Chap 30 Animal Reproduction and Development Flashcards
Animal development begins with what?
reproduction
What are the shared features of all multicellular life?
reproduction and development
What are sex cell that meet in fertilization?
gametes
The what of a sperm enters an egg a fuzes with what of an egg?
haploid nucleus of sperm
haploid nucleus of egg
What are male gonads?
the testes
How many testes do males have?
2
What is the sac that holds the testes?
the scrotum
Why are the testes located outside the abdominal cavity?
to allow for temperature regulation
When does sperm development (spermatogenesis) begin?
at puberty
Where are male germ cells formed?
in the developing fetus (they stay inactive inside the testes until puberty)
When does spermatogenesis occur?
begins at puberty and continues constantly throughout adulthood
Sperm are adapted for what?
swimming and fertilizing eggs
What does each mature sperm cell contain?
haploid nucleus
long flagellum
mitochondria
caplike acrosome
What does the caplike acrosome do on a sperm cell?
helps it penetrate the egg cell
What influences male reproductive function?
hormones
What are female gonads?
ovaries
How many ovaries in a female?
2
Where are the ovaries located?
inside the body cavity
Each ovary is surrounded by finger like extensions of a what leading to where?
uterine tube
uterus
Egg development (oogenesis) is similar to what?
spermatogenesis
Secondary oocytes do what?
rupture the follicle
Meiosis I produces two haploid cells what are they?
large secondary oocyte
polar body
The secondary oocyte is from the ovary to the uterine tube, what is this process called?
ovulation
The polar body contains almost no what?
cytoplasm
What influences female reproductive function?
hormones
Hormonal fluctuations produce two what?
interrelated cycles
What are the two interrelated cycles?
ovarian cycle
menstrual cycle
The ovarian cycle is regulated by what hormones?
FSH (follicle-stimulating hormone)
LH (luteinizing hormone)
The menstrual cycle is regulated by what hormones?
estrogen
progesterone
What stops the cycle?
a zygote
If pregnancy occurs the zygote divides in the uterine tubes and develops into a what?
blastocyst
Where does the blastocyst go?
it implants itself in the thickened endometrium
What does the blastocyst do?
secretes human chorionic gonadotropin
What does human chorionic gonadotropin do?
prevents regression of the corpus luteum
What keeps the endometrium intact?
continues progesterone production
When can conception occur?
as soon as an ovary releases an egg
How long can sperm survive inside the female reproductive tract?
a few days
Can ovaries release multiple eggs at different times?
yes
When does the fertile period begin?
five days before ovulations
How long does the fertile period last?
3-4 days after ovulations
Hormone contraception does what?
prevents reproduction
What are the types of hormonal contraceptives?
pills patched vaginal rings injections implants
How do hormonal contraceptives work?
they contain synthetic forms of progesterone and therefore prevents ovulation
What are the most effective methods of contraception?
surgery
intrauterine devices
What can be transmitted during sex?
diseases
Contraception is not generally intended to prevent what?
STDs
The spread of STDs can be prevented or decreased with what?
use of latex condoms
only one sexual partner
vaccinations (only for some)
abstinence
When does the zygote divide for the first time?
24 hours after fertilization
When the zygote fist divides is begins a period of rapid mitotic cell division called what?
cleavage
What happens around day 7 after fertilization?
the blastocyst (or pre-embryo at this time) becomes embedded in the endometrium
Where does the blastocyst obtains nutrients?
the uterine lining
What begins after implantation?
the embryonic
When does the embryonic stage start?
3 weeks
In the embryonic stage the embryo produces what?
structures that support its development
What are the strictures formed by the embryo?
chorionic villi
amniotic cavity
What does the chorionic villi do?
projects into the uterine lining and exchange nutrients with maternal blood
What does the amniotic cavity have/do?
fluid that cushions the embryo and maintains constant temperature and pressure
The chorionic villi will eventually develop into what?
the placenta
During what stage does organ formation occur?
embryonic stage
When do sex differneces become apparent
between 7-9 weeks after fertilization
When does the fetal stage begin?
at week 9
What happens in the fetal stage?
organs become functional
bones replace cartilage
nerves and muscles begin to coordinate actions
What matures near the end of pregnancy?
the digestive and respiratory systems
neural connections from in the brain
When does birth occur?
around 38 weeks
What are the 3 steps of childbirth
labor
delivery
uterus expels the placenta
What happens in labor?
the amniotic sac breaks
hormones prompt uterine muscle contractions
the baby’s head presses against and opens the cervix
What happens in delivery?
the baby descends through the vagina
How long do humans develop before birth?
9 months
A fetus born before when is not viable?
22 week (after this time the chance of survival increases)
When is birth considered premature?
if it occurs before 35 weeks (about 8 months) of gestation
