BIOD 152: Module 6 - Problem Set

The female reproductive system includes what internal organs?

Internal organs: the ovaries, the oviducts (fallopian or uterine tubes), the uterus, and the vagina.

What is ovulation? How often does it occur?

The release of a mature egg; occurs approximately every 28 days.

What is the ovarian cycle?

An egg is released from the ovarian follicle.

What does the ovarian follicle become after ovulation?

The corpus luteum

What is the purpose of the corpus luteum?

It helps maintain pregnancy if an egg is fertilized; if not, it disintegrates. Produces progesterone.

What are the three sections and three coats of the oviducts?

Sections- Infundibulum, ampulla and isthmus

Three coats: the outer serous coat, the middle muscular coat, and an inner mucosa coat.

What is the function of the fimbriae?

The fimbriae capture an egg from the ovary at the time of ovulation. When an egg (oocyte) bursts from follicle within an ovary during ovulation, it is swept into an oviduct.

An egg is most often fertilized in what region?

Ampulla OF THE Fallopain Tubes

Describe the shape and location of the uterus.

The uterus is a hollow, thick-walled muscular organ shaped like an inverted pear connecting the uterine tubes and the vagina and, in a forward-tilted position between the bladder and the rectum.

What are the three layers of the uterus?

The outer serous perimetrium, the middle muscular myometrium and the inner glandular endometrium.

What is the function of the myometrium?

It expands during pregnancy to hold the growing fetus and contracts during labor to push the baby out of the uterus.

What are the three regions of the uterus?

Fundus, body, cervix

What is the fundus?

The height of the fundus can be measured from the top of the pubic bone during pregnancy to provide growth rates and a crude indication of an abnormality (breech presentation or twins).

What is the function of the cervix just prior to ovulation?

Just prior to ovulation, the cervix swells, softens and secretes mucus allowing sperm better access to and viability within the uterus.

What are the three layers of the vaginal wall?

An inner tissue layer, intermediate muscle layer and outer tissue layer.

What is the function of the mucosal lining in the vaginal wall?

The mucosal lining of the vagina lies in folds and can extend which is important when the vagina serves as the birth canal and it also facilitates intercourse.

The _____ is a fat pad located in front of the pubic symphysis and is covered with hair after puberty.

Mons pubis

The _______is an outer fold of skin that is located posterior to the mons pubis.

Labia majora

The urethral orifice is located ________ the vaginal orifice.

Anterior to

Describe the structure of the mammary glands

Nipple >Lobules > Mammory Ducts > Alveoli

A mammary gland contains one to two dozen lobules, each with its own mammary duct. The duct begins at the nipple and divides into numerous other ducts ending in blind sacs called alveoli.

In a non-lactating breast, the ducts far outnumber the alveoli since alveoli are made up of cells that can produce milk.

Is milk produced during pregnancy?

Milk is not produced during pregnancy because prolactin is needed for lactation (milk production) to begin. Prolactin is suppressed by estrogen and progesterone.

What is colostrum?

A yellowish-white fluid which has a similar composition to milk but contains a higher concentration of protein.

What is oogenesis?

Oogenesis is the production of eggs in the ovaries which occurs during development of the fetus in the womb and is complete by the time of birth.

Describe the steps of oogenesis from primary oogonia to a mature ovum.

Oogonia 2n > Mitosis > Primary Oocytyes 2n (Primary Follicle)

FSH > Meiosis > Secondary Oocyte n (First Polar Body)

Ferilization > Meiosis > OVUM n (Second Polar Body)

Oogonia 2n(Female stem cells), undergo MITOTIC division into two daughter cells known as Primary Oocytes. These primary oocytes are covered by follicles, known as Primary Follicles. This process is completed by birth.

The anterior pituitary gland starts to secrete follicle-stimulating hormone (FSH) when a female reaches puberty. FSH causes a few follicles to mature each month. The primary oocyte in the follicle undergoes its first MEITOTIC division into two daughter cells: the Secondary Oocyte (n) and the First polar body (n).

If the secondary oocyte is united with a sperm after ovulation the second MEIOTIC division occurs which produces Second Polar Body and an Ovum with 23 chromosomes.

What is the function of estrogen and progesterone?

Estrogen is important in the production of eggs and the menstrual cycle. It is also responsible for secondary sex characteristics.

Progesterone is necessary for the maintenance of pregnancy but does not promote secondary sexual characteristics.

What are the three phases of the menstrual cycle?

The menstrual phase, proliferative phase, and the secretory phase.

What is contained in the menstrual flow?

Detached tissue of the endometrium and blood.

Describe the proliferative phase.

The proliferative phase occurs during days 6-14 as the endometrium rebuilds in response to increasing estrogen levels. Ovulation of an egg typically occurs in the ovaries on day 14. Ovulation is triggered when the anterior pituitary (in the brain) releases luteinizing hormone (LH) as a response to high levels of estrogen.

Describe the secretory phase of the Menstrual Cycle

During this phase the corpus luteum begins to secrete progesterone.

Progesterone causes an increased blood supply in the uterus and secretion of nutrients, preparing the uterus for implantation.

If fertilization has not occurred, the corpus luteum dies and the endometrium blood supply decreases because of decreased progesterone which begins the menstrual phase again.

Describe the structure and function of the testes.

The testes have the function of sperm and testosterone production.

Testosterone is a hormone produced by the interstitial cells inside the connective tissues.

Each testis has hundreds of lobules and each lobule contains several Seminiferous tubules where the site of sperm production takes place.

Where is the site of sperm maturation?

The epididymis

What would happen if the testes do not descend into the scrotum?

If the testes do not descend into the scrotum, gametes may not be produced because sperm production requires an environment cooler than body temperature.

What is the length of sperm maturation? Why?

