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HORMON
What is hormon?

Many organs in the body secreted biologically active compound
called endocrine hormones, which are transported via blood
stream to other tissues or organs where they exert a biological
effect

As classically defined, is a substance that is synthesized in one
organ and transported by the circulatory system to act on
another tissue

Hormones can act on adjacent cells (paracrine)

Hormones can act on the cell in which they were synthesized
without entering the sistemic circulation (autocrine)
Long-Distance Regulators
•
•
•
Animal hormones are chemical signals
that are secreted into the circulatory system
and communicate regulatory messages
within the body
Hormones reach all parts of the body, but
only target cells are equipped to respond
Hormones convey information via the
bloodstream to target cells throughout the
body
What is the importance of hormones?

Several hormones may control one, process or one
hormon may control several process

Provide communication beetween cells, tissues and
organs

This comunication is responsible for the regulation of
wide range of functions including growth, reproduction,
development, homeostasis, and response to external
stimuli. Failure in this comunication channels are
common and lead to many diseases of the endocrine
system
How do hormones act?

In order to act , hormones must interact
with other loci on or in the target cell

These sites are termed receptors

A receptor is a locus to which the hormone
binds in order to elicit its action
RECEPTOR

A receptor has two function :
First, it must be able to distinguish the hormone from
all the other chemicals present in the circulation and bind it.
The hormone binding sites on receptors have
evolved to have unique configurations that are
complementary to the hormones they bind.
Generally, hormone-receptor interactions are
noncovalent in nature and are reversible.
RECEPTOR
- Second, the receptor must able to
transmit the information gained from the
binding to trigger a cellular response.
Thus, subtances that bind hormones, even
tightly, but do not trigger subsequent
responses are not receptors.
Types of Hormones

Hormon can be clasisified in several ways,
according:
1-Chemical composition :
Cholesterol derivates– this include :
glucorticoid, mineralocorticoid, esterogen,
progestin
Amino acid -tyrosine
Polypeptyde-ACTH,TRH
Glycoprotein-TSH, FSH, LH
2-Solubility properties-lipophilic dan hidrophilic
3-Location of reseptor
4-Nature of signaling used to mediate hormonal
action within the cell
Clasification of hormones by mechanism of action

Group I hormones

Hormon that bind to intracellular receptors

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




Androgens
calcitriol
esterogens
glucocorticoids
mineralocorticoids
progestins
retinoic acid
Group II Hormones
Hormones that bind to cell surface
receptors
A.The second messenger is cAMP
Calcitonin, glucagon, LH, Somatosatin,
B.The second mesenger is cGMP
Nitric oxide, atrial natriuretic factor
C.The second messenger is calcium or phosphatidyl inositols (or
both)
Gastrin, oxitocyn, cholecistokinin, TRH, Acetilcholin
D.The second messenger is a kinase or phosphatase cascade
Adponectin, insulin , leptin, GH, Prolactin, IGF-I ,
II, EGF
IGF-
General features of hormon classes
Group I
Group II
Types
Steroid,
Polypeptides, protein,
iodothyronines,calcitri glycoproteins,
ol, retinoids
cathecolamines
Solubility
Lipophilic
Hydrophilic
Transport protein
Yes
No
Plasma halflife
Long ( hours to days)
Short (minutes)
Receptor
Intracellular
Plasma membran
Mediator
Receptor-hormone
complex
cAMP.cGMP,
Ca2+,metabolites
complex
phosphoinositols,
kinase cascade
WHERE HORMONES ARE SYNTHESIZED?

Hormones are synthesized in discrete organs designed solely for
spesific purpose
 Pituitary: TSH, FSH, LH, GH, Prolactin, ACTH

Some organs are disigned to perform two distinct but closely
related function
 Ovaries produce mature oocyte and reproductive hormones estradiol
and progesteron
 The testes produce mature spermatozoa and testesterone

Hormones are also produced in specialized cells within other
organs
 Small intestine : glucagon like peptide

Thyroid : calcitonin
 Kydney : angiotensin II

The synthesis of some hormones requires the parenchimal cells of
more than one organ
 Skin, liver, kidney : calcitriol.
Hormon are synthesized and modified for full
activity in a variety of ways

Some hormones are synthesized in final form and secreted
immediattely , included in this class are the hormon derived
from cholesterol

Others are synthesized in final form and stored in producing
cells, example catecholamine

The others hormone synthesized and from precursor
molecules in the producing cell, then are processed and
secreted upon a physiologic cue, examples insulin
Converted to active forms from precurssor molecules in the
periphery, examples: T3, DHT

