Pregnancy Overview: Sperm to Zygote

The nucleus of the egg is given to the sperm and then the process of gene mixing happens.

The female body is specifically prepared for one child but in some rare cases of twins. There are two types of twins. There are identical twins where the zygote basically splits into two first and these two go further from each other and create their own fetuses. These twins tend to be more alike. The other type of twins are called fraternal twins where by accident two eggs are produced from both the ovaries and if they both become fertilized there will be 2 babies.

Corpus luteum is produced in the follicle. This yellow body produces a hormone called Progesterone. Progesterone sends signals to the uterine lining/endometrium to stay healthy and thicken - This is especially useful during pregnancy - Helps get prepared for the baby and to turn into placenta

<p>The menstrual cycle is the process humans females go through where they are most likely to get pregnant and for pregnancy to occur, there are four stages to this cycle.</p> Signup and view all the answers

<p>The follicular phase (day 7-14) - Originally this should be the &quot;first part&quot; of the menstrual cycle but due to how scientists have structured it, it is placed after the actual shedding and the menstruation. During this phase the brain first starts by producing FSH (follicle stimulating hormone) - Tells the follicles in the ovary to grow the egg As the follicle grows it produces Estrogen - Estrogen helps the uterus prepare for a baby - It encourages the endometrium to thicken. finish the sentence Endometrium is the part that turns into the placenta if the egg is fertilized, this lining across the uterine wall then provides nutrients for the fetus to mature and develop Ovulation (14-16) This is the stage where the egg is actually released. The first part of this stage starts with the brain producing luteinizing hormone. This hormone then tells the follicle to release the egg. After this, the egg goes and sits in the fallopian tube waiting for the sperm. The egg lasts about 12-24 hours after ovulation waiting for the sperm. This is the time a woman can get pregnant if unprotected sexual intercourse is had. During this same time a yellow body called the corpus luteum is produced in the follicle. This yellow body produces a hormone called progesterone. - Progesterone sends signals to the uterine lining/endometrium to stay healthy and thicken - This is especially useful during pregnancy - Helps get prepared for the baby and to turn into placenta The luteal phase (16-25) If fertilisation has taken place and a sperm successfully meets an egg and creates a zygote then normal pregnancy will ensue (later in notes) but if the egg is not fertilised then it will die. The corpus luteum will continue producing progesterone and telling the endometrium to thicken until one point where it also break. Then both estrogen and progesterone stop getting produced endometrium starts breaking down. This then leads to the cycle repeating.</p> Signup and view all the answers

<p>With all the recently acquired liquid in the semen. The sperm then makes its way through the female reproductive system. First it enters through the vagina and swims up, after it goes through the cervix. (a lot of sperm die here and along the way) Then the sperm swims up the uterus and finally reaches the fallopian tube where the egg is waiting. Out of the millions of sperm released only a couple reach the fallopian tube and only one gets to create the zygote. Once the sperm reaches the egg it then gives its nucleus which has 23 chromosomes (male gamete) and the rest of the body is discarded.</p> Signup and view all the answers