The document discusses the endocrine system and hormones. It defines hormones as regulatory substances released by cells to regulate other cells. Hormones can travel through different systems like endocrine, neuroendocrine, and paracrine systems. The key glands of the endocrine system include the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal glands, pancreas, and gonads. Hormones maintain homeostasis, growth and development, metabolism, and reproduction. The document discusses the different types of hormones like proteins/peptides, steroids, and amines as well as their synthesis and mechanisms of action.

1. The Endocrine System

2. What is Hormone?
 A regulatory substance and chemical messenger
released by one cell to regulate another cell.
Delivered through
endocrine, neuroendocrine, neurocrine, paracrine, a
utocrine system to act on the target cells.
 Some hormones affect on many tissues:
Eg: Growth hormone, Thyroid hormone &
Insulin.
 Some affect on specific tissues (Target tissues):
Eg: Thyroid stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)

3. Condt..
 Endocrine: Endocrine hormones travel via
blood stream to target cells.
 Neurocrine: Neurocrine hormones released
via synapses and travel via blood stream.
 Paracrine: Paracrine hormones acts on
adjacent cells.
 Autocrine: Autocrine hormones acts on the
cell that secreted them.

4. Distance of Travelled Hormone

5. Principles of Hormone
 Need to maintain Homeostatic level.
 Regulation of growth and development.
 Control and maintenance of reproduction
including fertilization and fetal growth and
nourishment and development of the
newborn.
 Regulation of the metabolism.

6. Endocrine System

9. General principle of Endocrinology
 The glands of internal secretion.
End = Into
Crin = Secrete
 The body’s great 2nd controlling system which is
controlled metabolic activity of cells by hormones.
 A ductless gland composed of epithelial cells, that
secreted hormones directly into extracellular fluid.
 From the ECF the hormones diffuse into the
bloodstream.

10. Cond..
 Central Endocrine glands
1. Pineal gland
2. Hypothalamus
3. Pituitary gland
 Peripheral Endocrine glands
4. Thyroid
5. Parathyroid
6. Thymus
7. Adrenal glands
8. Pancreas
9. Gonads (Ovaries & Testes)
 Other tissues and organs that
produced hormones – adipose
cells, cells of the small
intestine, stomach, kidneys, and
heart.

11. Chemistry of hormones can be..
 Proteins and Polypeptides: Hormones from
anterior and posterior
pituitary, Pancreas, parathyroid gland. Usually
released into blood stream via exocytosis.
 Steroid hormones: Hormones from adrenal
cortex, ovaries and testes. These are usually
synthesized from cholesterol.
 Amine hormones: Thyroid and adrenal
medullary hormones. They are derived from
tyrosine.

12. Condt..
 Hydrophilic and Lipophobic
 Peptide – work via a second messenger
Adenylate cyclase
ATP 2,3 cAMP
 Catecholamines – via 2nd messengers.
 Hydrophobic
 Thyroxine
 Steroid

13. A structural classification of hormones

14. Synthesis of hormones
1.
(Protein)
In the nucleus, the gene for hormone
transcribed into mRNA.
2. The mRNA transferred to cytoplasm and
translated on ribosome of ER to the first
protein(peptide chain) product a
preprohormone.
3. The chain is directed into the ER lumen by a
signal sequence of amino acids.
4. The enzyme of ER cleaved the signal
sequence, to create an inactive prohormone.
5. The prohormone passes from the RE
through the golgi apparatus.
6. And prohormone bud off the Golgi.
7. Secretory vesicles containing enzyme which
is cleaved the prohormone into one or more
active peptides.
8. The secretory vesicle releases its contents
by exocytosis into extra cellular space.
9. The hormone moves into the circulation for
transport to its target.

