Week 6 - Study Guide - Part 2 Flashcards
The pea-sized Pituitary is AKA?
Hypophysis
Where is the pituitary gland located?
Underneath the brain
Hypophysis
hypo - below
-physis - physically connected to the hypothalamus
The pituitary gland (hypophysis) is split into two lobes called -
- Anterior pituitary (Adenohypohysis
- Posterior pituitary (Neurohypophysis
How many hormones total does the Pituitary gland produce?
Total = 9 hormones
Anterior = 7
Posterior = 2
Which lobe of the pituitary is considered a true endocrine gland?
the Anterior Pituitary Gland (adenohypophysis)
Produces 7 hormones
It is glandular tissue - meaning -
it makes its own hormones - so it is a true endocrine gland
Posterior Pituitary has 2 hormones and produces them where?
- Oxytocin & ADH
- Hormones produced in hypothalamus and transported via a nerve cell to the pituitary gland
- is physically connected to the anterior region called the Neurophysis.
Hypothalamus is not only important in the nervous system but also in what other system?
Endocrine system
Where is Pro-opiomelanocortin (POMC) (the Prohormone) made?
POMC is a large precursor molecule of the anterior pituitary
Can be converted into other hormones
POMC can be broken into 3 other new products:
- ACTH - AdrenoCorticTropic Hormone
(hormone that travels to the adrenal cortex gland) - Two natural opiates (painkillers) - enkephaline & beta-endorphin
- Melanocyte-Stimulating Hormone (MSH)
Anterior Pituitary Hormones have how many distinct hormones?
7 distinct
2 are prohormone
4 are tropic
Prolactin & Growth Hormone are neither
Name the prohormones
(causes secretion of something else)
- ACTH - AdrenoCorticoTropic Hormone
- MSH - Melanocyte stimulating hormone
Name the tropic hormones
(gets released and goes to target cell)
(affects activity of other endocrine glands)
- TSH - Thyroid-Stimulating Hormone (or thyrotropin)
- ACTH - AdrenoCorticoTropic Hormone
- FSH - Follicle-Stimulating Hormone
- LH - Luteinizing Hormone
Which Anterior Pituitary hormone is both tropic and prohormone origin?
ACTH - AdrenoCorticoTropic Hormone
Name the other two hormones of the Anterior pituitary that are neither prohormone or tropic
- GH - Growth Hormone
- PRL - PRoLactin
Characteristics of Anterior Pituitary Hormones —
(surface receptor)
- All have 2nd messenger system
- tropic hormones
- prohormones
- Protein-based (Amino acid based)
- Regulated by releasing or inhibiting factors
- Hypothalamus is the true master gland - the puppeteer- pulling the strings for the release of all these hormones from the anterior pituitary
What is the Goldi Locks rule in Endocrine (Health & Disease)?
- too much hormone = disease
- just right hormone = health
- too little hormone = disease
Hypothalamus hormones travel through a delivery system to the anterior pituitary in a circulatory organization known as the
Portal System
Why the Portal System?
Negative feedback allows control
SHORTCUT. - pathway of less travel
- The hypothalamus produces - releasing hormones-
- will descend into the portal circuit
- released into the capillary bed in the portal circuit
- and travel down in this portal system
- to the anterior pituitary
- in that pituitary there is a 2nd capillary bed
LONG WAY
If you did not have this short cut - you would need to release a hormone from the hypothalamus
1. it would go back to your heart
2. out to lungs
3. back to heart
4. up to brain
5. and find its way to the anterior pituitary
Two other names for Anterior Pituitary Gland
- Adenohypohysis
- glandular undergrowth
Growth Hormone is released by
Anterior Pituitary
Growth hormone gets released and causes stimulation of…
- bone and muscle growth (mostly)
- and most cells.
ROLE - Hypothalamus secretes a releasing hormone
- GHRH - Growth Hormone Releasing Hormone
- GHIH - somatostatin (inhibitory)
The releasing hormone (GHRH) is important because to tells the anterior pituitary to ….
- To release Growth Hormone
- which causes stimulation of bone growth and muscle growth
How does Growth Hormone (GH) cause stimulation of growth?
It is going to stimulate protein synthesis and fat mobilization
Why Protein Synthesis?
Protein synthesis is about building and increasing structures
Why Fat Mobilization
If you are growing - how expensive is that?
Going to need energy and resources to drive the growing functions
What are the two pathways that GH growth hormones act on?
- Indirect
(Growth promoting side)
(Growth side) - Direct
(Metabolic in Nature)
(Anti-insulin)
(Energetic Side)
What is the indirect pathway of GH?
