reproductions

Question 1

Name the three main classes of sex steroids, the chemical from which they are all produced and how their biosynthesis is related (3 marks).

Answer 1

• estrogens are formed from androgens
• androgens are formed from progestagens
• all sex steroids are formed from cholesterol

Question 2

The major male sex steroid is _____________________.

Answer 2

testosterone

Question 3

Dihyrotestosterone is produced in the __________________

Answer 3

target tissue

Question 4

Dehydroepiandrosterone (DHEA) is produced in the _______________________.

Answer 4

adrenal cortex

Question 5

The third peak in androgens in males occurs ___________________________
(when) and causes _________________________________.

Answer 5

formation of penis, scrotum and testes

Question 6

The major sex steroid in females is ___________________________.

Answer 6

estradiol

Question 7

The major progestin is ________________________.

Answer 7

progesterone

Question 8

Describe the role of the following in male development:

a) SRY
b) Mullerianinhibitingfactor

Answer 8

part of Y chromosome that stimulates the development of testes from the undifferentiated gonad
hormone produced by testes that inhibits the development of the oviducts and uterus

Question 9

In both males and females, puberty is caused by __________________

Answer 9

-increased production of GnRH from the hypothalamus - in a pulsatile pattern

Question 10

List a structural change and a functional change that occur as a primordial follicle
becomes a primary follicle.

Answer 10

• structure=cells that surround the oocyte become several layers thick
• function=begins to produce estrogens

Question 11

List a structural change and a functional change that occur as a secondary follicle
becomes a tertiary follicle.

Answer 11

structure=development of a fluid-filled antrum

-function=increased pressure in antrum promotes ovulation

Question 12

Name the two main ovarian cycle stages and the two main uterine cycle stages, list
the main event in each and how they are related in terms of time as well as function
(4 marks).

Answer 12

the ovarian cycle includes a follicular stage (first 2 weeks) and a luteal stage (last 2 weeks)

• several follicles mature during the follicular stage and produce estrogen
• after ovulation the remnants of the follicle form the corpus luteum which releases progesterone as well as estrogen (luteal stage)
• the menstrual cycle includes a proliferative stage (first 2 weeks) and a secretory stage (last 2 weeks)
• the proliferative stage involves the growth of glands and thickening of the endometrium
• during the secretory stage, endometrial glands mature and secrete a nutrient rich fluid

Question 13

Describe the three main hormones of pregnancy – their sites of production, the
timing of their formation and their main actions (3 marks).

Answer 13

human chorionic gonadotrophin is produced first by the placenta and causes the continued development of the corpus luteum

• estrogen and progesterone are produced by the corpus luteum as well as the placenta
• estrogen and progesterone:
  1) inhibit GnRH, preventing development of more follicles (prevents ovulation)
  2) promote the growth of the endometrium (prevent menstruation)
  3) stimulate the growth of acini in the ducts of the mammary gland
• estrogen and