Pituitary Gland

Question 1

There is a close anatomic relationship between the pituitary and the hypothalamus.

___ ___l tract runs thru the infundibulum

Answer 1

There is a close anatomic relationship between the pituitary and the hypothalamus.

Hypothalamic-Hypophoseal tract runs thru the infundibulum

Question 2

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

Answer 2

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

Question 3

• 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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

Axons of neurons from hypoth extend thru stalk and those axons form hypoth/hypoph tract and those go to pos pit

Answer 5

Axons of neurons from hypoth extend thru stalk and those axons form hypoth/hypoph tract and those go to pos pit

Question 6

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

Answer 6

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

Question 7

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 ____

Answer 7

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.

Question 8

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

Answer 8

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

Question 9

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.

Answer 9

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.

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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

Question 13

• 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

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Circadian: ___ hrs ___

Ultradian: ____ min ___

Infradian: ___ FSH, LH estrogen progesterone

Tropic hormones stimulate hormone secretion and maintain and stimulate growth of the gland. TSH ACTH

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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___ ___

Answer 17

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.

Question 18

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.

Answer 18

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.

Question 19

___ ___ ___
___ ___ ___
___ ___ ___

____ ___ ___
___ ___

Answer 19

Superior hypophyseal artery.

Primary capillary plexus.

Hypophyseal portal vessels.

Anterior pituitary sinusoids.

Hypophyseal vein.

Question 20

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

Answer 20

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

Question 21

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 ___ ___

Answer 21

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.

Question 22

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 ___

Answer 22

The exteroceptive organs, the interoceptive sensors, and the cerebral cortex send neural signals to the hypothalamus.

The signals may be excitatory or inhibitory.

Question 23

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

Answer 23

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

Question 24

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.

Answer 24

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.

Question 25

Growth Hormone (GH)

The anterior pituitary tropic hormones maintain target glands and stimulate production of target gland hormones

uGrowth hormone (HGH) is an exception:GH acts throughout the body.

GH secretion is regulated by

u___ for pathways it controls, e.g. certain __ __

u__ ___ products such as __ and ___ ___

Answer 25

Growth Hormone (GH)

The anterior pituitary tropic hormones maintain target glands and stimulate production of target gland hormones

uGrowth hormone (HGH) is an exception:GH acts throughout the body.

GH secretion is regulated by

usubstrates for pathways it controls, e.g. certain amino acids

umetabolic end products such as glucose or fatty acids.

Question 26

Growth is not uniform throughout life

Two periods of growth

___-___years: ___

_ (Female) __ (males): ___

Then start to level off

Many factors like nutrients, hormones, steroids, GF

Environemental and genetic factors determine how much we grow

Study showed importance of environmental factors.

Took fetus from pony and put it in a horse to develop

That fetus that developed in maternal environment of the horse was much larger than a regular pony. Not as big as a horse still

Only difference was the maternal environment that it grew up in.

Answer 26

Growth is not uniform throughout life

Two periods of growth

Birth – 2 years: Postnatal

11 (Female) 13 (males): Pubertal

Then start to level off

Many factors like nutrients, hormones, steroids, GF

Environemental and genetic factors determine how much we grow

Study showed importance of environmental factors.

Took fetus from pony and put it in a horse to develop

That fetus that developed in maternal environment of the horse was much larger than a regular pony. Not as big as a horse still

Only difference was the maternal environment that it grew up in.

Question 27

Hormones that Affect Linear Growth

• Growth hormone (GH)
• ___ ___ growth factors _ and _ (___ and___)
• ___
  
  • upromote growth by ↑ __ __ also resembles ___ so may interact with receptor
• ___ ___
  
  • uNot directly promote growth but cause ___ to be more___, ↓Th cause stunted growth

Answer 27

Growth hormone (GH)

Insulin-like growth factors I and 2 (IGF-1 and IGF-2)

Insulin

upromote growth by ↑ protein synthesis also resembles IGF-1 so may interact with receptor

Thyroid hormones (Th)

uNot directly promote growth but cause GH to be more effective, ↓Th cause stunted growth

Question 28

Hormones that Affect Linear Growth

Glucocorticoids

uGlucocorticoids modulate the secretion of __ __(GH) by various and competing effects on the hypothalamus and pituitary gland. The final effects of this modulation depend on hormone ___s and the___ of exposure.

