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84 Cards in this Set

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Purpose of the Endocrine system
Maintain homeostasis
Major classes of hormones
AA derivatives-Tyr, Trp, His

Peptides-Composed of AA, most DIVERSE group.

Steroids-Derived from Choles., lipid soluble.
Peptide hormones are free in circulation, except for...
1.GH
2.IGF-1

Inc half-life, and limit hormone to specific targets.
Adenohypophysis
Originated from pharyngeal epithelium
Neurohypophysis
Originated from developing hypothal.

Post Pit.
Hormones of Ant Pit
ACTH-cortisol production
TSH-thyroid production
FSH-follicle development
LH-ovulation and sex sterios syn
PRL-prolactin stim
GH-stim body growth, reg metabolism
TSH - FSH - LH are all composed of and alpha and beta subunit, which subunit is unique?
Alpha subunits are identicle,
Beta subunits are different.
Do releasing hormones from hypothalamus get diluted in systemic circ?
No, RH are contained to the hypophyseal-portal system.
What stimulates and inhibits GH?
GHRH=stimulates
SS=inhibits
3 types of Feedback loops
Long-originates from peripheral source
Short-Ant Pit acting on hypothal
Ultra Short-hypothal acting on itself
Is GH required for normal fetal growth?
No, only important for youth and adolescent growth.
GH stimulates the expression of...
IGF-1
Potent mitogen and differentiation factor.
Resembles pro-insulin.
Liver is major source of circulating IGF-1.
steve chaney
Direct effect of IGF-1
Metabolic - Anti-insulin effects
Inc lipolysis
Inc blood glucose
Indirect effects of IGF-1
Growth - Acting on Liver/peripheral tissues
Inc Chondrogenesis
Inc protein syn
Inc cell proliferation
Indirect effects of IGF-1
Growth - Acting on Liver/peripheral tissues
Inc Chondrogenesis
Inc protein syn
Inc cell proliferation
What are some positive effects of GH supplements in aging people?
Inc lean muscle
Dec fat
Inc SV
Inc physical motility, vitality
Negative effects of GH supplements?
Dec in GH may help prevent onset of cancer.
GnRH from Hypothal release...
releases LH and FSH from Ant Pit
Which cells produce testosterone?
Leydig cells under the influence of LH.
Leydigs are located outside of the sem. tubules.
These cells form the blood-testis barrier.
Sertoli cells residing in the S.Ts.

Support spermatogenesis under the influ. of FSH.
3 functions of androgens
Regulation of hormones from Ant Pit and Hypothal.

Support spermatogenesis

Reg of sexual behavior.
Basic route of hormones males
LH onto Leydigs which produce testosterone

FSH on sertoli cells which support spermatogenesis, and use test for Leydigs as "nutrition" for growing sperm.
Consequences of testosterone in the periphery?
*Converted to DHT by 5 alpha reductase.

