The endocrine system works with the nervous system to regulate and control bodily functions through the secretion of hormones. The major endocrine glands include the hypothalamus, pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries, and testes. Hormones are chemical messengers that are released into the bloodstream and target specific cells and tissues to bring about longer-term physiological adaptations in the body.

2. ENDOCRINE SYSTEM
by: 14-arid-2068,69,71,72

3. IMPORTANCE
 In order to survive, animals must
constantly adapt to changes in the
environment.
 nervous and endocrine systems both
work together to bring about this
adaptation.
 nervous system responds rapidly
 the endocrine system brings about longer-
term adaptations by sending out chemical
messengers called hormones into the
blood stream.

4. HORMONES
 Hormones are chemicals messengers that
are secreted by endocrine glands and
function in extremely small concentration

5. RESPONSE OF A HORMONE
 A nerve impulse travels rapidly . In contrast,
hormones act more slowly and their effects
may be long lasting.
 Target cells respond to minute quantities of
hormones and the concentration in the blood
is always extremely low.

6. ENDOCRINE GLANDS
 The major glands of the endocrine system
are:
 1. Hypothalamus
 2. Pituitary gland
 3. Pineal gland
 4. Thyroid gland
 5. Parathyroid glands
 6. Thymus gland
 7. Adrenal glands

7. ENDOCRINE GLANDS
 8. Pancreas
 9. Liver
 10. Kidneys
 11. Heart
 12. Testes
 13. Ovaries

8. 1. HYPOTHALAMUS
 The hypothalamus secretes hormones that
stimulate or suppress the release of
hormones in the pituitary gland, in addition to
controlling water balance, sleep,
temperature, appetite, and blood pressure.

10. LOCATION
 The hypothalamus is located in the brain.
This small but vital region of the brain lies
just above the pituitary and provides the link
between the nervous and endocrine
systems.

11. 2. PITUITARY GLAND (HYPOPHYSIS)
 The pituitary gland is often called the
“master” endocrine gland because it controls
many of the other endocrine glands in the
body.
 LOCATION
 The pituitary gland is a pea-sized structure
that is attached by a stalk, the infundibulum,
to the underside of the cerebrum of the brain

12. DIVISION
 The pituitary gland is divided into three lobes
with different functions;
 (i) Anterior pituitary (Adenohypophysis)
 (ii) Posterior pituitary (Neurohypophysis)
 (iii) Intermediate pituitary (Pars intermedia)

13. DIVISION

14. ANTERIOR PITUITARY LOBE
(ADENOHYPOPHYSIS)
 The anterior pituitary lobe secretes
hormones that regulate a wide range of
activities in the body.

15. POSTERIOR PITUITARY LOBE
(NEUROHYPOPHYSIS)
 The hormones of the posterior pituitary lobe
are not secreted in this lobe, merely stored.

17. 3. PINEAL GLAND (EPIPHYSIS)
 The pineal is a small ovoid or fusiform mass which
is found deep within the brain.
 It is sometimes known as the ‘third eye” as it
responds to light and day length.
 LOCATION:
 The pineal gland (epiphysis) is situated in a central
depression between the thalami (sing.
 thalamus) and corpora quadrigemina (also called
colliculi).

19. 4. THYROID GLAND
 The thyroid is a very vascular ductless gland,
firm in texture and dark red-brown in color.
 LOCATION
 It is situated below the larynx (voice box), on
the anterior part of the trachea, to which it is
 loosely attached.

22. 5. PARATHYROID GLAND
 The parathyroid are pale in color and not so
dense as thyroid.
 LOCATION
 They are small glandular bodies found in the
thyroid gland.

23. 6. THYMUS GLAND
 The thymus is a ductless gland which has
close resemblance to the lymphoid tissue.
 LOCATION
 It is situated in the anterior mediastinal
 space of the thoracic cavity.

25. FUNCTIONS
 The main function of the thymus is to
 provide an area for T lymphocyte
 maturation, and is vital in protecting
 against autoimmunity.
 The stock of T-lymphocytes is
 built up in early life, so the function of
 the thymus is diminished in adults. It is
 largely degenerated in elderly adults

26. CONT…
 and is barely identifiable, consisting mostly of
fatty tissue; however it continues to function
as
 an endocrine gland important in stimulating
the immune system.

27. 7. ADRENAL GLANDS
 The adrenal glands are two small, bean-
shaped organs.
 LOCATION
 The right adrenal gland lies along the
anterior part of the medial border of the
kidney, at the
 angle of the junction of the right renal vein &
caudal vena cava. The left one is usually
longer,
 flatter and somewhat bent.

30. DIVISION
 Each adrenal body presents two differential
parts;
 (i) An outer cortex
 (ii) An inner medulla

31. PANCREAS
 The pancreas is an oblong, pinkish organ
that lies in the first bend of the small intestine
 LOCATION
 The pancreas lies entirely to the right of the
median plane.
 It mostly lies on the visceral surface of the
liver and attached with the duodenum.

34. 9. LIVER
 The liver is the largest gland of the body,
constituting 1-2 % of total adult body
weight.
 LOCATION
 The liver is always located immediately
caudal to the diaphragm (in contact with it)
and tends
 to be located on the right side as the reti

36. 10. KIDNEYS
 The kidneys are a pair of excretory organs
situated in the dorsal part of the abdominal
cavity
 on each side of the aorta and caudal vena cava,
just ventral to the first few lumber vertebrae.
 LOCATION
 The kidneys usually lie ventral to the first three
lumbar transverse processes; against the
 dorsal wall of the abdominal cavity.

38. 11. HEART
 The heart is a conical hollow muscular organ
that pumps blood to various parts of the body
to
 meet their nutritive requirements.
 LOCATION
 The heart is situated in the middle
mediastinum and is enclosed within the
pericardium.

40. 12. TESTES
 The testes (testicles) are the male gonads.
They are homologue with the ovary of the
female.
 The spermatic cord suspends each individual
testis within the scrotum.
 LOCATION
 The testicles are held near to the sigmoid (S-
shaped) flexure of the penis.

42. 13. OVARIES
 The ovaries, like the testes in the male, are
the primary organs of reproduction in the
female.
 LOCATION
 The ovaries are paired glands usually found
in the lumber region of the abdominal cavity,
a
 short distance caudal to the kidneys. These
are almond-shaped.