[Chapter 39] Reproduction Flashcards Preview

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What happens during the ovulation phase of the menstrual cycle?

Around day 14, one ovary releases an oocyte.


What happens during the luteal phase of the menstrual cycle?

A glandular corpus luteum develops and its secretions cause the endometrium to thicken in preparation for pregnancy. This phase lasts for days 15-28.


What do Estrogens do?

They control how the female reproductive organs develop in embryos, and starting at puberty they control female secondary traits.


Estrogens and what else induce oocytes to mature and help prime the uterus for pregnancy?



What are Fraternal Twins?

Twins that form after two oocytes mature and are released during one menstrual cycle, and then get fertilized. They start as two genetically different zygotes and are no more alike than any other siblings.


What are Identical Twins?

Twins that form when one zygote or early embryo splits. This is a chance event.


What type of twins can run in families?

Fraternal twins.


What hormone causes women to be more likely to have fraternal twins?

FSH, with the average women's FSH levels rising later in life (mid-thirties).


How much sperm can ejaculation put into the vagina?

It can put 150-350 million sperm, which can live for about 3 days after ejaculation.


What is a mature egg called?

An ovum.


Give a brief description of how someone becomes pregnant.

Sexual arousal involves nervous signals and hormones in both males and females. Ejaculation releases millions of sperm into the vagina. Uterine contractions help some of them reach the oviducts, where fertilization usually occurs. Fertilization is over when a sperm nucleus and egg nucleus fuse and form the diploid nucleus of a new individual.


How many eggs form during a woman's lifetime?

As many as 500.


What does Rhythm Methods mean (in the context of Fertility Control Options)?

A form of abstinence where a women avoids sex during her fertile period.


What is a Vasectomy?

Surgery where the doctor makes a small incision into the scrotum, and cuts and ties off each vas deferens. Does not lead to permanent infertility.


What is Tubal Ligation?

A surgery that blocks or cuts the oviducts, resulting in permanent infertility.


What is HPV?

Human papillomavirus. Can cause genital warts and/or cervical cancer. A vaccine can prevent infection if given before the first viral exposure.


What is Trichomoniasis?

Trichomonas vaginalis, a flagellated protist, causes trichomoniasis. Symptoms include vaginal soreness, itching, yellowish discharge. Males usually show no symptoms. Untreated, can damage the urinary tract, cause infertility, invite HIV. An antiprotozoal drug can cure an infection.


What is Chlamydia?

Chlamydia trachomatis causes the disease, antibiotics can kill it quickly. Females will show no symptoms, males can have abnormal discharges from the penis and painful urination. Untreated males will risk inflamed reproductive tract and infertility, male and females could develop PID.


What are Genital Herpes?

Caused by type 2 Herpes simplex virus, small blisters form and causes painful sores. Antiviral drugs can treat it.


What is Gonorrhea?

Caused by Neisseria gonorrhoeae, infected females could suffer painful urination, cramps, fever, vomiting, and scarring leading to infertility. Males have yellow pus discharge. Urination becomes painful. Antibiotics can cure this. There are 16 strains of this STD.


What is Syphilis?

A spirochete bacterium Treponema pallidum causes syphilis. Lesions and scars appear in the skin and liver, bones, and other organs. Chronic immune reactions may damage the brain and spinal cord, and cause paralysis.


What is Aids?

Infection by HIV, the human immunodeficiency virus, leads to AIDS (acquired immune deficiency syndrome). AIDS is presently incurable. The immune system weakens, which opens the door to opportunistic infectious agents.


How long does pregnancy last?

It lasts an average of 38 weeks starting from fertilization.


What is a blastocyte?

The type of blastula that forms in mammals, takes about one week to form.


In what period do all major organs form?

The embryonic period, during the second to eighth week of pregnancy.


What is the developing individual called after the embryonic period?

A fetus.


What happens in the fetal period?

From week nine onto birth, organs grow and become specialized. There are three trimesters: the first three months, months 4-6, and months 6-end of pregnancy.


Describe what happens during days 1-2 after fertilization.

The first cleavage furrow extends between the two polar bodies. Later cuts are angled, so cells become asymmetrically arranged. Until the eight-cell stage forms, they are loosely organized, with space between them.


Describe what happens during day 3 after fertilization.

After the third cleavage, cells abruptly huddle into a compacted ball, which tight junctions among the outer cells stabilize. Gap junctions formed along the interior cells enhance intercellular communication.


Describe what happens during day 4 after fertilization.

By 96 hours there is a ball of sixteen to thirty-two cells shaped like a mulberry. It is a morula (after morum, Latin for mulberry). Cells of the surface layer will function in implantation and will give rise to a membrane, the chorion.