*Converted to estradiol by p450 aromatase.
3 characteristics of follicular phase of mens. cycle?
1.Estrogen dominate
2.growth/maturation of follicles
3.Endometrial proliferation
Ovulation occurs as a result of...
LH surge and temp spkie
Characteristics of Luteal/secretory phase of mens. cycle?
1.Progesterone dominated
2.Follicle is converted to C.L.
3.Endometrium develops secretory glands and vascularization.
T/F
Progression from primordial follicle to primary follicle requires gonadotropin.
False, this process occurs throughout life and is independent of hormone stimulus.
Primary to secondary follicle...
*Dependent on gonadotropin
*takes ~ 3 weeks
*requires LH surge; uses LH surge from previous cycle
FSH and LH are present in circulation in follicular phase. How do they interact with the follicle?
LH acts on Thecal cells to produce androgens.
FSH acts on granulosa cells, which convert androgens from thecal cells into estrogen.
*This leads to a rise in circ estrogen.
The rise in circ estrogen causes the follicle to develop?
LH receptors on granulosa cells, which incrase inhibin...which in combination with estrogen, acts on Ant Pit to dec FSH.
What causes the LH surge?
Elevated estrogen and progest serve as positive feedback for LH.
What causes the LH surge?
Elevated estrogen and progest serve as positive feedback for LH.
In the late luteal phase, do estrogen and progest. inhibit or stimulate FSH and LH?
They inhibit FSH and LH in the late luteal phase.
Why is it important for progest and estrogen to feedback inhibit FSH and LH in the late luteal phase.
B/C if fertilization does not occur, the lack of FSH and LH acting on CL will promote menses.
What is produced by the placenta to maintain pregnacy after fertilization?
Human chorionic gonadotropin.
What changes in the cervix can be measrured clinically during the prolif phase?
Cervix secretes a watery/elastic mucous which is easily penetrated by sperm.
What are the two hormones synthesized bt the thyroid gland?
Which one is more potent?
Which AA are they derived from?
Which one is more abundant?
*T3 and T4(thyroxine) are produced
*T3 is more potent and has a higher affinity for receptors.
*T3 and T4 are ionated derivatives from tyrosine.
T4 is more abundant anf has a longer half-life.
*T4 can be converted to T3.
Symptoms of Hyperthyroidism...
Heat intolerance
Inc appetite w/ weight loss
fatigue
tachycardia
inc sweating
polyuria
Symptoms of hypothyroidism...
fatigue
cold intolerance
peripheral edema
loss of appetite w/ weight gain
dec sweating
T/F
TH stim expression of gene for GH in Ant Pit.
True, a dec in TH leads to dec in GH
When is TH essential for brain development?
The last 6 mos of fetal life and the first 6 mos of post-natal life. A dec in TH during this time can lead to irreversible mental retardation.
4 characteristics of TH on neural development.
1.Inhibits nerve cell replication
2.stim growth of nerve cell bodies
3.stim branching of dendrites
4.stim myelination
What is TH role in body metabolism?
TH sets the bodies metabolic rate
What is the effect of hyperthyroidism on metabolic rate?
*Cell metabolism is inc
*Heat intol
*Inc appetite
*Weight loss
Where does TSH come from and what are its effects?
*From Ant Pit
*The effect of TSH is to inc release of T3 and T4 by
1.stim Iodine uptake
2.iodination of Tyr
3.pinocytosis of colloid
Which is a more potent regulator of TSH release, TRH or T3/T4?
Circulating levels of TH is the main factor on TSH secretion.
How is the majority T3/T4 circulating in blood (free or bound)?
*70% bound to TBG, the rest bound to albumin.
*Less than 1% is free.
Are thyroid nodules common? Are they dangerous?
They are uncommon, mostly seen in young females. If found, they must be biopsied b/c thyroid cancer is extrremely dangerous.
What is the difference b/t Graves and Hasimotos disease?
They are both autoimmune diseases affecting the thyroid.
Graves mimics TSH = Hyperthyroid
Hasimoto attacks thyroid = Hypothyroid.
T/F
The most critical function for Ca++ is w/n the nervous system.
True, and Ca is maintained w/n a narrow margain.
Ca++ homeostasis is manintained by three major organs.
1.Bone
2.Kidney
3.GI tract
Ca++ pools are compsed of three forms of Ca++
1.50% Ionized Ca - physio most imp
2.40% Protein bound - albumin
3.10% other
Ratio of free to bound Ca can be altered by two pathologies.
1.Liver disease
2.Resp. or Metabolic acidosis/alkalosis
Acidosis effects on Ca++?

Alkalosis effects on Ca?
Acidosis Increases ionzed Ca by dec Ca ability to bind to abumin.

Alk inc binding to albumin.
T/F
PTH is essential for life.
True, death will result from hypocalcemic tetany
FSH effect on Sertoli cells include...
*Induction of p450 aromatase, which converts testosteron to estrogen.
*Stim of sertoli cells
*Stim of ABP, which congrgates test. in one location.
*stim of inhibin which neg feedback onto Ant Pit to inhibit FSH.
What is the main funx of PTH?
Inc plasma Ca and dec plasma phosphate.

