Pituitary Gland Flashcards
There is a close anatomic relationship between the pituitary and the hypothalamus.
___ ___l tract runs thru the infundibulum
There is a close anatomic relationship between the pituitary and the hypothalamus.
Hypothalamic-Hypophoseal tract runs thru the infundibulum
The Hypothalamus and Anterior Pituitary
The hypothalamic – ____r pituitary ___ ___ provides a link between the ___l nervous system and the ___ system
This connection allows us to have the establishment of the endocrine axis
The Hypothalamus and Anterior Pituitary
The hypothalamic – anterior pituitary endocrine axis provides a link between the central nervous system and the endocrine system
This connection allows us to have the establishment of the endocrine axis
- Thyrotropin-Releasing Hormone (TRH
- uStimulate release of ___ (t___) and ___
- Corticotropin-Releasing Hormone (CRH)
- uStimulate release of ___ (___n)
- Gonadotropin-Releasing Hormone (GnRH)
- uStimulate release of___ and ___(___n)
- Growth Hormone-Releasing Hormone (GHRH)
- uStimulate release of ____
- Hypothalamus secretes ____ Hormones. That acts on pit.
- Pit gland secretes ___ hormone that stimulate the endocrine___d of interest that secrete the hormones of interest that lead to physiological effects
- And there is feedback inhibition
Thyrotropin-Releasing Hormone (TRH)
uStimulate release of TSH (thyrotropin) and prolactin
Corticotropin-Releasing Hormone (CRH)
uStimulate release of ACTH (corticotropin)
Gonadotropin-Releasing Hormone (GnRH)
uStimulate release of FSH and LH (gonadotropin)
Growth Hormone-Releasing Hormone (GHRH)
uStimulate release of growth hormone
Hypothalamus secretes releasing hormones. That acts on pit.
Pit gland secretes stimulating hormone that stimulate the endocrine gland of interest that secrete the hormones of interest that lead to physiological effects
And there is feedback inhibition
Somatostatin (_ ___ ___ ___)
___ release of __ and ___
Prolactin-Releasing Hormone (PRH)
uStimulate release of ____
Dopamine (___ ___ ___)
____ release of___
Most effects of somatostatin are inhibitory but it does have some stimulatory effects
Low dopamineà Parkinsons disease
Somatostatin (Growth Hormone-Inhibiting Hormone GHIH)
uInhibits release of GH and TSH
Prolactin-Releasing Hormone (PRH)
uStimulate release of prolactin
Dopamine (Prolactin-Inhibiting Hormone PIH)
uInhibits release of prolactin
Most effects of somatostatin are inhibitory but it does have some stimulatory effects
Low dopamineà Parkinsons disease
Axons of neurons from hypoth extend thru stalk and those axons form hypoth/hypoph tract and those go to pos pit
Axons of neurons from hypoth extend thru stalk and those axons form hypoth/hypoph tract and those go to pos pit
The pituitary is composed of two lobes.
2 lobes
Epithelial: ___ Pit
Neuronal: ___ pit
Post pit have neurons from hypoth that extend their axons all the way to the post pit.
At nerve terminals mainly 2 hormones are released (oxytocin and ADH)
Remember
____ pit does not make any hormone…Hormones are made in cell bodies in the hypothalamus. Stored in nerve terminals in the post pit
When there is an approp stimulus, oxytocin and ADH is released
Post pit is like an extension of the hypothalamus
Axons make up the hypothalamic/hypophyseal tract
Cell bodies in ___ and ___ nuclei send axons and release the ___g and ___ factors into the __ __
___ ___l artery branches into this___ network and you have drainage from ____ plexus
Vessels take __ __s to___ plexus that bathes the anterior pit cells
When you have one capillary bed connected to another without going to the heartà __ __
Most common portal system is in the liver.
Hepatic Portal System
There is also one present here
Capillaries here are ___ so they have pores in them so when hormones released from neurons, easy for hormones to make it into the capillary network and then they travel thru vessels to ant pit where they stimulate the cells to release stimulating hormone
Stimulating hormones then drain thru circ system
The pituitary is composed of two lobes.
2 lobes
Epithelial: Anterior Pit
Neuronal: Post pit
Post pit have neurons from hypoth that extend their axons all the way to the post pit.
