Exam 1 -- Pt2 Intro to Endocrinology Flashcards
What is known at “the master gland”
pituitary gland
What are the two distinct parts of the pituitary gland and what are they derived from?
- Anterior (adenohypophysis)–glandular, derived from mesoderm
- Posterior (neurophypophysis)–neural, derived from ectoderm
What does the adenohypophysis originate from and what does it do?
(=anterior pituitary gland)
the Rathke’s pouch (pharyngeal epithelium)
synthesizes and releases 6 major peptide hormones
What does the neurohypophysis originate from and what does it do?
(=post. pituitary gland)
is a neural tissue outgrowth from the hypothalamus
stores and secretes 2 hormones that are synthesized in the hypothalamus
What is the pars intermedia and what does it do?
boundary b/w the ante. and post. lobes of the pituitary
synthesizes and secretes melanocyte stimulating hormone (MSH)
Where does the Pituitary gland lay?
in the sella turcica of the sphenoid bone
What gland does the hypothalamus control almost all secretion of?
almost all pituitary secretion, either hormonally (ant. pit.) or neurally (post. pit.)
What secretions form the hypothalamus controls the secretion of the anterior pituitary gland?
hypothalamic releasing and inhibitory hormones (neuropeptides)
How do the hormones from the hypothalamus reach the anterior pituitary?
via the Hypothalamic-hypophyseal portal system (HHPS) –> hypothalamus has specialized neurons that secrete releasing and inhibitory hormones (neuropeptides) into median eminence –> then picked up an delivered to Ant. Pit. by HHPS
What are the Hypothalamic peptides (hormones)?
- Thyrotropin-releasing hormone (TRH)
- Corticotropic-releasing hormone (CRH)
- Growth hormone-releasing hormone (GHRH)
- Gonadotropin-releasing hormone (GnRH)
- Prolactin inhibitory hormone (PIH)*
- Thyrotropin-releasing hormone (TRH)
- Growth hormone inhibitory hormone
- Ghrelin
What does Thyrotropin-releasing hormone (TRH) stimulate?
thyroid stimulating hormone (TSH)
What does Corticotropic-releasing hormone (CRH) stimulate?
Adrenocorticotropic hormone (ACTH)
What two hormones stimulate Growth Hormone (GH)?
Growth hormone-releasing hormone (GHRH) and Ghrelin
What inhibits Growth Hormone?
Growth Hormone inhibitory hormone (aka somatostatin)
What does Gonadotropic-releasing hromone (GnRH) stimulate?
BOTH leutinizing hormone (LH) and Follicle-stimulating hormone (FSH)
Which is the only hypothalamic peptide (hormone) that is under ONLY inhibition?
Prolactin inhibitory hormone (PIH)–dopamine, which inhibits prolactin
If you transplanted the pituitary to a distant site of the body, what would happen to secretion rates of the anterior pituitary hormones—which hormones would be increased?
prolactin (b/c the inhibition of it isn’t reached as easily)
If you transplanted the pituitary to a distant site of the body, what would happen to secretion rates of the anterior pituitary hormones—which hormones would be decreased?
ones that have stimulatory effect
If you transplanted the pituitary to a distant site of the body, what would happen to secretion rates of the anterior pituitary hormones—which hormones would bu unchanged?
Growth hormone b/c it is controlled by both stimulation and inhibitory activity
What are the 6 hormones produced and released by the Anterior Pituitary gland?
- GH (aka somatotropin)
- TSH
- Adenocorticotropic hormone (ACTH)
- Prolactin
- FSH
- LH
What two hormones are released by the posterior pituitary gland?
- Antidiuretic hormone (ADH) also called vasopressin
- oxytocin
(both produced in hypothalamus)
What is the single most important hormone to normal growth to adult stature?
Growth Hormone (Somatotropin)– secreted throughout life by Ant. Pit.
What does the growth hormone stimulate?
- protein synthesis
- cell multiplication
- cell differentiation
T/F. Growth hormone exerts its effect only indirectly, just like all other AP hormones do.
False. GH exerts its effects directly OR indirectly (yes, all other AP hormone act indirectly, by stimulating target glands)
What synthesizes growth hormone? About how many cells of AP do this?
Somatotropes; 30-40% of AP cells
acidophilic
What metabolic effects does GH have?
- increases rate of protein synthesis
- decreases catabolism of amino acids and proteins
- enhances fat utilization for energy (E)
- decreases CHO utilization (carbs)
By the GH decreasing catabolism of A.A.s and proteins, how are proteins spared probably?
by increasing FA and therefore spare protein for energy (E) use
What does the GH do with fatty acids, where are they moved to/from
- increases mobilization of FA from adipose tissue
- increases FFA in blood
- increases use of FA for energy
T/F. Growth hormone with decrease use of FA for energy and will incrase rate of glucose/carbs (CHO) utilization?
