The Reproductive System (8th Grade Biology Test)

The Path of The Egg

After the egg is released, it enters the oviducts, or the Fallopian tubes. If a sperm fertilizes the egg, it usually happens in an oviduct. Short hairlike structures called cilia help sweep the egg through the oviduct, towards the uterus. The uterus is a hollow, pear shaped muscular organ in which a fertilized egg develops.

The First Trimester

All the embryo's organs systems, as well as the membranes that feed and protect the embryo, develop during the first trimester of gestation, or pregnancy.

Fertilization

Although hundreds of millions of sperm are released during an ejaculation, only 1% WILL reach the upper region of the Fallopian tubes. If an egg is present in one of the oviducts, it has a very high chance of fertilization.

The Third Trimester

By the end of the third trimester, the fetus is capable of living outside mother's body. The fetus leaves the mother's body in a process called labor, which usually lasts several hours. During labor, the walls of the uterus contract and expel the fetus from the uterus, through the vagina.

The Two Female Sex Hormones

Estrogen regulates the release of eggs and brings the female secondary sex characteristics; development of the reproductive system and breasts, and widening of the hips. Progesterone is called the pregnancy hormone ( think of PR- ogesterone and PR-egnancy.) since it prepares the uterus for the implantation of the zygote. The two ovaries are the organs that make eggs.

External Fertilization

External Fertilization is the process of the sperm fertilizing the egg outside of the females body. In moist environments, delicate zygotes do not dry out inside the tummy. Most fish and amphibians use external fertilization.

Multiple Births- Fraternal Twins

Fraternal twins develop from 2 different eggs, that have been fertilized by 2 different sperm.

Gestation (Pregnancy)

Gestation is the nine month period required for human development.

The Female Sex Hormones

Hormones from the pituitary gland stimulates the ovaries to produce estrogen and progesterone; which are the female sex hormones.

Phase Two of The Menstrual Cycle

Hormones named estrogen cause the lining of the uterus to thicken. Hormones also control the development of an egg in the ovary. Ovulation occurs on day fourteen. Once the egg is released, it must be fertilized within 24 hours or else it will begin to break down.

Phase Three of The Menstrual Cycle.

Hormones produced by the ovaries continue to cause an increase during phase three. If a fertilized egg does occur, the uterus is ready to support and to nourish the developing embryo. If the egg is not fertilized, the lining of the uterus breaks down ad the hormone levels decrease, menstruation begins and the cycle repeats itself.

Multiple Births- Identical Twins

Identical twins develop from 1 egg that has been fertilized by 1 sperm. The zygote will divide into two separate zygotes.

Asexual Reproduction

In asexual Reproduction, a single parent has offspring that are genetically identical to the parent. This type of reproduction does not involve the union of sex cells.

Sexual Reproduction

In sexual reproduction, sex cells of two parents UNITE to form a new individual. Sexual reproduction in animals usually requires two parents/male and female. The female parent produces sex cells called eggs. The male parent produces sex cells called sperm. When these two sex cells unite, a fertilized egg,(a zygote), is formed. This joining of an egg and sperm is named fertilization.

Internal Fertilization

Internal fertilization is the process in which the egg and the spermicide join inside the female' shoddy. Internal fertilization allows the zygote to be protected inside the female animal's body. Reptiles, birds, mammals, and some fish reproduce using internal fertilization. In most mammals, one or more zygotes develop inside the mother's body.

The Female Reproductive System

It produces eggs, nurtures fertilized eggs, zygotes, and gives birth.

Marsupials

Marsupials are mammals that give birth to partially developed live young. Most marsupials have pouches where their young continue to develop after birth, such as opossums, koalas, and kangaroos.

Monotremes

Monotremes are animals that lay eggs such as platypus, and echidnas.

The Birthing Process

Muscular contractions of he uterus push the baby out through the vagina, also known as the birth canal. The umbilical cord is cut after the baby's Bir, and the scar that forms is the navel. Babies who can not be delivered by through the birth canal, are delivered by a C-Section.

The First Trimester(2)

Other substances besides nutrients can also diffuse in the placenta. If the mother ingests harmful substances, the embryo is also affected. Pregnant women who smoke may have immature and underweight babies. Pregnant women who abuse alcohol may have babies that suffer from fetal alcohol syndrome, a group of birth defects that include facial deformation, and severe mental, behavioral and physical retardation.

Placental Mammals

Placental mammals are nourished in their mother's body before birth, such as armadillos, humans, bats, etc...

Phase One of The Menstrual Cycle

The 1st day of phase one starts when menstrual flow begins. This flow usually continues for 4-6 days, and is called menstruation.

The Vagina and The Cervix

The cervix is the narrow lower end of the uterus. The vagina, or the birth canal, is a muscular tube that opens to the outside the body

The Vulva

The external structures of the female reproductive system are called the vulva. Most of the reproductive organs are in the females body. The ovaries, the oviduct or the Fallopian tubes, the uterus and the vagina.

Secondary Sex Characteristics

The inset of Puberty brings about the progressive changes are called secondary sexual characteristics; they progressively transform boys into men, and girls into women.

The Three Trimesters

The period of gestation is divides into three trimesters, or 3-3 month periods.

The Types of Asexual Reproduction

There are three types of asexual reproduction. Budding, Fragmentation, and Regeneration. All of these involve a part of the parent organism breaking off of pinching off to create a new organism. (Such as Flatworm, Starfish and Yeast.)

The Egg

When the female is born, she already has all the immature eggs in her ovaries that will develop into mature eggs, which will be the female reproductive cells. About once a month, an egg is released from an ovary, in a hormone controlled process called ovulation.

Epidurals

With anesthesia ( epidurals), the woman is numb from the waist down, resulting in no pain. However, 4-10 cm dilation is extremely painful, which is about the time an epidural is presented, if the mother wishes to receive so.