At nerve terminals mainly 2 hormones are released (oxytocin and ADH)
Remember
Posterior pit does not make any hormone…Hormones are made in cell bodies in the hypothalamus. Stored in nerve terminals in the post pit
When there is an approp stimulus, oxytocin and ADH is released
Post pit is like an extension of the hypothalamus
Axons make up the hypothalamic/hypophyseal tract
Cell bodies in paraventricular and superoptic nuclei send axons and release the releasing and inhibiting factors into the portal system
Superior hypophyseal artery branches into this capillary network and you have drainage from primary plexus
Vessels take releasing factors to secondary plexus that bathes the anterior pit cells
When you have one capillary bed connected to another without going to the heartà Portal system
Most common portal system is in the liver.
Hepatic Portal System
There is also one present here
Capillaries here are fenestrated so they have pores in them so when hormones released from neurons, easy for hormones to make it into the capillary network and then they travel thru vessels to ant pit where they stimulate the cells to release stimulating hormone
Stimulating hormones then drain thru circ system
Pituitary gland (hypophysis)
uComposed of two anatomically and functionally distinct lobes
FAn epithelial component (___s or ___ pituitary)
FA neural structure called the ___s (___pituitary)
uThe adenohypophysis is composed of ___ cell types that secrete ___ hormones. The neurohypophysis releases several ____
Pituitary gland (hypophysis)
uComposed of two anatomically and functionally distinct lobes
FAn epithelial component (Adenohypophysis or anterior pituitary)
FA neural structure called the neurohypophysis (posterior pituitary)
uThe adenohypophysis is composed of five cell types that secrete six hormones. The neurohypophysis releases several neurohormones.
uPituitary gland is situated within a ___ of the____ bone called the ___ ___.
FCancers of the pituitary have only one way to expand, which is ___ into the brain and against the __ ___. Thus, any increase in size of the pituitary is often associated with ___s or___ problems, or both.
the sella turcicaà Means Turkish Saddle
You have bone surrounding the pit gland.
If you have tumor of pit gland, can only expand upwards.
Optic chiasm is above the pit gland.
Tumors will compress the optic nerve and you can get condition called Bitemporal hemianopsia
You can also have aneruism of the artery that can cause that
Or tumors of the meningies
In the ___ of ___, that condition is prob from tumor of pit gland
Peripheral vision is lost on both sides
uPituitary gland is situated within a depression of the sphenoid bone called the sella turcica.
FCancers of the pituitary have only one way to expand, which is up into the brain and against the optic nerves. Thus, any increase in size of the pituitary is often associated with dizziness or vision problems, or both.
the sella turcicaà Means Turkish Saddle
You have bone surrounding the pit gland.
If you have tumor of pit gland, can only expand upwards.
Optic chiasm is above the pit gland.
Tumors will compress the optic nerve and you can get condition called Bitemporal hemianopsia
You can also have aneruism of the artery that can cause that
Or tumors of the meningies
In the absense of trauma, that condition is prob from tumor of pit gland
Peripheral vision is lost on both sides
THE NEUROHYPOPHYSIS
____ neurons
uHave cell bodies in the ___ nuclei and ____r nuclei of the hypothalamus
uMake ___ __ ___ (ADH, or arginine vasopressin) and ___
uProject axons down the infundibular stalk to the ___ ___ as the____ tracts.
FThese axons transport oxytocin and ADH to the anterior pituitary for release. Glial-like supportive cells called ____ also exists. Extensive vascularization and ___ capillaries facilitate diffusion of hormones into the vasculature.
THE NEUROHYPOPHYSIS
Magnocellular neurons
uHave cell bodies in the supraoptic nuclei and paraventricular nuclei of the hypothalamus
uMake Antidiuretic hormone (ADH, or arginine vasopressin) and oxytocin
uProject axons down the infundibular stalk to the pars nervosa as the hypothalamohypophyseal tracts.
FThese axons transport oxytocin and ADH to the anterior pituitary for release. Glial-like supportive cells called pituicytes also exists. Extensive vascularization and fenestrated capillaries facilitate diffusion of hormones into the vasculature.
