Being able to name the hormones of the gonads and state their functions seemed like a pretty easy task, but I was left confused after reading the textbook. So I'll start with the common knowledge. The male and female gonads (sex organs) produce steriod hormones, like the ones produced by adrenal cortical cells. The female gonads consist of the ovaries, and the most important hormones they secrete are estrogens and progesterone. The male gonads consist of the testes (located in the scrotum), and the most important hormones that they secrete are testosterone. Sounds simple enough, right? The textbook was a great help in figuring out this information but instead of referring to the reproductive chapter, I referred to the endocrine chapter. But where does the gonadotrophins come into place? Since the gonadotrophins had the word gonad in them, I was pretty sure that they had to be part of the hormones that the gonads secrete. Wrong! The gonadotrophins actually regulate the release of the gonadal hormones. Im glad that the textbook was able to clear that up.
Functions:
Estrogens: responsible for maturation of the reproductive organs and appearance of the secondary sex characteristics of females at puberty
Progesterone: stimulate the growth of a cushion lining in the uterus where the fertilized egg can grow, promotes breast development and cyclic changes in the uterine mucosa
Testosterone: initiates the maturation of the male reproductive organs and the appearance of secondary sex characteristics and sex drive
Understanding mitosis and meiosis has always been an ongoing battle for me. For some reason when I first learned this concept I always got the two mixed up. I found this chart from chapter 26 page 899 that helped me in figuring out the differences between the diploid cell and the haploid cell. Well, I couldn't get a good picture of it from my camera ( I don't have a scanner) so I used the photo from the lecture outlines, but the photo and information is still the same. I promise. This photo also severed a double purpose because it helps me understand mitosis and meiosis. It never hurts to learn extra information!
So, basically the two cells go like this.
Diploid= Double. There are 46 chromosomes in each diploid cell
Haploid=Half. There are 23 chromosomes in each haploid cell
Through fertilization, two haploid cells combine to produce a zygote. The zygote has now two sets of 23 chromosomes. So 23+23= 46. The zygote now has 46 chromosomes and is a diploid cell. I'm glad that I finally figured out the difference between the diploid and haploid cells. All I seemed to need was a little math.
This video also reinforces the information that the textbook and class lectures gave me about diploid and haploid cells. Still, having an animated diagram allows me to have a visual to remember the information by.
Objective 75: Explain what happens during follicular, ovulatory, and luteal phases of the menstrual cycle Objective 77: Recognize that a blastocyst secretes human gonadotrophin, which prolongs the life of the corpus luetum
When I read this objective, I really believed that it was going to be a no brainer and I could just breeze right through it. But boy, was I wrong! There is a lot more to the menstrual cycle that I previously believed there to be. I honestly don't give my body enough credit, even though I'm pretty sure that all of us women would rather not have to deal with this very precious "gift" mother nature decides to give us. The textbook gave alot of great information regarding this topic, but there was way more information than I could comprehend. I never knew there was so much work when it came to our periods each month! The lecture outlines did a great job in summarizing the follicular, ovulatory, and luteal phases of the menstrual cycle. There is a chart in chapter 26 page 920, that really did reinforce the information, but it was kind of hard to take a clear picture of the chart so instead I borrowed them from our chapter 26 lecture outline. These charts inform you about the fluctuation of gonadotrophin levels, the ovarian cycle, the fluctuation of ovarian hormone levels, and a summary of the three phases of the uterine cycle. Wow, there is so much going on here!
Along with this helpful information from our textbook, I still was having a difficult time understanding all of the steps involved within the menstural cycle. The speaker is a little mono-tone I think, but he summarizes the information on the phases of the menstural cycle and also shows where on the charts the cycle is occuring. He actually breaks the cycle into 4 phases which was a little different then what the book said, but either way this video was helpful in reinforcing what I heard in lecture and read from the book. The video sums up the menstrual cycle perfectly when it states that it is "a complicated hormonal phenomenon". I wouldn't disagree with that logic!
