These slides explain the endocrine glands and their function.

1. puja kafle
BN 2nd year

3. INTRODUCTION
 It consist of glands, which are widely separated
from each other with no direct anatomical links.
 They are ductless glands, because the hormones
secreted directly into the blood stream.
 The study of endocrine glands and hormones is
knows as endocrinology.

4.  The function of endocrine system is the
production and regulation of chemical
substances called hormones.

5. GLANDS
 A gland is a group of epithelial cells which
produce special secretions . There are 3 types of
glands:-
• Endocrine gland
• Exocrine gland
• Heterocrine gland

6. ENDOCRINE GLAND
Glands that secret products(hormone) directly into
the blood rather than through a duct.
Example:
 Pituitary gland
 Pancreas
 Thyroid gland

7. EXOCRINE GLAND
Glands that secret their products into the duct.
Example:
 sweat glands
 salivary glands
 mammary glands
 stomach
 liver

8. HETEROCRINE GLAND/MIXED
GLAND
These are glands that perform both exocrine and
endocrine function.
Example:
 pancreas

9. Endocrine
 It is a ductless gland.
 Pour their secretions into
the blood.
 Target glands are located
away from the glands
 The secretion is hormone.
Exocrine
 It has duct.
 Pour their secretions directly
at the site of action.
 Target glands are very near to
the site.
 The secretion is enzymatic,
lubricants or excretory.
DIFFERENCE BETWEEN ENDOCRINE & EXOCRINE
GLAND

11. HORMONE
 Are the chemical messengers.
 Send message from one site to another site.
 Synthesized from amino acid and lipid.
 Formed in one organ then goes to target organ, after
that target organ produce cellular activities(growth
& metabolism).

12. There are 3 types of hormones.
 Steroid hormone
 Protein hormone
 Derivatives of amino acid tyrosine

13. STEROID HORMONE
 It is derived from cholesterol or its derivatives.
Example:
Corticosteroids and Sex hormones.

14. PROTEIN HORMONES
 It is the large or small peptides.
 The protein hormones secreted by
pituitary glands, parathyroid glands,
pancreas and placenta.

15. DERIVATIVES OF THE AMINO ACID
TYROSINE
 It is a type of hormones, which are the
derivatives of the amino acid called
tyrosine.
 Thyroid hormones and adrenal medullary
hormones are derived from tyrosine.

16. FUNCTION OF HORMONE
1. It stimulates growth in all organs or tissues.
2. It helps in metabolism.
3. It helps in reproduction.
4. It maintains homeostasis
5. It regulates water and electrolyte balance
within the body.
6. It helps in anti stress action.

18. ORGANS OF ENDOCRINE SYSTEM
1)Hypothalamus
2) Pituitary gland
3) Thyroid gland
4) Parathyroid gland
5) Adrenal gland
6) Islets of Langerhans of pancreas
7) Thymus
8) Pineal gland
9) Testes in male
10)Ovarian in female

20. 1. HYPOTHALAMUS
 A collection of specialized cells that is located
in the lower central part of the brain.
 It is the main link between the endocrine and
nervous system.
 The nerve cells of the hypothalamus control the
pituitary gland by stimulating or suppressing
the hormone secretion.

21.  The hormones from the hypothalamus govern
physiological function such as temperature
regulation, thirst, hunger, sleep, mood, sex drive
and the release of other hormones within the
body.

22. HYPOTHALAMUS RELEASING & INHIBITING
HORMONE
 Adrenocorticotrophic Releasing Hormone (ARH)
- It stimulates the anterior pituitary gland to secret its
adrenocorticotrophic hormone.
 Somatotropin Releasing Hormone/ Growth
Hormone Releasing Hormone (GRH)
-It stimulates the anterior pituitary to release its growth
hormone

23.  Thyrotropin Releasing Hormone (TRH)
-It stimulates anterior pituitary to secret thyroid
stimulating hormone(TSH).
 Gonadotrophin Releasing Hormone
- It stimulates anterior pituitary to secret its
follicle stimulating hormone and Luteinizing
hormone in ovaries and to secret its interstitial cells
stimulating hormones in testes.

24.  Prolactin Inhibiting Hormone
- It inhibits the secretion of prolactin from the
anterior pituitary gland.
 Growth Hormone Inhibiting Hormone
-It inhibits the pituitary release of growth hormone

26. 2. PITUITARY GLAND
Pituitary gland is also known as hypophysis.
It is situated in the hypophyseal fossa of the
sphenoid bone below the hypothalamus of the brain.
It measures about 1.3cm diameters and weight about
0.5gm.
It is also called the master of endocrine gland
because it produces a number of hormones, which
control the secretions of many other endocrine
glands of the body.

