Growing Fetus Flashcards
ovum
ovulation to fertilization
zygote
fertilization to implantation
embryo
implantation to 5 to 8 weeks
fetus
5 to 8 weeks- term
conceptus
developing embryo or fetus and placental structures
refers to condition of carrying an offspring within the body.
PREGNANCY
a form of reproduction that unites the cell of 2 individuals to form a unique new individual who embodies characteristics of both parents
PREGNANCY
union of ovum and spermatozoa
FERTILIZATION
union generally occurs in the
distal third of the fallopian tube
how many days does implantation occur?
7 days or 5 days
what happens after fertilization in implantation?
the trophoblast burrows into the endometrium ( upper part of uterus), embedding the fertilized egg into the uterine lining
what the endometrium is called after implantation
decidua
fertilization is also referred as?
conception and impregnation
union of ovum and spermatozoa.
fertilization
where does fertilization occur?
Occurs in the outer third of a fallopian tube –– AMPULLAR PORTION
how many times does a woman’s ova reach maturity
once a month
Once the mature ovum is released, fertilization must? and why?
occur fairly quickly
because an ovum is capable of fertilization for only 24 hours (48 hours at most)
after 24 or 48 hours what happens to mature ova?
it atrophies and become
nonfunctional.
describe total critical time span during which sexual relations must occur
72 hours (48 hours before ovulation + 24 hours afterward).
what happens when the ovum is released from the graafian foliicle of an overy during ovulation?
it is surrounded by:
o Zona Pellucida –– a ring of mucopolysaccharide fluid.
o Corona Radiata –– circle of cells.
circle of cells
Corona Radiata
Zona Pellucida
a ring of mucopolysaccharide fluid.
function of zona pellucida and circle of cells to ovum
increase the bulk of the ovum and serve as protective buffers against injury
The ovum and these surrounding cells are propelled into a nearby fallopian tube by currents initiated by the
Fimbriae
fine, hairlike structures that line the openings of fallopian tubes.
Fimbriae
what helps propel the ovum along the length of the tube
combination of peristaltic action of the tube and movements of the fimbrae
where is the ovum and the surrounding cells propelled at?
nearby fallopian tube
ejaculation of semen averages
2.5 mL of fluid
ejaculated semen per mL contains?
50 to 200 million spermatozoa per milliliter.
how many spermatozoa per ejaculation?
400 million sperm per ejaculation.
at ovulation what happens to cervical mucous? why?
reduction in the viscosity (thickness) Making it easy for spermatozoa to penetrate it.
spermatozoa deposited in the vagina generally reach thecervix
90 seconds
spermatozoa deposited in the vagina generally reach
outer end of a fallopian tube within 5 minutes after deposition.
mechanism whereby spermatozoa are drawn toward an ovum
species-specific reaction
how does Spermatozoa move through the cervix and the body of the uterus and into the fallopian tubes, toward the waiting ovum
combination of movement by their flagella (tails) and uterine contractions.
The sperm must undergo 2 processes before fertilization:
① Sperm Capacitation
② Acrosomal Reaction
A final process that sperm must undergo to be ready for fertilization.
Sperm Capacitation
when does Sperm Capacitation happen?
Happens as the sperm move toward the ovum
describe what happens in Sperm Capacitation
changes in the plasma membrane of the sperm head which reveal the sperm-binding receptor sites.
what happens in acrosomal reaction? where does it deposit?
why does it do it?
As millions of sperms surrounds the ovum, they deposit minute amounts of hyaluronidase in the corona radiata. Allows the sperm head to penetrate the ovum
The acrosomal covering of the head of the sperm contains
hyaluronidase.
As soon as the sperm penetrates the zona pellucida, and makes contact with the membrane of the ovum, a cellular change occurs in the ovum that inhibits other sperms to penetrate.
Block to polyspermy.
what mediates the block to polyspermy? where is it found?
by the release of
materials from the cortical granules, ORGANELLES, found just beneath the surface.
what happens after fertilization occurs?
zygote is created
created with a combination of genetic materials which creates a unique individual different from the parents and anyone else.
Zygote
