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ENDOCRINE SYSTEM ANATOMY
The endocrine system includes all of the glands of the body and the hormones produced by
those glands. The glands are controlled directly by stimulation from the nervous system as well
as by chemical receptors in the blood and hormones produced by other glands. By regulating
the functions of organs in the body, these glands help to maintain the body’s homeostasis.
Cellular metabolism, reproduction, sexual development, sugar and mineral homeostasis, heart
rate, and digestion are among the many processes regulated by the actions of hormones.
Hypothalamus
The hypothalamus is a part of the brain located superior and anterior to the brain stem and
inferior to the thalamus. It serves many different functions in the nervous system, and is also
responsible for the direct control of the endocrine system through the pituitary gland. The
hypothalamus contains special cells called neurosecretory cells—neurons that secrete
hormones:
o Thyrotropin-releasing hormone (TRH)
o Growth hormone-releasing hormone (GHRH)
o Growth hormone-inhibiting hormone (GHIH)
o Gonadotropin-releasing hormone (GnRH)
o Corticotropin-releasing hormone (CRH)
o Oxytocin
o Antidiuretic hormone (ADH)
Pituitary Gland
The pituitary gland, also known as the hypophysis, is a small pea-sized lump of tissue
connected to the inferior portion of the hypothalamus of the brain. Many blood vessels surround
the pituitary gland to carry the hormones it releases throughout the body. Situated in a small
depression in the sphenoid bone called the sella turcica, the pituitary gland is actually made of 2
completely separate structures: the posterior and anterior pituitary glands.
Pineal Gland
The pineal gland is a small pinecone-shaped mass of glandular tissue found just posterior to the
thalamus of the brain. The pineal gland produces the hormone melatonin that helps to regulate
the human sleep-wake cycle known as the circadian rhythm. The activity of the pineal gland is
inhibited by stimulation from the photoreceptors of the retina. This light sensitivity causes
melatonin to be produced only in low light or darkness. Increased melatonin production causes
humans to feel drowsy at nighttime when the pineal gland is active.
ENDOCRINE SYSTEM ANATOMY
The endocrine system includes all of the glands of the body and the hormones produced by
those glands. The glands are controlled directly by stimulation from the nervous system as well
as by chemical receptors in the blood and hormones produced by other glands. By regulating
the functions of organs in the body, these glands help to maintain the body’s homeostasis.
Cellular metabolism, reproduction, sexual development, sugar and mineral homeostasis, heart
rate, and digestion are among the many processes regulated by the actions of hormones.
Hypothalamus
The hypothalamus is a part of the brain located superior and anterior to the brain stem and
inferior to the thalamus. It serves many different functions in the nervous system, and is also
responsible for the direct control of the endocrine system through the pituitary gland. The
hypothalamus contains special cells called neurosecretory cells—neurons that secrete
hormones:
o Thyrotropin-releasing hormone (TRH)
o Growth hormone-releasing hormone (GHRH)
o Growth hormone-inhibiting hormone (GHIH)
o Gonadotropin-releasing hormone (GnRH)
o Corticotropin-releasing hormone (CRH)
o Oxytocin
o Antidiuretic hormone (ADH)
Pituitary Gland
The pituitary gland, also known as the hypophysis, is a small pea-sized lump of tissue
connected to the inferior portion of the hypothalamus of the brain. Many blood vessels surround
the pituitary gland to carry the hormones it releases throughout the body. Situated in a small
depression in the sphenoid bone called the sella turcica, the pituitary gland is actually made of 2
completely separate structures: the posterior and anterior pituitary glands.
Pineal Gland
The pineal gland is a small pinecone-shaped mass of glandular tissue found just posterior to the
thalamus of the brain. The pineal gland produces the hormone melatonin that helps to regulate
the human sleep-wake cycle known as the circadian rhythm. The activity of the pineal gland is
inhibited by stimulation from the photoreceptors of the retina. This light sensitivity causes
melatonin to be produced only in low light or darkness. Increased melatonin production causes
humans to feel drowsy at nighttime when the pineal gland is active.
