The endocrine system maintains homeostasis through the secretion of hormones directly into the bloodstream. It works more slowly than the nervous system to regulate processes like metabolism, tissue function, sleep, and development. Key endocrine glands include the hypothalamus and pituitary gland in the brain, thyroid and parathyroid glands in the neck, pancreas, adrenal glands above the kidneys, ovaries/testes, pineal gland and others. Each gland secretes specific hormones that target tissues to produce responses like growth, energy use, stress response, and reproduction. The hypothalamus controls many glands through the hypothalamic-pituitary axis.

1. Endocrine system
Basics

2. 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

3. Hormones
= substances secreted by endocrine tissue into
the blood
act on the target tissue
produce a
specific response

5. http://antranik.org/the-endocrine-system/

6. CNS control via
Hypothalamo – Pituitary axis
http://www.ksshopfitters.co.za/hypothalamus-definition&page=3

7. Hypothalamus
• location -lines the walls of 3rd ventricle - above the pituitary gland
www.truthonthenet.com

8. Hypothalamic nuclei

9. Paraventricular Nucleus
Contains 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 vasopressindirectly into
the posterior pituitary gland.

10. Hypothalamo – pituitary axis

11. Hypophyseal (pituitary) hormones
http://www.bio.miami.edu/tom/courses/protected/ECK/CH09/figure-09-15.jpg

12. 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

13. Thyroid gland
two major hormones:
Thyroxine (T4)
Triiodothyronine (T3)
+
Calcitonin - keeps
normal calcium levels
www.vcahospitals.com

14. 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

15. 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

16. Parathyroid glands
PTH - parathormone
↓
increases blood calcium
blogs.scientificamerican.com

17. Adrenal Gland
- located above the upper pole of the
kidney
- consists of the adrenal cortex and
adrenal medulla
regulation of fluid volume
stress response
http://physicianjobster.com/physician-guidelines/pathophysiology/the-
anatomy-and-physiology-of-adrenal-gland/

18. HPA axis
http://kcampbell.bio.umb.edu

19. cholesterol–steroid ring
Adrenal Cortex
Steroid Hormone Production
• Mineralocorticoids
• Glucocorticoids
• Sexosteroids

20. 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

21. Adrenal cortex - hormones
Mineralocorticoids
↓
aldosterone
hydro-electolitic balance

23. Adrenal cortex - hormones
Glucocorticoids
↓
cortisol
hydrocortisone
stim. gluconeogenesis
& h blood glucose
anti-inflammatory
anti-immunity
anti- allergy
http://www.wardelab.com

24. 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

25. 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

26. Adrenal cortex - hormones
Sexosteroids (small amounts)
↓ ↓
testosterone DHEA
(dehydroepiandrosterone)
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

27. 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

28. Adrenal medulla
(modified sympathetic ganglion)
http://faculty.pasadena.edu

29. Adrenal medulla - hormones
Catecholamines
↓
adrenaline
(epinephrine)
noradrenaline
(norepinephrine)
http://www.angelfire.com/sc3/toxchick/e
ndocrinology/endocrinology03.html
E – major determinant of response to
metabolic or global challenges
NE - response to reflexive changes in
cardiovascular tone

30. Adrenoceptor-Signal transduction
php.med.unsw.edu.au

31. Adrenal stress response
http://encyclopedia.lubopitko-bg.com/AdrenalGlands.html

32. Gonads
ovaries - testes
Sexual hormones
↓
testosterone
estrogen
progesterone
(corpus luteum, placenta)
promotes protein syntesis
maturation of sex organs
sperm development
maturation sex organs
http://health-
menstrual cycle
7.com/Textbook%20of%20Endocrinology/HYPOPHYSEOTROPIC%20HO
RMONES%20AND%20NEUROENDOCRINE%20AXES/13

35. Prolactin
Oxytocin
↓
PRL - milk synthesis
Oxt - milk ejection

36. 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

37. ADH
antidiuretic hormone
vasopressin
↓
regulates the body’s
retention of water
bio1152.nicerweb.com

38. Pineal gland
melatonin
↓
sleep-wake clock
www.coe.s.u-tokyo.ac.jp

39. Melatonin effect
www.jpp.krakow.pl

40. Pancreas
insulin
glucagon
↓
normal level of
blood glucose

41. www.precisionnutrition.com

42. anjungsainssmkss.wordpress.com