15. Steroid Hormones
•Are not packaged, but synthesized and
immediately released.
•All are derived from cholesterol. These are
located in mitochondria and smooth ER.
•Steroids are lipid soluble and thus are
permeable to membranes so are not stored in
cell.
•Steroids hormones are not water soluble so
have to be carried in the blood complexed to
specific globulins.
•Corticosteroid binding globulin carries cortisol.
•Sex steroid binding globulin carries
testosterone and estradiol.

16. Types of steroids
 Glucocorticoids: cortisol is the major
representative in most mammals.
 Mineralocorticoids: aldesterone being most
prominent.
 Androgens: such as testosterone.
 Estrogen: including estradiol, and estrone.
 Progestogens: ( also known a progestins)
such as progesterone.

17. Amine hormones
•Two types of hormones derived from the amino acid tyrosine.
Thyroid hormones and Catecholamines
•Thyroid hormones are basically a “double” tyrosine with the critical incorporation of
3 or 4 iodine atoms.
•Thyroid hormone is produced by the thyroid gland and is lipid soluble.
Catecholamine hormones
•Catecholamines both are both neurohormones and neurotransmitters.
•These include epinephrine and norepinephrine both are produced by adrenal
medulla and both are water soluble.
•Secreted like peptide hormones.

18. Condt..
 Two other amino acids are used for
synthesis of hormones:
 Tryptophan is precursor to serotonin and the pineal
hormone melatonin.
 Glutamic acid is converted to histamine.

19. Hormones and their
receptors

20. Hormone Transport In Blood
•Most water soluble hormones
circulates in plasma in
free, unattached form.
•Most lipid soluble hormones
bind to transport proteins to be
carried in blood.
•Protein and peptide
hormones, such as insulin, will
be destroyed by digestive
enzymes and must be given by
injection.

21. Mechanism of Hormone action
 Hormones bind and activate their specific receptors in two different
ways.
 Steroid hormones and thyroid affect cell function by binding and
activating an intracellular receptor( usually in nucleus).
 Water soluble hormones alter cell function by activating plasma
membrane receptors.
 After a water soluble hormones is released from an endocrine gland, it
circulates in the blood, reaches a target cell, and brings a specific
message to that cell.
 The plasma membrane is 1st messenger.
 A 2nd messenger needed to relay the message inside the cell where
hormone-stimulated take place. 2n messenger is cyclic AMP (cAMP)
 G-proteins are a common feature of the most second messenger
system.

22. Condt..
 Cyclic AMP does not
directly produce a
particular
physiological
response, but
instead activates one
or more enzymes
known as protein
kinases.
 The responsiveness
of target cell to a
hormone depends on
the hormone’s
concentration and
the number of
receptors.

23. Steroid (Water insoluble) Hormone Transport
 Most water- soluble hormones circulate in plasma in a free, unattached
form.
 Most lipid- soluble hormones bind to transport protein to be carried in
blood.
 The transport proteins improve the transportability of lipid soluble
hormones by making them temporarily water soluble, retard the passage
of the hormone through the kidney filter and slowing the rate of hormone
loss in urine. And provide reserve of hormone already present in hormone.
 Protein and peptide hormones, such as insulin, will be destroyed by
digestive enzymes and must be given by injection.
 Lipid soluble hormones bind and activate receptors within cell.
 The activated receptors then alter gene expression to form of the new
protein.
 The new proteins alter the cells activity and affect in the physiological
responses of those hormones.

25. Protein (water soluble) Hormone
Transport hormones binds on the plasma receptor to alter the cell function.
 Water soluble
 The cell membrane receptor is 1st messenger.
 2nd messenger is released when hormone stimulates response takes place inside
of cell.
 Typical action of water soluble hormones are using cyclic AMP as the 2nd
messenger.
 Firstly the hormone bind to the membrane receptor.
 The activated receptor activate s the membrane G-protein which turns on
adenylate cyclase.
 Adenylate cyclase converts ATP into cyclic AMP which activate protein kinase.
 Priotein kinases phosphorilated enzyme which catalyze reaction produce the
physiological response.

