Human Anatomy and Physiology-II: Endocrine System: Classification of hormones, mechanism of hormone action, structure and functions of pituitary gland, thyroid gland, parathyroid gland, adrenal gland, pancreas, pineal gland, thymus and their disorders.

1. Endocrine System
Represented By,
Mr. Audumbar Mali,
(Asst. Prof.)
Sahyadri College of Pharmacy
Methwade.

2. Definition:
The endocrine system is the collection of glands that
produce hormones that regulate metabolism, growth and
development and tissue function.
•The endocrine system is made up of the pituitary
gland, thyroid gland, parathyroid glands, adrenal
glands, pancreas, ovaries (in females) and testicles (in
males).
•The word endocrine derives from the Greek words
"endo," meaning within, and "crinis," meaning to
secrete.
•Endocrine system uses hormones as messenger. 2

3. 3

4. LOCATION OF DIFFERENT
ENDOCRINE GLANDS.

5. TYPES OF HORMONES
ENDOCRINE HORMONES – Travel through the
blood to act at a site distant from the secreting cell or
gland
PARACRINE HORMONES – Act on cells near the
secreting cell
AUTOCRINE HORMONES – Act on the secreting
cell
NEUROCRINE HORMONES – Secreted by neural
cells
○neurotransmitters
○neurohormones

6. CHEMICAL CLASSIFICATION OF
HORMONES
Depending upon chemical nature
Amines or amino acid derivatives:
Proteins & Polypeptides:
Steroid hormones
Depending upon mechanism of action.
Group I hormones.
Group II hormones. : A,B,C,D.

7. Figure 6-2b, c: Long distance cell-to-cell communication

8. Special Features:-
8
•Special features of endocrine
glands are, in general, their
ductless nature, their vascularity,
and commonly the presence of
intracellular vacuoles or granules
that store their hormones.

9. Functions of Endocrine system:
9
Controls the processes involved in movement
and physiological equilibrium.
Includes all tissues or glands that secrete
hormones into the blood.
Secretion of most hormones is regulated by a
negative feedback system.
The number of receptors for a specific
hormone can be altered to meet the body’s
demand.

10. Endocrine Glands:-
10
Thyroid gland
Parathyroid
gland
Adrenal gland
Pituitary gland
Pancreas

11. Pineal Gland
Thymus Gland
11

12. Hormones can classified into
two groups:
i)Based on their chemical nature
ii)Based on mechanism of action
a)Group 1 hormones- Bind to intracellular receptor to
form complex and carry out biochemical function.
b)Group 2 hormones- Bind to cell surface receptor and
stimulate the release of certain molecule namely
secondary messengers which in turn perform
biochemical function.

13. Mechanism of
Hormone
Action

14. GROUP 1 HORMONE ACTION

15. Quick recap..
Being lipophilic, these hormone can easily pass across the
plasma membrane. They act through intracellular receptors
( cytosol or nucleus).
They form hormone receptor complex binds to the specific
regions on the DNA called HRE (hormone response
element) and cause increased expression of specific genes.
It is believed that the interaction of hormone receptor
complex with HRE promotes initiation, elongation and
termination.
The ultimate outcome is the production of specific proteins
( translation) in response to hormonal action.

16. GROUP 2 HORMONE ACTION
Hormones that bind to surface receptors of the cells,
communicate through intermediary molecules called second
messenger which are generated as consequences of the
hormone action.
Example:- The heterotrimeric G protein. G protein was
discovered by Alfred Gilman and Martin Rodbell in 1990.

17. MECHANISM OF SECOND MESSENGER
1) Cyclic AMP ( adenosine 3’ 5’ monophosphate)
cAMP synthesized from nucleotide ATP by the enzyme adenylate
cyclase .

18. 2) Cyclic GMP
cGMP (guanosine 3’ 5’ monophosphate)
synthesized from nucleotide GTP by the
enzyme guanylyl cyclase. Cyclic GMP carries
different messages to different tissues:
1)In the kidney and intestine,
2)In the cardiac muscle it signal relaxation,
3)Nitric oxide stimulates the synthesis of cyclic
GMP.