False!! GH with INCREASE use of FA, and with DECREASE use of glucose/carbs
What occurs if there is GH in excess? What organ is involved?
there will be a ketogenic effect of the excess GH; acetoacaetic acid formation by liver (fatty liver)
What occurs as GH decreases CHO (carb) utilization?
- decreases glucose uptake in tissues (fat and skeletal muscle)
- increases glucose production by liver (help maintain blood glucose)
- increase insulin secretion
What hormones help to maintain blood glucose levels by increasing them?
- GH
- cortisol
- glucagon
- epinephrine
T/F. By GH decreasing use of CHO (carbs), and therefore decreasing glucose uptake into tissues, increasing glucose made by liver, and increasing insulin, will induce “insulin resistance”.
True
- GH attenuates (reduces effect of) of insulin
- GH may have anti-insulin activity
What is Metabolic Syndrome? What occurs?
(a cluster of conditions that occur together, increasing your risk of heart disease, stroke and type 2 diabetes)
- insulin resistance
- hypertension
- cholesterol abnorms
- increase clotting risk
- inflammation
What is an example of GH having a direct effect? What about an indirect effect?
Direct– on fat (to use it up)
Indirect– stimulates liver to release IGF-1 and increase bone size
(IGF-1 = insluin-like growth factor-1)
What effect does Ghrelin have on GH?
stimulates GH
main source from gut
What effect does somatostatin (SS) released from the hypothalamus have of GH?
inhibitory effect
What effect does IGF-1 released by the liver have on GH?
inhibitory effect
What does GHRH have on GH? What is GHRH released by?
stimulatory effect; GHRH is released by hypothalamus
GHRH = growth-hormone releasing hormone
What is GH most obvious effect on the body? How does it accomplish this?
to increase growth of skeletal frame (stimulate cartilage and bone growth)
- done indirectly by somatomedins, like IGF-1 released by liver
At a cellular level, what type of mechanisms take place as GH indirectly stimulates growth of skeletal frame?
- increase deposition of protein by chondrocytic and osteogenic cells
- increase mitosis of these cells
- converts chondrocytes to osteogenic cells
What occurs in long bones under simulation by GH?
- grow in length
- deposit cartilage at epiphysis and gets converted to new bone (elongates shaft_
- epiphyseal cartilage will be used up and eventually limits elongation of long bones
What occurs in the bone periosteum when stimulated by GH?
osteoblasts deposit new bone on surface of old bone
- and at same time osteoclasts remove all bone
If the rate of deposition is greater than rate of resorption what occurs? What disorder can this cause?
thickeness of bone increases and Acromegaly can result
What are somatomedins? What is an example of one? Why is this important to GH?
small proteins produced primarily by liver; like insulin-like growth factors (IGF-1); how GH exerts much of its effects on increase in bone size
What is the most important somatomedins? What effect does it have on GH? What group of people lack this?
somatomedin C (IGF-1)
- prolongs effects of GH (x60)
- Pymies of Africa–therefore adults rarely exceed 4’11’’
Overall, list some things that stimulate GH secretion.
- decrease blood glucose
- decrease FFA
- increase arginine
- starvation/fasting
- trauma/stress/excitement
- exercise
- testosterone/estorgen
- Deep sleep (stage III,IV Non-REM)***
- GHRH*
- Ghrelin*
Overall, list some things that inhibit GH secretion.
- increase blood glucose
- increase blood FFA
- aging
- obesity
- somatostatin
- exogenous GH
- somatomedins (like IGF-1)
How is the regulation of GH secretion controlled?
- hypothalamus
- Ghrelin from gut
How does the hypothalamus control the secretion of GH?
- GHRH stimulates GH
- somatostatin inhibits GH
How does Ghrelin have an effect on GH secretion?
released primarily by GI tract
- cells in AP have “growth hormone secretagoue receptor” (GHS-R) that when activate release GH
- Ghrelin –> stimulates hunger and promotes feeding behavior
What type of pattern is GH secreted in?
pulsatile pattern; burst ~ every 2 hrs
What time does the largest burst of GH occur?*
largest burst of GH occurs within 1 hour of onset of sleep
- during NREM stage III and IV
Desribe the secretion stages GH has throughout life.
- Birth to childhood–> increases steadily
- During childhood/puberty –> stable
- During puberty –> largest burst
- After puberty and with increase age –> gradually decreases
- Old age (senescence) –> secretion rates and pulsatility decrease to lowest levels
During puberty, GH is induced by what?
