Unit 2 Endocrine: Hypothalamus and Pituitary and Adrenal Flashcards
Where is the Hypothalamus located?
In diencephalon, midbrain
What is the Hypothalamus an important link between? According to the textbook
An important link between the nervous system and endocrine system.
According to the textbook, what does the Hypothalamus control?
Controls much of the body’s physiology: hunger, thirst, fluid balance, and body temperature.
According to the textbook, what does the Hypothalamus act as and for what?
And why?
Acts as a “commander in chief” for the other glands in the endocrine system since it controls the pituitary gland, and thus, most other glands in the endocrine system.
Does the Hypothalamus directly influence the endocrine glands? if not, how does it influence them?
The Hypothalamus doesn’t directly influence the endocrine glands. Instead, it influences the pituitary glands, which is the middle manager.
What is the Pituitary gland part of?
Also a part of diencephalon
What is the quotation for the Pituitary gland and why is it called like that?
“master gland.”
Because it’s controlling other endocrine glands.
What does the Pituitary gland really acts only under orders from?
The pituitary gland really acts only under orders from the hypothalamus.
So, what are the quotation words for the hypothalamus and the pituitary gland?
Hypothalamus: Commander in chief
Pituitary: High-ranking general (Master gland)
Which two parts is the pituitary gland split into?
Posterior pituitary glands
Anterior pituitary glands
What can we think of the Posterior Pituitary gland?
An extension of the hypothalamus
What does the extension of the hypothalamus have inside of it and what does it do?
The extension of the hypothalamus has Hypothalamic neurons inside it and can secrete hormones instead of neurotransmitters.
How do the Hypothalamic neurons inside the extension of the hypothalamus extend their axons?
They extend their axons through a stalk(줄기) in the posterior pituitary.
How many hormones can the Posterior Pituitary secrete and what are they called?
Hypothalamic neurons can secrete two hormones: ADH and Oxytocin.
Where is the ADH and oxytocin made by and secreted thorugh?
ADH and oxytocin is made by the hypothalamus and secreted through the Posterior Pituitary.
What is the hypothalamus an important link between? (maybe in the exam)
Hypothalamus is an important link between the nervous system and endocrine system.
What is the role of the Hypothalamus? (three)
Maintains homeostasis
Control over ANS (Autonomic)
Has influence over pituitary hormones
What 2 systems is the hypothalamus able to control? according to mott
Hypothalamus is able to control both Autonomic Nervous System and Endocrine System.
What are the hormones in the Hypothalamus known as and what are they secreted by?
Hormones are what we consider neurohormones for the posterior pituitary and they are secreted via neurons.
Are there neural connection between hypothalamus and anterior pituitary?
There is no neural connection between the hypothalamus and anterior pituitary
What connection do the Hypothalamus and Anterior Pituitary only have?
Vascular connection only
Which hormones are at the posterior pituitary?
ADH and Oxytocin
How many hormones does the Anterior Pituitary gland secrete?
7 Hormones
What do the hormones of the Anterior Pituitary regualte?
Regulates stress, growth, reproduction, and lactation
What is the Posterior Pituitary deal with?
Deals with the kidneys and urine muscles.
What are three components of the Anterior Pituitary?
Pars Distalis
Pars Tuberalis
Pars Intermedia
What does the Pars Distalis of the Anterior Pituitary do?
Pars Distalis is what’s doing the hormone production
What is the Hypothalamus connected to pituitary gland via?
Hypothalamus is connected to pituitary gland via stalk(줄기) called infundibulum
How many lobes does the pituitary gland have?
two major lobes
What are the two major lobes of the Pituitary gland?
Posterior pituitary
Anterior pituitary
What is the Posterior pituitary composed of?
It is composed of neural tissue, part of our nervous system.
What is the Anterior pituitary composed of?
It is composed of glandular tissue, able to produce its own hormone.
According to Mott, what can we think of the Posterior Pituitary?
