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)
gastrulation
-embryo is fully implanted and cell migrations transform into a 3-layered structure called a gastrula
germ layers of the gastrula
- ectoderm: integument, lens, retina, nervous system
- endoderm: epithelial lining of digestive and respiratory tracts, liver, pancreas, thyroid, and bladder
- mesoderm: musculoskeletal system, circulatory system, excretory system, gonads, CT
neurulation
-regions of the germ layers begin to develop into a rudimentary nervous system
notochord
rod of mesodermal cells under the dorsal layer of ectoderm, causes ectoderm to form a tube which gives rise to the brain and spinal cord
neural crest cells
cells at the tip of each neural fold, migrate laterally and give rise to sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann cells
development
- organogenesis: organs begin to form
- growth: organs increase in size
- gametogenesis: eggs and sperm develop
placenta development
-placenta and umbilical cord, supplies O2 and removes CO2
amnion
-thin, tough membrane containing amniotic fluid (shock absorber)
chorion
- surround amnion
- placenta formation begins
allantois
-connects fetus to the developing placenta
yolk sac
-site of early development of blood vessels
gestation (pregnancy)
- first trimester: organs begin to develop, heart beats, bones begin to form; fetus
- second: face appears, growths
- third: growth and brain development
labor
- series of strong uterine contraction
- cervix thins, uterus contracts
