Endocrine system basics

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

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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

↓

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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

www.precisionnutrition.com

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