Processes of Conception (exam 1) Flashcards
Spermatogenesis
the meiotic process by which male gametes are produces
Oogenesis
the process by which female gametes are produced
Meiosis occurs when
the germ cell divides and decreases their chromosomal numbers by 1/2 and are called gametes or zygotes
In the mitosis stage
the 23 chromosomes of the ovum unite with the 23 of the sperm making 46 chromosomes (germ cell)
smallest cell in the male body
sperm
production of sperm begins
at puberty in response to testosterone
- predictable amount of sperm production from early teens to advanced age (not cyclic)
important factor in production of adequate numbers of sperm
temperature (Dartos muscle)
sperm are transported in secretions from the
seminal vesicles and the prostate gland (seminal fluid)
pH of seminal fluid
Alkaline -> helps to neutralize the normally acidic female vagina in an attempt to assure viability of the sperm until it can fertilize an ovum
largest single cell in the body
Ovum
lifespan of sperm after ejaculation
48-72 hours
of sperm per normal ejaculation
200-500 million
average sperm travel time to egg
4-6 hours, but can be as little as 5 minutes
motion that transports sperm
flagellated, whip like motion
oocytes form by
12 weeks gestation
- females have a lifetime supply of oocytes at birth
- born with the amount of eggs they will ever have
amount of eggs that mature in a lifetime
400-500
hypothalamic-pituitary-ovarian axis
hypothalamus exerts control through release and inhibiting factors
ovarian cycle
maturation and ovulation of primary ova follicle is cyclic
- ovulation occurs 14 +/- 2 days before the next menstrual period
- 1 ovum matures each month with supportive cells
- increase in estrogen increases motility of the Fallopian tubes and fimbriae (cilia)
- captures the ovum and propels it to the uterine cavity
*An ovum cannot move by itself
conception
sperm meets egg (fertilization) in the outer 1st 1/3 of the fallopian tube
Females 22XX
Males 22Xy
- 23 chromosomes = 22 pairs are autosomes (traits in the body), leaving 2 chromosomes to determine the sex
Zygote (2 cells) begins descent through FT to uterus
prep for conception
Hyaluronidase -> path through cells for sperm to reach ovum
One sperm penetrates the ovum
Membrane of the ovum changes -> prevents entry of other sperms
Capacitation also occurs
Blastocyst
Inner layer of cells
undifferentiated embryonic cell
Secretes HCG to make sure that the corpus luteum remains viable
capacitation
removes the protective coating from the heads of the sperm - cannot penetrate the ovum
Corpus Luteum
secretes estrogen and progesterone first 2-3 months of pregnancy
main source of estrogen and progesterone until the 3rd month of pregnancy -> placenta takes over
First weeks of human development:
Follicular development in the ovary, ovulation, fertilization, and transport of early embryo down uterine tube and into uterus, where implantation occurs