We can think of the Posterior Pituitary as a storehouse for information or hormones coming from the hypothalamus.
According to Mott, what can we think of the Anterior Pituitary?
We can think of it as Anterior Pituitary is able to do its own hormone production and has its own production center.
So, it’s not just a storehouse for hormones.
What tissue is the Posterior Lobe?
The Posterior Lobe is neural tissue from a down growth of the brain.
How does the Posterior lobe maintain neural connection to hypothalamus?
It maintains neural connection to the hypothalamus via nervous system tissue that’s running through the infundibulum.
What neurohormones do the Posterior lobe secrete?
Secretes two neurohormones: Oxytocin and ADH
Where are the two neurohormones that are secreted by the posterior lobe stored in?
Oxytocin and ADH are stored in axon terminals in posterior pituitary
When are the hormones that are stored in the posterior pituitary released?
They are released into the blood when neurons fire or when it’s said, hey we need this to occur.
What tissue is the Anterior lobe?
The anterior lobe is glandular tissue developed from an out pocketing of oral mucosa.
How is the Anterior lobe connected to hypothalamus?
It is vascularly connected to the hypothalamus via the hypophyseal portal system that is still inside the infundibulum.
Portal system all that saying is it is venous connection, it is being done through blood flow.
What does the hypophyseal portal system consist of? (three)
Primary capillary plexus
Hypophyseal portal veins
Secondary capillary plexus
Just know that it’s part of the venous system and it is dealing with blood flow.
Why does the Hypothalamus secretes releasing and inhibiting hormones to the anterior pituitary?
To regulate hormone secretion.
What are the anterior Pituitary Hormones?
Maybe write this down on the cheat sheet
ACTH
Thyroid-stimulating Hormones
Follicle-stimulating Hormone
Luteinizing Hormone
Growth Hormone
Prolactin
What does the ACTH do?
Targets the Adrenal gland which is on top of our kidneys.
When ACTH go to the Adrenal gland, what is it going to target?
It targets the secretion of glucocorticoids, mineralocorticoids, and sex corticoids.
What does the Thyroid-stimulating Hormone do?
It goes to the Thyroid gland to upregulate the secretion of our thyroid hormones.
What does the Follicle-stimulating Hormone do?
It targets the gonads and affects the growth of the reproductive system.
What does the Luteinizing hormone do?
It also targets the gonads to affect sex hormone production.
So we have two hormones that are really working on targeting the reproductive system.
Follicle Stimulating hormone is working on the growth component
Luteinizing hormone is working on the sex-hormone component.
What does the growth hormone do?
It targets the liver and adipose tissue.
It promotes growth through lipid and carbohydrate metabolism.
So it’s saying let’s break down some fat and carbs so we can use them as part of our growth.
What does the Prolactin do?
It targets the ovaries and mammary glands.
They influence the secretion of estrogen/progesterone and milk production.
Not much influence on males.
Growth Hormones are also called what?
Growth Hormones are also called somatotropin
What does Growth hormone has direct actions on?
It has direct actions on metabolism and indirect growth-promoting actions.
More details of Direct actions on metabolism
Glucose-sparing actions decrease the rate of cellular glucose uptake and metabolism. (Anti-insulin effects)
(So it comes to the cells, and it says, hey, don’t use as much glucose right now. Leaves some glucose in the liver; because of that, it has anti-insulin effects, it’s going to cause blood sugar to increase.)
Then, it triggers the liver to break down glycogen into glucose.
Increases blood levels of fatty acids for use as fuel and encourages cellular protein synthesis.
More details of Indirect actions on growth
Growth hormone triggers the liver, skeletal muscle, and bone to produce insulin-like growth factors.
(So growth hormone itself is not doing the production)
IGFS then stimulates cellular uptake of nutrients used to synthesize DNA and proteins needed for cell division and causes formation of collagen and deposition of bone matrix.
Growth Hormone stimulates most cells to enlarge and divide, but major targets are bone and skeletal muscle.