19. 3. CALCIUM AND/ OR PHOSPHOINOSITIDES AS
SECONDARY MESSENGER
In many cells that respond to extracellular signals, calcium
serves as a second messenger.
Certain hormone receptor interaction result in activation of the
enzyme phospholipase C through a specific G protein.
Intracellular enzyme phospholipase C hydrolyzes
phosphotidylinositol-4,5 bisphosphate (PIP2) which is found in
inner layer of the plasma membrane. Hydrolysis of PIP2 yield
two products
a)Diacylglycerol ( DAG)
b)Inositol -1,4, 5 triphosphate( IP3)

20. 4. CALMODULIN AS SECONDARY
MESSENGER
Calcium calmodulin second messenger system operates
in response to the entry of calcium into the cells.
Calmodulin is an acidic protein with highly conserved
single polypeptide chain has four high affinity for
calcium binding sites.
Binding of calcium causes profound conformational
changes in calmodulin’s affinity for its effector
molecules.
Calmodulin, when activated, causes contraction of
smooth muscles.

21. Hypothalamus
21

22. 2
2

23. Hypothalamus:-
2
3
Location:
The hypothalamus is located below the thalamus, just
above the brainstem and is part of the limbic system.
Anatomy:
The hypothalamus is a region of the brain composed of
many small nuclei with diverse functions.
Physiology:
The hypothalamus is a small area in the ventral
diencephalon of the forebrain, in the floor of the third
ventricle, and is a functional link between
the nervous and endocrine systems.

24. Hypothalamus produces many hormones, some
of which are given below
• ADH ( vasopressin)
• DA (dopamine)
• CRH (corticotrophin releasing hormone)
 ADH:
Increases water permeability in the distal
convoluted tubule and collecting duct of nephrons,
thus promoting water reabsorption and increasing
blood volume.
2
4

25.  DA(Dopamine):
Inhibit prolactin released from anterior pituitary.
Prolactin (PRL), also known as luteotropic
hormone or luteotropin, is a protein that
in humans is best known for its role in
enabling female mammals to produce milk.
 CRH (Corticotrophin Releasing Hormone):
Stimulate adrenocorticotropic hormone (ACTH)
release from anterior pituitary.
The principal effects of ACTH are increased
production and release of cortisol by the
cortex of the adrenal gland.
25

26. Thyroid
Gland
2
6

27. 17
Thyroid Gland:-

28. Thyroid Gland:-
2
8
Location:
Thyroid Gland located at the base of the neck and wrapped
around the lateral sides of the trachea.
Anatomy:
The thyroid gland is a butterfly-shaped gland
Physiology:
The thyroid gland produces 3 major hormones:
Calcitonin:
Stimulates osteoblasts and thus bone construction Inhibits Ca2+
release from bone, thereby reducing
blood Ca2+

29. Tri iodothyronine (T3)
is a thyroid hormone. It affects almost every physiological
process in the body, including growth and development ,
metabolism, body temperature, and heart rate.
Thyroxin (T4)
(Acts as a prohormone to triiodothyronine )
Stimulates body oxygen and energy consumption, thereby
increasing the basal metabolic rate
Stimulates RNA polymerase I and II, thereby promoting
protein synthesis
2
9

30. Parathyroid
Gland
3
0

31. 31

32. Parathyroid Gland:-
3
2
Location:
Parathyroid gland found on the posterior side of the thyroid
gland.
Anatomy :
The parathyroid gland are 4 small masses of glandular
tissue
Physiology:
The parathyroid gland produces parathyroid hormone.

33. Parathyroid Hormone:
Parathyroid hormone which is involved in the calcium ion
homeostasis
3
3
Parathyroid hormone (PTH), parathormone or parathyrin, is
secreted by the chief cells of the parathyroid glands as
a polypeptide containing 84 amino acids, While PTH acts to
increase the concentration of ionic calcium (Ca2+) in the
blood,
Stimulators:
• Decreased serum [Ca2+].
• Mild decreases in serum [Mg2+].