*These must oppose eachother, b/c an increase in both would only lead to increases in crystaline structures.
PTH is controlled primarilly by circ Ca levels. What excatly to the Ca ions act on?
They act on a Ca receptor protein, as opposed to acitvating a Ca Channel.
What are the effects of PTH on the kidney?
*Inc Ca reabsorbtion and dec phosphate resorbtion.
*Stim biosyn of 1,25(OH)D from Vit D precursors.
PTH effect on Bone?
Stim osteoclast
Inc osteoclast maturation
Inhib growth of osteoblast
PTH effect on GI system?
Inc intestinal Ca uptake.
Humoral Hypercalemia Malignancy refers to what?
What was found when these tumors were analyzed?
HHM refers to the elevated Ca and low Pi levels exhibited by many cancer patients.
When tumors from these patients were examined, PTH-rP was discovered.
Do PTH-rp and PTH come from the same gene?
No, only 13 AA sequence similar. PTH-rp can however, bind to PTH receptors to mimic PTH activity.
Where is Vit D converted? And to what is it converted?
*Vit D is converted in the liver and kidney to 1,25(OH)D-3.
*D-3 can also be converted by the skin in the prescence of UV light.
T/F
PTH is required to convert 25-OH-D-3 into 1,25(OH)D-3?
True
T/F
PTH is required to convert 25-OH-D-3 into 1,25(OH)D-3?
True
3 roles of the placenta.
1.Delivery of nutrients from mom to fetus.
2.Synthesis of steroid and peptide horm.
3.Removal of metabolites.
How does the implanting embryo extend the life of the CL?
By synthesizing HCG...this is what is tested in preg test.
*specifically dev. by placenta.
What are the effects of hCG?
Stimulates progest. production by the CL, preventing menses.
*Trophoblast are cells responsible.
What is hCS (human chor. somatatropin)?
*Syn by placenta
*similar to Prolactin
*Main funx is to dec mom's glucose comsump and inc fat mobility.
*Basically give adequate nutrition to fetus.
Placenta derived estrogen does...
*Inc uterus size
*Inc mamm glands
*inc breast size
*induces receptors for ox and progest.
Placental derived progest does...
*maintains implantation
*inhib myometrial contraction
*supresses moms immune response
T/F
While initially CL is main supplier of hormone, by the 8th week, the placenta has taken over this role.
TRUE.
What does the placenta have a problem converting acetate into into?
So what does it do instead?
The placenta cannot convert acetate into cholesterol, therefor, the placenta uses mom's LDL to get cholesterol to make progesterone.
Since the placenta lacks enzymes to make estrodiol, where and what does the placenta use?
The placenta uses DHEA-S from Mom AND fetus to make DHEA, then to make estrodiol. Having the DHEA sulfanated allows it to cross the B-P-B.
What does the fetal zone of the adrenal cortex produce?
DHEA-S
What is Estriol?
*Major estrogen produced during preg.
*Weak biological activity.
*Was once used to measure fetal well-being
*Can be used to maintain Estrogen levels.
After fert., what keeps another follicle from ovulating?
Elevated steriod levels in moms circ suppress LH and FSH levels.
*principle behind BCP.
Preg causes the Thyroid to increase production of T3/T4, so why don't women show signs of hyperthyroidism?
B/c along with elevated T3/T4 levels, the binding protein, TBP, is also increased. Therfor you have elevated complexes.
Do moms show an increase or decrease in PTH? Why?
An increase in PTH is seen. This occurs to deliver as much Ca to the fetus as possible.
During Preg, is there an inc in hormones that oppose insulin, or act like insulin?
Oppose insulin(glucagon, cortisol, prl). This ensures there are high levels of glucose and metabolic fuel for fetus.
What prevents maternal peptide hormones from reaching the fetus?
Blood-placenta-barrier.
name two hormone producing glands that develop early in fetal life.
Thyroid and adrenal glands.
We learned that GH is not important for fetal growth. What hormone is responsible?
IGF-II - maybe.
In knockout mice, if IGF-II is gone, mice have decreased birth weight, then grow normally after birth.