So in general, the growth hormone does what directly and indirectly?
Directly, ups our glucose
Indirectly, it causes increased division at the cellular level, mostly at our bone and skeletal muscle
How do we regulate growth hormone?
Growth hormone release or inhibition is regulated by hypothalamic hormones on somatotropic cells.
Where are both growth hormone-releasing hormone and growth hormone-inhibiting hormone from?
Hypothalamic hormones
The hypothalamus can either release GHRH or GHIH. This is saying that this is how I am going to control how much growth hormone is coming out at our anterior pituitary gland.
What does the Growth hormone-releasing hormone do and what is it triggered by?
It stimulates growth hormone release and is triggered by low blood growth hormone or glucose, or high amino acid levels.
What does the Growth hormone-inhibiting hormone do and what is it triggered by?
It inhibits release, and it is triggered by the increase in growth hormone and IGF levels.
(Insulin-like growth factors)
What also stimulates growth hormone release outside of hypothalamus?
Ghrelin (hunger hormone)
What is Thyroid-stimulating hormone?
It is Tropic hormone that is also called thyrotropin as it is produced by thyrotropic cells in the anterior pituitary.
What does the Thyroid-stimulating hormone stimulate?
It stimulates the normal development and secretory activity of the thyroid.
What is the release of the Thyroid-stimulating hormone triggered by?
Release is triggered by the thyrotropin-releasing hormone from the hypothalamus.
What is the Thyroid-stimulating hormone inhibited by?
Inhibited by rising blood levels of thyroid hormones that act on both the pituitary and hypothalamus.
It is also inhibited by Growth hormone-inhibiting hormone.
What is the ACTH secreted by?
It is secreted by corticotropic cells.
What does the ACTH stimulate?
It stimulates adrenal cortex to release corticosteroids.
What is the regulation of ACTH release triggered by?
Triggered by hypothalamic corticotropin-releasing hormone (CRH) in daily rhythm.
When is the highest level of ACTH?
In the morning
Cortisol spikes around 9 am.
Cortisol is one of the hormones that is stimulated by ACTH.
Cortisol comes from our adrenal gland. It is one of the hormones that is stimulated by ACTH.
What are the internal and external factors that alter release of CRH?
fever, hypoglycemia, and stressors.
What are the two Gonadotropins?
FSH (follicle-stimulating hormone)
LH (luteinizing hormone)
What are the FSH and LH secreted by?
They are both secreted by gonadotropic cells of anterior pituitary gland.
What does FSH stimulate?
FSH stimulates production of gametes (egg or sperm)
What does LH promote?
LH promotes the production of gonadal hormones
In females, what does the LH do?
LH helps mature the follicles of the egg, triggers ovulation, and releases estrogen and progesterone.
Follicle-stimulating hormone does production of gamet,
Luteinizing hormone is going to mature the follicles of the egg cell.
Remember that the follicle-stimulating hormone does not go with the maturation of follicles.
In males, what does the LH stimulate?
LH stimulates the production of testosterone.
so in general, what does the LH and FSH deal with?
So LH really deals with our sex hormones.
FSH deals with the production of gametes.
What is the Prolactin secreted by?
By prolactin cells of anterior pituitary gland
What does Prolactin stimulate in females?
Stimulates milk production
What does Prolactin stimulate in males?
Role in males not well understood but it is present.
What is the Prolactin regulation primarily controlled by?
The regulation is primarily controlled by the prolactin-inhibiting hormone (PIH), which is dopamine.
How does the PIH (Prolactin-inhibiting hormone, also called dopamine, prevent the release of Prolactin?
PIH or dopamine prevents the release of Prolactin until needed, with decreased levels leading to lactation.
means that dopamine acts as a natural brake on prolactin secretion, keeping it low until lactation is required.
What stimulates Prolactin (PRL)?
Increased estrogen levels
What is the reason behind breast swelling and tenderness during menstrual (생리) cycle?
