Endocrine System
Anatomy of the Endocrine System
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 nerv-
ous system, and is also responsible for the direct control of the endocrine system
through the pituitary glanThe hypothalamus contains special cells called neuro-
secretory cells—neurons that secrete hormones:
1. Thyrotropin-releasing hormone (TRH)
2. Growth hormone-releasing hormone (GHRH)
3. Growth hormone-inhibiting hormone (GHIH)
4. Gonadotropin-releasing hormone (GnRH)
5. Corticotropin-releasing hormone (CRH)
6. Oxytocin
7. Antidiuretic hormone (ADH)
➢ Thyrotropin-releasing hormone (TRH) → stimulates → APG → release → TSH
→ stimulate → thyroid gland → T3 & T4
➢ Growth hormone-releasing hormone (GHRH) →stimulates →GH
➢ Growth hormone-inhibiting hormone (GHIH) →inhibits →GH
➢ Gonadotropin-releasing hormone (GnRH) →stimulates →FSH & LH→
➢ FSH stimulates the follicle cells of the gonads→ produce→ gametes
- ova in females and sperm in males
➢ LH →stimulates → gonads → produce → sex hormones - estrogens in fe-
males and testosterone in males
➢ Corticotropin-releasing hormone (CRH) → stimulate→ APG → release→ACTH
→blood→adrenal cortex→stimulates → adrenal cortex→Aldosterone, Cortosol
➢ Prolactin (PRL) → stimulates → mammary glands of the breast → produce
milk.
➢ Oxytocin & Antidiuretic hormone (ADH) →produced by the hypothalamus
and transported to the posterior pituitary, where they are stored and later re-
leased.
➢ Oxytocin triggers uterine contractions during childbirth→ the release of milk
during breastfeeding
➢ Antidiuretic hormone (ADH) prevents water loss in the body by increasing the
re-uptake of water in the kidneys and reducing blood flow to sweat glands
,→
,Hypothalamus →Anterior Pituitary
• Thyrotropin-releasing hormone • Thyroid stimulating hormone
(TRH) (TSH)
• Growth hormone-releasing hormone • Adrenocorticotropic hormone
(GHRH) (ACTH)
• Growth hormone-inhibiting hormone • Follicle stimulating hormone (FSH)
(GHIH) • Luteinizing hormone (LH)
• Gonadotropin-releasing hormone • Human growth hormone (HGH)
(GnRH) • Prolactin (PRL)
• Corticotropin-releasing hormone • Dopamine
(CRH)
• Antidiuretic hormone (ADH)
Posterior Pituitary
• Dopamine → Oxytocin
• Oxytocin
Antidiuretic hormone (ADH)
→
Pituitary Gland
→ Thyroid Gland
→
Calcitonin
Triiodothyronine (T3)
Pineal Gland → Thyroxine (T4)
Melatonin
Parathyroid Gland
→ Parathyroid
Hormone
→
Thymus Gland → Adrenal gland
Thymosins Adrenal cortex
Glucocorticoids,
Mineralocorticoids
Androgens
Pancreas →
→
Alpha(α) Cells →
Glucagon
→
Beta(β) Cells
Insulin Adrenal Medulla
Delta(Δ) Cells Epinephrine
Somatostatin Norepinephrine
→
→
Ovaries Testes
Estrogen Testosterone
Progestogen Inhibin
Inhibin
Inhibin inhibit the secreation of FSH
, Pituitary Gland
Anterior Pituitary Posterior Pituitary
→
→
→
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 pos-
terior and anterior pituitary glands.
Anterior Pituitary
The anterior pituitary gland is the true glandular part of the pituitary glanThe
function of the anterior pituitary gland is controlled by the releasing and inhibit-
ing hormones of the hypothalamus.
The anterior pituitary produces 6 important hormones:
■ Thyroid stimulating hormone (TSH), as its name suggests, is a tropic hormone
responsible for the stimulation of the thyroid gland.
■ Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, the out-
er part of the adrenal gland, to produce its hormones.
■ Follicle stimulating hormone (FSH) stimulates the follicle cells of the gonads
to produce gametes—ova in females and sperm in males.
■ Luteinizing hormone (LH) stimulates the gonads to produce the sex hor-
mones—estrogens in females and testosterone in males.
■ Human growth hormone (HGH) affects many target cells throughout the body
by stimulating their growth, repair, and reproduction.
■ Prolactin (PRL) has many effects on the body, chief of which is that it stimu-
lates the mammary glands of the breast to produce milk.
