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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