It is due to increased estrogen levels, which stimulate prolactin.
What happens to the blood level toward the end of pregnancy?
Blood levels rise toward the end of pregnancy and thus increase in prolactin.
What is the interesting fact that stimulates Prolactin release?
Suckling stimulates prolactin release and promotes continued milk production.
What stimulates Prolactin?
Increased estrogen levels
Check slide 23
What is coming out from posterior pituitary gland?
Oxytocin and ADH
What is coming out from anterior pituitary gland?
All the hormones in slide 23
Where does the Adrenocorticotropic hormone (ACTH) go?
Adrenal gland
Where does the Thyroid Stimulating hormone go?
thyroid
Where does the Follicle Stimulating Hormone (FSH) go?
Testes or ovaries
Where does the Prolactin go?
Mammary glands
Where does the Growth Hormone go?
Bones and muscles
Also liver. It deals with the fatty acids in our bloodstream.
Technically, is Posterior Pituitary a separate organ?
Technically, it is not a separate organ.
If the Posterior Pituitary is technically not a separate organ, then what is it?
It is an extension of the hypothalamus.
It is still part of the brain.
What two hormones does the Posterior Pituitary gland secrete?
Oxytocin and ADH
Oxytocin and ADH are only secreted by the Posterior Pituitary. Then where are these two hormones produced?
The hormones are produced in the Hypothalamus.
So, in simple words, what does the posterior pituitary do?
It is a storage facility for the hypothalamus to store Oxytocin and ADH.
What is the Oxytocin a strong stimulant of?
They are a strong stimulant of uterine (자궁의) contractions during childbirth.
oxytocin plays a critical role in labor by causing the uterus to contract strongly and rhythmically, helping push the baby out.
What does Oxytocin also acts as?
Oxytocin also acts as a hormonal trigger for milk ejection.
What feedback mechanisms are the uterine contractions and milk ejection?
Positive feedback mechanism
Mott about the positive feedback loops of Oxytocin.
As one contraction happens, it’s going to increase the strength and rate of contraction, and we have this positive feedback loop.
As a child consumes breast milk, it is going to uptake more and more prolactin to cause an increase in relation.
Both of them via oxytocin
What does the Oxytocin also act as in the brain?
Oxytocin acts as a neurotransmitter in the brain.
Outside of pregnancy, what do we use oxytocin for?
We use a secondary messenger in the nervous system. Oxytocin deals with positive touch emotions.
Ex, when we get massage or a hug, why do we feel good?
So, to conclude, what three things deal with Oxytocin?
Childbirth
Milk Production
Positive touch emotion
Related to the ADH, the hypothalamus contains osmoreceptors that does what?
Monitor solute concentrations
If solute (K, Sodium, Calcium) concentration is too high, what happens? Related to ADH
Posterior Pituitary Gland is triggered to secrete ADH.
When the solute concentration is too high and posterior pituitary is triggered to secrete ADH, where does it target and what does it do?
Targets kidney tubules to reabsorb more water to inhibit or precent urine formation.
What also inhibits the ADH? Hint: pill
Diuretics (이뇨제)
Why do we pee more when we consume alcohol?
It is not because we are consuming liquid, it is because alcohol suck off the ADH or inhibits ADH.
Therefore, there’s nothing saying don’t produce more urine.
What is the release of ADH also triggered by?
Also triggered by pain, low blood pressure, and drugs.
What does the high solute concentration also cause?
High concentrations cause vasoconstriction, also called vasopressin.
So, ADH does long-term maintenance of our blood pressure to lower our blood pressure.
Check Slides 27, 28
What is Adrenal Axis?
It is the system that is controlling cortisol
What does Hypothalamus release in the Adrenal Axis?
Releases corticotropin-releasing hormone mostly in the morning.
After the hypothalamus releases corticotropin-releasing hormone, where does it go, and what is released from that area? (Adrenal Axis)
It goes down to the anterior pituitary gland and releases ACTH.