26. Condt..
 The cholera toxin modifies G-proteins in
intestine epithelial cells so they become
locked in an activated

27. Regulation Of Hormone
 Hormone secretion is
controlled by homeostatic
feedback.
 Negative feed back
mechanisms that reverse
the direction of a change
in physiological system.
 Positive feedback –
(Uncommon)
 Mechanisms that amplify
physiological changes.

30. Prostaglandins
 Prostaglandins (PGs) are powerful substances found in a
wide variety of body tissues.
 It is a local regulator(Paracrine Signals) of hormone.
 PGs are often produced in a tissue and diffuse only a
short distance to act on cells in that tissue.
 Several classes of PGs include
prostaglandinA, prostaglandin E and prostaglandin F
 Pgs influence many body functions, including
respiration, blood pressure, gastrointestinal
secretions, and reproduction.

31. Control of Endocrine
System

32. Central Endocrine System
 Hypothalamus : receives information from the nervous
system and initiates responses through the endocrine
system.
 Pituitary: Attached to the hypothalamus. Composed of
posterior pituitary and anterior pituitary.
 Pineal Gland: Pineal gland is located just posterior to the
3rd ventricle in the brain.
 Secrete Melatonin – regulates circadian rhythms.
 May induce sleep
 May initiate puberty
 May inhibit ovulation/ spermatogenesis
 May slow aging
 May enhance immunity

34. Pituitary Gland
 Anterior pituitary gland; name of
hormones:
TSH – Thyroid stimulating hormones
ACTH – Adrenocorticotropic hormone
FSH – Follicle stimulating hormone
LH – Luteinizing hormone
GH – Growth hormone
Prolactin

35. Functions of Hormones
 TSH – stimulate growth of thyroid gland, also
stimulate it’s hormone secretion.
 ACTH: stimulates growth of the adrenal cortex and
stimulate it to secrete glucocorticoids (mainly
cortisol)
 FSH – initiates growth of ovarian follicles each month
in ovary and stimulates one or more follicles to
develop to the stage of maturity and ovulation.
 FSH also helps to secretion of estrogen by
developing follicles and stimulate sperm production
in male.

36. Condt..
 LH – acts with FSH to stimulate estrogen secretion and
follicle growth to maturity. Stimulate the progesterone
secretion by corpus luteum. And stimulate the
testosterone in the male.
 GH – Stimulates growth by accelerating anabolism; also
accelerates fat catabolism and slows glucose catabolism;
by slowing glucose catabolism, tends to increase blood
glucose to higher than normal level (hyperglycemia)
 Hyper secretion during childhood results in gigantism and during
adult hood results in acromegaly.
 Hypo secretion during child hood results in pituitary dwarfism.
o Prolactin – stimulates breast development during
pregnancy and secretion of milk after the delivery of baby.

37. Posterior Pituitary gland
 Name of hormones:
- ADH – Antidiuretic hormone : Hypo secretion causes
diabetes insipidus, characterized by excessive volume of
urine.
- OT – Oxytocin
 Funtion Of Hormone
 ADH – accelerate water reabsorption from urine in
the kidney tubules into the blood, thereby deceasing
urine secretion.
 Oxytocin – stimulate the pregnant uterus to contract;
may initiate labor; causes glandular cells of breast to
release milk into ducts.

38. Control of Pituitary :
 Negative feedback
 Target organ
hormone level
inhibits release of
tropic hormones.
 Positive feedback :
 Stretching of uterus
OT release, causes
more stretching of
uterus, until
delivery.

