|
|
|
Structure
Interesting Questions, Facts and Information
- There are a total of 30 general entries.
Special Topics
|
 Interesting Questions, Facts, and Information
 Reproduction and Genetics
| Not all women have normal, predictable menstrual cycles. Many women encounter heavy bleeding. Some deal with intense pain. Others may stop having or skip periods. What condition does the term dysmenorrhea refer to? | Menstruation-The Facts
|
Excessively painful periods. In many young women, the hormone prostaglandin is responsible for uterine contractions causing severe menstrual cramping. Sometimes diseases such as endometriosis or uterine fibriods may be the cause of your pain. In any case a doctor should be consulted.
| After the egg (ovum) is released during ovulation, it makes its way via the Fallopian tube to the uterus. This is when the hormone progesterone comes into play. Its levels rise and help prepare the uterine lining for a possible pregnancy. If a pregnancy does not take place, levels of estrogen and progesterone drop and the uterine lining is shed as the woman's next menstrual cycle. What happens to the unfertilized ovum? | Menstruation-The Facts
|
It is dissolved or absorbed into the body. Menstrual blood is partly blood and partly tissue that is shed from the uterus. It escapes the uterus via the cervix and passes out of the body through the vagina.
| As FSH stimulates the follicles (eggs), a race begins. Usually one egg (although there can be more than one, as is the case in some multiple births,) will develop and mature quicker than the others. Suddenly there is a surge in the levels of luteinizing hormone (LH). This causes the egg to be released from the ovary. This is referred to as ovulation. In a normal 28 day cycle, on average, on what day would this take place? | Menstruation-The Facts
|
Day 14. As mentioned above not all fertile cycles are 28 days in length. Ovulation typically takes place 14 days before the first day of the next menstrual cycle. Thus in a 30 day cycle, ovulation would take place on day 16, not day 14.
| During the first phase of the menstrual cycle, a woman's estrogen levels are high. This results in the lining of the uterus growing and thickening in order to nourish a developing zygote (fertilized egg) should a pregnancy take place. What hormone acts on the eggs in the ovary causing them to mature? | Menstruation-The Facts
|
follicle-stimulating hormone (FSH). As its name implies, FSH, or follicle-stimulating hormone, acts on the follicles (or eggs) causing them to mature in readiness for a possible pregnancy.
| The length of an average menstrual cycle is 28 days, however, a 'normal' cycle can range anywhere from 23 to 35 days in length, depending on the woman. What part of the cycle is counted as day 1? | Menstruation-The Facts
|
First day of menstrual bleeding. When keeping track of the days in a cycle, day 1 is counted as the first day of menstrual flow. Some women will have brownish spotting for a day or two prior to actual blood flow. Your gynecologist will tell you to count the first day of 'bright red' flow as day 1.
| 'Menarche' is the medical term used to refer to a girl's first menstrual cycle. Every young girl's reaction to her first period is as individual as is each girl herself. How each will deal with this normal and natural event will depend largely on how well informed she is about menstruation. A wise mother will explain to her daughter that having a 'period' is a natural step toward becoming a woman and is something to feel good about. In developed countries, what is the 'average' age at which a girl will have her first period? | Menstruation-The Facts
|
12. Of course not all girls will begin their period at the same age. Some girls menstruate as early as age 8, while others will not start until 16 years of age. Heredity, as well as environmental and health issues, also seem to have an impact on when a girl will begin to menstruate. In any case, menstruation will not begin until all the parts of a girl's reproductive system have developed and have begun to work together.
German. Twin comes from the word 'twine', which in German means 'two together'. Twins are always two babies, and they are twins really because they come together, and not at separate births like other babies.
| When twins of the same gender, who share the exact same DNA, are born, they are called 'identical twins'. When twins don't share exactly the same DNA, and can be different genders, what are they called? | Double Doesn't Mean Trouble - Twin Quiz
|
Fraternal twins. Fraternal twins are just like normal brothers and sisters, but they are born at the same time. Identical twins are much rarer. My sister and I are identical twins - we're special! Siamese twins are twins that are born conjoined. This can be corrected by surgery, but depending on where the twins are conjoined, it can be very dangerous. The others I made up, however twins and single babies can be born through caesarean.
Bispecies, I'm not sure if it's a word, but if it is, it would mean two species.
Bi : two
Species: species
There are no types of twins that are two different species, that's for sure!
| A bit of a bonus question here: If the zygote consists of only one cell, and the average adult consists of about 100 trillion (10^14) cells, approximately how many cell divisions would have to occur between zygote and adult? | Reproduction and Development
|
47. Yup, only 47 divisions. The one-celled zygote divides by mitosis into 2 cells, which then each go on to divide into 2, giving a total of 4, then 8, then 16, and so on. The mathematics behind this is simply 2^47 = approx. 10^14.
I hope you enjoyed playing my quiz, and maybe you learned something new. Please remember to rate and happy playing!
| Homeotic genes are genes which specify anatomical identity to different parts of the embryo, e.g. which side will be the anterior and which will be the posterior. Also called segmentation genes, what are they normally known as when talking about vertebrates? | Reproduction and Development
|
Hox genes. The answer is Hox genes.
Homeotic genes encode transcription factors for proteins. It is the relative concentrations of these certain proteins that determines body axes.
Mesoderm. The correct answer is mesoderm, which goes on to form structures such as the skeleton, muscle and blood. The endoderm eventually forms the gastrointestinal tract, and the ectoderm forms the skin.
| When the sperm gets through the zona pellucida and into the egg cytoplasm, its pronucleus then fuses with the egg pronucleus to create the zygote. There are two methods of blocking polyspermy (the fertilization of the egg by more than one sperm). What are these blocks known as? | Reproduction and Development
|
fast and slow. The two blocks against polyspermy are known as the fast block and the slow block.
The fast block occurs when the first sperm enters the egg, which then causes the membrane of the egg to become depolarized, i.e. its transmembrane potential is reduced, making it harder for subsequent sperm to cross the membrane and fertilize the egg.
The slow block is a consequence of the fast block: the depolarization causes cortical granules within the egg cytoplasm to release their enzymatic content to the zona pellucida, which then interferes with the function of the receptor proteinon the acrosome of the sperm.
Day 28. The answer is Day 28. The corpus luteum develops from the follicle remnant after ovulation has occurred, and progesterone is produced. "Corpus luteum" is Latin for "yellow body", a name given due to the high lipid content that is synthesized within it.
400. The answer is about 400. After going through puberty at approximately the age of 13, a woman releases one egg per month for about 33 years until the menopause.
Chimpanzees experience overt menstruation just like humans!
|
Play Now! 