Reproductive Hormones Flashcards
What ensures life sustaining activities?
Hormones
Define autocrine mode of action
The hormone acts on the same cell that produced it.
Define endocrine mode of action
The hormone is distributed in blood and binds to distant target cells.
Define paracrine mode of action
The hormone acts locally by diffusing from its source to adjacent
target cells.
How are most reproductive hormones secreted?
In a pulsatile fashion.
How are hormones secreted in females compared to males?
Periodically in females (in regular cycles) and constitutively in males.
What is notable about the effectiveness of hormones?
They are effective even in very minute quantities (i.e., picograms per milliliter).
Is the half life of reproductive hormones long or short
Relatively short
What do hormones regulate in reproductive and some non-reproductive tissues?
Intracellular biochemical reactions.
What can reproductive hormones control/stimulate/maintain? (5)
- Control other hormone release (releasing hormones/ factors)
- Stimulate gonads (gonadotropic hormones)
- Stimulate sexual development and sustain gonadal function, alter secondary sex characteristics
- Maintain pregnancy, initiate and sustain parturition and lactation
- Control ovarian cyclicity (e.g., ovulatory process, CL formation and regression)
What are three ways to classify repro hormones?
-Source
-Mode of action
-Biochemical classification
What are the three sources of repro hormones?
Hypothalamic, pituitary, gonadal
What are the four modes of action for repro hormones?
- Neurohormones
- Releasing
hormones/factors - Gonadotropins
- Metabolic/sexual
stimulants
What are the 3 types of biochemical classification?
-Peptides, steroids, FA derivatives
Steps for the fate of steroid hormones after secretion (7 steps)
- Steroid secreted by gonad
- Steroid enters blood and goes to target tissue
- Steroid causes change in target tissue
- Steroid in blood passes through liver
- Liver renders sterid H2O soluble
- Re-enters blood and enters kidney or enters bile
- Excreted in urine and/or feces as glucuronide or sulfate
What is an example of POSITIVE feedback for repro hormones?
increased estradiol
-> increased GnRH from hypothalamus
-> increased LH from pituitary
-> increase stimulates terminal follicular development, ovulation and early CL
What is the surge center in the hypothalamus sensitive to?
Positive feedback
What is an example of NEGATIVE feedback for repro hormones?
increased progesterone and estradiol
-> decreased GnRH from hypothalamus
-> decreased LH from pituitary
-> decrease blocks ovulation
What is sensitive to negative feedback in the hypothalamus?
Tonic center
what is the process of formation of the steroid hormones?
cholesterol -> progesterone -> testosterone -> estradiol
Mechanisms of protein hormones (4 steps)
- Binding of hormone to receptor
- Activation of adenylate cyclase
- Activation of protein kinase
- Synthesis of new products
Mechanisms of steroid hormones (4 steps)
- Transport of steroid
- Transfer through cell membrane and cytoplasm
- Binding of steroid to the nuclear receptor
- Synthesis of mRNA and protein
What type of receptors do protein hormones act through?
Plasma membrane receptors
What type of receptors do steroid hormones act through?
Nuclear receptors