27. It is composed of 3 lobes:
I. The anterior lobe (adenohypophysis)
II. The posterior lobe (neurohypophysis)
III. The intermediate lobe

28. PARTS OF PITUITARY GLAND

30. THE ANTERIOR LOBE
 It is the largest part of the pituitary gland.
 It consists of glandular tissue.
 The hormones secreted by the anterior lobe of
pituitary gland are of two different kinds, first
controlling the functioning of other endocrine
glands and second controlling the targeting
organs.

31. Anterior pituitary secretes several hormones
like:
 Growth hormone
 Thyroid stimulating hormone
 Adrenocorticotrophic hormone
 Prolactin
 Gonadotrophic hormone
o Follicle stimulating hormone
o Luteinizing hormone

32. FUNCTION OFANTERIOR LOBE
HORMONES
1. Growth hormone
 it is necessary for the normal growth and
development of the body.
2. Thyroid stimulating hormone
 it regulates synthesis of thyroid hormone in the
thyroid gland.

33. 3. Adrenocorticotrophic hormone
 It stimulates adrenal cortex to synthesis adrenal
cortex hormones.
4. Prolactin
 It stimulates milk production in the breast.
5. Follicle stimulating hormone
 It stimulates growth of ovarian follicle in
female and helps in the production of sperm in
male.

34. 6. Luteinizing hormone
• It helps in ovulation.(release egg from ovary)
• Stimulate the production of testosterone.

35. POSTERIOR LOBE NEUROHYPOPHYSIS
 The posterior lobe secretes two different kinds
of hormones known as oxytocin and anti
diuretic hormone or vasopressin.
 These hormones are actually synthesized by the
cells in the hypothalamus and migrate to the
posterior lobe of the pituitary gland.

36. FUNCTION OF POSTERIOR LOBE
HORMONE
1. Oxytocin
 Contraction of uterus during delivery and
ejection of milk from the breast.
2. Anti-diuretic hormone/Vasopressin
 Decreasing urine output by increasing tubular
reabsorption in the kidney.
 Increasing blood pressure by contracting
capillaries and arterioles.

37. INTERMEDIATE LOBE
 The intermittent lobe is prominent in the
embryonic period of human life, but becomes
vestigial in the postnatal life.
 it secrets the melanocytes stimulating
hormone(MSH) which helps in the growth and
development of melanocytes which gives skin
its color.

38. NEGATIVE FEEDBACK MECHANISM

40. 3. THYROID GLAND
 Thyroid gland is butterfly in shape.
 The thyroid gland is situated in the neck in front
of the larynx and trachea at the level of 5th, 6th,
7th cervical and 1st thoracic vertebrae.
 The lobes are roughly cone shaped about 5cm
long , 3cm wide and weigh about 25 to 30gm.
 Consisting of two lobes one on either side of
the thyroid cartilage and upper cartilaginous
ring.

41. FUNCTION OF T3 AND T4
1. Increase in oxygen consumption and heat
production in the tissues.
2. Increase in basal metabolic rate(BMR).
3. Increase in the absorption and utilization of
glucose.
4. Increase in the cholesterol synthesis in the liver.
5. Synthesis of protein in the cells
6. Storage of iodine.

42. FUNCTION OF CALCITONIN
 Calcitonin lowers raised blood calcium level

44. 4. PARATHYROID GLAND
 There are 4 small parathyroid glands, each
weighing about 50g.
 It is located on posterior surface of the each lobe
of thyroid gland.
 They are surrounded by connective tissue capsule.
They are about 6mm long 4mm wide and 2mm
thick.
 Parathyroid glands produce a hormone called
parathormone (PTH).

45. FUNCTION OF PARATHORMONE
1. Increase absorption of calcium in the
gastrointestinal tract(GIT).
2. Increase absorption of calcium in the renal
tubules.
3. Increase absorption of calcium from bone into
extracellular fluid.

47. 5. ADRENAL GLAND
Adrenal glands are paired structure situated at
the tip of each kidney.
 It is also known as suprarenal gland.
These glands are small in size about 4cm in
length and 3cm in thickness.
 It weigh about 5 gm.

48. STRUCTURE OF ADRENAL GLANDS:
 The outer part of adrenal gland is known as
cortex and inner part is medulla.
 Histologically, the suprarenal cortex is divided
into 3 zones: zona glomerulosa , zona
fasciculate and zona reticularis.

49. HORMONES OF ADRENAL CORTEX
1. Mineralocorticoids
2. Glucocorticoids
3. Androgen (sex hormone)

50. HORMONES OF ADRENAL MEDULLA
Hormones secreted by adrenal medulla are:
1) Adrenalin
2) Nor-adrenalin

52. FUNCTION OF GLUCOCORTICOIDS
1.It increases blood glucose level.
2. It increases breakdown of protein into amino acid.
3. It helps in the breakdown of fat into fatty acid and
glycerol.
4. It blocks the inflammatory response to allergic
reaction.
5. It decreases body’s immunity.
6. It decreases the production of eosinophils and
lymphocytes.