Control Pathways and Feedback Loops
•
•
•
The endocrine system secretes hormones
that coordinate slower but longer-acting
responses including reproduction, development,
energy metabolism, growth, and behavior
A common feature is a feedback loop
connecting the response to the initial stimulus
Negative feedback regulates many
hormonal pathways involved in
homeostasis

Signaling by any of these hormones
involves three key events:


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Reception
Signal transduction
Response
SECRETORY
CELL
SECRETORY
CELL
Hormone
molecule
VIA
BLOOD
Hormone
molecule
VIA
BLOOD
Signal receptor
TARGET
CELL
TARGET
CELL
Signal
transduction
pathway
OR
Signal
receptor
Cytoplasmic
response
DNA
DNA
Signal
transduction
and response
mRNA
NUCLEUS
Nuclear
response
NUCLEUS
Receptor in plasma membrane
Synthesis of
specific proteins
Receptor in cell nucleus
Binding of a hormone to its receptor
initiates a signal transduction pathway
leading to responses in the cytoplasm or a
change in gene expression
 The same hormone may have different
effects on target cells that have



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Different receptors for the hormone
Different signal transduction pathways
Different proteins for carrying out the response
Different receptors different cell responses
Epinephrine
Epinephrine
Epinephrine
a receptor
 receptor
 receptor
Glycogen
deposits
Vessel
constricts
Intestinal blood
vessel
Vessel
dilates
Skeletal muscle
blood vessel
Glycogen
breaks down
and glucose
is released
from cell
Liver cell
Different intracellular proteinsdifferent cell responses
Paracrine Signaling by Local Regulators
In paracrine signaling, nonhormonal
chemical signals called local regulators elicit
responses in nearby target cells
 Types of local regulators:

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Neurotransmitters
Cytokines and growth factors
Prostaglandins help regulate aggregation of
platelets, an early step in formation of blood
clots
The hypothalamus and pituitary integrate many
functions of the vertebrate endocrine system
The hypothalamus and the pituitary
gland control much of the endocrine
system
 Tropic hormones, hormones that regulate
endocrine organs
 Tropic hormones are secreted into the blood
and transported to the anterior pituitary

Hypothalamus
Neurosecretory
cells of the
hypothalamus
Axon
Posterior
pituitary
Anterior
pituitary
HORMONE
TARGET
ADH
Kidney tubules
Oxytocin
Mammary glands,
uterine muscles
Tropic Effects Only
FSH, follicle-stimulating hormone
LH, luteinizing hormone
TSH, thyroid-stimulating hormone
ACTH, adrenocorticotropic hormone
Neurosecretory cells
of the hypothalamus
Nontropic Effects Only
Prolactin
MSH, melanocyte-stimulating hormone
Endorphin
Portal vessels
Nontropic and Tropic Effects
Growth hormone
Hypothalamic
releasing
hormones
(red dots)
Endocrine cells of the
anterior pituitary
Pituitary hormones
(blue dots)
HORMONE
FSH and LH
TSH
ACTH
Prolactin
TARGET
Testes or
ovaries
Thyroid
Adrenal
cortex
Mammary
glands
MSH
Endorphin
Melanocytes Pain receptors
in the brain
Growth hormone
Liver
Bones
Posterior Pituitary Hormones
The two hormones released from the
posterior pituitary act directly on
nonendocrine tissues
 Oxytocin induces uterine contractions and
milk ejection
 Antidiuretic hormone (ADH) enhances
water reabsorption in the kidneys

Anterior Pituitary Hormones
•
The anterior pituitary produces both
tropic and nontropic hormones
Tropic Hormones
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The four strictly tropic hormones are
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Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Each tropic hormone acts on its target
endocrine tissue to stimulate release of
hormone(s) with direct metabolic or
developmental effects
Nontropic Hormones
Nontropic hormones produced by the
anterior pituitary:
 Prolactin stimulates lactation in mammals
but has diverse effects in different
vertebrates
 MSH influences skin pigmentation in
some vertebrates and fat metabolism in
mammals
 Endorphins inhibit pain

Growth Hormone
Growth hormone (GH) has tropic and
nontropic actions
 It promotes growth directly and has diverse
metabolic effects
 It stimulates production of growth
factors

•
The thyroid gland produces calcitonin,
which functions in calcium homeostasis
Parathyroid Hormone and Calcitonin:
Control of Blood Calcium

