6.6 Reproduction

ASSESSMENT STATEMENTS

Draw and label diagrams of the adult male and female reproductive systems.

Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing hormone), estrogen and progesterone.

Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes in hormone levels and ovulation, menstruation and thickening of the endometrium.

List three roles of testosterone in males.

Outline the process of in vitro fertilization (IVF).

Discuss the ethical issues associated with IVF.

Female Reproductive Anatomy

Front view

Side view

Draw me!

Role of Hormones in Menstrual Cycle

• Starting at puberty, females begin a hormonal cycle known as the menstrual cycle

• The purpose is to time the release of a follicle (unfertilized egg) from an ovary to the potential for implantation (egg attaches itself to uterine lining endometrium)

• If no implantation occurs then the endometrium (which is tissue rich with blood vessels) will breakdown and the contents will be released (menstrual bleeding)

Where did my menstrual cycle go?

Hormone: Produced by:

Function:

FSH (follicle stimulating hormone)

Pituitary gland

Stimulates follicle growth (what houses maturing egg); stimulates estrogen secretion; a spike in FSH

levels stimulates ovulation

LH (luteinizing hormone)

Pituitary gland

Spike in LH levels stimulate ovulation; stimulate formation of

corpus luteum (empty follicle after ovulation)

Estrogen Maturing follicle cells

in ovary

Stimulates thickening of the endometrium

Progesterone Corpus luteum

Maintains endometrium; inhibits FSH and LH

Male Reproductive Anatomy

side view

vas deferens

Front view

Functions of the Male Reproductive Parts:

• Epididymis – after sperm is formed in testes they move to epididymis to be stored where they can mature and gain motility (mature in about 70 days)

• Seminal vesicle – pair of glands near bladder where fructose-rich fluid added ~70% of semen

• Prostate gland – adds additional fluid to semen; this fluid is basic and helps sperm survive in the vagina (which is usually acidic ~4) ~30% of semen

Function of Testosterone in Males:

Testosterone hormone produced in testes

• Determines the development of male genitalia during embryonic development (9-10th week of pregnancy it begins)

• Ensures the development of secondary sex characteristics during puberty (e.g., facial/chest hair, muscles, deeper voices)

• Maintains the sex drive of males throughout their lifetime

• Sperm production (spermatogenesis)

In-Vitro Fertilization (IVF)

• Couples may need in-vitro fertilization if:– Male has a low sperm count (<20 million/mL)– Males with impotence (failure to achieve erection)– Females who cannot ovulate normally (hormonal)– Females with blocked fallopian tubes

Process of IVF1. Woman is injected with FSH for ~10 days (this

insures the development of follicles)2. Several eggs are then harvested surgically3. Man donates sperm into sterile container4. Eggs are mixed with sperm in separate

containers5. Doctors observe via microscope which eggs

are fertilized and if they look healthy6. 1-3 healthy embryos are implanted in woman’s

uterus7. Any unused embryos can be frozen and stored

for future use

Ethical Issues of IVFPROS CONS

Enables unfertile couples to have kids

Embryos not implanted are frozen or destroyed

Unhealthy embryos can be discarded instead of implanted

Complex legal issues related to unused embryos during divorce

Genetic screening can be done on pre-implanted embryos

Genetic screening could lead to “ideal/perfect society” issues

IVF technology will advance knowledge/understanding of

reproductive biology

Reproductive issues passed on to children instead of allowing natural

selection to occur

Multiple births

Where did my menstrual cycle go?

1. Pregnancy

2. Menopause

3. Excess weight loss or gain

4. Eating disorders

5. High stress

6. Increased exercise

7. Medications and birth control

8. Breastfeeding