53. FUNCTION OF MINERALOCORTICOIDS
The mineralocorticoids are group of hormones; the
main hormones of the group is aldosterone.
Functions of mineralocorticoids includes:
 Increase the reabsorption of sodium ions from the
renal tubule.
 Increase the potassium excretion through the renal
tubule
 Increase in extracellular fluid volume and blood
volume. This is finally leads to increase in blood
pressure.

54. FUNCTION OF ANDROGEN HORMONE
 Androgens are crucial for male sexual and
reproductive function.
 They are also responsible for the development
of secondary sexual characteristics in men,
including facial and body hair growth and voice
change.
 Androgens also affect bone and muscle
development and metabolism.

55. FUNCTION OF MEDULLARY HORMONES
1. Increase in oxygen consumption.
2. Increase the heart rate and blood pressure.
3. Diverting of blood to essential organs like heart,
brain and skeletal muscles.
4. Increase the basal metabolic rate.
5. Dilatation of the blood vessels of muscle, heart
and brain.
6. Dilation of the bronchioles
7. Constriction of the blood vessels of skin.
8. Dilation of pupil

58. 6. ISLETS OF LANGERHANS IN
PANCREAS
 The pancreas is the pale, yellowish or grayish
largest gland of the body.
 It is situated in the epigastric and left
hypochondriac region of the abdominal cavity.
 It is about 12-15cm long and 60-90gm in
weight.

59.  The islets of Langerhans are the collections of
the cells scattered throughout the pancreas,
although they are more plentiful in the tail than
in the body and head.
 The pancreas has about one million of islets of
Langerhans. Each islet of Langerhans consists
of four cells.

60.  Alpha cells: Secretes
glucagon hormone.
 Beta cells: Secretes
insulin hormone.
 Delta cells: Secretes
somatostatin hormone.
 Pancreatic polypeptide
cells: Secretes
pancreatic polypeptide
hormones

61. FUNCTION OF INSULIN
1. It converts excess glucose into glycogen in the
liver and muscles.
2. It decreases breakdown of glycogen
3. It prevents formation of new glucose from
protein and fat
4. It promotes fatty acid synthesis and increases
storage of fat.
5. It increases protein synthesis.

62. FUNCTION OF GLUCAGON
1. It increases glycogenolysis (break down of
glycogen into glucose) in the liver.
2. It increases gluconeogenesis (formation of
glucose from proteins) in the liver.
3. It promotes fatty acid oxidation resulting in
energy production and ketone body synthesis.
4. It increases the secretion of bile.
5. It inhibits the secretion of gastric juice.

63. Function of somatostatin
1. It inhibits the secretion of insulin and glucagon.
2. It decreases the motility of stomach, duodenum
and gallbladder..
3. It decreases the rate of nutrient absorption into
blood from gastrointestinal tract.

64. Functions of pancreatic polypeptide
hormone
The exact physiological action of pancreatic
polypeptide is not known. It is believed to
increase the secretion of glucagon and
inhibits the release of pancreatic juice.

66. 7. THYMUS GLAND
 It is a specialized cell of the immune system.
 it is located behind your sternum and between your
lungs is only active until puberty.
 After puberty the thymus starts to slowly shrink and
became replaced by fat.
 At birth it weighs about 10-12gms whereas during
childhood and adolescence it weighs 20 to 30 gm.
 Thymosin is the hormone of thymus & it
stimulates the development of disease fighting T
cells.

68. 8. PINEAL GLAND
 The pineal gland is a small body attached to the
roof of the third ventricle and is connected to it
by a short stalk containing nerves.
 The pineal gland is about 10mm long, reddish
brown in color and is surrounded by a capsule.
 The gland tends to be atrophy after puberty and
may be calcified in later life.

69.  The physiological role of the pineal gland is
still unclear.
 The pineal gland secrets melatonin, which is
thought to promote sleepiness and help regulate
the circadian Rhythm

71. 9. TESTES IN MALE
 The testes (testicle) are a pair of sperm
producing organ that maintain the health of the
male reproductive organ.
 The testes are twin oval shaped organs.
 They are located in scrotum which is the loose
pouch of the skin that hangs outside the body
behind the penis.

72. HORMONE OF TESTES
 Hormone secreted by testes is testosterone.
 This hormone is important for,
• spermatogenesis
• growth and development of male secondary
sexual characteristics.
• skeletal and muscular growth.

74. 10. OVARIES IN FEMALE
 The ovaries are the female gonads, located in
the pelvic cavity. Ovaries have two main
function in the body:- to house and release
eggs(ova) and to make hormones.
 They secrets estrogen and progesterone.