34. Adrenal
Gland
3
4

35. 25
Adrenal Gland:-

36. Adrenal Gland:-
36
Location:
Adrenal gland found immediately superior to the kidneys.
Anatomy:
The Adrenal glands are a pair of roughly triangular glands.
Physiology:
The adrenal glands are each made of 2 distinct layers, each
with their own unique functions: the outer adrenal cortex and
inner adrenal medulla

37. Adrenal cortex produces many
cortical hormones in 3 classes i.e.
Glucocorticiods
Minralocoticoids
Androgens
Adrenal Medullaproduces hormones
i.e.
Epinephrine
Nor epinephrine 37

38. Pituitary
Gland
38

39. 29
Pituitary Gland:-

40. Pituitary Gland:-
40
Location:
Pituitary gland is connected to the inferior portion of
the hypothalamus of the brain.
Anatomy:
The Pituitary gland, also known as the hypophysis, is a small
pea-sized lump of tissue
Physiology:
Many Blood vessels surround the pituitary gland to carry the
hormones it releases throughout the body. It consists of 2
separate parts i.e.
Posterior pituitary
Anterior pituitary

41. Posterior pituitary
41
produces two hormones i.e.
• Oxytocin induces labor pain
• Antidiuretic hormone (ADH)
Increases water permeability in the distal convoluted tubule and
collecting duct of nephrons ,thus promoting water
reabsorption and increasing blood volume
Anterior pituitary produces many hormones i.e.
•TSH Stimulates thyroxine (T4) and triiodothyronine(T3)
synthesis and release from thyroid gland
Stimulates iodine absorption by thyroid gland etc

42. •Adrenocorticotrophic Hormone(ACTH)
•Stimulates corticosteroid (glucocorticoid and
mineralcorticoid) and androgen synthesis and release from
adrenocortical cells
•
•Follicle stimulating Hormone(FSH)
42
• In females: Stimulates maturation of ovarian follicles in
ovary.
In males: Stimulates maturation of seminiferous tubules
•Luteinizing Hormone(LH)
In females: Stimulates ovulation
In females: Stimulates formation of corpus luteum
In males: Stimulates testosterone synthesis from Leydig cells
(interstitial cells)

43. Pancreas
43

44. Pancreas:-
44

45. Pancreas:-
45
Location:
Pancreas is located in the abdominal cavity just inferior
and posterior to the stomach .
Anatomy:
The pancreas is a large gland
Physiology:
The pancreas is considered as heterocrine gland as it
contains both endocrine and exocrine tissues . Two
types of cells are present i.e. Alpha cells, Beta cells,
Delta cells and F-cells.

46. Alpha cells: This produce hormone Glucagon which is
responsible for increase blood glucose level .
Beta cells: This produces hormone Insulin which is
responsible for lowering blood glucose level.
Delta cells: This secrete somatostatin hormone or
growth hormone inhibiting hormone (GHIH) which inhibit
the secretion of alpha cells and beta cells of islets.
F- cells: This secretes pancreatic polypeptide which
regulates the release of pancreatic digestive enzymes.
46

47. Pineal
Gland
47

48. 48

49. Pineal Gland:-
49
Location:
The pineal gland is located in a central depression
between the thalami and the corpora quadrigemina
(colliculi)
Anatomy:
It is a small ovoid or fufiform mass which is found deep
within the brain also known as “third eye” as it response to
the light and day length
Physiology:
It secretes melatonin which influence the sexual
maturity and the seasonality of breeding and hibernation

50. Thymus
Gland
50

51. 51

52. 51
Thymus Gland :-
Location: It is situated in the anterior mediactinal space
(i.e. The area in the front part of the chest between the lungs)
of the thoracic cavity.
Anatomy: It is a ductless gland which has close
resemblance to the lymphoid tissue
Physiology: Its main function is to provide an area For
the T LYMPHOCYTE maturation and is vital in protecting
against autoimmunity. The stock of the T lymphocyte is built
up in early life, so the function of the thymus gland is
diminished in adult. It is largely degenerated in elderly
adults.

53. Endocrine Disorders:
Endocrine disorders are typically grouped into
two categories:
• Endocrine disease that results when a gland
produces too much or too less of an endocrine
hormone, called a hormone imbalance.
• Endocrine disease due to the development of
lesions (such as tumors) in the endocrine
system, which may or may not affect hormone
levels.

54. The endocrine's feedback system helps
control the balance of hormones in the
bloodstream. If your body has too much or
too little of a certain hormone, the
feedback system signals the proper gland
or glands to correct the problem. A
hormone imbalance may occur if this
feedback system has trouble keeping the
right level of hormones in the
bloodstream, or if your body doesn't clear
them out of the bloodstream properly.