Vasopressin
u____ water during urine formation by the ___ (antidiuretic effect)
uCauses ___ of ___ ___ muscles (___ effect)
uReleased in response to an ___ in plasma ___ that is sensed by ____ ___
uAlso ___ receptors in __ __a sense a___ in ECF volume and arterial____ (less important)
Conserves water.
pressin: Contraction of arteriolar smooth muscle which leads to increase in blood P
Released when osmolarity of plasma increases
Hypoth has osmoreceptors that senses this and that triggers the release, neurons are stimulated and then they release vasopressin. Then vasopressin acts on kidney tubules and they conserve water.
Also if there is a decrease in BP but this is less significant, there are receptors in the left atria that can sense that and then that sends a signal to hypoth and triggers release of vasopressin. Conserve water, increase blood volume and blood P is increased
Vasopressin
uConserves water during urine formation by the kidney (antidiuretic effect)
uCauses contraction of arteriolar smooth muscles (pressor effect)
uReleased in response to an ↑ in plasma osmolarity that is sensed by hypothalamic osmoreceptors
uAlso volume receptors in left atria sense a ↓in ECF volume and arterial bp (less important)
Conserves water.
Depressin: Contraction of arteriolar smooth muscle which leads to increase in blood P
Released when osmolarity of plasma increases
Hypoth has osmoreceptors that senses this and that triggers the release, neurons are stimulated and then they release vasopressin. Then vasopressin acts on kidney tubules and they conserve water.
Also if there is a decrease in BP but this is less significant, there are receptors in the left atria that can sense that and then that sends a signal to hypoth and triggers release of vasopressin. Conserve water, increase blood volume and blood P is increased
Oxytocin
uActs on the pregnant____ to induce labor by stimulating ____ of uterine smooth muscle
uActs on ____ cells of the breast to promote ___ __ __ during nursing
uRelease is promoted by reflexes that are triggered by ___ or from the __ __
uAlso facilitates bonding between mother and infant (love hormone), or couples (cuddle chemical).
Does not ____ parturition. (act or process of bearing or bringing forth offspring; birth)
Increases the Force and frequency of contraction during labor
Does not cause the beginning of labor though. Just aids in the process.
When the baby reaches a certain size and that pushes pressure on uterus and that triggers release of Oxytocin
Important for milk let down.
Suckling creates a reflex that leads to stimulating the neurons which cause release of oxytocin
Oxytocin
uActs on the pregnant uterus to induce labor by stimulating contraction of uterine smooth muscle
uActs on myoepithelial cells of the breast to promote milk let down during nursing
uRelease is promoted by reflexes that are triggered by suckling or from the birth canal
uAlso facilitates bonding between mother and infant (love hormone), or couples (cuddle chemical).
Does not stimulate parturition. (act or process of bearing or bringing forth offspring; birth)
Increases the Force and frequency of contraction during labor
Does not cause the beginning of labor though. Just aids in the process.
When the baby reaches a certain size and that pushes pressure on uterus and that triggers release of Oxytocin
Important for milk let down.
Suckling creates a reflex that leads to stimulating the neurons which cause release of oxytocin
Adenohypophysis
Anterior pituitary consists of 5 cell types that secrete 6 hormones
- Somatotropes
- uSecrete___ ___
- FRegulate body ___ and exert ___ effects
- Thyrotropes
- uSecrete __ __ ___
- FStimulate secretion of ___ hormone and ___ of the___ gland
- Corticotropes
- uSecrete _____
- FStimulate ___ secretion and ___ of the __ __
- Gonadotropes
- uSecrete ___ and ___
- FSH helps regulate ___ and ___ production. In females it stimulate __ ___ and development and promote ___ secretion. Needed for ___ production in males
u
Anterior pituitary consists of 5 cell types that secrete 6 hormones
Somatotropes
uSecrete Growth Hormone (GH, somatotropin)
FRegulate body growth and exert metabolic effects
Thyrotropes
uSecrete Thyroid-Stimulating Hormone (TSH)
FStimulate secretion of thyroid hormone and growth of the thyroid gland
Corticotropes
uSecrete Adrenocorticotropic Hormone (ACTH, adrenocorticotropin)
FStimulate cortisol secretion and growth of the adrenal cortex
Gonadotropes
uSecrete Follicle-Stimulating Hormone (FSH) and Luteinizing hormone (LH)
FFSH helps regulate sperm and ova production. In females it stimulate follicular growth and development and promote estrogen secretion. Needed for sperm production in males
u
- Luteinizing hormone (LH)
- uPlay a role in ___ hormone secretion in males and females.
