Endocrinology is the study of the endocrine system and hormones. The endocrine system includes glands that secrete hormones directly into the bloodstream to regulate distant target organs. The major endocrine glands include the pituitary, thyroid, parathyroid, adrenal, pancreas, and gonads. Hormones can be peptides, proteins, or steroids and have various metabolic effects in the body. Diseases of the endocrine system, such as diabetes and thyroid disorders, result from deficient or excessive hormone levels.

1. Endocrinology
Branch of biology and medicine
dealing with the endocrine
system , its disease and its
specific secretion known as
hormones.

2. Hormones – organic biologically active
compounds of different chemical nature that
are produced by the endocrine glands, enter
directly into blood and accomplish humoral
regulation of the metabolism of compounds and
functions on the organism level.
Hormonoids (tissue hormones) – compounds
that are produced not in glands but in different
tissues and regulate metabolic processes on the
local level, but some of them (serotonin,
acetylcholine) enters blood and regulate
processes on the organism level.

3. Specific stimulus for hormones
secretion is:
-nervous impulse
-concentration of the certain
compound in blood passing through
the endocrine gland

5. 1. Hypothalamus
2. Pituitary
3. Epiphysis
4. Thymus
5. Thyroid gland
6. Parathyroid glands
7. Langergans’ islands
of pancreas
8. Epinephrine glands
9. Sex glands
Endocrine glands:

6. Fate of hormones in the organism
•Are secreted directly into the blood
•Peptide and protein hormones are secreted
by exocytosis
•Steroid (lipophilic) hormones continuously
penetrate the membrane (they are not
accumulated in cells, their concentration in
blood is determined by the speed of
synthesis)

7. Transport of hormones in blood
Protein and peptide nature – in free state
Steroid hormones and hormones of thyroid gland –
bound with alpha-globulins or albumins
Catecholamines – in free state or bound with albumins,
sulphates or glucuronic acid
Reach the target organs
Cells have the specific receptors to certain hormone

8. PITUITARY GLAND
The pituitary gland(master gland) is about
the size of a pea (0.5 grams).
It lies at the base of the skull in a bony
cavity of the sphenoid bone (referred to as
the sella turcica)

9. CELLS OF THE ANTERIOR
PITUITARY
• On the basis of histological and
functional characters, two major types of
the cells are found in the anterior
pituitary gland:
Chromophobes: Histological structure
that does not stain readily, appear pale
under the microscope.
Chromophills (Acidophills & Basophills).

10. • A = Basophils
• B & C=
Chromophobes
• D = Acidophils

11. Acidophills include further
two types of cells
• Somatotropes
– Responsible for the secretion of Growth
hormone.
• Lactotropes.
– Secrete Prolactin.

12. Basophills are further subdivided
into three types On the basis of
their secretions
• Corticotropes.
–Responsible for the secretion of ACTH.
• Thyrotropes.
–The secretion of TSH.
• Gonadotropes.
–The secretion of FSH & LH.

13. Hormones of the anterior pituitary
• Somatotropin (GH).
• Corticotrophin (ACTH).
• Thyrotropin (TSH).
• Gonadotropins:
Follicle stimulating hormone (FSH).
Leutinizing hormone (LH).
• Prolactin.

14. Structure of the hormones of the
anterior pituitary
• Polypeptide chain
Prolaction (198 Amino Acids)
Growth hormone (191 Amino Acids)
ACTH (39 Amino Acids)
o Glycoproteins (Having an alpha and beta
chain)
FSH (Alpha: 89 Beta:115)
 LH (Alpha: 89 Beta:115)
TSH (Alpha: 89 Beta:112)

15. Structural similarities
• GROWTH HORMONE AND PROLACTIN
BELONG TO THE SAME FAMILY OF
HORMONES.
Homology in Amino Acid structure
Act through the tyrosine kinase receptor
system
Linked to growth

16. Growth Hormone
(GH; Somatotropin)
• The major hormone regulating growth in
the body is growth hormone
(GH;somatotropin).
• Actions of Growth Hormone:
- increases skeletal growth
- increases muscular growth
- increases amino acid uptake and protein
synthesis
- increased use of lipids for energy
- decreased storage of carbohydrates

17. Growth hormone
• Released under the influence of
hypothalamic Growth Hormone Releasing
Hormone (GHRH).
• Inhibited by the hypothalamic hormone
Somatostatin.
• Growth hormone is released in a pulsatile
fashion

18. BIOCHEMICAL FUNCTIONS OF
GROWTH HORMONE
• Growth hormones performs its functions on
the cells in two ways
Acts directly on the tissues
Acts on the liver to release somatomedians
(proteins) which then act on the tissues.
• Clinical levels of growth hormone can be more
specifically tested by somatomedians because
Greater half life(20 hours)
Growth hormone release is pulsatile

19. • Growth hormone has both catabolic and
anabolic functions.
• Anabolic functions: Proteins
• Catabolic Functions: Lipids

20. Endocrine secretion of pancreas
• The pancreas, in addition to it's digestive
functions secrets two important hormones
insulin and Glucagon that are crucial for normal
regulation of glucose ,lipids and protein
metabolism ,although the pancreas secrets
other hormones ,somatostatin, and pancreatic
polypeptide .