- in females –> estorogen
- in males –> testosterone
- ass. with “growth spurt”
What occurs if there is a deficiency of GH in children?
- failure to grow, short stature
- mild obesity
- delayed puberty
- could be due to defects at any level in hypothalamus
What occurs in children that have excess GH?
gigantism
recall: this is before puberty
What occurs in adults with increase GH?
Acromegaly
recall: this is after puberty
How is excess GH treated?
with somatotatin analogs, like octreotide
T/F. Overall, GH enhances body protein, uses up fat stores, and conserves carbs.
True
What do these abbreviations mean:
- TSH
- FSH
- LH
- HCG
- Thyroid stimulating hormone
- Follicle stimulating hormone
- Luteinizing hormone
- Human chorionic gonadotropin (placenta)
What do TSH, FSH, LH, and HCG all have in common?
- two noncovalently linked subunits (alpha and beta)
- alpha = identical in all
- beta = unique to each
What are two other names for Thyroid Stimulating Hormone?
Thyrotropic and Glycoprotein
What secretes TSH?
thyrotropes cells; ~5% all AP cells
What type of effect does TSH have? (4)
- increase proteolysis of stored thyroglobulin
- increase activity of iodine pump
- increase iodination of tyrosine
- increase size, number, and secretory activity of thyroid cells
The increase protelysis of stored thyroglobulin, by TSH, causes release of what?
T3 and T4 within 30 minutes
thyroglobulin = precursor for T3 and T4
As TSH increase activity of iodide pump, what occurs?
increase iodine trapping in glandular cells (can develop goiter)
As TSH increases iodination of tyrosine, the formation of what is increased?
increase formation of T3 and T4
What mechanism does TSH utilize?
adenylyl cylcase- cAMP mechanism
What inhibits TSH? (2)
- T3 and 4
- SNS
What stimulates TSH?
- TRH (Thyroid release hormone)
- cold
How are the effects of the TSH mediated?
hypothalamus
What does ACTH stand for?
Adrenocorticotropic hormone
What does ACTH stimulate secretion of? via what mechanism?
- cortisol and adrenal androgens from the adrenal cortex
via adenylyl cyclase-cAMP mechanism
Recall: What does the adrenal cortex release? What does the adrenal medualla release? Where are they derived from?
cortex–> cortisol and adrenal androgens; mesoderm
medulla –> NE/Epi; ectoderm
What secretes ACTH (adrenocorticotropic hormone)?
corticotropes cells in AP
What stimulates ACTH (adrenocorticotropic hormone)?
- hypothalamic Corticotropin releasing hormone (CRH)
- any physical or mental stress (i.e. pain)
What inhibits ACTH (adrenocorticotropic hormone)? What type of feedback loop is this?
cortisol, at level of pituitary and hypothalamus; negative feedback loop
What is ACTH (adrenocorticotropic hormone) also synthesized and secreted with?
- MSH (melanocyte-szltimulating hormone)
- Lipoptropic
- Endorphin
(POMC family = Pro-opiomelanocortin)
What do lactotropes cells synthesize?
Prolactin
What effect does hypothalamic dopamine have on prolactin?
aka prolactin inhibitory hormone; therefore inhibits prolactin
What does prolactin stimulate?
milk secretion and production
What does prolactin inhibit?
ovulation; inhibits synthesis and release of GnRH (gonadotropin releasing hormone)
When prolactin is in excess, what are three effects?
- destruction of hypothalamus or prolactinomas
- Galactorrhea (persistent secretion of milk)
- infertility (inhibition of GnRH)
T/F. Prolactin depresses aspects of immune response.
False, prolactin ENHANCES aspects of immune response
What do gonadotropic cells release?
FSH and LH (In AP)
FSH and LH is a glycoprotein with two subunits. What are those subunits and are they similar?
alpha – identical in both
beta – unique
What hormone causes ovulation?
LH
What are the combined functions of FSH and LH? (4)
- stimulate development of ovarian follicles
- regulates spermatogenesis in testes
- causes ovulation (LH) and formation of corpus luteum
- stimulates production of estrogen/progesterone in female and testosterone in males
What mechanism does FSH and LH function by?
adenyly cyclase- cAMP mechanism (recall it is 2nd MC messenger system)
Describe the complexes Activin and Inhibin.
closely related protein complexes with opposite effects
- both belong to TGF-beta protein superfamily
Where are the dimers, Activin and Inhibin produced?
gonads, pituitary, placenta, and other organs
Activin is ____ subunits
Inhibin is ____ subunits
Activin – is two beta subunits
Inhibin – is one beta and one alpha subunit
What does Activin have an effect on?
it enhances FSH synthesis and secretion
What does Inhibin have an effect on?
it inhibits FSH synthesis and secretion
What helps regulated the menstrual cycle and has a role in cell proliferation, apoptosis, metabolism, homeostasis, immune response, and wound repair?
