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73 Cards in this Set

  • Front
  • Back
the reproductive system consists of
gonads, reproductive tract,and accessory sex glands
Primary reproductive organ for male
pair of testes
primary reproductive organ for females
pair of ovaries
Both male and female primary reproductive organs produce:
gametes (germ cells)
male germ cells (gametes):
spermatozoa
female germ cells(gametes):
ova
Both male and female primary reproductive organs secrete hormones, ------ for males and -------- and ------ for females:
testosterone
estrogen and progesterone
unique secondary sexual characteristics found in each gender. traits include:
differences in body configuration and distribution of body hair
essential functions of male:-------- and --------
production of sperm and delivery of sperm to female
essential functions of female: 6
production of ova, reception of sperm, transport of sperm and ovum to a common site for union, maintenace of the developing fetus, partuition (giving birth),and nourishing the infant (lactation)
production of fertilization = embryo
After --- months, considered a fetus.
two
human somatic (body) cells have -- chromosomes (--homologous pairs)
46,23
reproductive cells (ova or sperm) each contain a half set of chromosomes
gametes (sperm or ova) have the haploid chromosome number 23
a sex cell (ovum or sperm) has one chromosome of each kind, not 2 as in the ------- state
diploid
cell division requires division of the --- and ---
nucleus and cytoplasm
-----maintains the chromosome number, chromosome combination, and genetic identity of the chromosomes from the dividing parent cell to the two daughter cells produced
mitosis
mitosis produces ---- cells
somatic
----: one chromosome from each chromosome pair is inherited in each of the four daughter cells produced from a parent cell
meiosis
---- produces gametes (gametes have 1/2 the chromosome number)
meiosis
gametogenesis
occurs by meiosis, sperm and ova have unique haploid number of chromosomes, fusion of sperm and ovum results in new diploid individual
Autosomes
22 of the 23 chromosome pairs
sex chromosomes
23rd pair is either XX or XY
gamete normally receives one member from each pair (X or Y male or X or X female)
combination of sex chromosomes determines the sex of an individual (the genetic sex), which determines the gonadal sex (testes or ovaries)
sexual differentiation (development of embryonic external genialia and reproducyive tract) depends on:
the presence or absence of masculinizing determinants in utero
female reproductive physiology is more complex than male reproductive physiology
female reproductive physiology involves complex cycling of female sex hormones
menstrual cycle repeats unless fertilization occurs
if fertilization occurs, cycle is interrupted and system adapts for nurturing and protecting developing embryo and fetus
ovaries produce:
ova and hormones (estrogen and progesterone)
Functions of estrogen
maturatoin and maintenance of the female system, establishment of female secondary sexual characteristics, ova maturation and release,and transport of sperm from vagina to site of fertilization in oviduct
important progesterone function:
prepares suitabe environment for nourishing dveloping embryo and fetus
oogenesis =
female gametogenesis
oogonia =
undifferentiated primordial sex cells
ooginia divide ________
mitotically
first meiotic division of oogonium produces
a primary oocyte (diploid)
oogonium is surrounded by
granulosa cells
together, an oocyte and surrounding granulosa cells make the
primary follicle
from puberty to menopause, some primary follicles develop into secondary follicles on a cyclical basis
these follicles, including the oocytes enlarge
just before ovulation, the primary oocyte completes its first meiotic division
one product: a larger secondary oocyte
another product: first polar body
secondary oocyte is ovulated and possibly fertilized
sperm entry into the oocyte triggers the second meiotic division. this meiosis produces a second polar body (haploid) abd a haploid mature ovum.
reproduction depends on the union
male and female gametes (germ cells)
accessory sex glands:
empty their supportive secretions into the reproductive tract
pubic and axillary hair gowth during puberty is not considered a secondary sexual characteristic because it occurs in both males and females
it is promoted in both sexes by androgens (different androgens for males than females)
placenta=
organ of exchange between mother and fetus
oviducts=
fallopiam tubes
cervix=
lowest portion of the uterus, projects into the vagina
vulva=
the female external genitalia (labia minora, labia majora and clitoris)
diploid = 46 chromosomes
haploid = 23 chromosomes
chromosomes composing a matched pair are called
homologous chromosomes, one member of each pair having been derived from the individual's meternal parent and the other member having been derived from the paternal parent
gametes contain only 1 member of each homologous pair for a total of 23 chromosomes
haploid number
gametogenesis is accomplished by
meiosis
nuclear divisoin in gametes is accomplished by meiosis
in which only half set of genetic info (haploid # of chrom.) is distributed to each of the four new daughter cells
in mitosis, the chromosomes replicate (make duplicate copies of themselves), then the identical chromosomes are separated so that a complete set of genetic info (diploid # of chrom.) is distributed to each of the --- new daughter cells.
