reproductive systems and development Flashcards
—which hormone controls reproductive cycles in males?
androgens
which hormone controls reproductive cycles in females?
estrogens
adrenal glands produce small amounts of both sex hormones, and then…
the gonads start producing a much larger amount of gender-specific sex hormones at puberty
the purpose for the structure of male land animal’s reproductive system?
sperm need to be transferred internally (they die if exposed to air) AND testes are outside the body because the temperature required for sperm production does not match body temp
in females, urinary system and reproductive system are
separate
hormone controls in males: 1 hypothalamus
releases GnRH which controls the entire reproductive cycle
hormone controls in males: 2 stimulates the anterior pituitary to secrete which hormones
-FSH and LH
hormone controls in males: 3. LH (luteinizing hormone) promotes…
testosterone production, which encourages sperm production
hormone controls in males: 4. FSH promotes…
sperm nourishment
hormone controls in males: negative feedback
high levels of androgens inhibit GnRH, FSH, and LH release. this prevents androgen levels from getting too high (too much testosterone lowers sperm count)
in females, the bladder and urethra are
separate from the reproductive system
cervix function:
seals off uterus and traps embryo inside
female reproductivity is based on
cycles
ovarian cycles occurs where?
occurs in ovaries
menstrual/uterine cycles occur where?
uterus
ovarian cycle: 1 Hypothalamus releases…
GnRH which controls the entire reproductive cycle
ovarian cycle: 2 stimulates ____ pituitary to secrete…
anterior pituitary; FSH and LH
ovarian cycle: 3 FSH stimulates ____ and ____ to mature
follicle and egg
ovarian cycle: 4 maturing follicle begins producing
estradiol
ovarian cycle: 5 increasing estradiol levels cause spike in…
LH (luteinizing hormone)
ovarian cycle: 6 luteinizing hormone spikes causes…
egg to be released from follicle (ovulation)
ovarian cycle: 7 swollen follicle had been…
on the surface of the ovary
ovarian cycle: 8 luteinizing hormones stimulates remaining follicle cells to secrete
progesterone and estradiol
uterine cycle: 9 progesterone and estradiol stimulate thickening of …
uterine wall
-increase in blood vessels
-preparing for embryo implantation
uterine cycle: 10
-_____ stops stimulating pituitary,
-pituitary stops producing ______ ___________
- follicle cells stops producing ____ and ______ and uterine lining collapses
hypothalamus
lutenin hormone
progesterone and estradiol
where are gametes produced?
gameotogenesis
oogenesis occurs where?
ovaries
spermatogenesis occurs where?
testes
all gametes are produced via
meiosis
-2 cell division phases
-reduces genetic info by half
spermatogenesis: sperm produced in…
sperm produced in seminiferous tubules
spermatogenesis overview
spermatogonium produced via mitosis divides via mitosis to produce primary spermatocyte. spermatocyte undergoes meiosis 1 and 2 to produce spermatids, which are rearranged to produce sperm. the sperm move to center of seminiferous tubules as they mature
what are sperm essentially?
tiny cells with flagellum, mitochondria, and acrosome with enzymes
females produce all follicles before
birth
oogenesis: each follicle contains…
a primary oocyte which will become an egg
oogenesis: during the ovarian cycle,
the follicle surrounding 1 primary oocyte develops
oogenesis: primary oocyte completes meiosis 1 to create
secondary oocyte
oogenesis: secondary oocyte is released from
ruptured follicle
oogenesis: upon fertilization, egg immediately finishes
meiosis 2
some species are hermaphrodites
-produce male and female gametes
-no separate genders
asexual reproduction: no exchange of
gametes
parthenogenesis:
egg begins development without fertilization
parthenogenesis is most common in
insects (male bees are haploid and arise via parthenogenesis)
examples of mammals that undergo parthenogenesis?
kimodo dragons; hammer head sharks
body division is found only among
invertebrates
fission:
parent animal splits itself in half, creating roughly 2 equally sized organisms
budding:
new individuals develop from small outgrowths of parents, creating multiple smaller organisms
fragmentation:
body is broken into several pieces, regeneration recreates full bodies from each piece
asexual reproduction rate
much faster than sex
fertilization of egg and sperm
-both are haploid with 1 copy of genetic material
-form diploid zygote with 2 copies of genetic information
steps of fertilization
- Acrosomal reaction
- Surface binding
- Blocks to polyspermy
polyspermy
fertilization by more than 1 sperm (kills the embryo)
acrosomal reaction: egg
-eggs are surrounded by a protective coat
acrosomal reaction: sperm
sperm contains acrosome vesicle (has enzymes that break down the egg’s protective coat)
acrosomal reaction
-enzymes released from acrosome
-create a path for sperm through protective layer
surface binding: membrane proteins on __ and ___ must match
sperm and egg
surface binding: if sperm and egg have membrane proteins that fit…
their plasma membranes merge
blocks to polyspermy: the first block
-triggered by correct binding of recognition proteins
-ion channels open allow Na+ into the egg, depolarizing it
-new sperms cannot fuse with depolarized membrane
-starts in 1-3 seconds and lasts a minute
blocks to polyspermy: slow block (cortical reaction)
-only in mammals
fertilization envelope prevents further sperm to fuse with membrane
cleavage:
series of rapid cell divisions during early development
fertilization stage ends when
egg and sperm nuclei fuse
fertilized egg is called a
zygote
blastula:
-ball of cells resulting from cleavage
-cells begin migrating outward from center, forming a larger hollow ball called a blastula
blastocoel:
empty space in the middle of blastula
gastrulation starts…
long series of cell differentiations
reorganization of cells into germ layers:
endoderm cells on OUTSIDE
ectotherm cells in CENTER
mesoderm cells BETWEEN endo and ectos
organogenesis:
organs begin to be formed in the embryo
called a ___ after rudimentary organs form
fetus
neurulation
formation of neural cord, which becomes the CNS
notochord
-forms on one side of the gastrula
-long think round bundle of cells
-releases growht factor
somites
the head begins to form at one end of embryo
morphogenesis:
development of animal shape (controls movement of cells to create that shape)
mechanisms involved in morphogenesis
- Cytoskeletal changes
- Cell rearrangement
- Apoptosis
cytoskeletal changes
- Cytoskeletal changes
- Cell rearrangement
- Apoptosis
cytoskeletal changes
- Internal skeleton creates cell shape
- Cell shape changes can result in movement
- Growth factors initiate change in cytoskeleton
apoptis: is programmed
death
apoptis:
*Cell stops inhibiting internal digestive enzymes
*Crucial part of development
*Some cells or tissues are only important in development
-Are destroyed after they are no longer useful
*Some due to evolutionary developmental history –Are created, perform no function, and are destroyed
-Did something useful in ancestral species
stem cells can form from
dif kinds of cells
totipotent stem cells:
can become any cell in the body
pluripotent stem cells
can become any cell from one germ layer.
multipotent stem cells
can become several related cell types
therapeautic stem cells use what kind of stem cells?
totipotent or pluripotent cells (can only be found in embryos)
stem cells function
divide to create new cells