39. f

40. Pituitary Disorders
 Hypersecretion of growth hormone
○ Acromegaly
- Middle – aged adult
- Abnormal growth of the hands/feet
- Bone changes alter facial features including the apacing of
teeth
- Arthritis
- Thick, coarse, oily skin, skin tags, enlarge lips, nose and
tongue
- Deepening of the voice due to enlarged sinuses and vocal
cords; snoring due to upper airway obstruction
- Excessive sweating and skin odor
- Enlargement of body organs, including the
liver, spleen, kidneys and heart
- Thickening of the bones and soft tissues
- Problem in childhood or adolescence - gigantism

41. Hypothalamus
 Regulates the activity of the nervous and endocrine systems.
 Highest level of endocrine control
 Secretes regulatory hormones that control the anterior pituitary gland.
 Release hormones at the posterior pituitary gland.
 Exerts direct neural control over the endocrine cells of the adrenal medullae.
 Actual production of ADH and oxytocin occurs in the hypothalamus.
 After production in the hypothalamus, hormones pass along axons into
the pituitary gland.
 The secretion and release of posterior pituitary hormones is controlled
by nervous stimulation.
 The hypothalamus controls many body functions released to
homeostasis (temperature, appetite, and thirst)

43. Hypothalamic Hormones

44. Thyroid Gland
 Names of Hormones:
 Thyroid Hormone – Thyroxin (T4)
Triiodothyronine (T3)
 Calcitonin (CT)
 Function of Hormone
 Thyroid Hormones : Accelerate catabolism (increase the body’s metabolic rate)
 Calcitonin – decreases the blood calcium concentration by inhibiting breakdown of
bone, which would release calcium into blood.
 Hyperthyroidism ( hyper secretion of thyroid hormones) increases
metabolic rate.
○ Characterized by restlessness and exophthalmoses ( protruding eyes)
○ Graves disease is an inherited form of hyperthyroidism.
 Hypothyroidism (hypo secretion of thyroid hormones)
○ May result from different condition
○ Simple goiter – painless enlargement of thyroid causes by dietary deficiency of iodine
○ Hypo secretion during early development may result in cretinism (retardation) and during
adulthood in myxedema ( characterized by edema and sluggishness)

46. Thyroid Gland Disorders
 Congenital hypothyroidism
○ Abnormal bone development, thickened facial
features, low temperature, brain damage, lethargy
 Myxedema (adult hypothyroidism)
○ Low metabolic
rate, sluggishness, sleepiness, weight
gain, constipation, dry skin and hair, cold
sensitivity, high blood pressure and tissue
swelling
 Endemic goiter (enlarge thyroid gland)
○ Iodine deficiency, no TH, no – feed back, high
TSH
 Toxic goiter ( graves disease)
○ Antibodies mimic TSH, high TH, exophthalmos

47. Parathyroid Gland
 Name of Hormone
 PTH - Parathyroid hormone
 Function of Hormone
 Increase blood calcium concentration by
increasing the break down of bone with the
release of calcium into the blood.

48. Parathyroid Disorders
 Hypoparathyroid
○ Surgical excision during thyroid surgery
○ Fatal tetany 3-4 days
 Hyperparathyroid
○ Tumor in gland
○ Causes soft, fragile and deformed bones
○ High blood calcium
○ Renal calculi

49. Adrenal Gland
 Names of Hormones (Corticoids)
○ Glucocorticoids (GCs) – Chiefly cortisol
○ Mineralocorticoids (MCs) – Chiefly aldosterone
○ Sex hormones – small amount of male hormones
(androgens) secreted by adrenal cortex of both
sex.
 Three cell layers (ZONES)
○ Outer layer – secreted mineralocorticoids
○ Middle layer – secretes glucocorticoids
○ Inner layer – secretes sex hormones

50. Functions of Hormones
 Mineralo corticoids :
 Increase blood sodium and decrease body potassium concentration by
accelerating kidney tubule.
 Reabsorption of sodium and excretion of potassium.
 Function of glucocorticoids :
 Help maintain normal blood glucose concentration by increasing
gluconeogenesis.
 Gluconeogenesis – the formation of new glucose from amino acids
produced by breakdown of proteins, mainly those in muscle tissue cells;
also the conversion to glucose of fatty acids produced by the breakdown
of fats stored in adipose tissue cells.
 Play an essential part in maintaining normal blood pressure – make it
possible for epinephrine and norepinephrine to maintain a normal degree
of vasoconstriction, a condition necessary for maintaining normal blood
presure.

