The document provides an overview of the endocrine system. It describes that the endocrine and nervous systems work together to coordinate body functions. The endocrine system releases hormones to control activities, unlike the nervous system which uses neurotransmitters. There are two types of glands - exocrine glands which secrete through ducts, and endocrine glands which secrete directly into blood. Key endocrine glands and tissues discussed include the pituitary, thyroid, parathyroid, adrenal glands, pancreas, ovaries, testes and others. The roles, secretions and regulations of various hormones are explained in detail.

1. Endocrine System
By: Mr. Tengse Kiran A.
(Assistant Professor)
DJPS College of Pharmacy (B. Pharm)
Pathri

2. Introduction
• The nervous and endocrine systems act
together to coordinate functions of all body
systems.
• At synapses, nerve impulses trigger the
release of mediator (messenger) molecules
called neurotransmitters
• The endocrine system also controls body
activities by releasing mediators, called
hormones, but the means of control of the two
systems are very different.

3. Bodyglands
and secrete their
• Twotypes of bodyglands:
• Exocrineglands:
• These are the glands which possess ducts
secretions through ducts.
• E.g.Salivarygland, Sweatglands& Sebaceousglands
• Endocrineglands:
• These are ductless glands & secrete their secretions directly in the
surrounding spaces which is further distributed throughout the body by
blood.
• E.g.Pituitary gland,Thyroid gland, Parathyroid gland,Adrenal gland and
Pinealgland

4. Bodyglands
• Several organs & tissues are not endocrine gland but
contain cells that secretehormones.
Hypothalamus
Thymus
Pancreas
Ovaries
Testes
Kidneys
Stomach
Liver
Small Intestine
Skin
Heart
Adiposetissue
Placenta

6. Circulating and local Harmones
• Circulating hormone: They pass from the
secretory cells into the bloodstream.
• Local hormone: They act locally on
neighbouring cells or on the same cell
without entering the bloodstream.
• Hormone those act on the neighbouring cells
called as paracrine hormones.
• Hormone those act on the same cell called as
autocrine hormones.

7. Functionsofhormones
Helps to regulate:
• Chemical composition & volume of interstitial
fluid
• Metabolism & energy balance
• Contraction of smooth & cardiac muscle fibers
• Immune system activities
• Growth & development
• Regulate function of reproductive systems
• Helps to establish circadian rhythms

8. Chemicalclassesofhormones
• Divided into 2classes;
Lipid soluble
Water soluble

9. Lipid Soluble Harmones
It includes;
1.Steroid hormone:
• Theseare derived from cholesterol.
• Structure similar to that of cholesterol.
• Adrenal glands: Cortisol &Aldosterone
• Ovaries: Estrogen & Progesterone
• Testes: Testosterone

10. 2. Thyroid hormone:
• T3and T4are synthesized from thyroid gland.
3.Nitric Oxide:
• It is both hormone &neurotransmitter.
• Itis synthesized by the enzyme nitric oxide
synthase

11. WatersolubleHormone
• It includes;
1. Amino Hormones:
• Theseare synthesized from certain aminoacids.
• E.g.Histamine is synthesized from Histidine by mast
cells & platelets.
2. Eicosanoid hormones:
• These are derived from arachidonic acid a 20
carbon fatty acid.
• There are two major types are PGandLT.

12. WatersolubleHormone
3. Peptide & Proteinhormones:
• Smaller peptide hormones consist of 3 to49
amino acids.
• Larger protein hormone includes 50 to200
amino acids.
• Peptide hormone:ADH & Oxytocin
• Protein hormones: Human growth hormone &
Insulin

13. Hypothalamus& Pituitarygland
• Cells in the hypothalamus synthesize different
hormones, and the pituitary gland secretes
seven.
• Together, these hormones play important
roles in the regulation of virtually all aspects
of growth, development, metabolism, and
homeostasis.

14. • The pituitary gland is a pea-shaped structure that
measures 1–1.5 cm (0.5 in.) in diameter and lies in
the hypophyseal fossa of the sella turcica of the
sphenoid bone. It attaches to the hypothalamus by
a stalk, the infundibulum.
• and has two anatomically and functionally separate
portions:
• the anterior pituitary and (Adenohypophysis)
• the posterior pituitary (Neurohypophysis)

16. • Those anterior pituitary hormones that act on
other endocrine glands are called tropic
hormones or tropins.