2
autosomal chromosomes:
code for general human characteristics as well as for specific traits such as eye color
differences between males and females exist at 3 levels:
genetic, gonadal, and phenotypic(anatomic) sex
SRY
the single gene that is responsible for sex determination
the ovaries, as the primary female reproductive organs, perform the dual function of producing ova (oogenesis) and secreting the female sex hormones, estrogen and progesterone
these hormones act together to promote fertilization of the ovum and to prepare the female reproductive system for pregnancy.
oogenesis (producing ova) contrasts sharply with spermatogenesis in several ways even though the identical steps of chromosome replication and division take place during gamete production in both sexes
the undifferentiated primordia germ cells in the fetal ovaries, the oogonia, divide mitotically to give rise to 6-7 million oogonia by the 5th month of pregnancy, when mitotic proliferation ceases.
during the last part of fetal life, the oogonia begin the early steps of the first meiotic division but do not complete it
known now as primary oocytes (they contain the diploid number of chrom. which are gathered into homologous pairs but do not separate.)
the primary oocytes remain in this state of meiotic arrest for years until they are prepared for
ovulation
before birth, each primary oocyte is surrounded by a single layer of granulosa cells
together an oocyte and surrounding granulosa cells make up a primary follicle.
oocytes that fail to be incorporated into follicles self destruct by
apoptosis
at birth only about 2 million primary follicles remain, each containing a single primary oocyte capable of producing a single ovum
NO new oocytes or follicles appear after birth; the follicles already present in the ovaries at birth serve as a reservoir fro which all ova throughout the reproductive life of a female must arise. of these follicles, only bout 400 will mature and release ova.
the pool of primary follicles present at birth gives rise to an ongoing trickle of developing follicles.
once it startes to develop, a follicle is destined for 1 of 2 fates: it will reach maturity and ovulate, or it will degenerate to form scar tissue (atresia).
until puberty, all the follicles that start to develop undergo atresia in the early stages without ever ovulating.
even for the first few years after puberty, many of the cycles are anovulatory (no ovum is released).
of the initial pool of follicles, 99.98% never ovulate but instead undergo atresia at some stage in development.
by menopause, few primary follicles remain, having either already ovulated or become atretic. from this point on, the woman's reproductive capacity decreases.
this limited gamete potential, which is already determined at birth in females, is in sharp contrast to the continual process of spermatogenesis in males, who have the potential to produce several hundred million sperm in a single day.
furthermore, considerable chromosome wastage occurs in oogenesis compared with spermatogenesis.
the primary oocyte within a primary follicle is still a diploid cell that contains 46 doubles chromosomes.
from puberty until menopause, a portion of the resting pool of follicles starts developing into secondary follicles on a cyclical basis.
the mechanisms that determine which follicles in the pool develop during a given cycle are unknown.
development of a secondary follicle is characterzed by growth of the primary oocyte and by expansion and differentiation of the surrounding cell layers.
the oocyte enlarges about a thousandfold.
this oocyte enlargement is aused by a buildup of cytopllasmic materials that will be needed by the early embryo
just before ovulation, the primary oocyte, whose nucleus has been in meiotic arrest for years, completes its first meiotic division.
this division yields two daughter cells, each receiving a haploid set of 23 doubles hromosomes.
most all of the cytoplasm remains with one of the daughter cells, now called the secondary oocyte, which is destined to become an ovum.
the chromosomes of the other daughter cell together with a small share of the cytoplasm form the first polar body.
in this way, the ovum-to-be loses half of its chromosomes to form a halpoid gamete but retains all of its nutrient rich cytoplasm.
the nutrient poor polar body soon degenerates.
actually, the secondary oocyte, and not the mature ovum, is ovulated and fertilized, but common usage refers to the developing female gamete as an ovum even in its primary and secondary oocyte stages.
sperm enrty into the secondary oocyte is needed to trigger the second meiotic division. oocytes that are not fertilized never complete this final division.
during the second meiotic division, a half set of chromosomes along with a thin layer of cytoplasm is extruded as the second polar body.
the other half set of 23 maternal chromosomesunite with the 23 paternal chromosomes of the penetrating sperm to complete fertilization.