After the anterior pituitary gland releases ACTH, where does it go, and what does it release?
(Adrenal Axis)
That then goes to the Adrenal Gland and releases cortisol into the body.
What can the Adrenal Axis be overridden by?
By Stress
Adrenal Axis diagram (Slide 31)
The hypothalamus releases the corticotropin-releasing hormone (CRH). It goes down to the Anterior Pituitary gland and releases ACTH and goes to the Adrenal gland to release cortisol.
This should cause an increase in blood glucose, Sodium retention, Potassium excretion, and suppression of the immune system.
Upregulation should come back up and tell the hypothalamus that cortisol has been released, so stop telling us to release more.
However, if stress comes along, stress is going to be like, actually, I need some of this glucose, I need some of this energy right now to be alert. So stress is going to say I’m taking over, ignore what’s happening, and keep pumping out cortisol.
What does the Thyroid Axis do?
Does production of Thyroid hormones
what does the Hypothalamus produce in the Thyroid Axis?
Thyroid releasing hormone
After the Hypothalamus produces Thyroid Releasing hormone, where does it go to, and what does it release?
Anterior pituitary and release Thyroid Stimulating hormone.
After the Anterior pituitary gland release Thyroid Stimulating Hormone, where does it go and what does it release?
Goes to Thyroid and produce T3 and T4.
What causes the Thyroid to produce T3 and T4?
Thyroid is going to produce T3 and T4 when it has higher levels of TSH (Thyroid Stimulating Hormone).
What goes back and inhibits Thyroid Stimulating Hormone and Thyroid Releasing Hormone?
(Thyroid Axis)
T3 is the major hormone that goes back and inhibits TSH and TRH.
What is T3?
T3 is active form of thyroid hormone.
What does the Hypothalamus release in the Gonadal Axis?
Gonad Releasing Hormone. (GnRH)
After the Hypothalamus releases the Gonad-releasing hormone (GnRH), where does it go, and what does it produce?
Anterior Pituitary and Produces Luteinizing Hormone and Follicle Stimulating Hormone.
What does Follicle Stimualting Hormone do? (Gonadal Axis)
FSH stimulates ovarian development and spermatogenesis.
What do Luteinizing Hormones do? (Gonadal Axis)
LH induces (유도) ovulation and stimulates the ovary to produce estrogen and progesterone. It also induces testosterone production.
Ovulation is a phase in the menstrual cycle where your ovary releases an egg (ovum).
What produces inhibin and where does it work?
Inhibin is produced by gonads to work in a feedback loop.
What does inhibin do in the Gonadal Axis?
Inhibin is going to inhibit.
Inhibin is produced by the Gonads in the production of either estrogen or testosterone.
Inhibin comes back up and says stop producing estrogen or testosterone. We are at the blood level that we need; stop producing.
What does the Hypothalamus release in the Growth Hormone Axis?
The hypothalamus releases Growth Hormone Releasing Hormone.
This is the positive influence, increase.
After the Hypothalamus releases GHRH in the positive influence, where does it go, and what does it release? (Growth Hormone Axis)
Anterior pituitary gland releases growth hormone.
After the Anterior pituitary gland releases growth hormone in the positive influence, what happens next?
Increases the expression of insulin-like growth factor.
Insulin-like growth factor is the thing that says things are good. We’ve done what we needed to do, shut back off.
When it comes to inhibition in the Growth Hormone Axis, what does the Hypothalamus release?
Hypothalamus releases somatostatin.
After the Hypothalamus release somatostatin in the inhibition of the Growth Hormone Axis, what happens after?
Anterior pituitary is inhibited.
What is so special about the Growth Hormone Axis? Slide 35
So we start at the top. The hypothalamus is going to release Growth Hormone Releasing hormone which stimulates the anterior pituitary to release Growth Hormone by release of GHRH and Release of GHIH or Somatostatin at the same time.
Stop releasing growth hormone releasing hormone and release growth hormone inhibiting hormone at the same time.