17. Histology of anterior pituitary
• Types of Anterior Pituitary Cells and Their
Hormones
1. Somatotrophs
2. Thyrotrophs
3. Gonadotrophs
4. Lactotrophs
5. Corticotrophs

19. Control of Secretion by the Anterior
Pituitary
• Secretion of anterior pituitary hormones is
regulated in two ways.
• First, neurosecretory cells in the
hypothalamus secrete five releasing
hormones, which stimulate secretion of
anterior pituitary hormones,
• and two inhibiting hormones, which suppress
secretion of anterior pituitary hormones

21. • Second, negative feedback in the form of
hormones released by target glands decreases
secretions of three types of anterior pituitary
cells
• In such negative feedback loops, the secretory
activity of thyrotrophs, gonadotrophs, and
corticotrophs decreases when blood levels of
their target gland hormones rise.

22. Negative
feedback
regulation of
secretion of
hormones
by the anterior
lobe of the
pituitary gland.

23. 1. Human Growth Hormone and
Insulinlike Growth Factors
• Somatotrophs.
• The main function of hGH is to promote synthesis
and secretion of small protein hormones from cells
in the liver, skeletal muscles, cartilage, bones, and
other tissues called insulinlike growth factors (IGFs)
or somatomedins

24. • The functions of IGFs include the following:
1. IGFs cause cells to grow and multiply by
increasing uptake of amino acids into cells
and accelerating protein synthesis.
2. IGFs also enhance lipolysis in adipose tissue,
…….ATP production
3. human growth hormone and IGFs influence
carbohydrate metabolism by decreasing
glucose uptake

25. • Somatotrophs in the anterior pituitary release
bursts of human growth hormone every few
hours, especially during sleep.
• Their secretory activity is controlled mainly by
two hypothalamic hormones:
(1) growth hormone–releasing hormone (GHRH)
promotes secretion of human growth hormone,
and
(2) growth hormone–inhibiting hormone (GHIH)
suppresses it.

26. • Hypoglycemia an abnormally low blood glucose
concentration, stimulates the hypothalamus to
secrete GHRH, which flows toward the anterior
pituitary in the hypophyseal portal veins.
• An increase in blood glucose above the normal
level inhibits release of GHRH.
• Hyperglycemia an abnormally high blood
glucose concentration, stimulates the
hypothalamus to secrete GHIH (while inhibiting
the secretion of GHRH).

27. 2. Thyroid-Stimulating Hormone
3. Adrenocorticotropic Harmone
4. Prolactin
5. Gonadotrophins
follicle stimulating hormone (FSH)
luteinising hormone (LH).

28. Posterior Pitutory
1. Oxytocin
2. ADH (Vasopressin)

29. THYROID GLAND
Location, blood supply, and histology of the thyroid gland.

31. Formation, Storage, and
Release of Thyroid Hormones
• The thyroid gland is the only endocrine gland
that stores its secretory product in large
quantities—normally about a 100-day supply.
• Synthesis and secretion of T3 and T4 occurs as

32. Formation,
Storage, and
Release of
Thyroid
Hormones

33. Actions of Thyroid Hormones
• Thyroid hormones increase basal metabolic rate
(BMR),
• increases, cellular metabolism of carbohydrates,
lipids, and proteins
• synthesis of additional sodium–potassium pumps
and calorigenic effect
• increase lipolysis
• The thyroid hormones enhance some actions of the
catecholamines

34. • Together with human growth hormone and
insulin, thyroid hormones accelerate body
growth, particularly the growth of the nervous
and skeletal systems.
• Deficiency of thyroid hormones during fetal
development, infancy, or childhood causes
severe mental retardation and stunted bone
growth

35. Regulation of secretion
and actions of thyroid
hormones.

36. Calcitonin (CT)
• Produced by the parafollicular cells
• CT can decrease the level of calcium in the blood by
inhibiting the action of osteoclasts.
• The secretion of CT is controlled by a negative
feedback system.
1. High blood Ca2+ levels stimulate secretion;
2. Low blood Ca2+ levels inhibit secretion.