Two antagonistic hormones, parathyroid
hormone (PTH) and calcitonin, play the
major role in calcium (Ca2+) homeostasis in
mammals. Calcitonin stimulates Ca2+
deposition in bones and secretion by
kidneys, lowering blood Ca2+ levels

Two Glands of Hormon Thyroid and
parathyroid Located

Produce hormone (PTH)
Thyroid gland
releases
calcitonin.
Calcitonin
Reduces
Ca2+ uptake
in kidneys
Stimulates
Ca2+ deposition
in bones
STIMULUS:
Rising blood
Ca2+ level
Blood Ca2+
level declines
to set point
Homoeostasis:
Blood Ca2+ level
(about 10 mg/100 mL)
Blood Ca2+
level rises
to set point
STIMULUS:
Falling blood
Ca2+ level
Stimulates Parathyroid
Ca2+ releasegland
from bones
PTH
Increases
Ca2+ uptake
in intestines
Stimulates Ca2+
Active
vitamin D uptake in kidneys
Insulin and Glucagon: Control of Blood
Glucose
The pancreas secretes insulin and
glucagon, antagonistic hormones that help
maintain glucose homeostasis
 Glucagon is produced by alpha cells
 Insulin is produced by beta cells

Body cells
take up more
glucose.
Insulin
Beta cells of
pancreas
release insulin
into the blood.
Liver takes
up glucose
and stores it
as glycogen.
STIMULUS:
Rising blood glucose
level (for instance, after
eating a carbohydraterich meal)
Blood glucose level
declines to set point;
stimulus for insulin
release diminishes.
Homeostasis:
Blood glucose level
(about 90 mg/100 mL)
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes.
Liver breaks
down glycogen
and releases
glucose into the
blood.
STIMULUS:
Dropping blood glucose
level (for instance, after
skipping a meal)
Alpha cells of pancreas
release glucagon into
the blood.
Glucagon
Target Tissues for Insulin and Glucagon

Insulin reduces blood glucose levels by
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Promoting the cellular uptake of glucose
Slowing glycogen breakdown in the liver
Promoting fat storage

Glucagon increases blood glucose
levels by
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Stimulating conversion of glycogen to glucose in
the liver
Stimulating breakdown of fat and protein into
glucose
Diabetes Mellitus
Diabetes mellitus is perhaps the bestknown endocrine disorder
 It is caused by a deficiency of insulin or a
decreased response to insulin in target
tissues
 It is marked by elevated blood glucose
levels

Adrenal Hormones: Response to Stress
The adrenal glands are adjacent to the
kidneys
 The adrenal medulla secretes epinephrine
(adrenaline) and norepinephrine
(noradrenaline)
 They are secreted in response to stressactivated impulses from the nervous system
 They mediate various fight-or-flight
responses

Melatonin and Biorhythms
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•
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The pineal gland, located in the brain,
secretes melatonin
Light/dark cycles control release of
melatonin
Primary functions of melatonin appear to relate
to biological rhythms associated with
reproduction
Invertebrate regulatory systems also involve
endocrine and nervous system interactions
Diverse hormones regulate homeostasis
in invertebrates
 In insects, molting and development are
controlled by three main hormones:
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Brain hormone stimulates release of ecdysone
from the prothoracic glands
Ecdysone promotes molting and
development of adult characteristics
Juvenile hormone promotes retention of
larval characteristics
Hormones Released from the Anterior
Pituitary or Adenohypophysis
Somatotrophs
Human Growth
Hormone (hGH)
Hypothalamic control
hGH releasing hormone
hGH inhibiting hormone
Target Tissues:
General body cells,
particularly bone,
muscle, cartilage, and
the liver.

Hormones Released from the Anterior
Pituitary or Adenohypophysis

1.
2.
3.
Hormone affects:
promotes the synthesis of
insulin-like growth
factors
Controls normal growth
patterns by increasing
protein synthesis,
lipolysis, ATP production,
and carbohydrate
metabolism
In adults, it help maintain
muscle and bone mass
and promote healing and
tissue repair
Hormones Released from the Anterior Pituitary
or Adenohypophysis
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
Hypo-secretion:
During childhood causes Dwarfism
Hyper-secretion:
During childhood causes
Gigantism (up to 8 – 9 ft.)
During Adulthood causes
Acromegaly:
Enlargement of the small bones of the hand and
feet
Enlargement of the cranium, nose, and lower
jaw
Tongue, liver, and kidneys become enlarged
Hormones Released from the Anterior
Pituitary or Adenohypophysis