21. The Endocrine Pancreas

22. Islets of Langerhans
• 1 million islets
• 1-2% of the pancreatic mass
• Beta (β) cells produce insulin
• Alpha (α) cells produce glucagon
• Delta (δ) cells produce somatostatin
• F cells produce pancreatic polypeptide

23. • Hormone of nutrient abundance
• A protein hormone consisting of two
amino acid chains linked by disulfide
bonds
• Synthesized as part of proinsulin (86 AA)
and then excised by enzymes, releasing
functional insulin (51 AA) and C peptide
(29 AA).
Insulin

24. 1- Large polypeptide 51 AA (MW 6000)
2- Tow chains linked by disulfide bonds.
A chain (21 AA)
B chain (30 AA)
3 disulfide bonds.
Insulin Structure

25. Physiologic anatomy of the pancreas
• The pancreas is composed of two major types
tissues :1- the acini which secrets digestive juices into
the duodenum
2- the islets of Langerhans ,which secrete insulin and
Glucagon directly into the blood
The islets contain three major types of cells :alpha ,beta
and delta cells , the alpha cells secrete glucagon
hormone. And delta cells secrete somatostatin
The beta cells ,constituting about 60 percent of all cells
of the islets , and secrete insulin.
insulin inhibits Glucagon secretion,and somatostatin
inhibits the secretion of both insulin and Glucagon .

26. Insulin and it’s metabolic effects
• insulin has profound effects on :
• carbohydrate metabolism
• fat metabolism
• protein metabolism

27. Factors and conditions that increase and decrease
insulin secretion
decrease insulin secretionIncrease insulin secretion
-Decrease blood glucose
-fasting
-somatostatin
-Alfa-adrenergic activity
-increase blood glucose
-increase blood free fatty acid
-increase blood amino acid
-gastrointestinal hormones
(gastrin, choleccystokinin
secretin, gastric inhibitory
peptide)
-glucagon, growth hormone,
cortisol.
-parasympathetic stimulation
-insulin resistance ;obesity

28. • A 29-amino-acid polypeptide hormone that is a potent
hyperglycemic agent
• Produced by α cells in the pancreas
• Its major target is the liver, where it promotes:
– Glycogenolysis – the breakdown of glycogen to
glucose
– Gluconeogenesis – synthesis of glucose from lactic
acid and noncarbohydrates
– Release of glucose to the blood from liver cells
Glucagon

29. • A serious disorder of carbohydrate metabolism
• Results from hyposecretion or hypoactivity of
insulin
• The three cardinal signs of DM are:
–Polyuria – huge urine output
–Polydipsia – excessive thirst
–Polyphagia – excessive hunger and food
consumption
Diabetes Mellitus (DM)

30. Glucagon and it’s functions
• Glucagon ,a hormone secreted by the alpha cells of the
islets of Langerhans ,when the blood glucose
concentration falls. has several functions that are
diametrically opposed to those of insulin .Most
important of these functions is to increase the blood
glucose concentration ,an effect that is exactly the
opposite that of insulin
• Like insulin ,glucagon is a large polypeptide .it has a
molecular weight of 3485 and is composed of a chain of
29 amino acids
• glucagon is also called the hyperglycemic hormone.

31. Diabetes mellitus
• Is a syndrome of impaired carbohydrate ,fat, and
protein metabolism caused by either lack of insulin
secretion or decreased sensitivity of the tissue to
insulin
• There are two types of diabetes mellitus
1-type 1 diabetes also called insulin –dependent diabetes
mellitus (IDDM) is caused by lack of insulin secretion
2-type 2 diabetes mellitus also called non-insulin-
dependent diabetes mellitus (NIDDM) is caused by
decrease sensitivity of target tissue to the metabolic
effects of insulin (also called insulin resistance )

32. Adrenal (Suprarenal) Glands
Comprised of two parts –each with separate
functions
 outer adrenal cortex &
 inner adrenal medulla
(“suprarenal” means on top of the kidney)

34. Adrenal Cortical Steroids
• Mineralocorticoids
– eg. aldosterone
– Controls ion
transport in the
kidney function
– Regulates expression
of a Na channel
– Important for water
reabsorption
• Glucocorticoids
– eg. cortisol
– Important for
metabolism esp.
glucose
– Activate enzymes (in
liver) that increase
glucose production
–  blood glucose

35. Steroid Hormones
• Steroid hormones: produced in the
adrenal cortex, testis, ovary, and
some peripheral tissues (adipose
tissue, the brain!)
• All steroid hormones share a typical
(but not identical) ring structure.

