Transcript Human Endocrine System - Frontier Central School District

Human
Endocrine
System
Human Endocrine System
 The endocrine system consists of
ductless glands that produce hormones
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Hypothalamus, pituitary, pineal, thyroid,
parathyroid, thymus, adrenal, pancreas,
ovary, testes
 Hormones are chemical messengers
that travel through the blood stream and
affect activities throughout the body.
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Steroid hormones
Nonsteroid hormones
Hormones
 Hormones are chemical messengers that
bind to target cells and affect cell activities
 Nonsteroid hormones are made from amino
acids and generally cannot pass through the
cell membrane. These hormones bind to a
receptor site on the outside of a cell in order
to initiate chemical reactions inside the cell.
 Steroid hormones are produced from the
lipid, cholesterol and are able to pass
through cell membranes and bind to
receptor proteins.
Nonsteroid hormones – cannot go through cell membrane,
must activate proteins in the cell membrane
Steroid hormones – can go through cell membrane to reach
receptors inside the cell
Negative Feedback
 The release of hormones is controlled through a
negative feedback system
 Negative feedback systems are control mechanisms
that operate by inhibiting a process or activity that
originally led to starting the process or activity
 For example, as glucose levels in the body
increase, sensors in the pancreas signal the
release of the hormone insulin
 Insulin promotes the entry of glucose into cells,
lowering glucose levels
 As the glucose levels in the blood decrease, the
pancreas stops secreting insulin.
Endocrine System Diagram
Hypothalamus and
Pituitary gland
Thymus
Adrenal gland
Thyroid and
Parathyroid glands
Pancreas
Ovary
Testis
Glands I
 Hypothalamus – coordinates activities of the
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nervous and endocrine systems and produces
hormones to regulate the pituitary gland
Pituitary – produces hormones that direct the
activities of other endocrine glands
Pineal – releases melatonin which is involved
in rhythmic or cyclic activities
Thyroid – produces hormones that regulate
metabolism and development
Parathyroid – helps maintain appropriate
calcium levels
Glands II
 Thymus – involved with immune development
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during childhood
Adrenal – regulates the body’s stress response
(epinephrine, norepinephrine, cortisol,
aldosterone)
Pancreas – controls glucose levels in the blood
(insulin, glucagon)
Ovary – secretes estrogen and progesterone to
regulate reproduction
Testes – produces testosterone to control
formation of sperm and sexual behavior