Reproductive System Flashcards
sexual reproduction requires:
- production of functional sex cells (gametes) by adults
- union of these gametes (fertilization or conjugation) to form a zygote
- development of the zygote into another adult
gonads
- organ where gametes are produced
- male: testes (sperm), female: ovaries (oocytes)
- hermaphrodites: have both functional male and female gonads
gametogenesis
- production of functional sex cells
- spermatogenesis (seminiferous tubules) or oogenesis (ovaries)
internal fertilization
- provides a direct route for sperm to reach the egg cell
- increases change of fertilization success and females produce fewer eggs
male reproductive system
-testes are located in an external pouch called the scrotum, which maintains the testes temp at lower than body temp
sperm passes from:
testes thru the vas deferens to the ejaculatory duct then to the urethra which passes thru the penis to the outside
testosterone
- produced in testes
- regulates male sex characteristics (facial hair, voice)
spermatogenesis
- spermatogonia (diploid cells) differentiate into primary spermatocytes (diploid cells), which undergo the first meiotic division to yield 2 haploid secondary spermatocytes
- second meiotic division produces 4 haploid spermatids, which eventually leads to mature sperm (spermatozoa)
mature sperm
- elongated cell with head, neck, body, and tail
- acrosome: cap-like structure develops over the anterior half of head, contains enzymes to penetrate through ovum
female reproductive system
- ovaries consist of follicles (multilayer sac that contains and protects immature ovum)
- oviduct (Fallopian tubes): opens into the uterus, the site of fetal development
- cervix: narrow end of uterus, connects to vaginal canal
oogenesis
- primary oocytes (diploid cells) form by mitosis
- primary oocyte completes meiosis I yielding 2 daughter cells, a secondary oocyte and a polar body
- meiosis II occurs when the zona pellucida (inner layer) and the corona radiate (outer layer) of the oocyte are penetrated by a sperm cell, yielding 2 haploid cells, mature ovum and a polar body
female sex hormones
- estrogen: secreted by ovarian follicles and corpus luteum, stimulate development of reproductive tract , sex characteristics, and thicken the endometrium
- progesterone: secreted by corpus luteum during the luteal phase of mensuration, stimulates development and maintenance of endometrium walls
menstrual cycle
-follicular phase, ovulation, luteal phase, and menstruation
follicular phase
- begins with cessation of the menstrual flow
- FSH from anterior pituitary promote development of the follicle, which secretes estrogen
ovulation
-mature ovarian follicle bursts and releases an ovum
luteal phase
-LH induces the ruptured follicle to develop into the corpus luteum, which secretes estrogen and progesterone
menstruation
-if ovum is not fertilized, hormone levels drop and the endometrium sloughs off, giving rise to menstrual flow (menses)
fertilization
- occurs in widest portion of Fallopian tube
- sperm must penetrate thru corona radiata and zona pellucida
- once in contact with the membrane, sperm forms an acrosomal process which penetrates the membrane and fuses the sperm cell with the ovum, ovum completes meiosis II
cortical reaction
- acrosomal reaction triggers this causing calcium ions to be released into the cytoplasm of the ovum
- initiates a series of reaction that result in formation of the fertilization membrane which prevents multiple fertilizations
monozygotic (identical) twins
-single zygote splits into 2 embryos
dizygotic (fraternal) twins
-2 ova are released in one ovarian cycle and fertilized by 2 sperm, develop from 2 distinct zygotes
cleavage
- series of rapid mitotic divisions
- results in smaller cells with increasing ratio of nuclei to cytoplasm
morula
-solid ball of embryonic cells formed from cleavage
blastulation
morula develops a fluid-filled cavity called the blastocoel, which becomes a hollow sphere of cells called the blastula (implants into the uterus)