The traditional view is that chronically raised levels of glucocorticoids ____ the secretion of GH

Answer 28

Glucocorticoids

uGlucocorticoids modulate the secretion of growth hormone (GH) by various and competing effects on the hypothalamus and pituitary gland. The final effects of this modulation depend on hormone concentrations and the duration of exposure. The traditional view is that chronically raised levels of glucocorticoids suppress the secretion of GH

Question 29

Hormones that Affect Linear Growth

Androgens

uStimulate ___ synthesis in many organs, important during ___y, promote growth, weight gain, muscle mass. Work synergistically with GH to promote linear growth, not much effect __ __. Androgens also ___ growth by promoting ___ of the __ __

Estrogens

uStimulate ___ of epiphyseal plates by conversion to___

Androgens: male sex hormone

Also important for puberty in females

Two other important hormones are androstenedione and dehydroepiandrosterone. Those are not very important in males bc DHEA and AD are secreted by adrenal cortex. Weak sex hormones but overshadowed by testosterone in males. Females don’t have that level of testosterone so DHEA and AD are more important during pubertal growth in females

Estrogen in females and testosterone in males regulate closure of epip plates. This stops linear growth

That’s why these hormones have to be balanced

Excess of these can lead to early closure of the plates

Can lead to shorter growth

You need testosterone to make estrogen

Answer 29

Hormones that Affect Linear Growth

Androgens

uStimulate protein synthesis in many organs, important during puberty, promote growth, weight gain, muscle mass. Work synergistically with GH to promote linear growth, not much effect without GH. Androgens also stop growth by promoting closure of the epiphyseal plates

Estrogens

uStimulate closure of epiphyseal plates by conversion to bone

Androgens: male sex hormone

Also important for puberty in females

Two other important hormones are androstenedione and dehydroepiandrosterone. Those are not very important in males bc DHEA and AD are secreted by adrenal cortex. Weak sex hormones but overshadowed by testosterone in males. Females don’t have that level of testosterone so DHEA and AD are more important during pubertal growth in females

Estrogen in females and testosterone in males regulate closure of epip plates. This stops linear growth

That’s why these hormones have to be balanced

Excess of these can lead to early closure of the plates

Can lead to shorter growth

You need testosterone to make estrogen

Question 30

Growth Hormone

___ endocrine regulator of growth

Secreted by ___ in the___pituitary

uExcess secretion of GH during childhood leads to ___

uDeficiency leads to ___ ___

Excess of GH during adult life leads to acromegaly.

Don’t increase in height

Deficiency in adulthood doesn’t seem to affect anything

Answer 30

Growth Hormone

Principal endocrine regulator of growth

Secreted by somatotrophs in the anterior pituitary

uExcess secretion of GH during childhood leads to gigantism

uDeficiency leads to pituitary dwarfism

Excess of GH during adult life leads to acromegaly.

Don’t increase in height

Deficiency in adulthood doesn’t seem to affect anything

Question 31

Growth Hormone

An excess (pituitary tumor) of GH after puberty leads to___

uGrowth of bones and other tissues but not lengthening of bones as epiphyseal growth plates close at puberty

uResults in )___ of bones, soft tissue of___ ___ ___. Leads to___n, __ __, ___ problems and premature ___

GH deficiency beginning in adult life __ __ cause __ ___ ___

Answer 31

An excess (pituitary tumor) of GH after puberty leads to acromegaly

uGrowth of bones and other tissues but not lengthening of bones as epiphyseal growth plates close at puberty

uResults in thickening of bones, soft tissue of hands , head, feet. Leads to hypertension, heart failure pulmonary problems and premature death

GH deficiency beginning in adult life does not cause any major illness.

