Essay Example on The actual date of ovulation is often difficult to Know

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Assignment 1 Bibliography https www plannedparenthood org learn pregnancy pregnancy month by mont https health howstuffworks com pregnancy and parenting pregnancy conception conception process2 htm https www khanacademy org test prep mcat cells embryology a egg meets sperm 1 1 Describe in depth stages of development from conception to birth in groups of 4 weeks i e 0 4 4 8 8 12 12 16 16 20 20 24 24 28 28 32 32 36 and 36 40 weeks Week 0 4 The actual date of ovulation is often difficult to know so the first day of the last period is often looked at as being the beginning of the pregnancy Therefore the process that brings a baby comes to life actually begins with a normal process of a monthly period In the last period before the point of conception the body is already beginning to prepare for a pregnancy

This happens when the lining of the uterus also known as the endometrium is shed causing the menstrual flow While this happens the follicle stimulating hormone FSH kicks in and causes the development of several ovarian follicles These follicles are yellow bulbs and they contain a single egg that is immature The FSH causes these follicles to grow which allows the eggs to mature while this is happening the ovary is producing oestrogen which is a key female hormone that causes ovulation Inside the ovarian follicles are the eggs which contain half the genetic makeup that an individual needs The eggs are maturing and triple in their size ready for release The hormones continue to prepare the body and the increase in oestrogen causes luteinizing hormone to release the largest of the follicles to rupture which spews the egg into one of the fallopian tubes This process is known as ovulation and is often between day 14 and 18 in a woman's cycle After the egg is released it is now ready to meet with a sperm cell During intercourse the male releases his sperm inside the female where they swim towards the egg where it is waiting in the fallopian tube

The sperm may need about ten hours to make this journey struggling through thin channels in the cervical mucus propelled by lashings of their tiny tails The process of fertilization begins when one sperm penetrates the egg s tough outer membrane During fertilization the sperm fuses with the plasma membrane and then penetrates the egg Fusing to the is not an issue for the sperm However penetrating through the egg s hard shell can cause more of a problem to the sperm Therefore sperm cells have to go through a process known as the acrosome reaction which is the reaction that occurs in the acrosome of the sperm as it approaches the egg The acrosome is located at the very end of the sperm at its head As the sperm approaches the egg the membrane surrounding the acrosome fuses with the plasma membrane of the sperm's head exposing the contents of the acrosome The contents include surface antigens necessary for binding to the egg s cell membrane and numerous enzymes which are responsible for breaking through the egg s tough coating and allowing fertilization to occur Within the following day the sperm's nucleus merges with the nucleus of the egg The egg is now a zygote which is the first step in its journey toward babyhood

The zygote then travels down the fallopian tube toward the uterus Along the way its single cell begins to divide about every 12 hours About four days after fertilization the egg has about sixteen cells and the cluster now called a morula pushes its way along the narrowest part of the fallopian tube and finally enters the uterus which is read to receive it The mix of oestrogen and progesterone hormones has triggered the growth of a nutrient rich bed of blood vessels the perfect place for the egg to attach itself to also known as implantation The fertilized egg changed and grown so much in the last week and this week causes yet more changes Inside the egg a cavity forms which causes two groups of cells to gather at different sides One group goes on to become the placenta while the other group becomes an embryo The amniotic fluid and the yolk sac begin to form now and are there to protect the embryo during its early days The cell s are still dividing and they morula now become a blastocyst About six or seven days after fertilization the blastocyst bursts tumbling out of its surrounding membrane so its growing mass of cells can more easily bond with the uterus Using chorionic villi the blastocyst anchors itself in the uterine lining where incubation starts This marks the start of a linkage between mother and embryo where they share hormones and other essential fluids

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