■ Dopamine is the primary neuroendocrine inhibitor of the secretion of prolac-
tin from the anterior pituitary gland
Posterior Pituitary
The posterior pituitary gland is actually not glandular tissue at all, but nervous
tissue insteaThe posterior pituitary is a small extension of the hypothalamus
through which the axons of some of the neurosecretory cells of the hypothalamus
extenThese neurosecretory cells create 2 hormones in the hypothalamus that are
stored and released by the posterior pituitary:
Anatomy of the Endocrine System
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 nerv-
ous system, and is also responsible for the direct control of the endocrine system
through the pituitary glanThe hypothalamus contains special cells called neuro-
secretory cells—neurons that secrete hormones:
1. Thyrotropin-releasing hormone (TRH)
2. Growth hormone-releasing hormone (GHRH)
3. Growth hormone-inhibiting hormone (GHIH)
4. Gonadotropin-releasing hormone (GnRH)
5. Corticotropin-releasing hormone (CRH)
6. Oxytocin
7. Antidiuretic hormone (ADH)
➢ Thyrotropin-releasing hormone (TRH) → stimulates → APG → release → TSH
→ stimulate → thyroid gland → T3 & T4
➢ Growth hormone-releasing hormone (GHRH) →stimulates →GH
➢ Growth hormone-inhibiting hormone (GHIH) →inhibits →GH
➢ Gonadotropin-releasing hormone (GnRH) →stimulates →FSH & LH→
➢ FSH stimulates the follicle cells of the gonads→ produce→ gametes
- ova in females and sperm in males
➢ LH →stimulates → gonads → produce → sex hormones - estrogens in fe-
males and testosterone in males
➢ Corticotropin-releasing hormone (CRH) → stimulate→ APG → release→ACTH
→blood→adrenal cortex→stimulates → adrenal cortex→Aldosterone, Cortosol
➢ Prolactin (PRL) → stimulates → mammary glands of the breast → produce
milk.
➢ Oxytocin & Antidiuretic hormone (ADH) →produced by the hypothalamus
and transported to the posterior pituitary, where they are stored and later re-
leased.
➢ Oxytocin triggers uterine contractions during childbirth→ the release of milk
during breastfeeding
➢ Antidiuretic hormone (ADH) prevents water loss in the body by increasing the
re-uptake of water in the kidneys and reducing blood flow to sweat glands
,→
,Hypothalamus →Anterior Pituitary
• Thyrotropin-releasing hormone • Thyroid stimulating hormone
(TRH) (TSH)
• Growth hormone-releasing hormone • Adrenocorticotropic hormone
(GHRH) (ACTH)
• Growth hormone-inhibiting hormone • Follicle stimulating hormone (FSH)
(GHIH) • Luteinizing hormone (LH)
• Gonadotropin-releasing hormone • Human growth hormone (HGH)
(GnRH) • Prolactin (PRL)
• Corticotropin-releasing hormone • Dopamine
(CRH)
• Antidiuretic hormone (ADH)
Posterior Pituitary
• Dopamine → Oxytocin
• Oxytocin
Antidiuretic hormone (ADH)
→
Pituitary Gland
→ Thyroid Gland
→
Calcitonin
Triiodothyronine (T3)
Pineal Gland → Thyroxine (T4)
Melatonin
Parathyroid Gland
→ Parathyroid
Hormone
→
Thymus Gland → Adrenal gland
Thymosins Adrenal cortex
Glucocorticoids,
Mineralocorticoids
Androgens
Pancreas →
→
Alpha(α) Cells →
Glucagon
→
Beta(β) Cells
Insulin Adrenal Medulla
Delta(Δ) Cells Epinephrine
Somatostatin Norepinephrine
→
→
Ovaries Testes
Estrogen Testosterone
Progestogen Inhibin
Inhibin
Inhibin inhibit the secreation of FSH
, Pituitary Gland
Anterior Pituitary Posterior Pituitary
→
→
→
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 pos-
terior and anterior pituitary glands.
Anterior Pituitary
The anterior pituitary gland is the true glandular part of the pituitary glanThe
function of the anterior pituitary gland is controlled by the releasing and inhibit-
ing hormones of the hypothalamus.
The anterior pituitary produces 6 important hormones:
■ Thyroid stimulating hormone (TSH), as its name suggests, is a tropic hormone
responsible for the stimulation of the thyroid gland.
■ Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, the out-
er part of the adrenal gland, to produce its hormones.
■ Follicle stimulating hormone (FSH) stimulates the follicle cells of the gonads
to produce gametes—ova in females and sperm in males.
■ Luteinizing hormone (LH) stimulates the gonads to produce the sex hor-
mones—estrogens in females and testosterone in males.
■ Human growth hormone (HGH) affects many target cells throughout the body
by stimulating their growth, repair, and reproduction.
■ Prolactin (PRL) has many effects on the body, chief of which is that it stimu-
lates the mammary glands of the breast to produce milk.
■ Dopamine is the primary neuroendocrine inhibitor of the secretion of prolac-
tin from the anterior pituitary gland
Posterior Pituitary
The posterior pituitary gland is actually not glandular tissue at all, but nervous
tissue insteaThe posterior pituitary is a small extension of the hypothalamus
through which the axons of some of the neurosecretory cells of the hypothalamus
extenThese neurosecretory cells create 2 hormones in the hypothalamus that are
stored and released by the posterior pituitary:
