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84 Cards in this Set
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- Back
- 3rd side (hint)
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Purpose of the Endocrine system
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Maintain homeostasis
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Major classes of hormones
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AA derivatives-Tyr, Trp, His
Peptides-Composed of AA, most DIVERSE group. Steroids-Derived from Choles., lipid soluble. |
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Peptide hormones are free in circulation, except for...
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1.GH
2.IGF-1 Inc half-life, and limit hormone to specific targets. |
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Adenohypophysis
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Originated from pharyngeal epithelium
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Neurohypophysis
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Originated from developing hypothal.
Post Pit. |
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Hormones of Ant Pit
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ACTH-cortisol production
TSH-thyroid production FSH-follicle development LH-ovulation and sex sterios syn PRL-prolactin stim GH-stim body growth, reg metabolism |
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TSH - FSH - LH are all composed of and alpha and beta subunit, which subunit is unique?
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Alpha subunits are identicle,
Beta subunits are different. |
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Do releasing hormones from hypothalamus get diluted in systemic circ?
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No, RH are contained to the hypophyseal-portal system.
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What stimulates and inhibits GH?
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GHRH=stimulates
SS=inhibits |
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3 types of Feedback loops
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Long-originates from peripheral source
Short-Ant Pit acting on hypothal Ultra Short-hypothal acting on itself |
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Is GH required for normal fetal growth?
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No, only important for youth and adolescent growth.
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GH stimulates the expression of...
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IGF-1
Potent mitogen and differentiation factor. Resembles pro-insulin. Liver is major source of circulating IGF-1. |
steve chaney
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Direct effect of IGF-1
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Metabolic - Anti-insulin effects
Inc lipolysis Inc blood glucose |
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Indirect effects of IGF-1
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Growth - Acting on Liver/peripheral tissues
Inc Chondrogenesis Inc protein syn Inc cell proliferation |
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Indirect effects of IGF-1
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Growth - Acting on Liver/peripheral tissues
Inc Chondrogenesis Inc protein syn Inc cell proliferation |
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What are some positive effects of GH supplements in aging people?
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Inc lean muscle
Dec fat Inc SV Inc physical motility, vitality |
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Negative effects of GH supplements?
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Dec in GH may help prevent onset of cancer.
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GnRH from Hypothal release...
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releases LH and FSH from Ant Pit
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Which cells produce testosterone?
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Leydig cells under the influence of LH.
Leydigs are located outside of the sem. tubules. |
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These cells form the blood-testis barrier.
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Sertoli cells residing in the S.Ts.
Support spermatogenesis under the influ. of FSH. |
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3 functions of androgens
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Regulation of hormones from Ant Pit and Hypothal.
Support spermatogenesis Reg of sexual behavior. |
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Basic route of hormones males
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LH onto Leydigs which produce testosterone
FSH on sertoli cells which support spermatogenesis, and use test for Leydigs as "nutrition" for growing sperm. |
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Consequences of testosterone in the periphery?
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*Converted to DHT by 5 alpha reductase.
*Converted to estradiol by p450 aromatase. |
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3 characteristics of follicular phase of mens. cycle?
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1.Estrogen dominate
2.growth/maturation of follicles 3.Endometrial proliferation |
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Ovulation occurs as a result of...
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LH surge and temp spkie
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Characteristics of Luteal/secretory phase of mens. cycle?
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1.Progesterone dominated
2.Follicle is converted to C.L. 3.Endometrium develops secretory glands and vascularization. |
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T/F
Progression from primordial follicle to primary follicle requires gonadotropin. |
False, this process occurs throughout life and is independent of hormone stimulus.
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Primary to secondary follicle...
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*Dependent on gonadotropin
*takes ~ 3 weeks *requires LH surge; uses LH surge from previous cycle |
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FSH and LH are present in circulation in follicular phase. How do they interact with the follicle?
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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. |
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The rise in circ estrogen causes the follicle to develop?
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LH receptors on granulosa cells, which incrase inhibin...which in combination with estrogen, acts on Ant Pit to dec FSH.
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What causes the LH surge?
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Elevated estrogen and progest serve as positive feedback for LH.
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What causes the LH surge?
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Elevated estrogen and progest serve as positive feedback for LH.
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In the late luteal phase, do estrogen and progest. inhibit or stimulate FSH and LH?
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They inhibit FSH and LH in the late luteal phase.
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Why is it important for progest and estrogen to feedback inhibit FSH and LH in the late luteal phase.
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B/C if fertilization does not occur, the lack of FSH and LH acting on CL will promote menses.
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What is produced by the placenta to maintain pregnacy after fertilization?
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Human chorionic gonadotropin.
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What changes in the cervix can be measrured clinically during the prolif phase?
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Cervix secretes a watery/elastic mucous which is easily penetrated by sperm.
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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. |
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Symptoms of Hyperthyroidism...
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Heat intolerance
Inc appetite w/ weight loss fatigue tachycardia inc sweating polyuria |
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Symptoms of hypothyroidism...
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fatigue
cold intolerance peripheral edema loss of appetite w/ weight gain dec sweating |
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T/F
TH stim expression of gene for GH in Ant Pit. |
True, a dec in TH leads to dec in GH
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When is TH essential for brain development?