52. Adrenal Gland
 Act with epinephrine and norepinephrine to produce
an anti inflammatory effect, to bring about normal
recovery from inflammations of various kinds.
 Produced anti-immunity, anti allergy effect ; bring
about a decrease in the number of lymphocytes and
plasma cells and therefore a decrease in the amount
of antibodies formed.
 Secretion of glucocorticoid quickly increase when the
body is thrown into a condition of stress; high blood
concentration of glucocorticoids, in turn, brings about
many other stress responses.

54. Adrenal Gland
 Adrenal medulla
○ Names of hormones – epinephrine (Epi) , or
adrenaline, and norepinephrine (NR)
○ Functions of Hormones
 Helps the body resist stress by intensifying and
prolonging the effect of sympathetic stimulation.
 Increased epinephrine secretion is the 1st endocrine
response to stress.

55. Adrenal Gland
 Adrenal abnormalities
○ Hypersecretion of glucocorticoids causes Cushing
syndrome – moon face, hump on back, elevated
blood sugar levels, frequent infection.
○ Hypersecretion of adrenal androgens may result
from a virilizing tumor and cause masculinization
of affected women.
○ Hyposecretion of cortical hormones may result in
Addison disease ; muscle weakness, reduced
blood sugar, nausea, loss of appetite, and weight
loss.

56. Adrenal disorders
Cushing Syndrome
Addison Disease Masculinization

57. Pancreatic Islets
 Names of Hormone
○ Glucagon – secreted by alpha cells
○ Insulin – secreted by beta cells
 Function of Hormones
○ Glucagon increases the blood glucose level
by accelerating liver glycogenolysis
(conversion of glycogen to glucose)

59. Functions of Hormone
 Insulin decreases the blood glucose by
accelerating the movement of glucose out
of the blood into cells, which increases
glucose metabolism by cells.
 Diabetes mellitus
- Type 1 results from hyposecretion of insulin
- Type 2 result from target cell insensitivity to insulin
- Glucose cannot enter cells and thus blood glucose
levels rise, producing glycosuria (glucose in the urine)

61. Female Sex Glands
 The ovaries contain two structures that secrete hormones
:
- The ovarian follicles
- And The corpus luteum
 Granulosa cells ; produces estradiol, first half of cycle
 Corpus luteum ; follicle after ovulation, produce estradiol
and progesterone
 Effects of estrogen
 Development and maturation of breasts and external genitals
 Development of adult female body contours
 Initiation of menstrual cycle

62. Male Sex Gland
 The interstitial cells of testes secrete the
male hormone testosterone.
 Effect of testosterone (Masculinizing
hormone)
- Maturation of external genitals
- Beard growth
- Voice change at puberty
- Development of musculature and body contours
typical of the male

63. Thymus
 Name of Hormone – Thymosin
 Function of Hormone – plays an
important role in the development and
function of the body’s immune system.

64. Endocrine Function of Other Organs
 Heart –
○ ANP (atrial natriuretic peptide) released with an
increasing BP
○ Decrease Na+ and H2O loss by kidneys cause low
blood volume and low BP
 Skin – Helps produce vitamin D3
 Liver –
○ 15% of erythropoietin secrete (stimulates bone marrow)
○ Angiotensinogen ( a prohormone) – precursor of
angiotensin II causes increase BP
○ Converts D3 to calcidiol
○ Hepcidin – promotes intestinal absorption of iron

65. Endocrine Function of Other Organs
 Kidneys –
○ Erythropoietin – stimulate production of RBC’s
○ Converts angiotensinogen to angiotensin I
○ Converts calcidiol to calcitriol ( activate from
vitamin D)
 Stomach and small intestine –
Coordinate digestive motility and secretion
 Placenta –
○ Secretes estrogen, progesterone and others
○ Regulate pregnancy, stimulate development of
fetus and mammary gland.