37. • Calcitonin lowers the amount of blood calcium
and phosphates by two ways
1. By inhibiting bone resorption by
osteoclast
2. by accelerating uptake of calcium
and phosphates into bone extracellular
matrix.

38. PARATHYROID GLANDS

40. • There are four small parathyroid glands, two
embedded in the posterior surface of each lobe
of the thyroid gland
• Each has a mass of about 40 mg (0.04 g).
• Parathyroid glands contain two kinds of
epithelial cells
1. chief (principal) cells, produce parathyroid
hormone (PTH), also called parathormone.
2. oxyphil cell: unknown function
With respect to regulation of blood Ca2+ level,
calcitonin and PTH are antagonists.

41. The roles of calcitonin (green arrows), parathyroid hormone (blue
arrows), and calcitriol (orange arrows) in calcium homeostasis.

42. ADRENAL GLANDS
• Also called as suprarenal gland
• There are two adrenal glands, one situated
on the upper pole of each kidney enclosed
within the renal fascia.
• They are about 4 cm long and 3 cm thick.

43. (a) Anterior view

45. • The adrenal cortex produces steroid hormones
that are essential for life.
• The adrenal medulla produces three
catecholamine hormones— norepinephrine,
epinephrine, and a small amount of dopamine.

46. Mineralocorticoids
• Aldosterone
• It regulates homeostasis of two mineral ions—
namely, sodium ions (Na+) and potassium ions
(K+)—and helps adjust blood pressure and
blood volume.
• promotes excretion of H+ ion in the urine
• The renin–angiotensin–aldosterone or RAA
pathway controls secretion of aldosterone

48. Glucocorticoids
• cortisol (also called hydrocortisone), (95%)
• corticosterone and
• cortisone

49. Negative feedback
regulation of
glucocorticoid secretion.

50. Glucocorticoids have the following effects:
• Glucocorticoids increase the rate of protein breakdown,
• gluconeogenesis in liver
• Lipolysis
• Resistance to stress
• Anti-inflammatory effects.
• Depression of immune responses.

51. Androgens
• Adrenal cortex secretes small amounts of weak
androgens. e.g. dehydroepiandrosterone (DHEA)
• In male their role is insignificant because
testosterone (androgen ) secreted by testes have
significant effect.
• But in females
- promote libido (sex drive)
-converted into estrogens
• also stimulate growth of axillary and pubic hair in
boys and girls and contribute to the prepubertal
growth

52. Adrenal Medulla
• 80% epinephrine and 20% norepinephrine by
chrommafin cells .
• In stressful situations and during exercise,
impulses from the hypothalamus stimulate
sympathetic preganglionic neurons, which in
turn stimulate the chromaffin cells to secrete
epinephrine and norepinephrine.

53. PANCREATIC ISLETS
• both an endocrine gland and an exocrine gland.
• 12.5–15 cm (5–6 in.) in length, the pancreas is
located in the curve of the duodenum.
• head, a body, and a tail

54. Histology of pancreas

55. • pancreatic islets or islets of
Langerhans
1. Alpha or A cells constitute about 17% of
pancreatic islet cells and secrete glucagon
2. Beta or B cells constitute about 70% of
pancreatic islet cells and secrete insulin
3. Delta or D cells constitute about 7% of
pancreatic islet cells and secrete somatostatin
4. F cells constitute the remainder of pancreatic
islet cells and secrete pancreatic polypeptide.

56. Relation between pancreatic
harmones
• glucagon increases blood glucose levels
• insulin reduces blood glucose levels.
• Somatostatin inhibit the secretion of both insulin
and glucagon. In addition, somatostatin inhibits
the secretion of growth hormone.
• Pancreatic polypeptide inhibits somatostatin
secretion, gallbladder contraction, and secretion
of digestive enzymes by the pancreas.

57. Negative
feedback
regulation of the
secretion of
glucagon (blue
arrows) and
insulin
(orange arrows).

58. Thank You!!!