Question 32

Growth Hormone

Synthesized as large ___ and then processed to other forms

Major forms are the _kDa and __ kDa.

u20kDa may exert ____ acute metabolic actions

Stored in secretory granules in the ___ of somatotrophs.

Answer 32

Synthesized as large prehormone and then processed to other forms

Major forms are the 20kDa and 22 kDa.

u20kDa may exert fewer acute metabolic actions

Stored in secretory granules in the cytosol of somatotrophs.

Question 33

Four other hormones have homology to GH

• u___hormones
  
  • __ ___ __ ___
  • ___ ___ ____ I and 2
• uPituitary hormone ____
  
  • GH and PRL have similar ___s for the___ receptor but PRL has___significant affinity for ___ receptor and___growth promoting action
    *

Answer 33

Four other hormones have homology to GH

uPlacental hormones

FPlacental-variant GH (pvGH)

FHuman chorionic somatomammotropins I and 2 (hCS1 and hCS2)

uPituitary hormone prolactin (PRL)

FGH and PRL have similar affinities for the PRL receptor but PRL has no significant affinity for GH receptor and no growth promoting action

F

Question 34

PRL promotes ___ ___ in lactating women

uMade by lactotrophs in the anterior pituitary

uBoth GH and PRL are coupled to the___ family of __ __

uBoth men and women make PRL throughout life but __ __ for PRL in males defined

uIf hypersecretion (in males) of PRL then develop ____ (breast milk secretion)

Answer 34

PRL promotes milk production in lactating women

uMade by lactotrophs in the anterior pituitary

uBoth GH and PRL are coupled to the Jak family of tyrosine kinases

uBoth men and women make PRL throughout life but no role for PRL in males defined

uIf hypersecretion (in males) of PRL then develop galactorrhea (breast milk secretion)

Question 35

GH secretion is pulsatile and the pattern depends on sleep-wake cycle

uStimulated by ___, ___, high ___ meal, ___. ___of stimulation is affected not ___

uGHRH form the hypothalamus travels to the somatotrophs in the anterior pituitary via the hypophyseal portal system

uStimulates a rise in ___ which cause ↑__ __ and synthesis of __. Also release of GH via a rise in [___]i

Answer 35

GH secretion is pulsatile and the pattern depends on sleep-wake cycle

uStimulated by exercise, stress, high protein meal, fasting. Frequency of stimulation is affected not amplitude

uGHRH form the hypothalamus travels to the somatotrophs in the anterior pituitary via the hypophyseal portal system

uStimulates a rise in cAMP which cause ↑gene transcription and synthesis of GH. Also release of GH via a rise in [Ca2+]i

Question 36

Many hypothalamic‑pituitary‑target organ systems exhibit periodic fluctuations in levels of secretion. These may be related to the light‑dark, sleep‑wake cycle.

Many are circadian (about 24 hours) rhythms.

Some are ultradian (90 ‑ 120 minutes) rhythms.

A few are infradian (monthly) rhythms.

Answer 36

Many hypothalamic‑pituitary‑target organ systems exhibit periodic fluctuations in levels of secretion. These may be related to the light‑dark, sleep‑wake cycle.

Many are circadian (about 24 hours) rhythms.

Some are ultradian (90 ‑ 120 minutes) rhythms.

A few are infradian (monthly) rhythms.

