5. Hormonal Control of Reproduction

Question 1

What three parts of the hypothalamus have a direct influence on reproduction?

Answer 1

• Surge center
• Tonic center
• Paraventricular nucleus (PVN)

Question 2

What is the hormonal axis that is key to hormonal regulation of the reproductive system?

Answer 2

Hypothalamic-Pituitary-Gonadal Axis

Question 3

What is the hypothalamo-hypophyseal portal system?

Answer 3

Specialized capillary network that allows delivery of hormone or regulatory molecule from hypothalamus to pituitary without entering general circulation

Question 4

What does the hypothalamo-hypophyseal portal system allow?

Answer 4

Minute quantities of releasing hormones to act on the anterior pituitary before being diluted by general circulation

Question 5

Substance produced by a gland that acts on a target tissue to bring about a change in the tissue

Answer 5

endocrine hormone

Question 6

What is a half-life and do hormones have relatively long or short half-lives?

Answer 6

• 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

Question 7

Substance produced by target tissue in response to hormone stimulates production of more hormone.

Answer 7

positive feedback

Question 8

Substance produced by target tissue in response to hormone inhibits production of hormone.

Answer 8

negative feedback

Question 9

What type of feedback does progesterone have on the hypothalamus and what is the impact on follicular development?

Answer 9

• negative ffeedback
• high progesterone causes decreased GnRH secretions –> decreased LH/FSH –> little follicular development

Question 10

What type of feedback does estrogen have on the hypothalamus and what does it cause on the ovary?

Answer 10

• Positive feedback
• High estrogen causes increased GnRH –> LH surge –> ovulation

Question 11

What role do kisspeptin neurons play in reproduction?

Answer 11

stimulate activity in GnRH neurons

Question 12

what is a second messenger?

Answer 12

• An intracellular material that responds to a hormone-receptor complex and initiates a specific set of intracellular reactions
• cAMP

Question 13

How are the chemical structures of luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) related?

Answer 13

The alpha subunit for FSH, LH, and TSH are identical within species

Question 14

What are the three classifications of hormones used in this class?

Answer 14

• Source
• Mode of action
• Biochemical classification

Question 15

What are the 5 sources of reproductive hormones and give examples of what kind of hormone each source secretes.

Answer 15

• Hypothalamus – releasing factors
• Pituitary – gonadotropin, somatotropin, prolactin, oxytocin
• Gonads - steroids
• Uterus – prostaglandins, steroids
• Placenta – steroids, others

Question 16

List the actions of reproductive hormones

Answer 16

• Release of other hormones
• Stimulation of the gonads: gonadotropins
• Sexual promotion: steroids
• Pregnancy maintenance
• Luteolysis

Question 17

List the four biochemical structures of hormones studied in this course.

Answer 17

• peptide
• protein
• steroids
• prostaglandins

Question 18

_____________ have carbohydrate moieties that effect stability and increase half-life.

Answer 18

glycoproteins

Question 19

What do steroid hormones have in common?

Answer 19

• common molecular core
• 4 carbon rings
• synthesized from cholesterol

Question 20

What molecule is the precursor for steroid hormones?

Answer 20

cholesterol

Question 21

What is the precursor of estradiol?

Answer 21

testosterone

Question 22

What enzyme converts testosterone into estradiol?

Answer 22

aromatase

Question 23

What are prostaglandins derived from?

Answer 23

arachidonic acid

Question 24

what hormones causes luteolysis?

Answer 24

prostaglandin f2a

Question 25

what is luteolysis?

Answer 25

destruction of the CL

Question 26

which organ metabolizes steroids?

Answer 26

liver

Question 27

which two organs metabolize proteins?

Answer 27

liver and kidneys

Question 28

Which type of hormone is metabolized quicker: steroid or protein/peptide?

Answer 28

steroid

Question 29

What hormone acts on the anterior pituitary to signal the release of LH and FSH?

Answer 29

GnRH

Question 30

What hormones stimulates testosterone production in males and stimulates ovulation in females?

Answer 30

LH

Question 31

What hormone is responsible for sertoli cell function in the male and follicular development in the female?

Answer 31

LSH

Question 32

What hormone is responsible for lactation, maternal behavior, and CL function?

Answer 32

prolactin , PRL

Question 33

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?

Answer 33

oxytocin

Question 34

What hormone is responsible for sexual behavior, GnRH, elevated secretory activity of the entire tract, and enhanced uterine motility in the female?

Answer 34

estradiol

Question 35

what hormone inhibits GnRH release and reproductive behavior while promoting maintenance of pregnancy and endometrial secretion?

Answer 35

progesterone

Question 36

What hormone promotes anabolic growth, spermatogenesis, and accessory sex gland activity in the male?

Answer 36

testosterone

Question 37

what hormone inhibits FSH secretion?

Answer 37

inhibin

Question 38

what hormone promotes the softening of cervix and pelvic ligaments?

Answer 38

relaxin

Question 39

High concentrations of what hormone inhibit the release of GnRH, FSH, and LH, through a negative feedback control?

Answer 39

progesterone

Question 40

High concentrations of what hormone stimulate a greater surge of of GnRH, LH, and FSH, through positive feedback control?

Answer 40

estradiol

Question 41

what effect does progesterone have on GnRH?

Answer 41

negative control; inhibits secretion

Question 42

describe the conversion of cholesterol to estradiol

Answer 42

cholesterol --> pregnenolone --> progesterone --> testosterone --> estradiol

Question 43

What is the source of progesterone?

Answer 43

CL and placenta

Question 44

What are sources of estradiol?

Answer 44

granulosal cells of follicle, placenta, sertoli cells of testes

Question 45

What cells produce testosterone?

Answer 45

leydig cells in male & theca interna cells in female

Question 46

What cells produce inhibin?

Answer 46

granulosal cells (female) & sertoli cells (male)

Question 47

What sources produce prostaglandin?

Answer 47

uterine endometrium & vesicular glands

Question 48

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.

Answer 48

alpha beta

Question 49

the primary mechanism of action of steroid hormones involves the ____________________ mechanism.

Answer 49

slow response

Question 50

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

Answer 50

prostagladin luteolysis decrease progesterone