The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems.
3. The body contains two kinds of glands:
Exocrine and endocrine glands
Exocrine glands secrete their products into the ducts, and ducts carry the secretions
into the body cavities, into lumen of organs or to the outer surface of the body.
Exocrine glands include sweat, sebaceous, lacrimal, gastric, intestinal, mucus glands.
5. Endocrine glands
•Endocrine glands are groups of secretory cells
surrounded by network of blood capillaries.
•They are also referred to as ductless glands because
they release hormones directly into the bloodstream.
7. Hormones are carried in the bloodstream to target
tissues and organs that may be quite distant,
where they influence cell growth and metabolism.
These hormones help regulate metabolism, water
and electrolyte concentrations in cells, growth,
development, and the reproductive cycles.
9. Hormones
• Hormones act as chemical messengers synthesized form the
glands and transported through the blood towards target
cells and regulate the cellular activities of target organs.
11. HYPOTHALAMUS
• Hypothalamus is the small area
of the brain below the thalamus.
• It is the major integrating link
between the nervous and
endocrine systems.
12. Hypothalamus is the important regulatory
center in the nervous system which controls
autonomic nervous system, endocrine
system and regulates body temperature,
thirst, hunger, sexual behavior, stress, fear
and emotional experiences.
13. Cells in the
hypothalamus synthesize
at least nine different
types of hormones to
regulate pituitary
hormone secretions.
15. GHRH and GHIH works to regulate the release of
growth hormone- GHRH stimulate growth
hormone release whereas GHIH inhibits its release.
TRH stimulates the anterior pituitary gland to
release thyroid-stimulating hormone.
16. GnRH stimulates the release of follicle stimulating hormone and
luteinizing hormone
CRH stimulate release of adrenocorticotropic hormone.
The last two hormones: oxytocin and antidiuretic hormone produced
by the hypothalamus and transported to the posterior pituitary gland.
18. PITUITARY GLAND
• Pituitary gland is a small pea-sized structure about 1.3 cm in
diameter, situated in the cranium. Pituitary gland is connected
to the inferior portion of the hypothalamus in the brain.
• The pituitary gland is actually made of three distinct structures:
• anterior pituitary lobe (adenohypophysis), posterior pituitary
lobe (neurohypophysis) and intermediate lobe.
21. The pituitary gland is surrounded by network of
blood capillaries to carry the hormones secreted
from hypothalamus to the anterior pituitary.
The releasing and inhibiting hormones secreted
by hypothalamus stimulate and inhibit
secretions of anterior pituitary hormones.
22. Five principal types of anterior
pituitary cells which secrete seven
major hormones are somatotrophs,
thyrotrophs, corticotrophs,
lactotrophs and gonadotrophs.
23. The anterior pituitary hormones are shown
in table. Some of the tropic hormones
secreted by the anterior lobe of pituitary
gland stimulate or inhibit secretion of other
endocrine glands (target glands) while others
have a direct effect on target tissues.
26. Ho rmo na l secreted by a nterio r
pituitar y gland with their
functio ns
27. Human growth
hormone (hGH)
It stimulates the growth of bones, muscles,
cartilage and other tissues
Stimulates protein metabolism, tissue repair and
lipolysis in most of body tissues
Thyroid-stimulating
hormone ( TSH)
Stimulates triiodothyronine (T3) and thyroxine
(T4) synthesis and release from thyroid gland
Stimulates iodine absorption by thyroid gland
Adrenocorticotropic
hormone (ACTH)
Stimulates corticosteroids (glucocorticoids and
mineralocorticoids)
Synthesis of sex hormones (androgens) and
release.
28. Melanocyte
stimulating
hormone(MSH)
Increases the production of melanin in melanocytes
in the skin Thus causing a deepening pigmentation
or darkening of the skin
Prolactin
Stimulates milk production and secretion by the
mammary glands
Follicle-stimulating
hormone (FSH )
In Females: Stimulates maturation of ovarian follicles
in ovary
In males: Stimulates maturation of sperms
Stimulates spermatogenesis
Luteinizing hormone
(LH)
In female: Stimulates ovulation and stimulates
formation of corpus luteum
In males: Stimulates testosterone synthesis by
testes
29. POSTERIOR PITUITARY
• Posterior pituitary gland does not synthesize hormone but it
stores and releases two hormones.
• It consists of pituicytes and nerve endings of hypothalamic
neurosecretary cells.
• These neurosecretary cells produce two hormones: oxytocin
and antidiuretic hormone (ADH).
30. Posterior pituitary
Hormones
Functions
Antidiuretic Hormone
ADH
Decreases urine volume
Maintains the water balance by increasing water
reabsorption in the tubules of the nephrons of
kidneys, thereby increasing blood volume
Oxytocin
Stimulates contraction of smooth muscles of the
pregnant uterus in the late stages of child birth.