- It goes to the liver and other tissues
- Causes the release of insulin-like growth factors (IGFs)
Think about what insulin does -
1. hormone causes uptake of nutrients in the cells.
2. Helps put sugar into the cells
Why would you do that?
~SKELETAL:
If you are stimulating skeletal structures to grow and develop - they will need nutrients.
~It will allow the formation of cartilage and skeletal growth
~EXTRASKELETAL
~Increased protein synthesis, cell growth, and proliferation
Most of what the GH does is about those insulin-like growth factors (IGFs).
Hoping to make muscle grow bigger and stronger.
Helping the skeletal system grow as well.
What is the Direct pathway of GH?
- Going to need Fat mobilization
- Break it down out of the fat stores
- and release it into the bloodstream
- Break down CHO
- Release into the bloodstream
Why is it Anti-insulin?
~insulin is about storing nutrients
~Anti-insulin is about RELEASING nutrients (Keeping blood sugar high)
SO- the insulin-like growth factors (IGFs) are going to cause the tissues to take up these nutrients so the tissue can grow
Anti-insulin effect is moving storage of nutrients out of the fat/CHO store and delivers to other tissues to be able to undergo growth and development
Insulin and anti-insulin
relationship with sugar
Insulin - helps put sugar into the cell
Anti-insulin - helps keep blood sugar high
What is secreted that inhibits GH?
GHIH - Somatostatin
Hypersecretion of Growth Hormone (GH) in children
Gigantism
Epiphyseal plates open
~Lengthwise growth - interstitial bone growth
Possible to also experience Acromegaly in adulthood
(Andre the Giant - Princess Bride)
Possibility of losing peripheral vision due to tumor pinching and damaging the optic nerve at the optic chiasm
Hypersecretion of Growth Hormone (GH) in Adults
Acromegaly
~Bones get thicker - Appositional growth
~Big head
~Big Hands
Hyposecretion of Growth Hormone (GH) in children
Pituitary Dwarfism
Epiphyseal plates are open but no growth because there is a low secretion of growth hormone.
Just small - no other deficits
Hyposecretion of Growth Hormone (GH) in Adults
Simmond’s Disease
~wasting disease
~lack of muscle mass
~bones starting to break down
~rapid aging (no mitosis of the cells)
Why is gigantism often associated with loss of peripheral vision?
(tunnel vision)
- A tumor associated with the pituitary gland (near Turkish saddle)
- Tumor can grow and grow
- Pinch and damage the optic nerve at the Optic Chiasm.
So they not only suffer from hormone problems but also the possibility of vision problems
Thyroid-Stimulating Hormone (TSH) is coming from …
- Anterior Pituitary
- Travels through the blood
- to the thyroid gland in the neck
If it is a releasing hormone, we are talking about it coming from where?
hypothalamus
The regulation of the release of Thyrotropin (TSH) is coming from?
the hypothalamus
Thyrotropin (TSH) stimulates the normal development and secretory of the
thyroid
Thyroid Releasing Factor …
- Hypothalamus sends out THR (thyrotropin-releasing hormone)
- TRH travels to the anterior pituitary
- causes the release of TSH (Thyroid-stimulating hormone aka thyrotropin)
- which will go out to the thyroid gland
- causing the release of thyroid hormones (T3 & T4) to target cells
- to stimulate or inhibit
- When there is adequate amount of TSH - don’t need more - negative feedback gets involved -
Regulation of TSH (Thyroid-stimulating hormone) release -
stimulation
inhibition
Stimulation = TRH (thyrotropin Releasing hormone) (Thyroid hormone)
Inhibition = thyroid hormones (T3, T4)
2 impacts
What hormone causes the release of corticosteroids in the adrenal cortex?
ACTH
Adrenocorticotropic Hormone
comes from the cortex of the adrenal gland
steroid-based hormone
ACTH (Adrenocorticotropic hormone is AKA ?
Corticotropin
Regulation of ACTH (adrenocorticotropic hormone) release -
Hypothalamus releases a releasing hormone called (CRH) corticotropin hormone) in a daily rhythm
Also for fever, hypoglycemia, stress, F/F
to a portal system
Causes release of get up and go
deal with stress
get up in the morning
Two hormones from the anterior pituitary gland that stimulate the reproductive organs…
- FSH - Follicle stimulating hormone
- LH Luteinizing
FSH stimulates…
gamete production
(egg or sperm)
testosterone
estrogen
LH stimulates different things depending in gender…
Women -
1. Ovulation - release of an egg
2. formation of a new hormone secretory structure called the CORPUS LUTEUM (produces ovarian cycle)
Men -
1. Sperm Production
Progesterone
Both absent in prepuberty
Regulation of Gonadotropin Release …
- Hypothalamus releases (GnRH) Gonadotropin-Releasing Hormone
- To the Anterior pituitary
which releases FSH and LH. - two pathways depending on gender
- Testes - Testoreone
- Ovaries - Estrogen and Progesterone
Does have negative feedback
Prolactin (PRL) comes from the
Anterior Pituitary gland
PRL - Prolactin stimulates
Milk production
What stimulates the release of PRL - prolactin?
