16 Human Reproduction

The chapter talks about differences between the sexes, reproductive anatomy in humans, and how a sperm meets up with an egg to produce an embryo.

There is a discussion of reproductive hormones at the end of the chapter.

The internal structures that assist in procreation are the primary sex characteristics.

The physical characteristics of males and females are different.

If you have time, you can learn the specific details of embryology.

Take the time to learn which structures are produced by the germ layer.

The topic of cell division was discussed in Chapter 9.

The chapter begins by looking at the differences between the sexes.
A discussion of reproductive anatomy and the wild ride that a sperm must take to fertilize the female egg will follow.
The formation of gametes and embryo development will be reviewed.

It's not something you should get hung up on.

The big picture is what you want to know about development.
The AP Biology exam is not an embryology exam.
The chapter ends with a discussion of hormones and their effects on the reproductive system.

Sex characteristics are one of the major differences.

The testes, ovaries, and uterus are included.

Since males tend to be impatient, we will cover male anatomy first.

The delivery of sperm to the female reproductive system is designed for the male.
The journey of a sperm starts at the beginning and ends at the end.

The scrotum is where the male has two testes.

We go back later to look at how the sperm are created.

The hormones involved in the male reproductive system are produced in these structures.
The testis is where sperm and hormones are produced in the male reproductive system.

The coiled structure extends from the testes.

The sperm waits until it is called on to do its duty in the epididymis.
The sperm exits the urethra during ejaculation.

Let's look at some other important players in this process.

The male reproductive system's function is to add a basic (pH > 7) liquid to the mix to help eliminate any urine that may remain in the common urethral passage.
The acidity of the vaginal region of the female helps to combat this.

Everyone should follow us, more to see.

The success of the sperm on its way to the female ovum depends on these characters.
The seminal vesicles dump fluids into the vas deferens when the male ejaculates.

We want to take a quick tour of the female reproductive structures before we observe the sperm as it enters the female reproductive system.

There are two ovaries on either side of the body.

You might be more familiar with that term.
The sperm enters the female reproductive system when we find ourselves in the vagina.

The female body presents different environments that the sperm must survive in.

The fallopian tube is where it must meet the egg and penetrate its outer surface to achieve successful fertilization.
The sperm travels through the vaginal region, up through the cervix, through the uterus, and into the fallopian tube.
If the timing is right, there will be a willing and waiting egg that is hoping to meet with a sperm to produce a new diploid zygote.
After successful fertilization, the new happy couple moves down to the uterus and builds a nice house in the endometrium where it will develop into an embryo and remain until it is ready to be born.

The process by which gametes are formed was discussed in Chapter 9.

The mechanics of gamete formation are different for men and women.

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The host female enters puberty a number of years later after the primary oocyte is stopped.

The menstrual cycle begins here.
Excess genetic info of the polar body is cast away each month.

Excess info is thrown away again.

A secondary oocyte is fertilized by a sperm.

The knowledge you need to score high of the primary oocytes frozen in the first act of meiosis should be reviewed.

The developing embryo will need more than one structure for proper development.

The secondary oocytes are free to travel into the fallopian tube as the menstrual cycle continues.

Fertilization happens in the oviduct.
If a successful fertilization occurs, the secondary oocyte enters meiosis II, again producing a polar body, as well as an egg that combines with the sperm to form a zygote.

It isn't all happening at once for the ova.

The first stage of meiosis can take 40 years for a primary oocyte to sit in the ovary.

The beginning of the menstrual cycle causes a primary oocyte to restart.

After fertilization with the sperm, oocytes undergo meiosis II.

The process is simpler for men.

Guys, let's face it.
Less effort is better.
Less time gives us more time to watch sports and play video games.

Males don't begin forming gametes until puberty.

The seminiferous tubules are where spermmatogenesis occurs.
After production, they enter the epididymis, where their waiting game begins.

You are not taking an AP exam in embryology.

Don't let the complex details get in the way of the basics.
The review questions at the end of this chapter will give you a good indication of the level of detail required for success on the embryology questions of the AP Biology exam.

This zygote divides many times without increasing its size.

The disparity exists because different cells produce different products and the distribution of the cytoplasm plays a role in that.

Humans take a long time to form these divisions.

The first three divisions are completed in three days.