66. Action of ADH : Water retention
 ADH has two actions, one on the kidney and the other on vascular
smooth muscle. These actions are mediated by different
receptors, different intra cellular mechanism, and different second
messengers
 ADH increase in water permeability
○ The major action of ADH is to increase the water permeability of
cells in the kidney distal tubule and collection duct.
○ The receptor for ADH on kidney cells is V2 receptor, which is
coupled to adenyl cyclase via G protein
○ The 2nd messenger is cAMP, which via phosphorylation
steps, directs the insertion of water channels, aquaporin 2, into
the kidney cell membrane
○ The increased water permeability of the cells allows more water
to be reabsorbed by the collecting ducts ( water moves from
urine to blood) and makes the urine more concentrated

67. ADH and Contraction of
vascular smooth muscle
 The 2nd action of ADH is to cause contraction
of vascular smooth muscle
 The receptor for ADH on vascular smooth
muscle is a V1 receptor, which is coupled to
phospholipase C via a G protein
 The 2nd messenger for this action is an IP2/Ca
cascade which produces contraction of
vascular smooth muscle, contraction of
arterioles, and increased total peripheral
resistance

68. Pathways involved in control of
ADH

69. ADH Disorders
 Hyposecretion due to damaged of
hypothalamic nucleus or
neurohypophysis – diabetes insipidus –
excessive urine production (polyuria)
and thirst
 Hypersecretion – SIADH ( Syndrome of
inappropriate ADH secretion)
○ Water retention, cerebral
edema, headache, weight gain, hypo-
osmolarity

70. Questions
 The ____ gland located in front of neck and secretes a hormone that
aids in the regulation of the body’s metabolic rate.
 The _____ gland the smallest of the endocrine glands, secrete a
hormone which regulates the concentration of calcium and phosphorus
in the blood.
 The ______ secretes glucocorticoids which help the body meet
condition of stress.
 A small cone shaped gland, the ______ gland is located inside the
cranial cavity, secretes the hormone melatonin which seems to inhibit
reprodutive activities.
 The alpha cells of the ______ secrete glucagon, a hormone produced
when the body’s blood sugar gets too low.
 ________ cells secrete insulin which causes a decrease in blood sugar
by increasing the body’s ability to take up and use sugar.

71. Questions
 The hormone somatostatin is produced by the ______
 A principle effect of the _______ gland is to regulate the body’s
metabolic rate.
 ______ is the hormone which releases milk formed by the glandular
cells of the nursing female.
 The adrenocorticotropic hormone (ACTH) has the primary action of
_________________________________
 The _________ hormone is secreted by the anterior lobe of the
pituitary gland and stimulate the normal growth cycle of the ovarian
follicle in females
 ____________ hormone is secreted by the posterior lobe of the
pituitary gland. This hormone makes the collecting duct of the kidney
permeable to water and allows concentration of water.

72. Questions
 The hormone which promotes the maturation of the ovarian follicle as well
as the secretion of progesterone is the _____ hormone.
 The hormone which works with estrogen to regulate menstruation is
_______
 The hormone responsible for the secondary sex characteristic of voice
pitch, broad pelvis, and hair pattern in women is _____
 The hormone responsible for secondary sex characteristic for men is
______
 The gland responsible for animal coming into heat is the ___________
gland.
 The mineralocorticoid help maintain _______ balance and ______
balance.
 The catecholamine hormones epinephrine and norepinephrine are
commonly known as the _________ hormones because they give body
extra energy in stressful situation.

73. Answers
•Follicle stimulating
 Thyroid
•Antidiuretic
 Parathyroid
•Lutenizing
 Adrenal cortex
•Progesterone
 Pineal
•Estrogen
 Pancreas
•Testosterone
 Beta cells
•Pineal
 Delta cells
•Electrolyte fluid
 Thyroid
•Fight or flight
 Oxytocin
 Promoting and maintaining
normal growth and
development of the
adrenal cortex