suckling of the baby stimulates the release of PRL - prolactin which helps maintain milk production
If men have Hypersecretion of PRL…
reduced sexual drive
infertility
low testosterone
erectile dysfunction
If men have Hyposecretion of PRL…
sexual disorders
psychological fluctuations
Hormonal regulation of PRL via hypothalamus…
Prolactin release - enhancement of those from the estrogen levels
Hypothalamus
Dopamine inhibitory hormone
Stimulatory factors and enhancement from estrogen get the pituitary to release Prolactin (PRL)
Melanocyte Stimulating Hormone (MSH) released from
Anterior Pituitary Gland
Jobs of the Melanocyte Stimulating Hormone (MSH)
- Stimulates the melanocytes to produce and deposit melanin in the skin.
- hormonal control of energy balance (appetite control)
ACTS as CNS NT involved in Appetite Control
For skin pigmentation and protection from UV
Tissues and hormones being produced. that help regulate when and how we intake food - when hungry, when full
Posterior pituitary AKA
- Neurohypophysis
- Neural undergrowth
AND -
are amino acid-based
rely on 2nd messenger systems
Posterior pituitary has relationship with neurons that produce these two hormones in the hypothalamus and are stored in the axon terminals that extend into the pituitary
- ADH (antidiuretic hormone)
- Oxytocin
How are ADH and Oxytocin made, stored, and released
- Hormones are made by the cell bodies of neurons in the hypothalamus
- Hormones sent down the axon to the axon terminals in the posterior pituitary
When a stimulus comes in:
3. nervous signal stimulates the release (not chemical) of the hormone that comes from the posterior pituitary
4. gets to the axon terminal
5. causes the hormones to be released into the blood stream
6. Relies on a 2nd messenger system
Interconnectin between nervous system action and endocrine action.
Two Posterior pituitary hormones to know
- ADH - Antidiuretic hormone (aka vasopressin)
- Oxytocin
Another name for ADH - Antidiuretic Hormone
Vasopressin
When is ADH really important?
When we start to become dehydrated
Homeostasis mechanism of ADH
- Initial stimulus - dehydration - loss of water
Solute levels in the body fluids is too high and there is not sufficient body water.
Which tends to mean that you also have blood pressure that is falling - Hypothalamus stimulates the posterior pituitary gland to secrete ADH
- causing vasopressin (vasoconstriction) out in the periphery - helping to push blood away from the periphery to the core.
- ADH travels from the posterior pituitary–> through the bloodstream –> to the kidney
- At the kidney - reaches the nephron - which helps retain water
Meaning - the kidneys filter blood, create urine, retain water instead of peeing it out and put it back into the bloodstream - Resulting in blood volume and blood pressure to increase because you. are holding onto more water
- And because of the vasoconstriction - it allows the body to continue to have more blood supply
- So - instead of being too dehydrated - you start to come back to a more normal concentration
- Receptros in hypothalamus detect this increase in blood volume
- signal for ADH secretion to slow down
What measures the blood solute?
Hypothalamus
What is the function of ADH (antidiuretic hormone aka vasopressin)?
- increases water retention at kidneys
- Arteriole vasoconstriction
What condition can you develop due to Hyposecretion of ADH?
Diabetes Insipidus
Usually due to head trauma - concussion
Diuretic makes you
urinate more
Antidiuretic makes you
urinate less
Why are you urinating more in diabetes insipidus?
urinating more
becoming more dehydrated
- You are holding onto less water
- so more goes out in the urine
- leads to greater risk of dehydration
Symptoms of Diabetes insipidus include…
looks like diabetes mellitus
- Extra solutes - urinate out - reclaim solute - water goes with it
Glucose - Water - urine –> polyuria (a lot of urine)
Head trauma -
Too little ADH causes you to urinate more
Causing a greater risk of dehydration
Signal goes to the hypothalamus - so the cause starts there
What does Oxytocin (hormone of the posterior pituitary) do?
- stimulates uterine contractions during labor (positive feedback loop)
- triggers milk ejection (letdown reflex) during nursing
3.
Clinically you can use a synthetic form of oxytocin to help in both
- inducing labor
- stopping postpartum bleeding
When thinking of hormonal imbalances - think of these three imbalances:
- imbalance in production
- imbalance of removal
- imbalance in regulatory hormones