55. Increased or decreased levels of endocrine
hormone may be caused by:
• A problem with the endocrine feedback system
• Disease
• Failure of a gland to stimulate another gland to release
hormones (for example, a problem with the hypothalamus can
disrupt hormone production in the pituitary gland)
• A genetic disorder, such as multiple endocrine neoplasia (MEN)
or congenital hypothyroidism (it is partial or complete loss of
function of the thyroid gland (hypothyroidism) that affects
infants from birth (congenital).
• Infection
• Injury to an endocrine gland
• Tumor of an endocrine gland

56. Most endocrine tumors and nodules (lumps) are
noncancerous. They usually do not spread to other
parts of the body. However, a tumor or nodule on the
gland may interfere with the gland's hormone
production.
• Types of Endocrine Disorders:
There are many different types of endocrine disorders
and Diabetes is the most common endocrine disorder.
1. Diabetes mellitus: It is refers to a group of diseases
that affect how your body uses blood sugar
(glucose). Glucose is vital to your health because it's
an important source of energy for the cells that make
up your muscles and tissues. It's also your brain's main
source of fuel.

57. • People with type 1 diabetes don’t produce insulin.
• People with type 2 diabetes don’t respond to insulin as well as they
should and later in the disease often don’t make enough insulin.
• Some of the signs and symptoms of type 1 diabetes and type 2 diabetes
are:
• Increased thirst
• Frequent urination
• Extreme hunger
• Unexplained weight loss
• Presence of ketones in the urine (ketones are a byproduct of the
breakdown of muscle and fat that happens when there's not enough
available insulin)
• Fatigue
• Irritability
• Blurred vision
• Slow-healing sores
• Frequent infections, such as gums or skin infections and vaginal infections

58. 2. Adrenal insufficiency: The adrenal gland releases
too less of the hormone cortisol and sometimes,
aldosterone. Symptoms
include fatigue, stomach upset, dehydration,
and skin changes. Addison's disease is a type of
adrenal insufficiency.
3. Cushing's disease: Overproduction of a pituitary
gland hormone leads to an overactive adrenal
gland. A similar condition called Cushing's
syndrome may occur in people, particularly
children, who take high doses of
corticosteroid medications.

59. 4. Gigantism (acromegaly) and other growth
hormone problems: If the pituitary gland
produces too much growth hormone, a child's
bones and body parts may grow abnormally fast. If
growth hormone levels are too low, a child can stop
growing in height.
5. Hyperthyroidism: The thyroid gland produces
too much thyroid hormone, leading to weight loss,
fast heart rate, sweating, and nervousness. The
most common cause for an overactive thyroid is
an autoimmune disorder called Grave’s disease
(i.e. It is disorder that results in the overproduction
of thyroid hormones such as hyperthyroidism).

60. 6. Hypothyroidism: The thyroid gland does not
produce enough thyroid hormone, leading
to fatigue, constipation, dry skin, and
depression. The underactive gland can cause
slowed development in children. Some types
of hypothyroidism are present at birth.
7. Hypopituitarism: The pituitary gland releases
little or no hormones. It may be caused by a
number of different diseases. Women with this
condition may stop getting their periods.

61. 8. Multiple Endocrine Neoplasia I and II (MEN I and
MEN II): These rare, genetic conditions are passed
down through families. They cause tumors of the
parathyroid, adrenal, and thyroid glands, leading
to overproduction of hormones.
9. Polycystic ovary syndrome (PCOS):
Overproduction of androgens interfere with the
development of eggs and their release from the
female ovaries. PCOS is a leading cause of
infertility.
10. Precocious puberty: Abnormally early puberty
that occurs when glands tell the body to release
sex hormones too soon in life.

62. References:
1. A Textbook of Human Anatomy and Physiology-
II, By, Dr. S. B. Bhise and Dr. A. V. Yadav.
Nirali Prakashan, Page No.:- 6.1-6.14.
2. https://www.slideshare.net/pramodkumarsikaraw
ar/endocrine-ppt-66501464.
3. https://www.slideshare.net/9426401633/endocrin
e-system-1-73527168
4. https://www.webmd.com/diabetes/endocrine-
system-disorders.
5. https://www.niddk.nih.gov/health-
information/endocrine-diseases.

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