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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.
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4 characteristics of TH on neural development.
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1.Inhibits nerve cell replication
2.stim growth of nerve cell bodies 3.stim branching of dendrites 4.stim myelination |
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What is TH role in body metabolism?
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TH sets the bodies metabolic rate
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What is the effect of hyperthyroidism on metabolic rate?
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*Cell metabolism is inc
*Heat intol *Inc appetite *Weight loss |
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Where does TSH come from and what are its effects?
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*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 |
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Which is a more potent regulator of TSH release, TRH or T3/T4?
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Circulating levels of TH is the main factor on TSH secretion.
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How is the majority T3/T4 circulating in blood (free or bound)?
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*70% bound to TBG, the rest bound to albumin.
*Less than 1% is free. |
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Are thyroid nodules common? Are they dangerous?
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They are uncommon, mostly seen in young females. If found, they must be biopsied b/c thyroid cancer is extrremely dangerous.
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What is the difference b/t Graves and Hasimotos disease?
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They are both autoimmune diseases affecting the thyroid.
Graves mimics TSH = Hyperthyroid Hasimoto attacks thyroid = Hypothyroid. |
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T/F
The most critical function for Ca++ is w/n the nervous system. |
True, and Ca is maintained w/n a narrow margain.
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Ca++ homeostasis is manintained by three major organs.
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1.Bone
2.Kidney 3.GI tract |
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Ca++ pools are compsed of three forms of Ca++
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1.50% Ionized Ca - physio most imp
2.40% Protein bound - albumin 3.10% other |
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Ratio of free to bound Ca can be altered by two pathologies.
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1.Liver disease
2.Resp. or Metabolic acidosis/alkalosis |
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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. |
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T/F
PTH is essential for life. |
True, death will result from hypocalcemic tetany
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FSH effect on Sertoli cells include...
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*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. |
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What is the main funx of PTH?
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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. |
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PTH is controlled primarilly by circ Ca levels. What excatly to the Ca ions act on?
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They act on a Ca receptor protein, as opposed to acitvating a Ca Channel.
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What are the effects of PTH on the kidney?
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*Inc Ca reabsorbtion and dec phosphate resorbtion.
*Stim biosyn of 1,25(OH)D from Vit D precursors. |
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PTH effect on Bone?
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Stim osteoclast
Inc osteoclast maturation Inhib growth of osteoblast |
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PTH effect on GI system?
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Inc intestinal Ca uptake.
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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. |
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Do PTH-rp and PTH come from the same gene?
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No, only 13 AA sequence similar. PTH-rp can however, bind to PTH receptors to mimic PTH activity.
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Where is Vit D converted? And to what is it converted?
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*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. |
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T/F
PTH is required to convert 25-OH-D-3 into 1,25(OH)D-3? |
True
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T/F
PTH is required to convert 25-OH-D-3 into 1,25(OH)D-3? |
True
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3 roles of the placenta.
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1.Delivery of nutrients from mom to fetus.
2.Synthesis of steroid and peptide horm. 3.Removal of metabolites. |
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How does the implanting embryo extend the life of the CL?
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By synthesizing HCG...this is what is tested in preg test.
*specifically dev. by placenta. |
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What are the effects of hCG?
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Stimulates progest. production by the CL, preventing menses.
*Trophoblast are cells responsible. |
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What is hCS (human chor. somatatropin)?
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*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. |
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Placenta derived estrogen does...
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*Inc uterus size
*Inc mamm glands *inc breast size *induces receptors for ox and progest. |
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Placental derived progest does...
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*maintains implantation
*inhib myometrial contraction *supresses moms immune response |
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T/F
While initially CL is main supplier of hormone, by the 8th week, the placenta has taken over this role. |
TRUE.
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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.
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Since the placenta lacks enzymes to make estrodiol, where and what does the placenta use?
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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.
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What does the fetal zone of the adrenal cortex produce?
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DHEA-S
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What is Estriol?
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*Major estrogen produced during preg.
*Weak biological activity. *Was once used to measure fetal well-being *Can be used to maintain Estrogen levels. |
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After fert., what keeps another follicle from ovulating?
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Elevated steriod levels in moms circ suppress LH and FSH levels.
*principle behind BCP. |
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Preg causes the Thyroid to increase production of T3/T4, so why don't women show signs of hyperthyroidism?
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B/c along with elevated T3/T4 levels, the binding protein, TBP, is also increased. Therfor you have elevated complexes.
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Do moms show an increase or decrease in PTH? Why?
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An increase in PTH is seen. This occurs to deliver as much Ca to the fetus as possible.
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During Preg, is there an inc in hormones that oppose insulin, or act like insulin?
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Oppose insulin(glucagon, cortisol, prl). This ensures there are high levels of glucose and metabolic fuel for fetus.
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What prevents maternal peptide hormones from reaching the fetus?
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Blood-placenta-barrier.
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name two hormone producing glands that develop early in fetal life.
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Thyroid and adrenal glands.
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We learned that GH is not important for fetal growth. What hormone is responsible?
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IGF-II - maybe.
In knockout mice, if IGF-II is gone, mice have decreased birth weight, then grow normally after birth. |
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