Activin –> which enhances FSH synthesis and secretion
How man hormones does the posterior pituitary gland secrete? Which ones?
two:
- ADH (antidiuretic hormone) aka vasopressin
- Oxytocin
What nuclei is the primary source of ADH?
supraoptic nuclei
What nuclei is the primary source of oxytocin?
paraventricular nuclei
Both ADH and oxytocin are ______ synthesized in _________ and secreted from nerve terminals in the _____ ____.
neuropeptides; synthesized in hypothalamic neurons; secreted from posterior pituitary
T/F. Both the supraoptic and paraventricular nuclei can secrete both ADH and oxytocin.
True (the just secrete primarily one over the other)
T/F. ADH and oxytocin are made up of 9 amino acids of which 7 are identical.
true (they are very similar)
What does oxytocin produce and stimulate?
- produces milk “letdown” from lactating breast
- stimulates uterine contraction
Oxytocin stimulates uterine contraction when it is released in response to what? (2)
- dilation of cervix (parturition)
- orgasm
What is used to induce labor and reduce postpartum bleeding?
oxytocin
What inhibits oxytocin?
opioids (endorphins)
What effects does oxytocin have on the brain?
- relaxation, fearlessness, bonding, contentment
- activated daily by closeness and touch
What causes oxytocin to be released and therefore produce milk “letdown” form lactating breast?
- to suckling or conditioned responses (sight, sound, or smell of infant)
- stimulates contraction of myoepithelial cells lining milk ducts
What is know as the “trust hormone”
oxytocin
What produces melatonin?
the pineal gland (neural tissue)
What happens to melatonin as we age?
decreases
What type of sleep does melatonin enhance?
slow wave sleep
What controls cyclicity in seasonal breeders?
melatonin
What does melatonin have to do with the circadian cycle?
it is released during it; and peaks during dark phase (middle of night)
T/F. Melatonin enhances immune function and is a potent antioxidant.
True– protects against free radical damage
T/F. Melatonin may increase risk of cancer and heart disease.
False, it reduces the risk, silly!
T/F. Melatonin has no known toxicity.
true :)
What 5 important hormones does the liver synthesize and secrete?
- insulin-like growth factor-1 (IGF-1)
- Angiotensinogen
- Thrombopoietin
- Hepcidin
- Betatrophin
What hormone does IGF-1 secreted from the liver mediate the effects of?
of growth hormone
What is IGF-1 also called?
IGF-1 = insulin-like growth factor -1
aka somatomedin C
What is angiotensinogen a precursor for? Where is it sythesized and secreted from?
angiotensin I and II
liver
Where is Thrombopoietin produced besides the liver? What does it stimulate?
kidney
stimulates production of platelets
What is the key regulator of entry of iron into cells? Where is is synthesized and produced?
Hepcidin
liver
Where is betatrophin also produced besides the liver? What does it promote?
adipose tissue
promotes pancreatic beta cell proliferation (therefore enhances insulin production)
How does damage to the liver effect steroid hormone levels?
decreases steroid hormone levels, b/c steroid hormones are conjugated mainly by the liver and excreted in the bile
What is the major way steroid hormones are removed?
by the liver; they are conjugated there and excreted in bile
What stimulatory modulation does the NS have on the endocrine system?
humoral, hormonal, and neural
What inhibitory modulation does the NS have on the endocrine system?
feedback inhibition
Can subluxations/ nerve interference have detrimental effect on hormones?
yes, because NS gives added dimension of control/safeguard to endocrine system
What is the MC cause of death and disability in young people?
Traumatic brain injury (TBI)
What gland suffers dysfunction following a TBI (Traumatic Brain Injury)?
pituitary; due to placement in sella tucica of sphenoid bone
What percentage of TBI’s cause pituitary dysfunction?
25-40% (common and it is poorly recognized)
Pituitary dysfunction due to a TBI will most commonly cause a deficiency in what hormones?
GH and FSH/LH
What is a GH deficiency associated with?
inability to concentrate, memory problems, anxiety, and fatigue
What is an LH/FSH deficiency associated with?
hypogonadism (b/c gonads are not properly stimulated)
Pituitary dysfunction due to a TBI can cause what disorder?
Central diabetes insipidus–> which is a lack of ADH (aka vasopressin)