Stimulates release of milk during breastfeeding i.e.
lactation.
32. The pituitary gland secretes hormones including
• Human growth hormone (hGH),
• Thyroid-stimulating hormone (TSH),
• Adrenocorticotropic hormone (ACTH),
• Melanocyte stimulating hormone (MSH),
• Prolactin,
• Follicle-stimulating hormone (FSH),
• Luteinizing hormone (LH),
• antidiuretic hormone and Oxytocin.
33. Some of the hormones secreted by the
pituitary gland stimulate or inhibit secretion
of other endocrine glands such as thyroid
gland, adrenal gland, pancreas, ovary, testes
and pineal gland; while others have a direct
effect on target tissues.
36. Dwarfism Dwarfism is characterized by one or more
body parts being relatively large or small in
comparison to those of an average sized adult.
• Insufficient secretion of growth hormone from anterior
pituitary gland (growth hormone deficiency)
• Abnormal (slow or delayed) growth of skeleton system
• Epiphyseal plates of bones closed before reaching to
normal height
Symptoms
• Overall rate of growth is decreased in children.
• An adult height of less than 4 feet 10 inches
37. GIGANTISM Gigantism is characterized by excessive
growth and height significantly above
average. This condition is caused by
over- production of growth hormone in
childhood resulting in persons between
7-9 feet in height.
• Tumor formation in pituitary glands
• Hyper activation of anterior pituitary gland start
producing excess of growth hormone.
• Higher levels of growth hormone causing repaid
growth of body tissues
• It can be passed on genetically through a mutated
gene
• It causes excess growth of the hands, face and feet
38. ACROMEGALY Acromegaly most commonly affects adult in
middle age due to excessive pituitary growth
hormone secretion.
• Soft tissue swelling visibly resulting in enlargement of
the hands. Feet, nose, lips, and ears, and a general
thickening of the skin.
• Soft tissue swelling of internal organs ,notably the heart
with attendant weakening of its muscularity, and the
kidneys, also the vocal cords resulting in a
characteristic thick, deep voice and slowing of speech
• Generalized expansion of the skull
• Pronounced brow protrusion with ocular distension
(frontal bossing)
• Pronounced lower jaw protrusion with enlargement of
the tongue and teeth gapping.
39. THYROID GLAND
The thyroid gland is
located just below the
larynx (voice box).
It consists of two lateral
lobes connected by a
smaller the isthmus.
40. The lobes are situated on the right and left
sides of the trachea.
It is highly vascular gland that weighs about
25 grams and covered by a fibrous capsule.
The lobes of thyroid gland are made up of
thyroid follicles and parafollicular cells.
41. Thyroid follicles are
composed of follicular cells
which are made up of simple
cuboidal epithelium.
These follicular cells produce
and secrete two thyroid
hormones: Triiodothyronine
(T3) and Thyroxine (T4).
42. Follicular cells require iodine for production of T3 and T4.
Sources of iodine include seafood, vegetables grown in
iodine rich soil & iodinated salt in diet.
Thyroid secretion is regulated by the hypothalamus, which
secretes TRH to send signals to the pituitary to release TSH
to increase thyroid hormone (T3 and T4) production.
43. Thyroid
Gland cells
Thyroid gland
hormones
Functions
Follicular cells Thyroid Hormones
Triiodothyronine (T3)
and Thyroxine (T4)
1. Increasing basal metabolic rate
(BMR) & heat production
2. Regulating metabolism of
carbohydrates, proteins and fats
3. Normal growth and development
of skeleton and nervous system
4. Increasing the rate of protein
synthesis
5. Stimulate RNA polymerase I and ll,
thereby promoting protein
synthesis
6. Stimulates body oxygen and
energy consumption, thereby
increasing the basal metabolic rate
44. Parafollicular
cells
Calcitonin Calcitonin hormone decreases the
calcium and phosphate levels into
the blood by increasing uptake of
calcium and phosphate ions into
the bones matrix.
This hormone is important during
childhood when bones undergo
considerably changes in size and
shapes.
45. Regulation of thyroid hormone
Low blood levels of T3 and T4 stimulate the hypothalamus to secrete
thyrotropin releasing hormone (TRH). TRH also stimulates the anterior
pituitary gland to secrete thyroid stimulating hormone (TSH).
Then TSH stimulates thyroid gland activity to secrete T3 and T4 until
metabolic rate returns to normal.
46. This condition may be increased due
to a cold environment, hypoglycemia,
high altitude, pregnancy and trigger
this negative feedback mechanism to
increase thyroid hormone secretions.
