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Bio Quiz ch. 39 sect. 3 n 4


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what is the single most important system for the continuation of a species and why?
reproductive system-without it, no species could produce another generation
what happens during the seventh week of development for human male and female embryos?
during the first six weeks, they are identical in appearance. during the seventh week, the testes in the males and the ovaries in the females begin to develop.
what is testosterone?
a male sex hormone produced by the testes that is required for sperm production and the development of male physical characters.
what is estrogen and progesterone?
sex hormones that the ovaries produce. estrogen is required for the development of eggs and for the formation of female physical characteristics. progesterone prepares the uterus for the arrival of a developing embryo
what determines whether the embryo is a male or a female??
male- has sex hormone testosterone
female-has sex homrones estrogen and progesterone
the period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. after birth, neither the testes nor the ovaries can produce active reproducing cells until puberty. at the completion of puberty, the male and female reproductive system becomes fully functional and the male and female reproductive organs are fully developed. it may occur between ages 9 and 15, and begins about a year earlier in males than females.
when does puberty begin???
when the hypothalamus signals the pituitary to produce increased levels of two horomones that affect the gonads. these hormoones are follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
what are some sex characteristics produced by testosterone in males at puberty??
the growth of facial and body hair, inscrease in body size, and deepening of the voice.
when is the process of puberty in males completed??
when large numbers of sperm have been produced in the testes. this means a male can produce and release active sperm.
what are the main structures of the male reproductive system and what do they work together to do??
the testes, the epididymis, the vas deferends, the urethra, and the penis. they work together to deliver sperm.
where are sperm produced???
in the seminiferous tubules, which are tighty coiled and twisted together in the testis.
how does the testes get to the scrotum and why is it there?
just before birth or sometimes after, the testes descend from the abdomen through a canal into an external sac called the scrotum. it remains in the scrotum where the temperature is about 1 to 3 degrees lower than the internal temperature of the body. this is for proper development of the sperm
what is at the tip of the head of a sperm and what is it important for?
a small cap is vital to the process of fertilization.
explain sperm development.
sperm produced in the seminiferous tubules are moved into the epididymis, where it fully matures and is stored. some go from there through a tube called the vas deferens. it merges with the urethra, the tube that leads to the outside of the body through the penis.
what are the glands lining the male reproductive tract and what do they do??
the seminal vessicles, the prostate, and the bulbourenthral glands produce a nutrient-rich fluid called seminial fluid, which combines with sperm to form semen.
explain sperm release from a male.
when a male is sexually excited, the autonomic nervous system prepares the male organs to deliver sperm. sperm are ejected from the penis by the muscle contrations of the smooth muscles lining the glands in the reproductive tract, called ejaculation, which is not completely voluntary.
what are the sex characteristics of females produced by the interaction of estrogen with target cells??
the deveopment of the female reproductive system, the widening of the hips, and development of breasts.
what are the main structures of the female reproductive system and what do they work together to do?
the ovaries, the Fallopian tubes, the uterus, and the vagina. in addition to producing eggs, the female reproductive system prepares the female's body to nourish a developing embryo.
clusters of cells surrounding a single egg. the function of a follicle is to help an egg mature for relase into the reproductive tract. eggs mature within their follicles.
how many immature eggs (primary follicles) is a female born with and how many will she release in her lifetime??
born- 400,000
what happens after eggs mature within their follicles??
roughly once a month, under the influence of FSH, a follicle gets larger and the egg passes through the early stages of meiosis. when meiosis is complete, a single large haploid egg and three smaller cells called polar bodies will be produced.
explain egg release.
when a follicle has completely matured, its egg is released in a process called ovulation. the follicle breaks open and the egg is swept from the surface of the ovary into the opening of one of the two Fallopian tubes. the egg moves through the fluidfilled tube pushed along by cillia lining it. during its journey the egg can be fertilized. after a few days, the egg passes from the fallopian tube into the cavity of an organ known as the uterus. the lining of the uterus is ready to receive a fertilized egg, if fertilization has occured. the outer end of the uterus is called the cervix. beyond the cervix is a canal, the vagina, that leads to the outside of the body.
what simply happens during the menstrual cycle??
an egg develops and is relased from an ovary. in addition, the uterus is prepared to receive a fertilied egg. if the egg is fertilized after ovulation, it is implanted into the uterus and the embryonic development begins. its its not, it is discharged, along with the lining of the uterus.
what are the four phases of the menstrual cycle??
follicular phase, ovulation, luteal phase, and menstration.
describe the follicular phase of the menstrual cycle.
it begins when the level of estrogen in the blood is relatively low. the hypothalamus reacts by producing a releasing hormone that acts on the pituitary gland. the releasing hormone stimulates the anterior pituitary to secrete PSH and LH. they travel through the circulatory system to the ovaries, where they cause a follicle to develop to maturity. as it develops, the cells surrounding the egg enlarge and begin to produce increased amounts of estrogen. this causes the lining of the uterus to thicken in preparation for receiving a fertilized egg. this cycle takes about 10 days.
