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Endocrinology for ME, CUNY |
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======================
Hormones of the Hypothalamus
The hypothalamus is a region of the brain . It contains several types of neurons responsible for secreting different hormones.
All of these are released into the blood in the capillaries and travel immediately – in portal veins – to a second capillary bed in the anterior lobe of the pituitary, where they exert their effects.
All of them are released in periodic spurts. In fact, replacement hormone therapy with these hormones does not work unless the replacements are also given in spurts.
Two other hypothalamic hormones:
travel in the neurons themselves to the posterior lobe of the pituitary where they are released into the circulation.
TRH is a tripeptide (GluHisPro).
When it reaches the anterior lobe of the pituitary it stimulates the release there of
GnRH is a peptide of 10 amino acids. Its secretion at the onset of puberty triggers sexual development, and from then on it is essential for normal sexual physiology in both males and females. In both sexes, its secretion occurs in periodic pulses usually occurring every 1–2 hours.
| Primary Effects |
Secondary Effects |
| FSH and LH Up |
estrogen and progesterone Up (in females) |
| testosterone Up (in males) |
| The signal that stimulates GnRH secretion - Link. |
After puberty, a hyposecretion of GnRH may result from
- intense physical training
- anorexia nervosa
Synthetic agonists of GnRH are used to treat
- inherited or acquired deficiencies of GnRH secretion.
- prostate cancer. In this case, continuous high levels of the GnRH agonist
- reduces the number of GnRH receptors in the pituitary, which
- reduces its secretion of FSH and LH, which
- reduces the secretion of testosterone, which
- reduces the stimulation of the cells of the prostate.
Growth hormone-releasing hormone (GHRH)
GHRH is a mixture of two peptides, one containing 40 amino acids, the other 44.
As its name indicates, GHRH stimulates cells in the anterior lobe of the pituitary to secrete growth hormone (GH).
CRH is a peptide of 41 amino acids.
As its name indicates, its acts on cells in the anterior lobe of the pituitary to release adrenocorticotropic hormone (ACTH)
CRH is also synthesized by the placenta and seems to determine the duration of pregnancy.
It may also play a role in keeping the T cells of the mother from mounting an immune attack against the fetus. [Discussion]
Somatostatin is a mixture of two peptides, one of 14 amino acids, the other of 28.
Somatostatin acts on the anterior lobe of the pituitary to
Somatostatin is also secreted by cells in the pancreas and in the intestine where it inhibits the secretion of a variety of other hormones.
Dopamine is a derivative of the amino acid tyrosine. Its principal function in the hypothalamus is to inhibit the release of prolactin (PRL) from the anterior lobe of the pituitary.
Vasopressin and Oxytocin
These peptides are released from the posterior lobe of the pituitary and are described in the page devoted to the pituitary. [Vasopressin] [Oxytocin]
Please dont print/copy any diagrams
however u can read as many time u want
I WILL ADD OTHER TOPIC LATER ON
Hypothyroidism
usually is a primary process in which the thyroid gland produces insufficient amounts of thyroid hormone
Cretinism refers to congenital hypothyroidism, which affects 1 per 4000 newborns
CAUSES
local disease
iodine deficiency
Autoimmune: The most frequent cause of acquired hypothyroidism is autoimmune thyroiditis (Hashimoto thyroiditis
Central hypothyroidism (secondary or tertiary) results when the hypothalamic-pituitary axis is damaged. Various causes should be considered:
- Pituitary adenoma
- Tumors impinging on the hypothalamus
- History of brain irradiation
Symptoms
cold intolerance, puffiness, decreased sweating, and coarse skin,
,Myxedema coma is a severe form of hypothyroidism that results in an altered mental status, hypothermia
T/T THYROID HORMONE REPLACEMENT
=================================================================
Hyperthyroidism
overactivity of the thyroid gland leading to excessive synthesis of thyroid hormone
the hypothalamic-pituitary-thyroid negative/positive feedback system.
SYMPTOMS
hyperactivity, nervousness
- Weight loss despite excellent appetite
- Insomnia
- Fatigue
- Palpitations
- Heat intolerance
- Sweating
- Diarrhea
T/T .ANTITHYROID DRUGS
===================================================================
DIABETES
insulin is functionally absent because of the destruction of the beta cells of the pancreas
SYMPTOMS
- Polyuria and thirst:.
- Polyphagia with weight loss:
- Fatigue and weakness
T/T insulin
=======================================================================
Diabetes insipidus
decreased secretion of antidiuretic hormone (ADH), also known as arginine vasopressin
ADH is the primary determinant of free water excretion in the body. Its main target is the kidney, where it acts by altering the water permeability of the cortical and medullary collecting tubules.
SYMPTOMS
Polyuria, polydipsia, and nocturia
T/T DRINK WATER
REPLACE ADH SYNTHETICALLY
==========================================================================
CUSHING DISEASE
elevated levels of either endogenous glucocorticoids or exogenous glucocorticoids
weight gain, especially in the face,.
changes in their skin, including purple stretch marks, T/T
SURGERY
MEDICINES
================================================================
REMANING TOPIC I WILL ADD LATER
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Biology
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