- uFemales
- FRegulates secretion of___ and ____ from the ovaries
- FPlay a role in___ and luteinization (formation of ___-secreting __ ___)
- uMales
- FStimulate secretion of___ by the testes
- Progesterone is required for pregancy
Luteinizing hormone (LH)
uPlay a role in sex hormone secretion in males and females.
uFemales
FRegulates secretion of estrogen and progesterone from the ovaries
FPlay a role in ovulation and luteinization (formation of hormone-secreting corpus luteum)
uMales
FStimulate secretion of testosterone by the testes
Progesterone is required for pregancy
Lactotropes
uSecrete____ (PRL) which enhance ___ ___ and ___ in females
uMay ___ ____ system
uPRL is only one that has no ___effect, does not stimulate secretion of another hormone but rather act directly on____ tissue to exert its effect.
Has no tropic effect.
Doesn’t stimulate the release of any other hormone
Lactotropes
uSecrete Prolactin (PRL) which enhance breast development and lactation in females
uMay enhance immune system
uPRL is only one that has no tropic effect, does not stimulate secretion of another hormone but rather act directly on nonendocrine tissue to exert its effect.
Has no tropic effect.
Doesn’t stimulate the release of any other hormone
Circadian: ___ hrs ___
Ultradian: ____ min ___
Infradian: ___ FSH, LH estrogen progesterone
Tropic hormones stimulate hormone secretion and maintain and stimulate growth of the gland. TSH ACTH
Circadian: 24 hrs Cortisol
Ultradian: 90-120 min Cortisol
Infradian: monthly FSH, LH estrogen progesterone
Tropic hormones stimulate hormone secretion and maintain and stimulate growth of the gland. TSH ACTH
Feedback regulation.
Glands secrete hormones particular to that gland.
These hormones can inhibit the pituitary and/or the hypothalamus
Long or short loop
These are very important.
Can have life threatening consequences
People take steroids for an inflammatory condition
Those mimic endogenous hormone like cortisol
Will inhibit pit and hypoth at high doses
If they inhibit pitl, No ACTH release.
Can cause atrophy of adrenal gland and low cortisol
If they stop taking steroids abruptly. Adrenal gland cant make any/little cortisol
Has to be tapered to allow adrenal gland to regrow and start production of cortisol
Feedback regulation.
Glands secrete hormones particular to that gland.
These hormones can inhibit the pituitary and/or the hypothalamus
Long or short loop
These are very important.
Can have life threatening consequences
People take steroids for an inflammatory condition
Those mimic endogenous hormone like cortisol
Will inhibit pit and hypoth at high doses
If they inhibit pitl, No ACTH release.
Can cause atrophy of adrenal gland and low cortisol
If they stop taking steroids abruptly. Adrenal gland cant make any/little cortisol
Has to be tapered to allow adrenal gland to regrow and start production of cortisol
Regulation of Pituitary and Hypothalamus
Portal System
There is a portal circulation between the hypothalamus and the pituitary.
Blood enters this system via the ___ ___ ___. This artery branches into a ___ capillary plexus in the ___ ___
The primary capillary plexus drains into the ___ __ ___s, which travel down the stalk to the ___ pituitary where they form the anterior pituitary ___
The anterior pituitary sinusoids empty into the ___ ___. Blood from the hypophyseal vein passes into the___ ___
Portal System
There is a portal circulation between the hypothalamus and the pituitary.
Blood enters this system via the superior hypophyseal artery. This artery branches into a primary capillary plexus in the median eminence.
The primary capillary plexus drains into the hypophyseal portal vessels, which travel down the stalk to the anterior pituitary where they form the anterior pituitary sinusoids.
The anterior pituitary sinusoids empty into the hypophyseal vein. Blood from the hypophyseal vein passes into the general circulation.
