko-bg.com/AdrenalGlands.html
Adrenal stress response
Gonadsovaries - testes
http://health-7.com/Textbook%20of%20Endocrinology/HYPOPHYSEOTROPIC%20HORMONES%20AND%20NEUROENDOCRINE%20AXES/13
Sexual hormones ↓ testosterone estrogen progesterone(corpus luteum, placenta)
promotes protein syntesismaturation of sex organssperm development
maturation sex organsmenstrual cycle
ProlactinOxytocin
↓
PRL - milk synthesisOxt - milk ejection
STH – Somatotropin - Growth hormone
growth of almost all tissues in the body that are capable of growing
promotes increase in cell size
cell number
↓
www.hghbodybuilding.com
ADH antidiuretic hormone
vasopressin
bio1152.nicerweb.com
↓
regulates the body’s retention of water
Pineal gland melatonin
↓
www.coe.s.u-tokyo.ac.jp
sleep-wake clock
Melatonin effect
www.jpp.krakow.pl
Pancreas
insulinglucagon
↓
normal level of blood glucose
