This document provides an introduction to the endocrine system. It describes the endocrine system as consisting of glands that secrete hormones directly into the bloodstream to regulate distant target organs and tissues. Some key points mentioned include: - Hormones are chemical messengers that influence cellular activity, especially related to growth and metabolism. - Homeostasis is maintained by both the autonomic nervous system and endocrine system, with hormones providing slower, more precise adjustments. - Major endocrine glands include the pituitary, thyroid, parathyroid, adrenal, pancreas, pineal, thymus, ovaries and testes.

1. ENDOCRINE SYSTEM-
Introduction
PREPARED BY:
USHA RANI KANDULA,
ASSISTANT PROFESSOR,
DEPARTMENT OF ADULT HEALTH NURSING,
ARSI UNIVERSITY,ASELLA,ETHIOPIA,
EAST AFRICA.

2. INTRODUCTION
The endocrine system consists of glands
widely separated from each other with no
direct anatomical links.

4. Endocrine glands consist of groups of
secretory cells.

5. It is surrounded by an extensive network of
capillaries which facilitates diffusion of
hormones (chemical messengers) from the
secretory cells into the bloodstream.

6. They are commonly referred to as the
ductless glands ,
because the hormones are secreted and
diffuse directly into the bloodstream.

7. A hormone is formed in one organ or gland
and carried in the blood to another organ
(target organ or tissue),

8. It is quite distant, where it influences cellular
activity, especially growth and metabolism.

9. Most hormones are synthesised from amino
acids.
(amines, polypeptides and proteins; or
cholesterol-based lipids (steroids).

10. Homeostasis of the internal environment is
maintained partly by the autonomic nervous
system and partly by the endocrine system.

11. The autonomic nervous system is
concerned with rapid changes, while
hormones of the endocrine system are
mainly involved in slower and more precise
adjustments.

12. The endocrine system consists of a number
of distinct glands and some tissues in other
organs.

13. The hypothalamus is classified as a part of
the brain and not as an endocrine gland.
it controls the pituitary gland and has an
indirect effect on many others.

14. The ovaries and the testes secrete
hormones associated with the reproductive
system after puberty.

15. When a hormone arrives at its target cell, it
binds to a specific area, the receptor, where
it acts as a switch influencing chemical or
metabolic reactions inside the cell.

16. The receptors for water-soluble hormones
are situated on the cell membrane and those
for lipid-soluble hormones are inside the
cell.

17. The level of a hormone in the blood is
variable and self-regulating within its normal
range.

18. A hormone is released in response to a
specific stimulus and usually its action
reverses or negates the stimulus through a
negative feedback mechanism.

19. This may be controlled either indirectly
through the release of hormones by the
hypothalamus and the anterior pituitary
gland,

20. e.g. steroid and thyroid hormones,
 or directly by blood levels of the stimulus,
e.g. insulin and glucagon.

21. The effect of a positive feedback mechanism
is amplification of the stimulus and
increasing release of the hormone until a
particular process is complete and the
stimulus ceases,
e.g. release of oxytocin during labour.

23. The list of endocrine glands:
1 pituitary gland
1 thyroid gland
 4 parathyroid glands
2 Adrenal (suprarenal) glands
The pancreatic islets (islets of langerhans)

24. Con---
1 pineal gland or body
1 Thymus gland
2 ovaries in the female
2 Testes in the male.

25. HORMONES OF THE
HYPOTHALAMUS

26. HORMONES OF THE
HYPOTHALAMUS
GHRH- growth hormone releasing
hormone.
GHRIH -growth hormone release
inhibiting hormone (somatostatin).

27. TRH -thyroid releasing hormone.
CRH -corticotrophin releasing
hormone.

28. PRH -prolactin releasing hormone.
PIH -prolactin inhibiting hormone

29. LHRH -luteinising hormone releasing
hormone
GnRH-Gonadotrophin releasing
hormone

30. THANKING YOU