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ENDOCRINE SYSTEM
BURÇİN GÜMÜŞ
What does the endocrine system do?
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The endocrine
system produces
and regulates the
body’s hormones,
which are
chemicals created
by the body to
control many of its
functions.
Functions controlled by hormones controlled
by the endocrine system include:
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activities of entire organs
growth and development
reproduction
sexual characteristics
usage and storage of energy
levels of fluid, salt, and sugar in the blood
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The endocrine
system consists
primarily of
hormones and
glands, and
overlaps with the
nervous system
and the exocrine
system.
Gland
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1.
2.
Gland , organ made of cells that secrete
materials into other areas of the body
Gland has two types:
Exocrine glands
Endocrine glands
Gland
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Exocrine glands  secrete nonhormonal
chemicals into ducts which transport chemicals
to specific locations inside and outside the body
Ex. Sweat, mucous, salivary glands
Endocrine glands  ductless glands located
throughout body – secrete hormones into
bloodstream
Hormones
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Chemical messengers
Produced in endocrine glands
Travel through blood
Affect the target tissues
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The hormones are released into the bloodstream
and may affect one or several organs throughout
the body.
Types of Hormones
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Amino acid-based hormones ( Peptide
Hormones)
Include proteins, peptides, amino acids, other
forms derived from amino acids
Not lipid soluble
Ex. Epinephrine (adrenaline)
Types of Hormones
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Steroid hormones
Lipids that made from cholesterol
Lipid soluble
Diffuse through cell membranes
Ex. Estrogen, testosterone
Hormone Actions
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Steroid Hormones
Pass straight through the plasma membrane.
Combine with a receptor molecule in the cell
cytoplasm
Hormone Actions
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Peptide Hormones
Attachment to plasma membrane receptor (c)
stimulates a secondary messenger
Secondary messenger alter the action of the cell
Endocrine Glands
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Pituitary Gland
Hypothalamus
Pineal Gland
Thyroid Gland
Parathyroid Gland
Adrenal Gland
Pancreas
Gonads : Ovaries & Testes
Hypothalamus
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Has many receptors for
changes of internal
conditions
Serves as a link between
the nervous system and
the endocrine system
(pituitary)
Controls each lobe of the
pituitary gland
Pituitary Gland
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Located at the
base of the brain.
Composed of two
parts and called
the “master
gland” because it
controls the
activities of other
glands.
Posterior Pituitary
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Posterior pituitary is part of the hypothalamus
and does not secrete its own hormones
Hormones released by the posterior lobe are
synthesized by neurons in the hypothalamus
Antidiuretic hormone (ADH)- Vasopressin
regulates the kidneys to reduce water loss in the
urine.
Oxytocin stimulates uterine contraction during
childbirth.
Anterior Pituitary
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Anterior pituitary releases 6 major hormones :
Prolactin
Growth Hormone ( GH)
Luteinizing Hormone ( LH)
Adrenocorticotropin hormone (ACTH)
Thyroid Stimulating Hormone (TSH)
Follicle Stimulating Hormone (FSH)
Anterior Pituitary
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1. Prolactin
Released after pregnancy, stimulates milk
production in females
2. Growth Hormone (GH)
This hormone controls the growth of the body by
stimulating the elongation of bones .
Anterior Pituitary
3. Luteinizing Hormone (LH)
 Triggers ovulation and the development of the
“ corpus luteum” in females.
 In males it stimulates the release of testosterone
by the testes
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4. Follicle Stimulating Hormone (FSH)
Stimulates the activities of the ovaries and
testes.
Anterior Pituitary
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5. Adrenocorticotropin hormone (ACTH)
Stimulates the adrenal cortex to release corticoid
hormones.
6. Thyroid Stimulating Hormone (TSH)
Stimulates the thyroid to release thyroxine
How to remember the 6
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P
GH
LH
FSH
TSH
ACTH
Please Get Lunch For Their Aunt
Pineal Gland
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Located in the brain
Secretes melatonin &
serotonin
Believed to be involved
with daily biorhythms,
such as sleep cycles
Possibly responsible for
mood disorders, such
as “ winter depression ”
or “ seasonal affective
disorder syndrome ”
Thyroid Gland
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Located along the
midline of the neck
 Produces
hormones
that stimulate body
heat production,
bone growth, and
the body's
metabolism
Thyroid Gland
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This gland secretes thyroxin which contains
iodine.
