Human Reproduction 6.6. Male Reproductive System 6.6.1.

Human Reproduction

6.6

Male Reproductive System6.6.1

Female Reproductive System6.6.1

6.6.2

The menstrual cycle·The menstrual cycle is regulated by hormones of the hypothalamus, anterior pituitary, and ovaries

http://health.howstuffworks.com/sexual-health/female-reproductive-system/menstruation.htm

6.6.2

Menstruation Phase(The egg or ovum from the previous cycle was not fertilized)·The endometrium is shed

- the inner lining of the uterus that becomes highly vascular (rich with blood vessels) so that a fertilized egg can implant.

- break down of blood vessels leads to the menstrual bleeding of a typical cycle.

6.6.2Menstruation Phase·Hypothalamus releases Gonadotropin Releasing Hormone (GnRH).

- target tissue of GnRH is the anterior pituitary

·GnRH stimulates the anterior pituitary to release Follicle Stimulating Hormone (FSH) and Lutenizing Hormone (LH)

- target tissue of FSH and LH are the ovaries.

6.6.2

Preovulatory (Proliferative) Phase·FSH stimulates the development of a few follicles in the ovary

- Follicles are immature egg cells in the ovaries that are in the process of going through meiosis in order to become oocytes (mature eggs)·In response to FSH and LH the ovaries produce the hormone estrogen.

- the target tissue of estrogen is the endometrium of the uterus.

- results in endometrium becoming highly vascular.·Spike in FSH and LH leads to ovulation (release of oocyte from a follicle)

Youtube: Ovulation by nucleusanimation

6.6.2Postovulatory (Secretory) Phase·the outer ring of cells from the ruptured follicle remain in the ovary and become to corpus luteum

- a glandular structure that fills in the 'wound' left by ovulation

- produces progesterone for 10-12 days after ovulation ·Progesterone targets the uterus to maintain the thickened endometrium

- also provides negative feedback to the hypothalamus to prevent production of GnRH

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__maturation_of_the_follicle_and_oocyte.html

6.6.2

Postovulatory (Secretory) Phase·If fertilization does not occur, the corpus luteum degenerates and ceases production of hormones, causing menstruation·If fertilization does occur, implantation occurs in the uterus on about the third day after fertilization

6.6.3

6.6.4

The role of testosterone in males·During week 7 of embryonic development, testosterone intiates the formation of male genitalia·During the midteens testosterone intiates the development of male secondary sex characteristics

- Increase in muscle mass- Increase in the length of the vocal chords (voice

deepens)- Increase in the length of the bones (height)- Spermatogenesis (creation of sperm)- Facial hair

·maintains the sex drive of males throughout their lifetime

6.6.5

In Vitro Fertilization (IVF)·Treatment for infertility in which an egg is fertilized outside of the mother’s womb·Process involves hormonally controlling the woman’s ovulation cycle, removing ova from the woman’s ovaries surgically, and letting sperm fertilize them in a fluid medium·Once the ova are fertilized they are then transferred to the woman’s uterus in hopes that one of them will implant itself in the endometrium and result in a successful pregnancy

6.6.5

·Often, IVF results in multiple birth pregnancies which can be a risk factor for several reasons:

- increased chance of miscarriage

- complications during birth- increased chance of

premature birth

B. There are many ethical issues in regards to IVF1. Does the mother or father have more say in

regards to disposing frozen embryos?2. Why do IVF if adoption is an option?3. Some couples try to solve marital problems by

having a child through IVF

4. What others can you find?