36. Steroid hormones
All steroid hormones are derived from
cholesterol and differ only in the ring
structure and side chains attached to it.
All steroid hormones are lipid soluble

37. Types of Steroid hormones
• Glucocorticoids; cortisol is the major
representative in most mammals
• Mineralocorticoids; aldosterone being most
prominent
• Androgens such as testosterone
• Estrogens, including estradiol and estrone
• Progestogens (also known a progestins) such
as progesterone

38. Cortisol, the important glucocorticoid
• It is essential for life
• Helps the body deal with stressful situations
within minutes
– Physical: trauma, surgery, exercise
– Psychological: anxiety, depression, crowding
– Physiological: fasting, hypoglycemia, fever,
infection
• Regulates or supports a variety of important
cardiovascular, metabolic, immunologic, and
homeostatic functions including water balance

39. 39
• Keeps blood glucose levels high enough to
support brain’s activity
– Forces other body cells to switch to fats and amino
acids as energy sources
• Catabolic: break down protein
• Redirects circulating lymphocytes to lymphoid
and peripheral tissues where pathogens usually
are
In large quantities, depresses immune and
inflammatory response

40. Aldosterone, the main mineralocorticoid
• Secreted by adrenal cortex in response to a
decline in either blood volume or blood
pressure (e.g. severe hemorrhage)
– Is terminal hormone in renin-angiotensin
mechanism
• Prompts distal and collecting tubules in
kidney to reabsorb more sodium
– Water passively follows
– Blood volume thus increases

41. Functions of Steroid Hormones
• Steroid hormones play important roles in:
- carbohydrate regulation (glucocorticoids)
- mineral balance (mineralocorticoids)
- reproductive functions (gonadal steroids)
• Steroids also play roles in inflammatory
responses, stress responses, bone metabolism,
cardiovascular fitness, behavior, cognition, and
mood.

42. Steroid hormone synthesis
•The cholesterol precursor comes from
cholesterol synthesized within the cell from
acetate, from cholesterol ester stores in
intracellular lipid droplets or from uptake of
cholesterol-containing low density lipoproteins.
•Lipoproteins taken up from plasma are most
important when steroidogenic cells are
chronically stimulated.

43. Functions of Hormones
Derived from Cholesterol
Product Functions
Progesterone prepares uterus lining for
implantation of ovum
Glucocorticoids (cortisol)
(produced in adrenal cortex)
(catabolic steroid)
promote gluconeogenesis;
favor breakdown of fat and
protein (fuel mobilization);
anti-inflammatory
Mineralocorticoids
(aldosterone) (produced in
adrenal glands)
maintains blood volume and
blood pressure by increasing
sodium reabsorption by kidney

44. Androgens (strongest = testosterone)
(produced in testes primarily but weak
androgens in adrenal cortex) (anabolic
steroid)
development of male
secondary sex
characteristics; prevents
bone resorption
Estrogen
(produced in ovaries primarily but also
in adipose cells of males and females)
development of female
secondary sex
characteristics; prevents
bone resorption
Vitamin D (not a steroid hormone)
(produced in the skin in response to
UV light and processed to active form
in kidney)
intestinal calcium
absorption; promotes
bone formation; prevents
phosphate loss by
kidneys
Product Functions
Functions of Hormones
Derived from Cholesterol

45. Cortisol: Role in Diseases and Medication
• Use as immunosuppressant
– Hyperimmune reactions (bee stings)
– Serious side effects
• Hypercortisolism (Cushing's syndrome)
– Tumors (pituitary or adrenal)
– Iatrogenic (physician caused)
• Hypocortisolism (Addison's disease)

46. Adverse Effects
1. Complications during chronic uses
1) Cushing’s syndromes body obesity, rounded face, increased fat
around the neck, thinning arms & legs, acne, hirsutism, edema,
hypokalemia, hypertension, diabetes.
2) Inducement or aggravation of infections
3) Complications of digestive system or aggravation of peptic ulcer,
pancreatitis, sebaceous hepatitis appeared occasionally

48. 4) Complications of cardiovascular system
hypertension, atherosclerosis.
5) Osteoporosis, sweeny and wound healing delay
6) Other complications
anoia, teratogenesis
2. Withdraw
1) Iatrogenic adrenal insufficiency
2) Original disease relapse or aggravation

59. Thyroid Hormone
• The thyroid hormones, triiodothyronine (T3)
and its prohormone, thyroxine (T4),
are tyrosine-based hormones produced by
the thyroid gland that are primarily
responsible for regulation of metabolism.

60. Biosynthesis of T3 & T4
• T3 & T4 are synthesized from
tyrosine amino acid by the help of
thyroglobulin
• Biosynthesis covers the following
steps
1. Uptake of iodine
2. Formation of active iodine
3. synthesis of T3 & T4

63. Goiter
• Any abnormal increase in size of thyroid gland is
goiter
• Enlargement is mostly to compensate ↓ thyroid
hormones & ↑ TSH
• This is primarily due to a failure in the
autoregulation of T3 & T4 synthesis
• May be caused by deficiency or excess of iodine
• Goitrogenic substances: thiocyanates, nitrates &
percholates and drugs like thiourea, thiouracil,
thiocarbamide etc.
• Simple endemic goiter: due to iodine deficiency in
diet. Mostly found in those geographical regions
where iodine is less in soil & water