48. DISORDERS OF THYROID GLAND
Hypersecretion of thyroid hormone
• Graves’ disease
Hyposecretion of thyroid hormone
• Cretinism, Myxedema and Goiter
49. CRETINISM Characteristic features
Hypothyroidism during fetal life leads to Cretinism.
This condition is prevalent in certain areas distant
from the sea where soil and diet are deficient in
iodine. Therefore there is insufficient iodine
available for synthesis of T3 and T4 in such
patients.
Symptoms
Retarded physical and mental growth
Retarded sexual development
Disproportionately short limbs
Large protruding tongue
Muscular weakness
Dry skin
50. MYXEDEMA Characteristic features
Hypothyroidism during adult life leads to
myxedema. Deficiency of T3 and T4 in adult
life results in low basal metabolic rate.
Myxedema is most common in females.
Causes include ionizing radiations, anti-
thyroid drug therapy etc.
Symptoms
Accumulation of fats on face i.e. puffy face
Low body temperature
Bulginess under the eye due to swelling
Sleeping time up to 12-14 hours per day
Decreased hair growth
51. SIMPLE GOITRE
Characteristic features
Extra enlargement of thyroid gland
characterized by deficiency of T3 and T4 due to
inadequate dietary iodine.
The resultant low level of thyroid hormone in
the blood stimulates secretion of TSH which
causes thyroid gland enlargement.
52. GRAVES’ DISEASE Characteristic features
Graves’ disease is an autoimmune disease
characterized by enlargement of thyroid glands due to
excessive secretion of T3 and T4 which is not regulated
by normal negative feedback mechanism. Hypersecretion
of thyroid hormones increases food intake, basal
metabolic rate and heat production. Generally women are
more affect than men mostly at 30-50 years of age.
Symptoms
Protrusion of the eyes due to deposition of excess fats
behind eyeballs
Difficulty during blinking of eyelids and sleep leads to
incomplete closure of eyelids and drying of
conjunctiva hence eye infection may occur
Increased sweating
Basal metabolic rate increased
56. Pancreas is a flattened organ that measures about
12-15 cm in length. It is located posterior and slightly
inferior to the stomach.
The pancreas is consists of head, body and tail. The
pancreas is also referred as an exo-endocrine gland.
Because is composed of both exocrine and endocrine
glands.
57. The exocrine pancreas consists of about 99% pancreatic
acini cells which produce digestive enzymes and juice,
which are transported in gastrointestinal tract.
The endocrine pancreas consists of 1-2 millions of
group of cells called as pancreatic islets of Langerhans,
which secrete hormone in blood capillary network.
58. PANCREATIC GLAND SECRETIONS FUNCTIONS
Exocrine pancreas made
up of pancreatic acini cells
Pancreatic juice:
Pancreatic Amylase,
Pancreatic Lipase,
Trypsinogen,
Chymotrypsinogen,
Chemical digestion of
carbohydrates, proteins and
lipids
Endocrine pancreas made
up of pancreatic islets of
Langerhans
Hormones:
Alpha cells: Glucagon
Beta cells: Insulin
Delta cells: Somatostatin
Increases blood glucose level
Reduces blood glucose level
Maintains glucagon and
insulin secretion
60. Glucagon
(alpha cells)
On liver
1. Increases blood glucose level by raising conversion of
glycogen in to glucose in liver i.e. Increase
glycogenolysis (Glucose synthesis)
Glycogen Glucose
2. Conversion of other nutrients into glucose in liver
Nutrients Glucose
61. Insulin
(Beta cells)
Lowers blood glucose levels by several mechanisms
On liver cells
1. Increases glycogenesis (glycogen synthesis)
2. Reduces gluconeogenesis (glucose synthesis)
3. Increases lipogenesis (lipid synthesis)
On skeletal muscles
1. Increases glucose uptake in muscle cells
2. Increases glycogenesis (glycogen synthesis)
3. Increases Protein synthesis
On fat tissue
1. Increases lipogenesis (lipid synthesis)
62. Diabetes mellitus
• Diabetes is a chronic disease associated with abnormally
high levels of the sugar glucose in the blood.
• Diabetes is due to one of two mechanisms:
• Inadequate production of insulin (which is made by the
pancreas and lowers blood glucose), or Inadequate
sensitivity of cells to the action of insulin.
63. The two main types of diabetes correspond to these
two mechanisms and are called insulin dependent
(type 1) and non-insulin dependent (type 2)
diabetes.
In type 1 diabetes there is no insulin or not enough of
it. In type 2 diabetes, there is generally enough
insulin but the cells upon which it should act are not
normally sensitive to its action.
