Bio 142 - Exam 6 (Chapter 28 - Reproductive System)

Distinguish b/t an autosome and a sex chromosome

Autosomes contain genes that code for cellular functions (they also help determine human characteristics such as eye color, hair color, height, and skin pigmentation). Matching autosomes are caled homologous chromosomes. Sex chromosomes consist of either two X chromosomes or an X and Y chromosomes. They determine if a person is female (two X) or male (one X and one Y).

Describe the gross anatomy of the mammary glands

Each mammary gland, or breast, is located w/in the anterior thoracic wall. Composed of compound tubuloalveolar exocrine glands.

Describe the major hormones involved in each phase of the ovarian cycle

GnRH LH - stimulates ovulation

Name the hormones involved in spermatogenesis

GnRH stimulates the anterior pituitary to secrete FSH and LH, which target eht testes and stimulate spermatogenesis and androgen production. (LH stimulates interstitial cell sin teh testis to secrete testosterone, while FSG stimulatse the sustentacular cells to secrete androgen-binding protein (ABP). ABP bindsm to testosterone to ensure testosterone levels remain high in the testes. Testosterone facilitates spermatogenesis, but also inhibits GnRH (thus rising testosterone has a negative feedback effect on the entire cycle) Sustentacular cells respond to rising sperm count and secrete inhibin, which causes inhibition of FSH. Circulating testosterone stimulates libido and development of secondary sex characteristics.

Describe the gross anatomy and the microscopic anatomy of the testes

Gross anatomy: relatively sjmall, oval organs housed w/int he scrotum. They produce sperm and androgens (male sex hormones) Microscopic anatomy: Each testis is covered w/ a serous membrane, the tunica caginalis (derived from the peritoneum of the abdominal cavity). It has an outer parietal layer and inner visceral layer. A thick, whitish fibrous capsule called hte tunica albuginea covers the testes and lies dep to the visceral layer of the tunica vaginalis. The mediastinum testis of ea testis consists of blodo vessles, ducts, lymph vessels, and nerves.

Describe the events that occur during interphase

Interphase occurs before meiosis. During interphase, the DNA in ea chromosome is replicated in teh parent cell. After interphase, there are 23 PAIRS of relipcated chromosomes.

Describe the development of the egg during the different phases of a female's life: - Before birth: primary oocyte is halted in prophase I - Childhood - Monthly from puberty to menopause

- Before birth: Process of oogenesis begins before birth, at which time the ovaries contain primordial germ cells called oogonia (dpoid cells w/ 23 pairs of chromosomes). During the fetal period, the oogonia divide by mitosis to produce primary oocytes, which arrest in prophase I. (At birth, female child's ovaries contain approx 1.5 million primordial follicles. - Childhood: During childhood, a female's ovaries are inactive, and no follicles develop. Atresia occurs, in which some primordial follicles regress. By the time a girl reaches puberty, she only has about 400,000 follicles remaining. - From puberty to menopause: the hypothalamus begins releasing GnRH, which stimulates the anterior pituitary to release FSH and LH. Levels vary in a cyclical pattern, producing a monthly event called the ovarian cycle. - After menopause: When a woman stops having menstrual cycles for 1 year and is not pregnant. Is caused by no more ovarian follicles remaining or ovarian follicle maturation ceasing. Uterine lining no longer grows, and a woman no longer menstruates.

Differentiate b/t haploid and diploid gametes

A diploid gamete is one that contains 23 pairs of chromosomes (2n chromosomes, where n is the unpaired chromosome number). A haploid gamete (from either sex) contain 23 chromosomes only (not 23 pairs), and thus their chromosome number is designated as 1n (or just n)

Name the three major phases in meiosis

Meiosis I: the homologous pairs of replicated chromosomes are separated when teh cell divides. The result is two cells, each of which contains 23 chromosomes (not 23 pairs) that consist sof replicated sister chrmoatids. > Prophase: Homologous maternal and paternal replicated chromosomes pair up, forming a tetrad. Crossing over occurs, increasing genetic diversity. > Metaphase I: HOmologous replicated chromosomes line ujp and form a double line of chromosomes. pindle fibers attach to the centromeres. > Anaphase I: Pairs are seaparted and pulled to opposite ends of the cell (reduction division). > Telophase I and Cytokinesis: Nuclear division finsihes adn the nuclear envelopes reform. The cytoplansm divides and two new cells are proucted, each containing 23 replicated chroomes only. Meiosis II: chromatids spearate and become single chromosomes in haploid cells. > Prophase II: nuclear evnvelopes break down, replicated chromosomes cluster together. (No crossing over in prophase II) > Metaphase II: Spindle fibers extend and sister chromatids align the replicated chromosomes. > Anaphase II: Sister chromatids pull apart. > Telophase II and Cytokinesis: Nuclear division finishes. Four new daugher cells are producesd, each containing 23 single chromosomes.

Describe the difference b/t mitosis and meiosis

Meiosis is sex cell division that starts off w/ a diploid parent cell and produces haploid daughter cells (called gametes). - Mitosis produces two daughter cells that are genetically identical to the parent cell, while meiosis produces four daughter cells that are genetically different from the parent cell. - Mitosis produces diploid daughter cells, which meiosis produces haploid daughter cells - Meiosis includes a process called crossing over, whereby genetic material is exchanged b/t homologous chromosomes. (Does NOT occur in mitosis)

Compare the Ovarian and Uterine Cycle Phases Name the major hormones that influence the uterine cycle. Describe the effects of each hormone on the three phases of the uterine cycle.

