Ch.17: Reproductive System

Female gonads

(ovaries) produce oocytes (eggs)

Male gonads

(testes) produce sprem

Menstrual cycle

- follicular pase - ovulation - luteal phase - menstruation

Menstruation

- if the ovum is not fertilized, the corpus luteum degrades, result in decrease of estrogen and progesterone levels, which cause the endometrium to slough off, giving rise to the menstrual flow (menses) - if fertilization occurs, the developing placenta produces hCG (human chorionic gonadotropin), maintaining the corpus luteum as well as the supply of estrogen and progesterone that maintains the uterus. Eventually the placenta will take over production of these hormones

Progesterone

- steroid hormone secreted by the corpus luteum during luteal phrase of the menstrual cycle - stimulates the development and maintenance of the endometrium in preparation for implantation https://classconnection.s3.amazonaws.com/875/flashcards/1191875/jpg/femrep1335122672747.jpg

Estrogen

- steroid hormones necessary for normal female maturation - stimulate the development of the female reproductive tract, contribute to the development of secondary sexual characteristics, and influence libido - responsible for the thickening of the endometrium (the inner lining of the uterine wall) - secreted by the ovarian follicles and the corpus luteum

The production of functional sex cells is called___________

Gametogenesis

The gametes are produced in specialized organs called_____

Gonads

Egg production (female)

Oogenesis

Sperm production (male)

Spermatogenesis

Other than sperm, testes also produce_________

Testosterone

Female Sex Hormones

The ovaries synthesize and secrete female sex hormones, including estrogens and progesterone. The secretion of both estrogens and progesterone is regulated by luteinizing hormone (LH) and follicle stimulating hormone (FSH), which are regulated by gonadotripin-releasing hormone (GnRH)

Follicular phase

begins when the previous menstrual flow stop; during this phase, FSH from the anterior pituitary promotes the development of the follicle, which grows and begins secreting estrogen

Fertilization

egg and sperm combine to form zygote with diploid number of chromosomes - an egg can be fertilized during the 12-24 hr after ovulation - occurs in the lateral, widest part of the fallopian tube

Ovaries

found in abdominal cavity below digestive system; consist of thousands of follicles

Dizygotic twins

fraternal twins, result when 2 ova are released in one ovarian cycle and are fertilized by 2 different sperm. Share no more characteristics than any other siblings since they develop from 2 distinct zygotes

Sexual reproduction

genetic material of 2 organisms combines and results in genetically unique offspring Required: - functional sex cells or gametes by adult organisms - fertilization or conjugation to form zygote - development of zygote into another adult, completing the cycle

Monozygotic twins

identical twins, result when a single zygote splits into 2 embryos. Occasionally the division is incomplete, resulting in the birth of "Siamese" (conjoined) twins, which are attached at some point on the body and often share limbs and organs. Genetically identical twins

Ovum to sperm route (sperm actually travel to ovum in reverse order)

immature ovum released from ovary into abdominal cavity and drawn by cilia into the nearby oviduct (fallopian tube) --> uterus --> cervix --> vaginal canal - sperm remain viable for 1-2 days after intercourse

Follicle

multilayered sac of cells that contains nourishes and protects immature ovum; also produce estrogen

Luteal phase

occurs after ovulation, LH maintains fraction of the ruptured follicle (corpus luteum), which secretes estrogen and progesterone - Progesterone causes the glands of the endometrium to mature and produce secretions that prepare it for the implantation of an embryo - Progesterone and estrogen are essential for the maintenance of the endometrium

Ovulation

occurs midway through the cycle; a mature ovarian follicle bursts and release an ovum. Ovulation caused by a surge (increase) in LH that is produced, and in part caused by a peak in estrogen levels

Hermaphrodites

organisms that contain both male and female gonads (i.e. hydra and earthworm)

Internal fertilization

practice by terrestrial vertebrates and provides direct route for sperm to reach egg cell; thus, increase the chance of fertilization success and female produce fewer eggs. (species that care for their young produce fewer eggs)

Testosterone

regulates secondary male sex characteristics including facial and pubic hair, and voice changes

Testes are located in_______

scrotum - an external punch near penis that maintains testes' temp at 2-4C lower than body temp, which creates a condition where sperm can survive

Uterus

site of fetal development

Sperm route

sperm pass from testes --> vas deferens --> ejaculatory duct --> urethra --> penis --> glans of penis (see pg. 192)