Maturation for about 20 days is required for the sperm to gain the ability to swim.

What is the site where the vas deferens enters the abdomen?

Inguinal canal

What is the ejaculatory duct?

The ejaculatory duct connects with the urethra to provide a means for the sperm to exit the body.

What is a vasectomy?

A vasectomy can be performed as a permanent form of birth control. In this procedure, the vas deferens is cut and tied off which permanently prevents sperm from exiting the body to fertilize an egg.

The fluids of the semen are contributed by what three glands?

The seminal vesicles, the prostate and the bulbourethral glands

What is semen?

A thick, whitish fluid that contains sperm and accessory gland secretions.

Discuss the function of the antibiotics found in semen.

The antibiotics in semen kill any bacteria in the male urethra or female reproductive system that would kill the sperm.

What do the seminal vesicles contribute to the contents of semen?

The seminal vesicles secrete a thick, viscous fluid containing nutrients (fructose, vitamin C, and prostaglandins) for use by the sperm.

What does the prostate gland contribute to the contents of semen?

It secretes a milky alkaline fluid helping to increase the motility of the sperm.

What do the bulbourethral glands secrete?

The alkaline mucus secreted by the bulbourethral glands clears and neutralizes the acidity of any urine inside the urethra.

Describe the formation of sperm from spermatogonia.

Spermatogenesis =

Spermatagonia 2n > Pubery (FSH) > Primary Spermatocyte > Meiosis > Spermatids (Gametes, n)

Sperm are formed from spermatogonia in the seminiferous tubules located in the testes.

Spermatogonia are stem cells that go through mitotic divisions (with 46 chromosomes each) beginning at birth until puberty.

Once a male enters puberty his anterior pituitary gland begins to secrete follicle stimulating hormone (FSH). When FSH is secreted the spermatogonia undergo cell division; one of the cells continues the stem cell line.

The other cell, known as the primary spermatocyte, undergoes meiosis. Meiosis produces four gametes with (with 23 chromosomes each) known in the male reproductive system as spermatids. All four spermatids become viable gametes.

Describe the parts of a mature sperm.

Head = dna, acrosome, enzymes

midbody = mitochondria; energy for motility

tail = locomotion

The head is almost entirely nucleus containing the cell DNA with a crown called the acrosome which contains enzymes that breakdown the membrane of the egg to allow the sperm to penetrate. The midpiece contains numerous mitochondria that generate the locomotive energy needed by the sperm. The tail is a typical flagellum which is used to propel the sperm through the female reproductive tract.

What is the purpose of the hormone testosterone?

Testosterone stimulates the sex drive and growth in males. It also stimulates secondary sex characteristics such as broad shoulders, deep voice, increased muscle size and bone density, and increased hair.

Why are offspring different from their parents?

In sexual reproduction, the offspring inherits half its genes from one parent and the other half from the other parent. Therefore, an offspring has a different combination of genes than either parent. In this way, variation is introduced and maintained.

What is a haploid cell? A diploid cell?

A diploid cell is found throughout the body containing 46 chromosomes. A haploid cell is a gamete cell containing 23 chromosomes.

What is meiosis?

During meiosis, gametes divide to form four gametes each with only half of the chromosomes needed (23).

How many chromosomes does a zygote contain?

46 (full number for human development).

What determines the sex of the developing fetus?

Sex is also determined by the chromosomes. Males have one X chromosome and one Y chromosome. Females have two X chromosomes.

What is the corona radiata?

Follicle cells surrounding the egg.

How long are male and female gametes viable?

Sperm are viable for 3-5 days after ejaculation, depending on the environment, and an egg can survive for up to 24 hours after ovulation.

Describe the order of development from a fertilized egg to a fetus.

The zygote (fertilized egg) spends about three to four days undergoing mitosis in the oviducts forming the morula and another three to four days undergoing mitosis while unattached in the uterus, forming the blastocyst as the endometrium prepares for implantation. Upon implantation some cells in the blastocyst begin to develop into three layers which become the embryo. By the end of week eight the embryo is considered a fetus.

The presence of _____ in urine will result in a positive pregnancy test taken at home.

HCG (human chorionic gonadotropin)

Describe the supportive cells formed in the blastocyst.

Amnion forms a sac filled with fluid to cushion and protect the fetus.

Placenta is a temporary organ that carries out nutritive, respiratory, excretory and endocrine functions for the embryo. The baby continues to grow in the uterus with nutrition provided by the placenta for nine months until it is time for delivery.

Umbilical cord attaches the embryo to the placenta.

The skin and nervous tissue develop from the ----------- layer of the blastocyst.

Ectoderm

The inner endoderm layer forms the _________.

The inner endoderm layer forms the glands (thyroid, parathyroid and thymus), solid organs (liver and pancreas) and the lining of the hollow organs of the digestive and respiratory systems.

The cardiovascular system develops from what layer of the blastocyst?

Mesoderm

Describe the steps of the formation of the neural tube.

The lateral sides of the ectoderm move together (convergence) forming the epidermis superficially. The neural fold forms underneath the epidermis, becoming the neural crest. The neural plate becomes the neural groove and then finally the neural tube once convergence is complete. The anterior portion of the neural tube becomes the brain and the rest forms the brainstem and spinal cord.

What supplement is recommended to prevent neural tube defects?

Folic acid

Around what week does the heart begin to have blood flow?

Week 3

During what trimester do fingerprints develop?

2nd trimester

What trimester do the testes descend into the scrotum?

3rd trimester

What causes the cervix to dilate during labor?

The uterus contracts, which pushes the baby's head against the cervix causing it to dilate (widen).

What is the second stage of labor?

Delivery of the baby

What is the third stage of labor?

Delivery of the placenta

What stage of labor is the longest?

First - dilation of the cervix