Download The Endocrine System

THE ENDOCRINE SYSTEM
Miss Richardson
SBI4U
THE ENDOCRINE SYSTEM
The nervous system uses specific molecules
(hormones) as signals to control the vertebrate
body
 Advantages of chemical messengers:

Chemical messengers can spread to all the tissues via
the blood
 Hormones have a specific shape that will only work
on organs, tissues that are a match.

HORMONES
Released from
endocrine glands as
steroid or protein
 Can be transported or
stored to the target cell
 Induce long-lasting
effects

ENDOCRINE GLANDS


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Over 200 hormones have been identified and are secreted
from tissues and organs known as endocrine glands
Endocrine glands are ductless regions that produce
hormones
Endocrine glands (exclusive):

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
Pituitary
Pineal
Thyroid
Parathyroid
Adrenal
Other tissues and organs contribute:

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Hypothalamus
Thymus
Pancreas
Testes
Ovaries
ENDOCRINE GLANDS
SENDING MOLECULAR SIGNALS
1.
2.
3.
4.
CNS controls hypothalamus, which regulates release of hormones
from pituitary
Hormones can act on nearby cells or be transported through blood
until they reach a cell with matching receptor (target cell)
Target cell carries the receptor protein which will bind to hormone,
changing its shape
Cellular activity is triggered

STEROID HORMONES


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Located in cytoplasm of
target cell
Lipid soluble and can pass
through cell membrane
Once inside cell, binds to
receptor protein forming
receptor-hormone complex
Complex binds to DNA and
changes gene activity by
inhibiting or promoting
transcription
PROTEIN/PEPTIDE HORMONES

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Water soluble
Don’t enter target cell
Hormone receptors located within cell membrane
Protein hormone binds to receptor which triggers events
within cytoplasm through secondary messengers
Secondary messengers amplify original signal
PITUITARY GLAND
Located in the brain, linked to hypothalamus
 2 regions:


Anterior – controlled by hypothalamus


Growth hormone, THS, adrenocorticotropic hormone,
gonadotropic hormone, prolactin
Posterior – controlled by nerves

Antidiuretic hormone, oxytocin
HYPOTHALAMUS

Region of the middle of the base of the brain,
responsible for regulation of many functions

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
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Body temperature
Hunger
Moods
Sleep
Sex drive
Thirst
THYROID GLAND
Consists of two lobes,
located in neck below
larynx
 Produces thyroxine (T4)
which increases metabolic
rate
 Also produces
triiodothyronine (T3) and
calcitronin
 Responsible for regulation
of metabolism

THYROID GLAND - CALCITRONIN

Calcitronin
regulates
calcium levels in
blood

Essential for
healthy teeth
and bone
development
PARATHYROID GLAND
On surface of thyroid gland
 Release parathyroid hormone in response to low
calcium levels