Thyrotrophs:
Thyroid Stimulating
Hormone (TSH)

Hypothalamic Control
Thyrotropin Releasing
Hormone (TRH)

Target Tissue
Follicular cells of the
Thyroid gland

Hormone affects:
controls the
production of T3 and
T4
Endocrine activity of
the Thyroid Gland
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Follicular cells:
T3 and T4
Target Tissue;
Almost all body tissues
Hormone effects:
Increases body
metabolism
Increases
gluconeogenesis
Increases glycolysis
Increases lipolysis
Increased basal
metabolic rate (BMR)
Increases heart rate and
force of contraction
Endocrine activity of the Thyroid
Gland

Hypothyroidism:
endemic goiter: (due to I2 deficiency)
Myxedema: bagginess under the eyes and
swelling of the face.
Arteriosclerosis: due to increase in blood
cholesterol
Cretinism: extreme hypothyroidism during
infancy and childhood
Endocrine activity of
the Thyroid Gland

Hypothyroidism:
Cretinism: Physical and mental growth
and development is greatly retarded

Hyperthyroidism
Toxic goiter
Graves Disease with exophthalmos
Hormones Released from the Anterior
Pituitary or Adenohypophysis

Corticotrophs
Adrenocorticotropic
hormone (ACTH)

Hypothalamic Control
Corticotropic releasing
hormone (CRH)

Target Tissue
Adrenal cortex, Zona
Fasciculata

Hormone affects:
control production of
glucocorticoids such as
cortisol
Endocrine activity of
the Adrenal Cortex

Zona glomerulosa
Mineralocorticoids such
as Aldosterone

Hormonal control
renin-angiotensin
pathway
permissive effect of ACTH

Target tissue:

Hormone affects:
increases
reabsorption of Na+
and water
Principle cells of the DCT
and collecting duct
Endocrine activity of the Adrenal
Cortex


Hyper-secretion:
Aldosteronism:
Hypokalemia,
increase in
extracellular fluid and
blood volume,and
hypertension, may
also have period of
muscular paralysis
Hypo-secretion:
Addison’s disease
Mineralocorticoids
deficiency, death
occurs in four days to
two weeks if
untreated
Endocrine activity of
the Adrenal Cortex

Zona Fasciculata
Glucocorticoids such as
cortisol and cortisone

Hormone control:
ACTH

Target tissue:
Liver and general body
cells

Hormone affects:
Stimulates
gluconeogenesis by
the liver
Decreased glucose
utilization by cells
Endocrine activity of
the Adrenal Cortex

Hormone affects:
Elevated blood
glucose levels
Reduction of protein
stores in all body cells
except the liver
increased plasma
protein levels
promote lipolysis and
beta oxidation of fat
Helps body recover
from stress
Prevention of
inflammation
Endocrine activity of the Adrenal
Cortex

Hypo-secretion
Addison’s disease - glucocorticoid deficiency
person becomes highly susceptible to disease and
deteriorating effects of stress

Hyper-secretion:
Cushing’s Syndrome
mobilization of fat from lower body to the thoracic
and upper abdominal regions giving raise to “Buffalo
Torso”
Interactions
of hormones
in response to
stress
Endocrine activity of the Adrenal Cortex

Zona reticularis
Produces small
amounts of
androgens, mostly
dehydroepiandoster
one (DHEA), DHEA
may be converted
into estrogens

Hormone Control:
Believed to be ACTH

Target tissue:
General body cells
Endocrine activity of the Adrenal Cortex

Hyper-secretion:
Adrenogenital Syndrome
in females causes beard growth,
deeper voice, masculine distribution
of body hair, and growth of the
clitoris to resemble a penis.
Picture: In pre-pubertal males it
causes the rapid develop of
secondary sexual conditions
Endocrine Activity of the Adrenal Cortex

Hyper-secretion:
Adrenogenital Syndrome
in females causes beard growth, deeper
voice, masculine distribution of body hair,
and growth of the clitoris to resemble a
penis.
Picture: Virilizing adrenal hyperplasia in a
newborn female baby, DHEA was converted
to testosterone
Endocrine Activity of the Adrenal Cortex

Hyper-secretion:
Picture: micropenis in a newborn baby boy.
micropenis is a result of hypopituitarism
and lack of production of LH and therefore
testosterone by the cells of Leydig
Other Thyroid Hormones

Parafollicular
cells
Calcitonin
Parathyroid Hormones

Principle Cells
PTH
PTH and Calcitonin Interaction
Both Pancreatic
Hormones
interaction