describe the ovulation phase in the menstrual cycle
the shortest cycle which takes 3 to four days. during this phase something causes the hypothalamus to send a large amount of releasing hormone to the pituitary gland. this caues the gland to produce a sudden rush of SH and LH. The release of these hormones causes the follicle to rupture and a mature egg is released into one of the fallopian tubes.
describe the luteal phase of the mentrual cycle
As the egg moves through the fallopian tube, the reptured follcle turns yellow and is now known as the corpus luteum, meaning "yello body." it continues to release estrogenand begins to release progesterone. rising levels of estrogen stimulate cell growth and tussye development in the lining of the uterus. progesterone adds the fiishing touches to the lining until it is able to accept a fertilized egg. during the first two days of the phase, there is the greatest chance that an egg will be fertilized. if an egg is fertilized by a sperm, it will start to divide. after several divisions a ball of cells will form and implant itself in the lining of the uterus. after a few days, the uterus and the growing embryo will release hormones that keep the corpus luteum functioning for several weeks. this allows the lining of the uterus to mourish and protect the developing embryo.
describe menstration
within two to three days of ovulation, it fertilization does not occur, the egg will pass through the uterus without implantation. the corpus luteum will begin to disintegrate. the old follicle breaks down and releases less and less estrogen and progesterone. the result is a decrease in the level of these hormones in the blood. when the level of estrogen falls below a certain point, the lining of the uterus begins to detach from the uterine wall. this tissue, along with the blood and unfertilized egg, are discharged throuh the vagina. this phase lasts from 3 to 7 days on average. a few days later, levels of estrogen in the blood are once again low enough to stimulate the hypothalamus. this produces a releasing hormone that acts on the pituitary gland, which starts to secrete FSH and LH, and the menstrual cycle starts all over again.
describe fertilization
sperm are released during sexual intercourse, when semen is ejaculated through the penis into the vagina. the penis generally enters the vagina to a point just below the cervix, which is the opening that connects the vagina to the uterus. sperm swim actuvely through the uterus into the fallopian tubes. the egg is surrounded by a thick protective layer that contains binding sites to which the sperm can attach. when it does, a sac in the sperm head ruptures and releases powerful enzymes that break down the protective layer of the egg. once the sperm enters the egg, the membranes around the egg and sperm nuclei rupture and the nuclei are joined. this is fertilization.
the fertilized egg, which undergoes cell division to produce a two-celled embryo. these cells divide again and again to form a ball of cells. the ball of cells attaches itself to the wall of the uterus and continues to divide.
are four days of the zygote dividing in the fallopian tube, the embryo is a solid ball of about 50 cells called a morula.
as the embryo grows, a fluid-filled cavity forms in the center of the morula, transforming the embryo into a hollow structure called a blastocyst. about six or seven days after fertilization, the blastocyst attaches itself to the wall of the uterus. the embryo secretes enzymes that digest a path into the soft tissue.
a cluster of cells gradually forms within the blastocyst which sorts itself into two layers, which then produce a third layer by a process known as gastrulation. the result of gastrulation if the formation of three cell layers known as ectoderm, endoderm, and mesoderm. they are referred to as teh germ layers because alll of the organs and tissues of the embryo will be formed from them.
the germ layers
mesoderm, ectoderm, and endoderm
amnion and chorion
Two of the outer layers of cells of the blastocyst that produces important membranes that surround, protect, and nourish the developing embryo.
the connection between the mother and developing embryo. the developing embryo needs a supply of nutrients and oxygen. it also needs a means of eliminating carbon dioxide and other matabolic wastes. the placenta is the embryos organ of respiration, nourishment, and excretion.
after 8 weeks of development the embryo is called a fetus. by the end of 3 months, most of the major organs and tissues of the fetus are fully formed.
umbillicle cord
connects the fetus to the placenta. it
how long and heavy is the average ffetus after 3 months???
8 cm long and 28 grams.
when may the fetus be able to survive outside the uterus is life-supporing equipment is avaible??
6 months
what are the complex set of factors that affect the onset of childbirth
1. the release of hormone oxytocin from the posterior pituitary gland. it affects a group of large, involuntary muscles in the uterine wall. as these muscles are stimulated, they begin a series of rhythmic contractions known as labor.
2. the opening of the cervix explands until its large enough for the babys head
3. the amniotic sac breaks and the fluid it contains rushes out
the pituitary hormone prolactin stimulates the production of milk in the breast tissues of the mother. butrients packed into that milk contain everything the baby needs for growth and development during the first few months of life.
fraternal twins
when two eggs are released and fertilized during the ssame cycle
identical twins
formed when a single zygote splits apart to produce two embryos. identical twins are formed by the fusion of the same sperm and egg cell and therefore are genertically identical
signs during infancy
4 weeks-2 years
develops coordinated body movements
first teeth appear
begin to understand language
growth in skeletal and muscular systems
signs of childhood
-language is acquired
-motor coordination if perfected
-permanent teeth appear
-long bones reeach 80% of adult size
-personality and social skills formed
signs of adoloescence
-surge in sex homrmones that produces grow spurts
-continued development of intellectual skills and personality changes

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