Anatomy
Pituitary Anatomy
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Pituitary Anatomy
, Pituitary Gland, Lactotroph, Gonadotroph, Somatotroph, Corticotroph, Thyrotroph
See Also
Neuroanatomy
Intracranial Anatomy
Pituitary Adenoma
Anatomy
Pituitary Gland releases
Hormone
s with long-lasting autonomic effects
Anterior Pituitary
Contains no direct
Neuron
al connections
Responds to hypothalamic
Hormone
s via portal circulation
Hypothalamic hormonal stimulation results in
Hormone
release depending on the cells involved (see below)
Posterior Pituitary
Releases
Oxytocin
and
Vasopressin
(ADH) produced in the
Hypothalamus
and stored in the posterior pituitary
Images
Lewis (1918) Gray's Anatomy 20th ed
(in
public domain
at
Yahoo
or
BartleBy
)
Lewis (1918) Gray's Anatomy 20th ed
(in
public domain
at
Yahoo
or
BartleBy
)
Lewis (1918) Gray's Anatomy 20th ed
(in
public domain
at
Yahoo
or
BartleBy
)
Anatomy
Cell types of Pituitary Gland
Images
Lactotrophs
Prolactin
Secretin
g cells
Gonadotrophs
Luteinizing Hormone
(LH)
Secretin
g cells
Follicle Stimulating Hormone
(FSH)
Secretin
g cells
Somatotroph
Growth Hormone
Secretin
g cells (GH)
Corticotroph
Adrenocorticotropic Hormone
(
ACTH
)
Secretin
g cells
Thyrotroph
Thyroid Stimulating Hormone
(TSH)
Secretin
g cells
Physiology
Pituitary
Hormone
s
See
Hypothalamus
Posterior Pituitary Gland (
Hormone
s produced in the
Hypothalamus
, released from pituitary)
Oxytocin
Stimulates uterine contractions
Stimulates milk let-down in
Lactation
Antidiuretic Hormone
(ADH,
Vasopressin
)
Increases renal water reaborption
Anterior Pituitary Gland
Prolactin
Protein
synthesized and secreted by Lactotrophs (acidophil cells) in the anterior pituitary
Prolactin
stimulates milk secretion into the
Breast
alveoli in pregnancy and
Lactation
Oxytocin
stimulates myoepithelial cells to contract, expressing
Breast Milk
from the nipple
Stimulated by
Estrogen
, vasoactive intestinal polypeptide (VIP),
Thyroid Releasing Hormone
(TRH)
Inhibition by hypothalamic
Dopamine
(
Prolactin
Inhibiting Factor or PIF)
Human Growth Hormone
Polypeptide produced in the acidophil cells of the anterior pituitary
Triggered by
Hypoglycemia
(or low
Amino Acid
s) via hypothalamic release of GHRH
Promotes bone and cartilage growth,
Protein
synthesis, glycogen storage,
Fatty Acid
increase
Adrenocorticotropic Hormone
(
ACTH
)
Polypeptide synthesized and secreted by
Basophil
cells in the anterior pituitary
Stimulation (releasing factors) include
Corticotropin
Releasing
Hormone
(CRH) and stress
Inhibition by negative feedback loops (
Cortisol
inhibits CRH and
ACTH
release)
ACTH
stimulates the
Adrenal Cortex
to release
Cortisol
(and to a lesser extent
Aldosterone
and androgens)
Thyroid Stimulating Hormone
(TSH)
See
Thyroid Physiology
Thyroid Stimulating Hormone
(TSH) is a
Glycoprotein
synthesized in the
Basophil
cells of the anterior pituitary
Stimulated by
Thyroid Releasing Hormone
(TRH)
Inhibited by negative feedback from
Thyroid Hormone
s (T4, T3)
Thyroid Stimulating Hormone
(TSH) promotes all aspects of
Thyroid Hormone
production
Increases iodide uptake and incorporation of
Iodine
into
Thyroglobulin
Increases lysis into active
Thyroid Hormone
s T4 and T3
Follicle Stimulating Hormone
(FSH)
FSH is a glyoprotein secreted by
Basophil
cells in the anterior Pituitary Gland
Stimulation (releasing factors) is by Hypothalamic Gonadotrophic Releasing
Hormone
(GnRH)
Inhibited via negative feedback loop by
Testosterone
,
Estrogen
s,
Progesterone
and inhibin
FSH stimulates ovarian follicle growth (which secretes
Estradiol
) in women
FSH stimulates spermatogenesis and sperm maturation within Sertoli Cells in men
Luteinizing Hormone
(LH)
LH is a
Glycoprotein
secreted by
Basophil
cells in the anterior Pituitary Gland
Stimulation is by Hypothalamic Gonadotrophic Releasing
Hormone
(GnRH)
Inhibited via negative feedback loop by
Testosterone
,
Estrogen
s,
Progesterone
and inhibin
LH stimulates ovarian follicles to ovulate and mature into a corpus luteum (produces
Estrogen
,
Progesterone
)
LH stimulates Leydig Cells within
Testes
to produce
Testosterone
Physiology
See
Thyroid Physiology
Regulation
Positive Stimulation
Thyroid Releasing Hormone
(TRH, Thyrotopin Releasing
Hormone
, from
Hypothalamus
)
Negative feedback
Unbound
Thyroxine
(
Free T4
)
Unbound
Triiodothyronine
(
Free T3
)
Thyroid Stimulating Hormone
(TSH) promotes all aspects of
Thyroid Hormone
production
Increases iodide uptake
Incorporation of
Iodine
into
Thyroglobulin
Thyroglobulin
lysis into active
Thyroid Hormone
s T4 and T3
Stimulates proliferation of increased
Thyroglobulin
synthesizing cells (
Cuboid
al cells) in
Thyroid
follicles
Variation
TSH levels follow a circadian rhythm
TSH will vary as much as 1-2 uIU/ml over the course of the day
Consider drawing TSH at the same time of day for longterm serial measurements
TSH levels increase with normal aging in euthyroid patients
Consider using age-adjusted TSH interpretation
Age 20-29: 3.56 mIU/ml is 97th percentile
Age >80: 7.49 mIU/ml is 97th percentile
Surks (2007) JCEM 92: 4575 [PubMed]
Pregnancy
See
Thyroid Dysfunction in Pregnancy
See
Hypothyroidism in Pregnancy
Maintaining euthyroid state in pregnancy is critical
Euthyroid individuals still have considerable variation in TSH levels over time
Populations of euthyroid individuals also have considerable variation in TSH levels
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