The hypothalamus is a region of the brain composed of many small nuclei with diverse functions By synthesizing and secreting neurohormones, the nuclei of the hypothalamus act as a conduit between the nervous and endocrine systems via the pituitary gland (hypophysis), regulating homeostatic functions such as hunger, thirst, body temperature, and circadian rhythms
the hypothalamus releases hormone which have an activating or inhibitory effect on their target organ, hence they are named Releasing or Inhibitory Hormones respectively Releasing Hormones: Thyrotropin Releasing Hormone (TRH) Growth Hormone Releasing Hormone (GH-RH) Gonadotrophin Releasing Hormone (GnRH) Corticotropin Releasing Hormone (CRH) Prolactin Releasing Hormone (PRL-RH) nhibitory Hormones: Growth Hormone Inhibiting Hormone aka Somatostatin (GH-IH) Gonadotrophin Inhibiting Hormone (GnIH) Dopamine (PRL-IH)
the pituitary gland, or hypophysis -meaning undergrowth- , is an endocrine gland about the size of a pea. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragm sellae)the pituitary gland is divided into a larger frontal region (adenohypophysis) &lt;&lt;&lt;&lt;a smaller posterior region (neurohypophysis). And intermediate lobe. ##. In humans the intermediate lobe does not exist as a distinct anatomic structure but rather remains only as cells dispersed within the anterior lobeThe gland is connected to the hypothalamus by the pituitary stalk. which is composed of neurons of the axons and the hypophyseal-portal veins. .
The cells constituting the anterior lobe of the pituitary gland are embryologically derived from an outpouching of the roof of the pharynx known as Rathke’s pouch The anterior pituitary regulates several physiological processes including stress, growth, and reproduction.Its regulatory functions are achieved through the secretion of various peptide hormones that act on target organs The posterior lobe is composed of the endings of nerve cells located in specialized regions of the hypothalamus. These nerve cells produce two hormones oxytocin and vasopressin (antidiuretic hormone) , that are carried down the nerves and stored in the nerve endings that compose the posterior pituitary gland.
The hormones of the anterior pituitary are synthesized in the cytoplasm of the cells as large, inactive molecules called prohormones. These prohormones are stored in granules, within which they are cleaved into active hormones and are secreted into the circulation The hormones of the post pituitary are released into the circulation in response to nerve signals that originate in the hypothalamus and are transmitted to the posterior pituitary
Production of growth hormone is modulated by many factors, including stress, exercise, nutrition, sleep and growth hormone itself. However, its primary controllers are two hypothalamic hormones and one hormone from the stomach: Growth hormone-releasing hormone(GHRH) is a hypothalamic peptide that stimulates both the synthesis and secretion of growth hormone. Somatostatin (SS) is a peptide produced by several tissues in the body, including the hypothalamus. Somatostatin inhibits growth hormone release in response to GHRH and to other stimulatory factors such as low blood glucose concentration. Ghrelin is a peptide hormone secreted from the stomach. Ghrelin binds to receptors on somatotrophs and potently stimulates secretion of growth hormone.
GH- makes energy available for growth IGF- induces cells to grow (brings cells into G1)
As depicted in this slide, GH from the anterior pituitary is released in circulation and stimulates the synthesis and secretion of IGF-I from the liver. The IGF-I peptide then directly stimulates target cell growth In the last 2 decades, it has been recognized that the GH/IGF system is more complex, owing to the discovery of multiple IGFBPsIGFBPs bind the circulating IGF-I peptide with high affinity & specificity They function as carriers of the IGF-I peptide They prolong the half-life of IGF-I in circulation And they regulate IGF-I access to its cellular receptor
There are multiple IGFBPs in mammals IGFBP-3 is one of these IGFBPs, and it is the most important carrier of IGF-I in the blood circulation IGFBP-3 is the most abundant form of IGFBP and it promotes IGF-I mediated somatic growth High levels of IGFBP-3 is thus associated with growth stimulation Also shown here is IGFBP-1, which is present only at very low or undetectable levels in “growing” mammals However, when animals are under “catabolic states” such as prolonged stress, the levels of IGFBP-1 will increase several-fold Such increases in this protein are associated with growth inhibition
The following slide is an animation of how IGFBP-3 promotes IGF-I access to its cellular receptor
Unlike the Previous animation, the actions of IGFBP-1 is very different Instead of promoting IGF-I ligand binding to its receptor, IGFBP-1 in mammals HAS a higher binding affinity for IGF than the receptor itself, and thus it “disallows” access of IGF-I to the receptor IGFBP-1 is thus associated with growth inhibition, thereby blocking its access to its cellular receptor
Following puberty, GH levels decline during adulthood and decrease further with aging. Decline in lean body mass and metabolic rate as well as increased adipose tissue associated with aging may be attributed to declining GH levelsGH increases lean body mass through the increase of muscle protein synthesis.
.if u open their heads to look at their brains u will see normal brains inside
.x ray can be used to show the difference between bone age and child age, by hand x ray …depending on the defirences between adult bone hand and child bone hand .
.it is used to show tumors, some inflamations,atrophy.or hyperplasia and this is useful to diagnose the disease.
.pituitary tumor mri image
.fortunatly treatment of gh deficincy is easy when it diagnosed early(in young age) .its the first choice for treatment
. External fixator wich called (ilizarov) is used to jump start bone development and hopefully activate more growth. .doctors break the bone shaft and use the fixator to lenghth it.
.because some damages are iireversable .
dwarfism & GH
*Region of the brain
* Composed of small
*Act As Conduit
( hunger , thirst &
Pituitary gland anatomyPituitary gland anatomy
*Is an endocrine gland
* Size of a pea
* Located at the base of
* Rests in a small bony cavity
* Is divided into ???
* Connected to hypothalamus
Anterior & posterior lobeAnterior & posterior lobe
*The cells of the
Ant. Lobe are
derived from an ???
*The Ant. Pituitary
reproduction ( & Are
achieved through ??
*The post. Lobe is
composed of the
endings of nevre
*These nerve cells
Pituitary Hormones and TheirPituitary Hormones and Their
The hormones of the
anterior pituitary are
synthesized in the
cytoplasm of the cells as ????
The hormones of the
post pituitary are
released into the
circulation in response to????
Growth hormoneGrowth hormone
Growth hormone is a protein hormone of about 190
amino acids that is synthesized and secreted by
cells called somatotrophs
in the anterior pituitary
It is a major participant in control of several complex
physiologic processes, including growth and
Control of SecretionControl of Secretion
Liver: IGF (somatomedins)
direct effectsindirect effects
lipolysis in fat cells
Insulin-like Growth Factor
fat cells muscle
Increases FFA, glycerol, and sugars
IGFBPs—two main typesIGFBPs—two main types
most abundant form of IGFBP
main carrier of IGF in circulation
promotes IGF mediated somatic growth
high IGFBP-3 associated w/ growth stimulation
typically present in small amounts
high IGFBP-1 associated w/ growth inhibition
Signs and symptomsSigns and symptoms
•Obvious sign is kids
being much shorter
then kids of the same
age and gender
•Children with pituitary
dwarfism have a slow
rate of growth
•Children of this disorder
still have normal
Diagnostic proceduresDiagnostic procedures
•blood test for protien
chart : The growth
curve of children with
shows no growth or
X-rays to determine
bone age can also
help with the
.MRI of the brain can also be used to view the
hypothalamus and pituitary gland
which may include:
-surgical operation on
pituitary gland itself.
usually on the femur
Depends on whether there’s any permanent
damage and the age of the child
Earlier treated, the better chance child will
grow to average adult height
Growth improvement of the injections slowly