The blastocoel is a fluid filled space in the blastula.

The dividing occurred as the zygote moved toward the uterus through the fallopian tube.
The blastula has reached the uterus and is on the wall by the time it forms.
The chorion is later given rise to by the trophoblast.

The discussion of embryology gets a little tricky here.

Let's take a closer look at this process.

Permission was granted by The McGraw-Hill Companies.

The embryo's first blood cells can be found in the yolk sac.

The yolk sac is important for the embryo in birds and reptiles.

Different cells develop into different structures with different functions when cells are separated from the three primary germ layers.

The basic development of the nervous system is what you should focus on as far as structural and functional differentiation is concerned.

This is only found in the embryo.

The neural tube gives rise to the central nervous system.

The embryo is protected by a fluid-filled cushion.

To name a few, present in birds, lizards, and humans.

Not every cell gets the same amount of cytoplasm.

The asymmetric distribution of the cytoplasm is thought to play a role in the development of the daughter cells.
Different cells can perform different functions.

It is good to know about the experiments of the German embryologist Hans Spemann if you are asked to write an essay about it.

His experiments showed that the notochord causes the cells of the sphygmomanometer to develop into the neural plate.
When cells from the notochord of an embryo are transferred to a different location.
The cells from the notochord region act as project directors, telling the ectoderm where to make the neural tube and central nervous system.

Each segment should grow signal transmission.

The development of the poor can be interfered with by homeotic genes, which can lead to the production of too many cells.

It is found in a variety of organisms, including birds, humans, fish, and frog.

Different areas have different amounts of cytoplasm and may have different structures.

There are regulatory genes that determine how segments of an organisms develop.

The hormones that will be included in the AP exam were discussed in Chapter 15.

There are hormones involved.
You don't need to know everything about the big picture.
Ladies first.
There are hormones involved in the female reproductive system.

The Big Idea 2.C.1 monitors the levels of hormones in the female bloodstream to determine when to release them.

When the concentrations of hormones are low, organs use a feed example.

FSH causes the development of the follicle that contains the primary oocytes.

The hypothalamus releases more GnRH into the system when the follicular cells release estrogen.

There is a surge in the release of hormones from the follicular cells, which have now become a structure called the corpus luteum.

The endometrium is the site of future fertilized egg attachment.
The production of GnRH is cut off at this point in the cycle because of the elevated levels of hormones.
If fertilization has taken place in the fallopian tube and the blastocyst is able to attach to the uterine wall, hCG will be released, which will keep the corpus luteum alive.
The levels of hormones remain high and the endometrium remains intact.

If a blastocyst doesn't implant, the production of hormones will stop and the endometrium will be destroyed.

On average, a woman repeats this cycle every 28 days.

The cycle is disrupted when a spermfertilizes the egg.
The levels of hormones in the body change as a result of the presence of the corpus luteum.
Negative feedback reduces the levels of LH and FSH and leads to the endometrium being damaged if a sperm does not fertilize the egg.
When the levels of hormones in the blood drop low enough, the cycle will begin again with the release of LH and FSH.

In males and females, GnRH causes the pituitary to release hormones.

The production of testosterone in men is caused by the LH.
FSH and testosterone work together to help mature sperm.
Secondary sex characteristics in men are dependent on baseline levels of testosterone.

The answer has become 16 cells and is now given the name.

The developing embryo has a yolk sac.

It gives rise to the muscles and bones in mammals.

The hormones are produced in the cells.

During early pregnancies, this hormone is used to maintain C. Cervix.

The heart is a part of the circulatory system.

The only structure listed that is part of the female reproductive anatomy is the cervix.

The fallopian tube is where maturation occurs.

Humans usually have semi fertilization.
The sperm with the necessary materials to survive the embryo normally occur in the uterus, which is located in the nal vesicles.
The embryo goes from ejaculation to fertilization.
The vas deferens are on the wall of the uterus.
The urethra is a narrow pathway through the cervix.
The cells come from the uterus to the vaginal opening.
The cells that produce hormones are located in the ovary.

AP Biology exam writers at the beginning of each menstrual cycle.

FSH causes the signals to develop.

The germ layers are fed by the estrogen.

The primary oocyte is surrounded by a follicle during development.

Surge in this hormone causes the release of secondary oocytes from the ovary.