Question 37

Growth Hormone Receptor

uA __ ___-associated receptor

uBinding of one GH molecule to sites on __ __ leads to receptor ___

uThis increases the activity of a ___ ___ (JAK 2) that is associated with the receptor but is not an ___ part of it.

uThis tyrosine kinase triggers a series of phosphorylations that modulate the activity of target cells

Answer 37

Growth Hormone Receptor

uA tyrosine kinase-associated receptor

uBinding of one GH molecule to sites on two monomers leads to receptor dimerization

uThis increases the activity of a tyrosine kinase (JAK 2) that is associated with the receptor but is not an integral part of it.

uThis tyrosine kinase triggers a series of phosphorylations that modulate the activity of target cells

Question 38

Acute Effects of GH (min to hrs)

u____ or anti-insulin

uMuscle ___ Glucose uptake

uFat ___ lipolysis

uLiver ___ gluconeogenesis

uCause ___ ___ in muscle, fat and liver

Promote high levels of glucose in the blood

If glucose isn’t going into muscle, it will remain in blood and can promote hyperglycemia

Adipose tissue releases fa and glycerol

Fa are known to lead to insulin resistanceà predisposes you to diabetes

Glycerol can go back to the liver to make more glucoseà more glucose for the blood

Knowing that they are growing, what should kids do, knowing this information?

They should exercise

This promotes intake of glucose into the cells independent of insulin

Answer 38

Acute Effects of GH (min to hrs)

uDiabetogenic or anti-insulin

uMuscle ↓ Glucose uptake

uFat ↑ lipolysis

uLiver ↑ gluconeogenesis

uCause insulin resistance in muscle, fat and liver

Promote high levels of glucose in the blood

If glucose isn’t going into muscle, it will remain in blood and can promote hyperglycemia

Adipose tissue releases fa and glycerol

Fa are known to lead to insulin resistanceà predisposes you to diabetes

Glycerol can go back to the liver to make more glucoseà more glucose for the blood

Knowing that they are growing, what should kids do, knowing this information?

They should exercise

This promotes intake of glucose into the cells independent of insulin

Question 39

Long-term effects of GH

uPromote tissue growth by stimulating target tissues to produce ____ (somatomedins)

___ and___ can bind to receptors for each other.

uIGF-1 can exert ___-like actions in vivo including ____a due to __ ___ into muscle.

Answer 39

Long-term effects of GH

uPromote tissue growth by stimulating target tissues to produce IGFs (somatomedins)

uIGF-1 and insulin can bind to receptors for each other.

uIGF-1 can exert insulin-like actions in vivo including hypoglycemia due to glucose uptake into muscle.

Question 40

Leptin and Insulin in Brain

Both leptin and insulin stimulate ___ neurons to produce___

uNeurons also release POMC cleavage product _____

uα-MSH binds to its receptor and produce ___ and ___ food intake (___c) and ___ energy expenditure

Insulin has a role in appetite

Leptin is secreted by fat cells

When we eat, that is a stimulus for leptin to be secreted by fat cells

Insulin suppresses appetite within the brain.

Leptin too

Answer 40

Leptin and Insulin in Brain

Both leptin and insulin stimulate pro-opiomelanocortin (POMC) neurons to produce POMC

uNeurons also release POMC cleavage product melanocortin α-melanocyte-stimulating hormone (α-MSH)

uα-MSH binds to its receptor and produce satiety and decrease food intake (anorexigenic) and increase energy expenditure

Insulin has a role in appetite

Leptin is secreted by fat cells

When we eat, that is a stimulus for leptin to be secreted by fat cells

Insulin suppresses appetite within the brain.

Leptin too

Question 41

Leptin and Insulin in Brain

Insulin and leptin suppress neurons in the arcuate nucleus that release ___ and __

uNPY ___ ___ ___

uAgRP___ the ____ effect of ___

uBoth NPY and AgRP are ____

Neuro peptide Y

Aguti related peptide

Answer 41

Insulin and leptin suppress neurons in the arcuate nucleus that release NPY and AgRP

uNPY stimulate eating behavior

uAgRP inhibits the anorexigenic effect of α –MSH

uBoth NPY and AgRP are orexigenic

Neuro peptide Y

Aguti related peptide

Question 42

Ghrelin

Hormone made in specialized endocrine cells in__ ___ (mainly stomach)

uReleased in response to ___

uPromote___ (____)

Answer 42

Hormone made in specialized endocrine cells in gastric mucosa (mainly stomach)

uReleased in response to fasting

uPromote appetite (orexigenic)