65. Type I diabetes
• Type I diabetes is also known as Juvenile onset diabetes because
it manifests before the early 20’s.
• Symptoms of Type I diabetes include weight loss, glucose in the
urine (glycosuria), and poor wound healing or ulcers.
• If untreated, a buildup of ketone bodies occurs as a result of
excess fat metabolism.
• Treatment includes daily insulin injections.
67. Type II diabetes
• Type II diabetes, also known as adult onset diabetes,
develops in middle-aged adults from loss of insulin
receptors in the cell membranes.
• Risk factors include weight gain and sedentary
lifestyle. Treatment includes weight loss and exercise.
69. Differentiate between type 1 and type 2 diabetes mellitus
Sr.
No.
Point Type 1 diabetes Type 2 diabetes
1. Known as Insulin dependent diabetes
mellitus (IDDM)
Non-Insulin dependent
diabetes mellitus (NIDDM)
2. Frequency 10-20% 80-90%
3. Prevalence Early below 35 years
i.e. Juvenile-onset diabetes
Late after 30-40 years
i.e. Maturity-onset diabetes
4. Pathogenesis Loss of pancreatic beta cells
of Islets of Langerhans
Insulin resistance and impaired
insulin secretion
5. Causes 1. Viral infection
2. Autoimmune antibody
production
3. Genetic inheritance
4. Stress full lifestyle
1. Obesity
2. lack of exercise
3. smoking
4. fast junk food
5. stress
6. Insulin
secretion
No insulin secretion
(deficiency)
Normal or hyper insulin
secretion
7. complications Ketoacidosis Hyperglycemic coma
8. Clinical
management
Insulin injections and diet Diet, exercise, oral antidiabetic
drugs
70. Sr.
No.ro.
tDiabetes mellitus ell Diabetes Insipidus
1.
It is characterised by deficiency of
insulin or insulin resistance
It is characterised by deficiency of a
Antidiuretic hormone (ADH)
2.
Diabetes mellitus is a disorder of
pancreas and target cells: liver cell,
skeletal muscles and adipose cells
Diabetes insipidus is a disorder of the
brain, pituitary gland and kidneys
3.
It causes hyperglycemia and
glycoseuria
Normal blood glucose levels
4.
Symptoms are excessive thirst,
excessive urine formation, excessive
eating.
Symptoms are excretion of large
quantity of urine, thirst and
dehydration.
5.
It is treated with oral hypoglycemic
drugs and insulin
It is treated with synthetic antidiuretic
hormone.
72. ADRENAL GLAND
The adrenal glands are small glands founds superior to each kidney.
The adrenal glands are 3.5-5 cm in height and 2-3 cm in width, weigh
about 4-5 gm.
The outermost part of each adrenal gland is the adrenal cortex and
the innermost part is the adrenal medulla. Each section functions as
separate endocrine glands.
The adrenal cortex produces steroid hormones and adrenal medulla
produces two catecholamine hormones.
74. ADRENAL CORTEX
The adrenal cortex is subdivided into three different
zones that secrete different steroid hormones.
• The outer zone is zona glomerulosa which secretes group of
hormones mineralocorticoids.
• The middle zone is zona fasciculata which secretes mainly
glucocorticoids.
• The inner zone is zona reticularis which secretes mainly
androgens (male sex hormones).
76. Middle zone
Zona fasciculata
Glucocorticoids
Cortisol,
Corticosterone,
Cortisone
Gluconeogenesis (formation of
glucose) hyperglycemia
Lipolysis (breakdown of triglycerides
into fatty and glycerol and energy
production)
Metabolism of protein
Anti-inflammatory action
Resistance to stress in exercise,
fasting, extreme temperature, high
altitude, surgery, trauma, infection
etc.
Depress the immune response
77. Inner zone
Zona reticularis
Androgens
(Sex hormones)
Puberty: development of
secondary sexual
characteristics at 10-14 years
of age
Growth of axillary and pubic
hairs in boys and girls
Contribute in sex drive and sex
behavior
78. ADRENAL MEDULLA
Adrenal medulla consists of hormone
producing cells called chromaffin cells.
They are sympathetic postganglionic cells
that are specialized to secrete hormones
adrenaline and noradrenaline.
79. HORMONES SRCRETED
FROM ADRENAL MEDULLA
EFECTS
CATECHOLAMINES
Adrenaline,
Noradrenaline
are neurotransmitters of
sympathetic division of
autonomic nervous
system
Prepare the body for ‘fight or flight’
response under stress
Cardiac stimulant action
Increasing heart rate
Increasing blood pressure
Increasing basal metabolic rate
Constriction of blood vessels
Increasing blood supply to the heart,
brain, skeletal muscles, skin, blood,
vessels etc.