Principles and practice of Human Pathology – Lecture 9 + 10 (24-5-2018):
Pathology of the Endocrine System; anatomy and physiology of the hypothalamus-
pituitary system
Endocrine: internally secretion of hormones, into and through the blood vessels,
‘activating’ other organs.
Activation: production of other hormones, start of metabolic/degradation processes.
The major organ is the pituitary gland (hypofyse) the conductor of the endocrine
system; masters all endocrine activities in the human body.
The pituitary gland produces almost all hormones.
The central processor of the pituitary gland is the hypothalamus.
The pituitary gland (hypofyse):
Consists out of two suborgans:
Diencephalon + Rathke’s pouch (monddak - mesodermal)
- Is connected to the hypothalamus, via the pituitary stalk (hersenaanhangsel).
Anterior pituitary = derived from Rathke’s pouch.
Posterior pituitary = derived from diencephalon (brain).
*The optic chiasm (region of optic nerves) lies very close to the pituitary gland
Prolactinoma = tumor in the pituitary gland (hypofyse) can cause lose of sight,
because optic chiasm is very close.
Pituitary cell types:
There are two types of cells in the anterior pituitary gland:
1. Chromophobe cells: approximately 50% of epithelial cells and are clustered.
No or a limited number of secretory granules.
2. Chromophiele cells: contain no specific secretory granulae and can be
separated into acidophile and basophile cells (staining properties of the
secretion product) pH-dependency.
- Somatotrope cells Soma means body, so the growth hormone is produced
GH.
- Mammotrope cells prolactin PRL, produces breast milk
- Gonadotrope cells produces gonadotrophins LH and FSH
- Thyreotrope cells produces thyroid stimulating hormones TSH
- Corticotrope cells produce adrenocorticotrophe hormones, targets adrenal
glands and stimulates them to produce cortisol. ACTH
The posterior pituitary releases two hormones:
1. Oxytocin involved in parturition (bevalling)
2. Vasopressin (Anti-diuretic hormone ADH) involved in regulating
bloodpressure by contracting/dilating blood vessels.
, Which are both synthesized in the hypothalamus.
*High level of ADH within the kidney there is liberation of water, primary urine is
retracted/re-absorbed, lower water excretion. Retainment of water in the body.
- The products of the pituitary gland are intermediate products which stimulate
another organ to make the final product to being released in the body.
Exception: oxytocin already an active end product.
TRH (in the hypothalamus) stimulates TSH (in the anterior pituitary) stimulates
Thyroid gland produces thyroid hormones T3 and T4
TRH and TSH are the hormones which are responsible for the release of T3 and T4
hormones.
Negative feedback: when there is enough T4 in the body this is sensed, it stops
TRH production.
Hormones are expressed in different levels during daytime/nighttime.
Remarkable: growth hormone has a very pulsatile character not high at night/low
at daytime, it goes by pulses.
Frequency: number of pulses is altered.
Amplitude: height of signal is altered.
To stimulate the pituitary gland, hormones need to be given pulsatile, not
continuously.
Tests of pituitary function:
e.g. Arginine infusion test
Pathology of the Endocrine System; anatomy and physiology of the hypothalamus-
pituitary system
Endocrine: internally secretion of hormones, into and through the blood vessels,
‘activating’ other organs.
Activation: production of other hormones, start of metabolic/degradation processes.
The major organ is the pituitary gland (hypofyse) the conductor of the endocrine
system; masters all endocrine activities in the human body.
The pituitary gland produces almost all hormones.
The central processor of the pituitary gland is the hypothalamus.
The pituitary gland (hypofyse):
Consists out of two suborgans:
Diencephalon + Rathke’s pouch (monddak - mesodermal)
- Is connected to the hypothalamus, via the pituitary stalk (hersenaanhangsel).
Anterior pituitary = derived from Rathke’s pouch.
Posterior pituitary = derived from diencephalon (brain).
*The optic chiasm (region of optic nerves) lies very close to the pituitary gland
Prolactinoma = tumor in the pituitary gland (hypofyse) can cause lose of sight,
because optic chiasm is very close.
Pituitary cell types:
There are two types of cells in the anterior pituitary gland:
1. Chromophobe cells: approximately 50% of epithelial cells and are clustered.
No or a limited number of secretory granules.
2. Chromophiele cells: contain no specific secretory granulae and can be
separated into acidophile and basophile cells (staining properties of the
secretion product) pH-dependency.
- Somatotrope cells Soma means body, so the growth hormone is produced
GH.
- Mammotrope cells prolactin PRL, produces breast milk
- Gonadotrope cells produces gonadotrophins LH and FSH
- Thyreotrope cells produces thyroid stimulating hormones TSH
- Corticotrope cells produce adrenocorticotrophe hormones, targets adrenal
glands and stimulates them to produce cortisol. ACTH
The posterior pituitary releases two hormones:
1. Oxytocin involved in parturition (bevalling)
2. Vasopressin (Anti-diuretic hormone ADH) involved in regulating
bloodpressure by contracting/dilating blood vessels.
, Which are both synthesized in the hypothalamus.
*High level of ADH within the kidney there is liberation of water, primary urine is
retracted/re-absorbed, lower water excretion. Retainment of water in the body.
- The products of the pituitary gland are intermediate products which stimulate
another organ to make the final product to being released in the body.
Exception: oxytocin already an active end product.
TRH (in the hypothalamus) stimulates TSH (in the anterior pituitary) stimulates
Thyroid gland produces thyroid hormones T3 and T4
TRH and TSH are the hormones which are responsible for the release of T3 and T4
hormones.
Negative feedback: when there is enough T4 in the body this is sensed, it stops
TRH production.
Hormones are expressed in different levels during daytime/nighttime.
Remarkable: growth hormone has a very pulsatile character not high at night/low
at daytime, it goes by pulses.
Frequency: number of pulses is altered.
Amplitude: height of signal is altered.
To stimulate the pituitary gland, hormones need to be given pulsatile, not
continuously.
Tests of pituitary function:
e.g. Arginine infusion test