This illustration shows the relationship of the pituitary blood supply to hypothalamic magnocellular neurons and to hypothalamic neurosecretory cells that produce releasing hormones. The magnocellular neuron (larger, dark blue cell body) releases AVP or oxytocin at its axon terminals into capillaries that give rise to the venous drainage of the posterior lobe. The neurons with smaller, light blue cell bodies are secreting releasing factors into capillary networks that give rise to the long and short hypophyseal portal vessels, respectively. Releasing hormones are shown reaching the hormone-secreting cells of the anterior lobe via the portal vessels.
This illustration shows the relationship of the pituitary blood supply to hypothalamic magnocellular neurons and to hypothalamic neurosecretory cells that produce releasing hormones. The magnocellular neuron (larger, dark blue cell body) releases AVP or oxytocin at its axon terminals into capillaries that give rise to the venous drainage of the posterior lobe. The neurons with smaller, light blue cell bodies are secreting releasing factors into capillary networks that give rise to the long and short hypophyseal portal vessels, respectively. Releasing hormones are shown reaching the hormone-secreting cells of the anterior lobe via the portal vessels.
___ ___ ___
___ ___ ___
___ ___ ___
____ ___ ___
___ ___
Superior hypophyseal artery.
Primary capillary plexus.
Hypophyseal portal vessels.
Anterior pituitary sinusoids.
Hypophyseal vein.
Regulation
uThe hypothalamus has many interconnections is potentially connected to___ parts of the brain.
uNerve impulses arriving at the hypothalamus can trigger___ cells into secreting ___hormones.
uNeurosecretory cells are stimulated by ____ s such as a___ ___ __ ___
uNeurosecretory cells secrete ___ ___ (peptides).
u
Regulation
uThe hypothalamus has many interconnections is potentially connected to all parts of the brain.
uNerve impulses arriving at the hypothalamus can trigger neurosecretory cells into secreting releasing hormones.
uNeurosecretory cells are stimulated by neurotransmitters such as acetylcholine, norepinephrine, serotonin and dopamine.
uNeurosecretory cells secrete releasing hormones (peptides).
u
Hypothalamic releasing hormones control secretion of hormones by the ___ pituitary.
uReleasing hormones often exist in pairs: one ___es and the other___ the release of a pituitary hormone.
____ of releasing hormone will liberate ___ of pituitary hormone.
uFactors such as ___ can influence release of ____ factors such as CRH
u____s also affects hormone secretion since some women who are emotionally upset may experience ___ ___
Hypothalamic releasing hormones control secretion of hormones by the anterior pituitary.
uReleasing hormones often exist in pairs: one stimulates and the other inhibits the release of a pituitary hormone.
u10 nanograms of releasing hormone will liberate one milligram of pituitary hormone.
uFactors such as stress can influence release of hypothalamic factors such as CRH
uEmotions also affects hormone secretion since some women who are emotionally upset may experience menstrual irregularities.
Central nervous system signals influence the secretion of releasing hormones.
The ____ organs, the ___ sensors, and the ___ ___ send neural signals to the hypothalamus.
The signals may be ___ or ___
The exteroceptive organs, the interoceptive sensors, and the cerebral cortex send neural signals to the hypothalamus.
The signals may be excitatory or inhibitory.
Hypothalamus, pituitary, target glands and central nervous system feedback loops.
Short loop feedback
urefers to the effect of__ __ n the ___
Long loop feedback
urefers to the effect of __ __ hormones on the ___
F
u
Short loop feedback
urefers to the effect of pituitary hormones on the hypothalamus.
Long loop feedback
urefers to the effect of end‑organ hormones on the hypothalamus
F
u
Hypothalamus, pituitary, target glands and central nervous system feedback loops.
Most of the pituitary hormones stimulate a target gland to secrete its hormone.
uLow levels of a target gland hormone usually stimulate secretion of a releasing hormone.
uHigh levels of a target gland hormone usually inhibit secretion of a releasing hormone.
uThere is a __ __ for each system.
uSome end organ hormones may affect both the hypothalamus and the pituitary.
Most of the pituitary hormones stimulate a target gland to secrete its hormone.
uLow levels of a target gland hormone usually stimulate secretion of a releasing hormone.
uHigh levels of a target gland hormone usually inhibit secretion of a releasing hormone.
uThere is a set point for each system.
uSome end organ hormones may affect both the hypothalamus and the pituitary.
