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Introduction to Psychology
Endocrine System
DefinationThe Endocrine System is made of
glands and tissues that secrete hormones.
The Endocrine System is a set of glands that regulates the activities of certain organs by releasing their chemical products into blood stream.
These glands have no ducts or openings
Controls many body functions
Exerts control by releasing special chemical substances into the blood called hormones.
Hormones effects other endocrine glands or body systems.
Glands of Endocrine System
Following glands are included in endocrine system :
Pituitary GlandThyroid GlandParathyroid GlandThymus GlandAdrenal GlandPancreas GlandPineal GlandGonad Gland
Pituitary GlandLocated at the base of brain and
connected to the hypothalamus
Divided into interior and posterior lobes
Known as the master gland because of its major influence in body’s activities
Hormones of the Pituitary Gland
Divided into two lobes
Anterior pituitary lobe is larger and produces seven hormones.
Posterior pituitary lobe is smaller and consist primarily of nerve fibers and neuroglial cells.
Anterior pituitaryThe anterior pituitary synthesizes
and secretes the following important hormones under the influence of hypothalamus◦Adrenocorticotropic hormone (ACTH)◦Thyrotropin or thyroid stimulating
hormone◦Prolactin hormone◦Growth hormone◦Gonadotropin hormone
Posterior pituitary Posterior pituitary releases the
following hormones◦Oxytocin hormone◦Antidiuretic hormone (ADH)
Thyroid and Parathyroid GlandsThyroid Glands
Locted in the anterior part of neck
It is butterfly shape organ and is composed of two con-like lobes or wings
Secretes three hormones Thyroxine Triiodthyronine Calcitonin
Thyroid and Parathyroid GlandsParathyroid Glands
They are small endocrine glands in the neck that produce parathyroid hormone.
Humans have four parathyroid glands, which are located behind the thyroid gland.
Parathyroid glands control the amount of calcium in the blood and within the bones
It serves a completely different role than the thyroid gland.
Thymus GlandThe thymus gland is both an
endocrine gland and lymphatic organ.
The thymus secretes a large number of hormones
It is composed of two lobes and is located in front of the heart and behind the sternum.
Thymus is specialized organ in the immune system.
Structure of thymusStructure of the thymus can be
divided into two parts Medulla Peripheral cortex
The cortex and medulla play different roles in the development of T-cells.
Adrenal GlandsAdrenal glands are situated just
above the kidneys one on each side.
These are triangular shaped glands.
They are chiefly responsible for releasing hormones which are extremely important to neural functioning and to the ability of the body to cope with stress.
Adrenal GlandsTwo adrenal glands located at the
top of each kidney; each has two partsCortex – secretes 3 groups corticoids• Mineralocorticoids • Glucocorticoids• Sex hormones
Medulla – secretes• Epinephrine / adrenaline• Nor – epinephrine / nor adrenaline
Pancreas GlandLocated behind stomachPancreas is a dual function gland
i.e. endocrine or exocrine glandFunction as :• Exocrine glandoSecretes pancreatic juices into small
intestine to become digestive juices
• Endocrine glandoProduces insulin and diabetes.
Pineal GlandAttached to the third ventricle of
the brainProduces the hormone melatonin• Amount of light effects the amount
of melatonin secreted• Causes body temprature to drop
Gonad GlandGonads – sex organs
Ovaries – female sex organ• Ova• Estrogen and progesterone
Testes – male sex organ• Sperm• testosterone
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