Reproduction The Reproductive System Variation and Reproduction Hormones and puberty Male and female reproductive structures The Menstrual Cycle

Reproduction and Variation Variation results from:  Independent assortment of chromosomes Variation exists even between individuals of the same family produced by the same parents. This is due to the fact that the number of different gametes that can be produced from a cell undergoing meiosis is very big 2 23 or 8,338,608  Crossing over occurs in prophase I of meiosis and results in recombination of gene  Random fertilization (sexual reproduction)

Hormonal Regulation in Puberty Puberty in females  Over a period of ~4 yrs. In the life of females, the amount of estrogen secreted by the ovaries rises.  Estrogen causes girls to develop secondary sex characteristics (puberty) Vagina and uterus enlarge Vagina begins to secrete fluids Breasts enlarge Pubic and armpit hair begin to grow Pelvis enlarge Fat is deposited under the skin of the thighs and buttocks Ovulation begins, menstruation follows

Hormonal Regulation in Puberty Puberty in males  Over a period of ~4 yrs. in the life of males, the amount of testosterone secreted by the testes rises.  Testosterone causes the development of the following secondary sex characteristics (puberty): Penis and testes grow larger The prostate gland and seminal vesicles begin to secrete fluid Larynx grows larger, voice becomes deeper Pubic, armpit and facial hair begin to grow Skeletal muscles enlarge Sperm is produced and released during ejaculation

Male Reproductive Structures Draw a clearly labeled diagram of the male urogenital system Label and briefly describe the role of:  Urinary bladder  Ureters  Scrotum, testis  Epididymis  Vas deferens  Seminal vesicles  Prostate gland  Cowper’s gland  Urethra

Female Reproductive Structures Draw a clearly labeled diagram of the female reproductive system Label and briefly describe the role of:  Oviduct or fallopian tube  Fallopian funnels  Ovary  Ovarian follicle. Corpus luteum  Endometrium  Uterus  Cervix  Vagina

The Menstrual Cycle During this cycle that lasts ~28 days, one egg (ova) (in some cases a few) is produced and released into the fallopian funnel The egg travels through the fallopian tube and reaches the uterus. The uterine lining (endometrium) thickens periodically every month in anticipation of implantation If there is no fertilization, no implantation, the lining breaks and shed The menstrual cycle starts with menstruation, marked by the bleeding caused by the breaking of the endometrium

Hormonal Balance and Menstruation See charts (textbook)