5. Hormonal Control of Reproduction Flashcards
What three parts of the hypothalamus have a direct influence on reproduction?
- Surge center
- Tonic center
- Paraventricular nucleus (PVN)
What is the hormonal axis that is key to hormonal regulation of the reproductive system?
Hypothalamic-Pituitary-Gonadal Axis
What is the hypothalamo-hypophyseal portal system?
Specialized capillary network that allows delivery of hormone or regulatory molecule from hypothalamus to pituitary without entering general circulation
What does the hypothalamo-hypophyseal portal system allow?
Minute quantities of releasing hormones to act on the anterior pituitary before being diluted by general circulation
Substance produced by a gland that acts on a target tissue to bring about a change in the tissue
endocrine hormone
What is a half-life and do hormones have relatively long or short half-lives?
- The time required for one-half of a quantity of hormone to disappear from the blood or from the body
- Short; they are degraded after they cause an effect
Substance produced by target tissue in response to hormone stimulates production of more hormone.
positive feedback
Substance produced by target tissue in response to hormone inhibits production of hormone.
negative feedback
What type of feedback does progesterone have on the hypothalamus and what is the impact on follicular development?
- negative ffeedback
- high progesterone causes decreased GnRH secretions –> decreased LH/FSH –> little follicular development
What type of feedback does estrogen have on the hypothalamus and what does it cause on the ovary?
- Positive feedback
- High estrogen causes increased GnRH –> LH surge –> ovulation
What role do kisspeptin neurons play in reproduction?
stimulate activity in GnRH neurons
what is a second messenger?
- An intracellular material that responds to a hormone-receptor complex and initiates a specific set of intracellular reactions
- cAMP
How are the chemical structures of luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) related?
The alpha subunit for FSH, LH, and TSH are identical within species
What are the three classifications of hormones used in this class?
- Source
- Mode of action
- Biochemical classification
What are the 5 sources of reproductive hormones and give examples of what kind of hormone each source secretes.
- Hypothalamus – releasing factors
- Pituitary – gonadotropin, somatotropin, prolactin, oxytocin
- Gonads - steroids
- Uterus – prostaglandins, steroids
- Placenta – steroids, others
List the actions of reproductive hormones
- Release of other hormones
- Stimulation of the gonads: gonadotropins
- Sexual promotion: steroids
- Pregnancy maintenance
- Luteolysis
List the four biochemical structures of hormones studied in this course.
- peptide
- protein
- steroids
- prostaglandins
_____________ have carbohydrate moieties that effect stability and increase half-life.
glycoproteins
What do steroid hormones have in common?
- common molecular core
- 4 carbon rings
- synthesized from cholesterol
What molecule is the precursor for steroid hormones?
cholesterol
What is the precursor of estradiol?
testosterone
What enzyme converts testosterone into estradiol?
aromatase
What are prostaglandins derived from?
arachidonic acid
what hormones causes luteolysis?
prostaglandin f2a
what is luteolysis?
destruction of the CL
which organ metabolizes steroids?
liver
which two organs metabolize proteins?
liver and kidneys
Which type of hormone is metabolized quicker: steroid or protein/peptide?
steroid
What hormone acts on the anterior pituitary to signal the release of LH and FSH?
GnRH
What hormones stimulates testosterone production in males and stimulates ovulation in females?
LH
What hormone is responsible for sertoli cell function in the male and follicular development in the female?
LSH
What hormone is responsible for lactation, maternal behavior, and CL function?
prolactin , PRL
what hormone affects PGF synthesis and pre-ejaculatory movement of spermatozoa in the male and uterine motility, PGF synthesis, and milk ejection in the female?
oxytocin
What hormone is responsible for sexual behavior, GnRH, elevated secretory activity of the entire tract, and enhanced uterine motility in the female?
estradiol
what hormone inhibits GnRH release and reproductive behavior while promoting maintenance of pregnancy and endometrial secretion?
progesterone
What hormone promotes anabolic growth, spermatogenesis, and accessory sex gland activity in the male?
testosterone
what hormone inhibits FSH secretion?
inhibin
what hormone promotes the softening of cervix and pelvic ligaments?
relaxin
High concentrations of what hormone inhibit the release of GnRH, FSH, and LH, through a negative feedback control?
progesterone
High concentrations of what hormone stimulate a greater surge of of GnRH, LH, and FSH, through positive feedback control?
estradiol
what effect does progesterone have on GnRH?
negative control; inhibits secretion
describe the conversion of cholesterol to estradiol
cholesterol –> pregnenolone –> progesterone –> testosterone –> estradiol
What is the source of progesterone?
CL and placenta
What are sources of estradiol?
granulosal cells of follicle, placenta, sertoli cells of testes
What cells produce testosterone?
leydig cells in male & theca interna cells in female
What cells produce inhibin?
granulosal cells (female) & sertoli cells (male)
What sources produce prostaglandin?
uterine endometrium & vesicular glands
The structure of glycoproteins (FSH, LH, and TSH) consists of two subunits. The _____ subunit is the same among the three hormones, but the ____ subunit is unique for each hormone.
alpha
beta
the primary mechanism of action of steroid hormones involves the ____________________ mechanism.
slow response
when the female is not pregnant, the endometrium will produce __________ that will be redirected to the ovary and cause _________________. This will result in a _______________ of the hormone ___________________ which will remove the negative feedback on the hypothalamus and allow a new cycle to begin
prostagladin
luteolysis
decrease
progesterone
