Transcript for:
Understanding the Reproductive System

Hey everyone, today we're going to look at the reproductive system. Now this body system doesn't have too many updates. As you can see, in T7 you still need to know the structures and the functions and also the relationship between the reproductive system and the endocrine system. And we'll talk about a few important hormones.

I have discussed them previously in T's in the T6 video, but we can go over them again because there are a few and it can get really confusing. Some of the new content I noticed is in the female reproductive system. So it talks about, for example, the process of fetal development, which is new in T7. And also there's more description on the relationship between the reproductive system and the endocrine system.

Okay, so we are gonna go over some of those updates today. So first, let's look at the new material for the female reproductive system. In terms of structures, there are these three structures recently added to the system.

So in addition to ovaries where the eggs are produced and the fallopian tubes where fertilization takes place. So remember that fertilization occurs in the fallopian tube and not in the uterus. Uterus is where an embryo can implant and develop, right? So that's uterus. And the cervix, that's the opening of the uterus and vagina.

On the genitalia, there are these structures that are recently updated. So that includes Libya minora, Libya majora, and the clitoris. I don't know if you will necessarily see questions on those, but just be aware of it. Maybe there will be multiple choice questions and asks you, you know, which of the following structures are part of the female reproductive system or select all that apply. Then you need to remember to select these structures that are part of the external genitalia.

All right, next thing I want to go over is the process of fetal development. As I mentioned earlier, this is something really new in TEAS 7, so be familiar with the different steps in this process. Now we're going to start off with a fertilized egg, right?

Fertilization takes place when the egg and the sperm are fused, right? They kind of merge and they become one cell, their genetic materials are merged too. So a sperm will have 23 chromosomes, an egg will have the same number 23. So when they merge, they become a zygote, right?

And then the zygote will have the unique number of chromosomes for humans, which is 46. Okay, so you and me, we're all start off as a zygote. Now the zygote will go through a few rounds of very rapid cell division. So that's the next step. So one cell becomes two, and then two will become four, four will become eight, right? You can't imagine there's four more on the other side.

So it really kind of looks like a ball of cells. Now, eventually, after a few rounds of mitosis, this will become a blastocyst. So like I said, it really just looks like a ball of cells.

A blastocyst will try to implant in the uterus. So the next step is going to be implantation and the goal is to implant to implant itself in the uterine wall. Now if implantation is successful then this ball of cells will develop into an embryo and a placenta will form.

A placenta is how the fetus can get nutrients, including oxygen from the mother, right? Also, the fetus needs to get rid of all the metabolic wastes, including carbon dioxide. So the placenta is where, you know, the exchange of things happens.

Now, after about 40 weeks, the fetus is ready for birth, and the uterus contracts, and the fetus is being pushed out. So this is a very kind of high level review of the process of fetal development. So make sure you know the major steps, the order of the different steps. Okay, next thing. I know there's a lot of text here.

I was going to just kind of describe verbally, but I think there's just too much information. So I recently added these texts in here. So if you have my PPT slides, these are not on there. But I think it would be better to just put it on the slide so that you guys can see what's going on.

You can make notes if you want, right? But at least it's there. It's just easier to follow. In T7, it mentions puberty.

So during puberty, the hypothalamus secretes gonadotropin-releasing hormone. So think of this as the commander, right? So this gonadotropin-releasing hormone, based on the name, can stimulate the release of hormones that affected the gonads, right?

So what are the gonads? The gonads are testes and males and ovaries in females. These hormones that are stimulated by gonadotropin-releasing hormones include follicle-stimulating hormone FSH and luteinizing hormone LH.

So these hormones are released by the pituitary gland and they do slightly different things. In males, luteinizing hormone signals the testes to produce more testosterone. So it kind of affects the male hormone.

Now testosterone and follicle stimulating hormone together will stimulate spermatogenesis. Sperm-t that refers to sperm, genesis that refers to production, production generation. So spermatogenesis refers to the production of sperm cells.

Now in females, follicle stimulating hormone signals the ovaries to make more estrogen. And what does estrogen do? Estrogen can cause some eggs to mature in the follicles which are present in ovaries. So these eggs will develop and mature in follicles. And a surge of luteinizing hormone.

will cause these developing eggs to be released. And that process is basically ovulation, right, which happens once a month. And once the follicle is empty, right, because the egg has been released, that empty follicle is now called corpus luteum. Why do we mention that? Because corpus luteum is not just an empty follicle that doesn't do anything.

It's an important structure because it produces another female hormone known as progesterone. So progesterone will prepare for the endometrium, which is the innermost layer of the uterus wall, for implantation of the fertilized egg. So if there's a lack of progesterone, you can imagine that this implantation process would probably be affected.

Now progesterone can also calm down the uterus during pregnancy because you don't want the fetus to come out too early, right? So progesterone can keep the uterus calm so that you know the the fetus is not pushed out. All right so that's kind of a quick overview on those two hormones and what they do. And I didn't put this information here because I assume everybody is aware of it, but Male and female secondary characteristics are stimulated by testosterone in male and estrogen in female.

So think about all the secondary sex characteristics developed during puberty. Females enlarge, the breasts enlarge, some changes to the pelvis, right, and then the start of the period. So that's some of the female secondary characteristics. And in males, they can get really hairy, right? There's more rapid hair growth, voice change, more kind of muscle mass growth.

So those are what's commonly seen in males. All right, the last question is about the difference in the production of male and female gametes. So you need to know male gametes are sperm cells, right?

And then female gametes are eggs. How do the productions of those gametes differ? Now there are a few differences. When you think about the production, the actual production process, sperm cells are produced constantly, right?

A male can produce sperm every day, but for females, An egg and sometimes multiple eggs are only released once a month, right? It's not continuous. So that's one major difference.

And another difference is the locations where they're produced, right? One is testes and the other one is ovaries. So that's a pretty obvious difference. Now let's look at some of the practice questions.

Number one, arrange the following events in the correct order. So what happens first? You gotta have fertilization. And fertilization will result in a zygote.

So this zygote is going to undergo rapid mitosis, right? Remember, one cell has to become a ball of cells, right? So E is the second step.

And now we have a blastocyst. So the blastocyst is going to move toward the uterus, and it's going to try to implant in the wall of the uterus. So next step is B. And if implantation is successful, then a placenta will be formed.

And then we talk about the function of placenta. And after about 40 weeks, the fetus is ready to come out. The fetus will be pushed out through the vagina by the contraction of the uterine wall. right? The wall has some really strong smooth muscles and when they contract, they will push the fetus out.

Okay, so that's the correct answer. D, E, B, A, C. All right, next question. Which of the following changes in males could be a result of the production of the luteinizing hormone?

Select all that apply. All right, now personally, I think this question is a little bit tricky because it takes into consideration of the kind of indirect results of the luteinizing hormone. Now remember, luteinizing hormone can stimulate the production of testosterone, right? So D is definitely a correct answer. And testosterone will in turn stimulate or promote the production of sperm.

So B is also correct. Testosterone is also responsible for male secondary sex characteristics developed during puberty, right, which includes increased body hair. So B, C, D are correct answers.

A and E are, you know, are only present in females, so they're not relevant. All right guys, that's the end of the lesson. I forgot to mention that I recently added question number two because I saw a question in the TEAS study manual and I was thinking, this seems a little bit tricky. So I just wanted to have a similar question here so that you know where ATI came from with the answers. All right, well I hope it's helpful.

Good job everyone.