Male and Female Reproductive Endocrinology

Question 1

Puberty

Answer 1

puberty is triggered by increasing pulses of gonadotrophin releasing hormone which sets the process off.

Question 2

Tanner stages

Answer 2

This staging system can give people a score that we can use to detect early or late puberty and when we see people from month to month, we know whether their puberty is progressing or not.

Question 3

Normal age ranges of pubertal stages

Answer 3

Puberty happens to different people at different times and this is just a schematic range of when puberty can happen.

Question 4

What affects timing of puberty ?

Answer 4

On a whole its genetic, you are liekly to go into puberty at a similar time that your parent started puberty but may be changed by stressors particulalry problems with nutrition or could be early due to a variety of reasons listed in the diagnram.

Question 5

Male reproductive endocrinology

Answer 5

-LH works on the Leydig cells in the testes to stimulate the production testosterone which then has a negative feedback effect on the pituitarya nd the hypothalamus to decerease GnRH and LH.

-FSH stiumlates the seminiferous cells in the seminiferous tubules to make sperm.

Question 6

Effects of testosterone

Answer 6

-Increased aggression and libido*

-Enlargement of the larynx

-Male pattern pubic hair

-Maturation of genitalia

-Muscle development

-Sperm production

-Bone growth*

-Acne

Question 7

Female reproductive endocrinology

Answer 7

-GnRh is released from the hypothalamus, causing the pituitary to release both LH and FSH.

Question 8

Female reproductive endocrinology cont

Answer 8

• GnRH is released from the hypothalamus and it acts on the anterioir pituitary to release both LH and FSH.
• In the follicular phase of the menstrual cycle, FSH acts on the ovary to recruit and mature premodial follicles to become primary follicles and then one follicle will dominate and become a secondary follicle. This starts to make Estrogen.
• As the estrogen levels rise and in conjuction with leutenising hormone, the mature graafian folicles then releases its egg and a corpus luteum so that remnants of the follicle without the egg will go on and make progesterone and estrogen.
• The estrogen will then cause proliferation of the linin of the uterus, making it more receptive and the estrogen and progesterone can bidn to increase the blood supply and linning of the uterus.
• If fertilisation does not occur then the progesterone and estrogen levels will fall as the corpus luteum ages and then menstuation occurs.
• In the graph, you’ll see that FSH is the first to rise, the production of estrogen in the ovaries causes a gradual rise in estrogen levels then LH is released from the pitutary gland whioch causes the release of ovum.
• you will then have a gradual rise in estrogen and progesterone which then acts as a negative feedback to decerease the levels of FSH and LH.
• LH tends to peak just before ovulationat around day 12 and progesterone tends to peak at around day 21.

Question 9

Female reproductive endocrinology cont

Answer 9

• LH works on the Theca cells in the ovaries to make androgens which then move to the granulosa cells to make progesterone and estrogen under the stimulation of FSH.
• The granulosa cell also makes Activin and Inhibin which along with LH and FSH can cause a negative feedback on the release of GnRH and LH and FSH.

Question 10

What’s happening within the ovary

Answer 10

-In the theca cells in the ovaries , LH activates the receptor to encourage protein kinase A to convert cholesterol into Androstenedione, that the moves across to the granulosa cell which converts androsteindione to Estradiol which is released into the blood.

Question 11

Oxytocin

Answer 11

• Breast-feeding

• contracts the myoepithelial cells of the alveoli
• classic neuroendocrine reflex

• Childbirth (parturition)

• in late pregnancy, uterine smooth muscle (myometrium) becomes sensitive to oxytocin
• positive feedback

Answer 12

Higher centres in the brain release a chemical which causes a decrease in prolactin inhibitory hormone which causes an increase in prolactina nd oxytocin so that you have milk secretion and smooth muscle contraction so that milk is released from the nipple.

Question 13

• Childbirth (parturition)

Answer 13

In labour, the baby drops low causinf cervical stretch which encourages oxytocin production from the posterioir pituitary and prostaglandins in the uterine wall also cause uterine contractions which further increases cervical strech which further releases oxytocin from the pituitary so this is a positive feedback loop.

Answer 14