Increases the rate at which you use energy =
Metabolism
Thyroxin secretion is regulated by TSH, which is
secreted by the pituitary gland.
Regulates the rate of metabolism in the body
and is essential for normal physical and mental
development
Thyroid Gland
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A person who suffers from hypothyroidism has a
lower metabolic rate, which can cause obesity
and sluggishness.
The opposite condition, known as
hyperthyroidism, occurs when the thyroid
produces too much thyroxine.
It can lead to excessive perspiration, high body
temperature, loss of weight, and a faster heart
rate
Thyroid Gland
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Lack of iodine in the diet will lead to lack of
thyroxin secretion.
This produces enlargement of the thyroid gland
and is called Goiter.
Goiter is the result of iodine deficiency in the
diet.
Parathyroid Gland
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Releases parathyroid hormone ( PTH), which
plays a role in regulating calcium levels in the
blood and bone metabolism.
Parathormone controls calcium metabolism.
Calcium is necessary for proper growth of teeth
and bones, blood clotting, and nerve
function.
Thymus Gland
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Regulates the immune response, which helps
your body fight disease
Adrenal Glands
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The adrenal glands
are made up of two
parts.
The outer part is
called the adrenal
cortex
The inner part is
called the adrenal
medulla.
Adrenal Glands
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Adrenal Cortex
Aldosterone helps maintain salt-and-water
balance in body by affecting kidneys
Maintains electrolyte balance
Stimulates the kidneys to reabsorb Na+ and
secrete K+ into the urine
Adrenal Glands
Adrenal Glands
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Adrenal Medulla
Nervous system’s reaction to stress (“fight-or-flight”)
 Epinephrine
 Increase
(Adrenaline)
respiration, metabolism
 Norepinephrine
 House
(Noradrenaline)
keeping system
Adrenalin
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Increases blood glucose level by speeding up the
breakdown of glycogen to glucose
Increases metabolic rate
Constricts arterioles in skin
Causes pupils to dilate to enhance vision
Contracts hair muscles
Pancreas
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The pancreas has digestive and hormonal
functions.
One part of the pancreas, the exocrine
pancreas, secretes digestive enzymes.
Pancreas
The other part of the pancreas, the endocrine
pancreas, secretes hormones called insulin and
glucagon
 These hormones
regulate the level of
glucose (sugar)
in the blood
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Pancreas
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Islets of Langerhans
Specialized tissues in which the endocrine
functions of the pancreas occurs
Secrete insulin and glucagon.
 include
 alpha
2 types of cells:
( )
 beta ()
Pancreas
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Insulin ( Beta Cells () )
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Increases glucose uptake by the cells
Convert glucose into glycogen
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Glucagon ( Alpha Cells ( ) )
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Stimulates conversion of glycogen, fats, amino
acids, and lactic acid into glucose
Insulin secretion
Blood glucose level
decreases
Blood glucose level
increases
Glucagon secretion
Diabetes
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Insulin deficiency causes diabetes mellitus 
abnormally high blood glucose concentration
Type 1 diabetes
childhood disorder where insulin-producing islet
cells die
Usually treated with daily injections of insulin
Sometimes islet cell transplant
Diabetes
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Type II diabetes usually happens over 40 years
old
More common, less severe than type I
Caused by insufficient insulin or unresponsive
target cell receptors
Type II is hereditary
Also related to obesity
Can control through exercise and diet
Gonads : Ovaries & Testes
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Produce gametes and secrete hormones
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Ovaries produce estrogen and progesterone
Testes produce testosterone
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Control sexual behavior and development
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Ovaries
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Estrogen
stimulates the growth of the uterine lining for
pregnancy.
Progesterone
prepares the uterus for implantation.
Testes
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Testosterone
necessary for sperm production
responsible for secondary sex characteristics in
males
Feedback Mechanisms
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is a mechanism that maintain homeostasis
occurs when the level of one substance
influences the level of another substance or
activity of another organ
There are two types…
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Negative Feedback
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Positive Feedback
Negative Feedback
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If hormone levels are found to be too high,
the hypothalamus tells the pituitary to send out
inhibitory factors which tell the gland that makes
the hormone to stop producing so much
So, inhibits the production of another hormone
Final step of events inhibits initial signal in series
Positive Feedback
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If levels of a particular hormone are low in the
blood,
the hypothalamus senses this and
tells the pituitary to send out releasing factors
which turn on the gland that makes that
particular hormone
ADH and Negative Feedback Control
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