The Human Body: The Reproductive System

8th Grade Science

Mrs. Christopherson Mrs. Goede

Review

Mitosis is the type of cell division that occurs in non-reproductive cells. Produces exact copies of the parent cell

Meiosis is cell division that occurs in reproductive cells; gametes. Produces egg and sperm cells with half the

genetic material of the parent cells. 23 chromosomes are contained in gametes; this

is so that when egg and sperm meet, they produce offspring with 46 chromosomes.

Organs of the Male Reproductive System

Penis Urethra Vas Deferens Scrotum Testes Bladder* *Not a part of the reproductive

system

External Organs of the Male Reproductive System

Penis: the external reproductive organ, urethra passes through the penis and allows urine and semen to exit the body.

Scrotum: a sac or pouch which holds the testes. The function of the scrotum is to maintain the

proper temperature of the testes. Sperm is destroyed unless a temperature of 97o is

maintained.

Internal Organs of the Male Reproductive System

Bladder*: holds urine prior to urination. Urine leaves the bladder via the urethra.

Urethra: a tube which allows urine and semen to exit the body. Connects to the bladder

Vas deferens: a tube which connects the testes to the urethra and allows semen to exit the body.

Testes: two glands which produce sperm and hormones (testosterone)

Organs of the Male Reproductive System

Let’s fill in our diagrams of the male reproductive system.

Organs of the Female Reproductive System

Vagina Cervix Uterus Fallopian Tubes Ovary

Organs of the Female Reproductive System

Vagina: also called the birth canal, a tube leading from the uterus to the outside of the body.

Cervix: the lower portion of the uterus; where the vagina and uterus meet.

Uterus: a hollow, fist-sized organ located between the bladder and rectum.

Fallopian Tubes: also called oviducts; are two tubes connecting the uterus with the ovaries.

Organs of the Female Reproductive System

Ovaries: small organs on the ends of the Fallopian tubes responsible for the production and release of eggs (ova-pl). Females are born with all of the eggs they will

ever produce. Ovaries alternate the release of eggs each month. Like testes, the ovaries produce hormones-

estrogen. This release of the ova is called ovulation.

Organs of the Female Reproductive System

Lets label the parts of the female reproductive system now.

The Menstrual Cycle

The menstrual cycle typically lasts 28 days; approximately 1 month. One cycle is the amount of time from the

beginning of one period to the beginning of the next period.

The beginning of a period is marked by the release of the blood and lining from the inside of the uterus. This flow of blood typically lasts 3-7 days and is

called menstruation.

The Menstrual Cycle

After menstruation, the ovaries release hormones that tell the uterus to grow a new lining and prepare to receive a new egg.

As the uterus prepares a new lining, one of the ovaries releases an egg. This is called ovulation. Ovulation occurs about halfway through a

woman’s cycle. The egg travels through the Fallopian tube. If it is

not fertilized it breaks down and is released with the lining and blood of the uterus.

Menstrual Cycle Timeline

Menstrual Cycle Timeline

The Menstrual Cycle and Fertilization

If the egg is fertilized by a sperm cell, the egg will implant in the lining of the uterus and begin to develop. Zygote: The first cells of a new organism; the time

from fertilization to implantation. Embryo: The zygote is called an embryo from

implantation to 8 weeks. Fetus: After 8 weeks of development, the embryo

is known as a fetus.

Genetics & Inheritance

Gregor Mendel: 1822-1884. Austrian monk who is often called the “Father of

Genetics” Studied the inheritance of traits in pea plants His research has led to a greater understanding

of dominant and recessive traits, as well as how to predict the probability of those traits in offspring

Genetics & Inheritance: Important Vocabulary

Phenotype: the observed traits of an organism. Example: hair color

Genotype: the genetic makeup of an organism. Example: the gene that says what your hair color will be.

Gene: a region of DNA that describes a trait of an organism. Example: eye color gene

Allele: a different form of a gene Example: brown eye color allele, blue eye color allele

Genetics & Inheritance: Important Vocabulary

Dominant allele: Traits that mask the effect of other traits

Recessive allele: Traits that are masked by dominant traits

Examples of dominant and recessive traits Heterozygous: the organism has one dominant

allele and one recessive allele. Example: Bb Homozygous: the organism has either 2 dominant

alleles or 2 recessive alleles. Example: BB or bb

Predicting patterns of heredity: Punnett Squares

A man who is heterozygous for brown eyes marries a woman who is homozygous recessive for blue eyes. What are the phenotypes, genotypes of their 4 children?

B b

b

b

Bb bb

Bb bb

Predicting patterns of heredity: Pedigree Charts

A pedigree chart is a family tree showing genetic information.

A represents males, while represents females. or means that the individual shows the trait.

Married people: Children:

Predicting patterns of heredity: Pedigree Charts

Pictures of the traits you can use in your pedigree chart.

Twins

Multiple eggs are released or there is more than one ovulation. Both (or more) eggs are fertilized and you have fraternal twins.

One egg is released but splits in two. Identical twins are made. If the egg does not completely split in two, conjoined twins are produced.

Chromosomal Disorders

http://www.pregnancy-info.net/chromosomal_abnormalities.html

http://en.wikipedia.org/wiki/List_of_genetic_disorders

http://www.familyvillage.wisc.edu/Lib_chro.htm

http://www.thetech.org/genetics/ask.php?id=209