I believe that objective 77 fits very nicely with the menstural cycle, because if fertilization occurs then the blastocyst implants and the corpus luetum prepares for pregnancy. But let's back up here a bit. Human Gonadotrophin is very important in prolonging the lifespan of the corpus luetum. If fertilization occurs, the implanted blastocyst secretes human gonadotrophin, which then effects the corpus luetum. The corpus luetum then secretes estrogen and progesterone until the placenta develps. If fertilization does not occur, the corpus luetum degenerates and the uterine lining sloughs off. The book doesn't do a good job of explaining this whole process to me, but this picture here gives me a little more insight.
When I was trying to differentiate between zygote, morula and blastocyst I could not find anything about them in the textbook. I did, however, find information about the three of them in our lab book and it was very helpful. The lab book describes the accurately describes the three, and is straight to the point. The zygote is the fertilized egg, the morula is a solid ball of blastomeres, and the blastocyst consists of a sphere of trophoblast cells and a cell cluster called the inner cell mass. The diagram in the lab book made figuring out the differences of the three easier because I was able to see where each process took places within the uterus and also a picture of each cell structure. Being able to see where each process takes place in the uterus helps me understand the differences of the three better because I don't have to wonder by reading, I can actually see the pictures of the cell structures. This diagram refreshed my memory of information that I learned in my human growth and development class two years ago. I had just found out I was pregnant and was extremely scared and also a little bit curious on how the process of fertilizating really occurred. My teacher at the time was very animated and vocal, so when she came across this information she made it very interesting and with my new curiousity for the subject it kind of stuck. So this chart and clips of texts from the book were a great refresher.
When I was trying to understand the similarities and differences of spermatogenesis and oogenesis, the text book was not very helpful. The paragraphs were long and the wording was very confusing to me. And there was nothing in lab that I could get to help me have a better understanding of the two. So I searched on the internet and found a video that compared and contrasted Spermatogenesis and Oogenesis under the Pearson website. Although the video wasn't from the book that we are currently studying from, this textbook is also from Pearson and provided the help I was looking for. The video shows the phases of meiosis for each the male and the female. The chart in the middle of the video was also very beneficial because it showed the male and female timing, location and haploid vs diploid product for before birth, during puberty and after puberty.
Objective 71: Explore how spermatozoa move through the female reproductive tract
Objective 72: Evaluate fertilization in terms of evolutionary fitness
I know us woman really hate to admit it, but the sperm is a pretty amazing thing. The textbook was what I referred to figure out how spermatozoa moved through the female reproductive tract, but it really didn't do me any justice. I was able to find a picture on another site that shows the path of the sperm as it traveled through the female reproductive tract and that was pretty simple and to the point. What the textbook did inform me of was the structure of the sperm that allows it to make this incredible journey to fertilization. Spermatozoa consists of a head, mid piece, and tail. The head of the sperm contains compacted DNA and an outer helmet like layer called the acrosome that helps pierce the egg for fertilization. The mid piece contains the mitochondria, which provides the ATP needed for the movements of the tail to propel the sperm along. The tail allows the sperm to move easily and help it reach the egg.
But wait, there's more! Every sperm is perfectly equipped to make that long journey to fertilization, but not every sperm will reach the egg. This is where evolutionary fitness comes into play. Basically, only the "strongest" and "fastest" swimmer will make it to the egg. So, I see it as natural selection out of millions of sperm trying to reach that one "goal". The book gives a very good description on how the sperm adapts to the enviroment of the female reproductive system. Sperm is transported in semen that activates the sperm, helps their movement and protects them. The alkalinity of semen helps neutralize the acid enviroment of the male's urethra and the female's vagina. This protects the sperms and enhances their motility. Without the special structure of the sperm and the amazing adaptations of the body, the sperm would not be fit enough to make it to fertilization.
Here's a little photo I was sent a couple years ago. It made me laugh, and I believe it ties in very well with this subject.
Viewing diagrams of the male and female reproductive systems are what really helped me learn and understand them. Along with the text in our textbook about the reproductive systems, the diagrams I was able to research of each system allowed me to visually see where each organ was located instead of just reading the terms. I have a hard time remember the directional anatomy terms at times, so just reading the text is not enough. These diagrams were informative and detailed, and accurately showed each important part of both reproductive systems.
