9
Thyroid stimulating hormone (TSH) enhances entire known actions of cells
located in thyroid gland and increases the making as well as release of T4 (thyroxine) and T3 (triiodothyroxine). There is increased vascularity and thyroid hypertrophy as a result of constant elevated levels of TSH [6].
Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
In women and men, the production of FSH as well as LH, respectively, in anterior
pituitary is controlled via release of gonadotropin releasing hormone (GRH) from
hypothalamus, which is transmitted to pituitary gland in hypothalamohypophyseal
portal system. Feedback effects of testosterone, estrogen as well as statin (made in
testes and ovaries in response to Follicle stimulating hormone stimulus) on the
hypothalamus and together with anterior pituitary gland control levels of LH and
FSH in blood stream.
In females, FSH is responsible for early maturation of ovarian follicles, while in
men, spermatogenesis through Sertoli cells in the testes is stimulated by FSH. In
females, LH is accountable for the final stage of maturation of follicles located in
ovaries and hence the release of estrogen, while in men it makes Leydig cells in
testes to release testosterone [6].
Adrenocorticotropic Hormone (ACTH)
ACTH is released from anterior lobe of pituitary gland, and is translocated along the
hypothalamohypophyseal portal system to pituitary, once the hypothalamus secretes
the corticotropin releasing hormone (CRH). Any type of stress that stimulates the
hypothalamus is responsible for CRH release that leads to the release of ACTH in
anterior pituitary, followed by secretion of cortisol from adrenal cortex. To stabilize
plasma cortisol concentrations, there is a direct feedback mechanism of cortisol
hormone on the hypothalamus and anterior pituitary gland.
Release of androgens as well as cortisol (hydrocortisone) from zona fasciculata
and zona reticularis of adrenal cortex is stimulated by ACTH. Adrenocorticotropic
hormone also has influence on zona glomerulosa cells, allowing them to make aldosterone in order to respond to decreased total sodium concentration, elevated potassium levels or higher amount of angiotensin, or in the body [6].
Posterior Pituitary Gland’s Hormones
Antidiuretic Hormone (ADH)
Supraoptic nucleus of hypothalamus is mainly responsible for production of
ADH. The secretion of ADH is caused by elevated plasma osmotic pressure, pain,
reduced extracellular fluid volume (EFV), in addition to other stress situations, and
also includes certain drugs like barbiturates and morphine. Alcohol inhibits the
1 Physiology of Endocrine System and Related Metabolic Disorders
Thyroid stimulating hormone (TSH) enhances entire known actions of cells
located in thyroid gland and increases the making as well as release of T4 (thyroxine) and T3 (triiodothyroxine). There is increased vascularity and thyroid hypertrophy as a result of constant elevated levels of TSH [6].
Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
In women and men, the production of FSH as well as LH, respectively, in anterior
pituitary is controlled via release of gonadotropin releasing hormone (GRH) from
hypothalamus, which is transmitted to pituitary gland in hypothalamohypophyseal
portal system. Feedback effects of testosterone, estrogen as well as statin (made in
testes and ovaries in response to Follicle stimulating hormone stimulus) on the
hypothalamus and together with anterior pituitary gland control levels of LH and
FSH in blood stream.
In females, FSH is responsible for early maturation of ovarian follicles, while in
men, spermatogenesis through Sertoli cells in the testes is stimulated by FSH. In
females, LH is accountable for the final stage of maturation of follicles located in
ovaries and hence the release of estrogen, while in men it makes Leydig cells in
testes to release testosterone [6].
Adrenocorticotropic Hormone (ACTH)
ACTH is released from anterior lobe of pituitary gland, and is translocated along the
hypothalamohypophyseal portal system to pituitary, once the hypothalamus secretes
the corticotropin releasing hormone (CRH). Any type of stress that stimulates the
hypothalamus is responsible for CRH release that leads to the release of ACTH in
anterior pituitary, followed by secretion of cortisol from adrenal cortex. To stabilize
plasma cortisol concentrations, there is a direct feedback mechanism of cortisol
hormone on the hypothalamus and anterior pituitary gland.
Release of androgens as well as cortisol (hydrocortisone) from zona fasciculata
and zona reticularis of adrenal cortex is stimulated by ACTH. Adrenocorticotropic
hormone also has influence on zona glomerulosa cells, allowing them to make aldosterone in order to respond to decreased total sodium concentration, elevated potassium levels or higher amount of angiotensin, or in the body [6].
Posterior Pituitary Gland’s Hormones
Antidiuretic Hormone (ADH)
Supraoptic nucleus of hypothalamus is mainly responsible for production of
ADH. The secretion of ADH is caused by elevated plasma osmotic pressure, pain,
reduced extracellular fluid volume (EFV), in addition to other stress situations, and
also includes certain drugs like barbiturates and morphine. Alcohol inhibits the
1 Physiology of Endocrine System and Related Metabolic Disorders