chap 46 study guide

Why do organisms have a reproductive system?

To facilitate the production of offspring and ensure the continuation of a species.

What are the two main types of reproduction in animals?

Asexual and sexual reproduction.

What are the benefits of asexual reproduction?

Rapid population increase and no need for a mate.

What is a cost of sexual reproduction?

Requires finding a mate and may be slower to reproduce.

What are four types of asexual reproduction seen in animals?

Binary fission, budding, fragmentation, and parthenogenesis.

What is gametic meiosis?

A type of meiosis that produces haploid gametes from diploid cells.

Are individuals that undergo gametic meiosis haploid or diploid?

They are diploid before meiosis and haploid after gamete formation.

What does it mean to be oogamous?

To have large immobile eggs and smaller motile sperm.

What are gonads?

Reproductive organs that produce gametes (e.g., testes and ovaries).

What is copulation?

The act of sexual intercourse or mating.

What is fertilization?

The fusion of male and female gametes to form a zygote.

Differentiate between internal and external fertilization.

Internal fertilization occurs inside the female body; external fertilization occurs outside in the environment.

Benefits of internal fertilization?

Higher chance of offspring survival and protection from harsh environmental conditions.

Costs of external fertilization?

Higher risk of gametes and embryos being exposed to predators and environmental factors.

What are unisexual organisms?

Organisms that have separate sexes.

What are hermaphroditic organisms?

Organisms that possess both male and female reproductive organs.

In what situations is it beneficial to be hermaphroditic?

In environments where mates are scarce, it increases reproductive opportunities.

Name the parts of the human male reproductive system.

Testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis.

Where in the testis does spermatogenesis begin?

In the seminiferous tubules.

Where do sperm finish maturing?

In the epididymis.

What are the steps in spermatogenesis?

Spermatogonia divide and differentiate into primary spermatocytes, which undergo meiosis to form sperm.

When does spermatogenesis occur in a male’s life?

Starts at puberty and continues throughout life.

When does spermatogenesis usually stop?

It does not have a definitive end but may slow down with age.

What is the route of sperm through the male reproductive system?

Seminiferous tubules → Epididymis → Vas deferens → Ejaculatory duct → Urethra.

Why are the testes found in the scrotum?

To maintain an optimal temperature for sperm production.

Distinguish between sperm and semen.

Sperm refers to the male gametes; semen is the fluid containing sperm and other secretions.

What structures contribute to the composition of semen?

Seminal vesicles, prostate gland, and bulbourethral glands.

Describe the hormonal regulation of spermatogenesis.

LH stimulates testosterone production which supports spermatogenesis; FSH acts on Sertoli cells to facilitate sperm development.

What is oogenesis?

The process of egg cell (oocyte) development in females.

Where are oocytes made?

In the ovaries.

What are the steps in oogenesis?

Oogonia develop into primary oocytes, which undergo meiosis but are arrested in prophase I until ovulation.

At what stages is meiosis halted in oogenesis?

Arrested at prophase I until puberty and then at metaphase II until fertilization.

When do events of oogenesis occur in a woman’s life?

Starts before birth, resumes at puberty, and continues until menopause.

What causes a secondary oocyte to finish meiosis?

Fertilization by a sperm.

What is ovulation?

The release of a mature egg from the ovary.

Where does fertilization occur in humans?

In the fallopian tubes.

What is the average length of the female ovarian cycle?

About 28 days, but can vary.

What is the average day of ovulation in the cycle?

Around day 14.

What are the follicular and luteal phases?

Follicular phase is before ovulation; luteal phase occurs after ovulation.

What hormones are involved in regulating the ovarian cycle?

FSH and LH.

What does FSH do?

Stimulates follicle growth and estrogen production.

What does LH do?

Triggers ovulation and promotes formation of the corpus luteum.

What regulates the concentrations of FSH and LH?

Feedback from estrogen and progesterone.

What changes occur in the ovary during the menstrual cycle?

Follicles develop, ovulation occurs, and the corpus luteum forms.

What is the thickening layer of the uterus during the menstrual cycle?

The endometrium.

What are the changes during the female menstrual cycle?

Menstruation occurs when hormone levels drop, leading to shedding of the endometrium.

How do hormones regulate the female reproductive system?

Hormones like FSH, LH, estrogen, and progesterone coordinate the ovarian and menstrual cycles.

What are the various types of contraception?

Barrier methods, hormonal methods, intrauterine devices, and natural methods.

What are symptothermal indicators of ovulation?

Changes in basal body temperature and cervical mucus consistency.

How does fertilization occur?

Sperm penetrates the egg's outer barrier to fuse with the oocyte's membrane.

What barriers does the sperm cell have to pass through for fertilization to occur?

The corona radiata and the zona pellucida.

What are the fast and slow blocks following fertilization?

Fast block is a membrane depolarization; slow block involves changes in the egg that prevent polyspermy.

What is a zygote?

The fertilized egg resulting from the union of sperm and egg.

What is the process of cleavage in embryonic development?

Rapid cell division with no significant growth, leading to a multicellular embryo.

When does cleavage begin after fertilization?

About 24 hours after fertilization.

When does the embryo enter the uterus and implant?

About 5-7 days after fertilization, during the blastocyst stage.

What is a blastocyst?

A hollow ball of cells formed from the embryo that implants into the uterine wall.

What is hCG?

Human Chorionic Gonadotropin; a hormone produced by the placenta.

Where does hCG come from?

It is secreted by the developing placenta after implantation.

What does hCG do?

Maintains the corpus luteum and supports early pregnancy.

What is the placenta?

An organ that develops in the uterus during pregnancy, providing nutrient and waste exchange.

When does a developing baby start being called a fetus?

From the end of the eighth week of pregnancy.

How many phases is human gestation usually divided into?

Three phases: the first, second, and third trimesters.

When are anatomy scans performed on healthy fetuses?

Typically around 18-20 weeks of pregnancy.

What is one of the last organ systems to finish developing in a baby?

The respiratory system.

Describe the human birthing process.

Involves three stages: dilation, expulsion, and the delivery of the placenta, regulated by hormones like oxytocin.