Download Homeostasis depends on mechanisms of regulation!

Endocrine System
 The endocrine system is a system of
glands, each of which secretes hormones
into the blood stream to regulate the
body.
Homeostasis
 Homeostasis is maintaining a stable
internal environment. It is the job of the
endocrine system to make sure that
Negative Feedback
 Negative Feedback occurs when a
change in conditions in the environment
triggers responses in your body that
counteract that change.
Thermoregulation
Cellular Communication
and Hormones
 Chemical messengers called hormones trigger many
of the responses that maintain homeostasis.
 Hormones are secreted by organs of the endocrine
system called endocrine glands.

Target Cells
 Hormones are secreted into bodily fluids.
It may reach all parts of the body, but,
only certain cells, called target cells are
equipped to respond to that particular
hormone. This is because of the
presence of a special receptor.
 Specificity
Regulation of Metabolism
 The thyroid gland
regulates the
metabolism with the
hormone thyroxin.
 Hyperthyroidism is an
overactive thyroid gland.
 Hypothyroidism is a
under active thyroid.
 The thyroid also controls
the amount of calcium in
the body.
Calcitonin and parathyroid
hormone
Insulin and Glucagon
 The Pancreas releases
insulin to stimulate
uptake of glucose from
blood. Lowers Blood
Sugar Level.
 The pancreas also
secretes glucagon which
stimulates breakdown of
glycogen to glucose in
liver. Raises Sugar
level.
Ovaries and Testes
 Ovaries release estrogen
which is responsible for
secondary sex characteristics
and progesterone which
controls the thickness of the
uterus.
 Testes release testosterone
which is responsible for
secondary sex characteristics
in males and causes sperm to
mature.