Ovarian Cycle Uterine Cycle Day 1-5 Follicular Phase Menstrual Ph. Day 6-13 Follicular Phase Proliferative Ph Day 14 Ovulation Proliferative Ph Day 15-28 Luteal Phase Secretory Ph. Days 1-5 - GnRH stimulates FSH and LH secretion. Some ovarian follicles develp and produce estrogen. Functional Layer of endometrium is shed. Day 6-12 - Estrogen and inhibin inhibit the hypothalamus and anterior pituitary, causing a drop in FSH. One follicle continues to mature and poduce estrogen. Functional layer of the endometrium is rebuilding. Day 13-14 - Increase in estrogen above the threshold stimulates the hypothalamus and anterior pituitary, causing an LH surge, which induces ovulation. Day 15-28 - Corpus luteum forms and secretes large amounts of estrogen, progesterone, and inhibin. Combined, these inhibit GnRH, FSH, and LH secretion. Progesterone stimulates uterine lining growth. If the oocyte is not fertilized, teh corpus luteum regresses and hormone levels drop.

Describe the gross anatomy of the ovary

Ovaries are paired, oval organs located w/in the pelvic cavity lateral to the uterus. In an adult, they are slightly larger than an almond (2-3 cm long, 2cm wide, and 1-1.5 cm thick). Size varies during ea menstrual cycle and during pregnancy. Ovaries are anchored to the pelvic cavity by a double fold of peritoneum, called hte mesovarium, which attaches to each ovary at its hilum. The broad ligament is a drape of peritoneum that hangs over ea ovary.

Explain the differences b/t erection and ejaculation with regards to: - its general response - its regulation by the autonomic nervous system

Parasympathetic innveration (through teh pelvic splanchnic nerves) is resonsible for increased blood flow and erection of the penis. Sympathetic innervation (from teh lumbar splanchinic nerves) is responsible for ejaculation Remember: Point and Shoot. (P: Point - erection - for parasympathetic. S: Shoot - ejaculation - for sympathetic)

Describe the three tunics of the uterine wall and the function of each tunic

Perimetrium - the outer, serosa tunic, which is continuous w/ the broad ligament. Myometrium - thick,, middle tuynic of the uterine wall. Formed from three intertwining layers of smooth muscle. Endometrium - innermost tunic; intricate mucosa composed of a simple columnar epithelium and an underlying lamina propria.

Describe the role of prolactin and oxytocin on milk production and ejection.

Prolactin is produced in th anterior pituitarty and is responsible for milk production. WHen the prolactin increases, mammary glands grown and form mor eexpanded and numerous alveoli. Oxytocin is produced by the hypothalamus and released from teh posterior pitiutiary, and is responsible for milk ejection.

Name and describe the general function of the hormones secreted at puberty in males and in females

Puberty is initiated when the hypothalamus begins secreting gonadotropin-releasing hormone (GnRH). This acts on endocrine cells int eh anterior pituitary and stimulates them to release follicle-stimulating hormone (FSH) and Lutenizing hormones (LH).

Explain the differences among sister chromatids, replicated chromosomes, paired chromosomes, and a single chromosome

Replicated chromosomes: a chromosomes tha tinitially has two identical sister hromatids joined at teh cnetromere Paired chromosomes: a homologous maternal chromosome and a paternal chromosome Single chromosome: a chromosome consisting of a single chromatid and a centromere Sister chromatids: identical struxtures that contain identical DNA. They are attached at teh cnetromere.

Name the components that make up semen

Semen consists of seminal fluid from the accessory glands combined with sperm.

Describe the four major events of spermatogeneis

Spermatogenesis: 1) Sperm origin cells are diploid germ cells called spermatogonia. Mitotic division results in a new germ cell and committed cell. The committed cell is a primary spermatocyte. 2) Meiosis I begins in teh diploid primary spermatocytes. the Haploid cells (contianing 23 chromosomes) produced during meiosi I are called secondary spermatocytes 3) Meiosis II originates w/ the secondary spermatocytes and produces spermatids. 4) The process of spermiogenesis begins w/ spermatid and results in morphologic chnages needed to form sperm that will be motile.

Describe the main steps in spermiogenesis

Spermiogenesis: The spermatid sheds excess cytoplasm and its nucleus elongates. The acrosome cap forms over the nucleus (contains digestive enzymes that help penetrate the secondary oocyte for fertilization. As the spermatid elongates, a tail (flagellum) forms from the organized microdtubules. The tail is attached to a midpiece, or neck region, that contains mitochondria and a centriole, which provide energy to move the tail.

Name the major cell types of the seminiferous tubules & Name the hormones produced by each cell type

The Seminiferous tubules consist of 1) sustentacular cells, which are nondividing support cells (aka sertoli cells or nurse cells) and 2) a populaton of dividing germ cells that continuously produce sperm. Sustentacular cells release inhibin when sperm count is high (which inhibits FSH relese and regulates sperm production).

Name the components of the female external genitalia and describe their functions

The external reproductive organs of the feaml are the external genitalia, or vulva.

Describe the gross anatomy of the scrotum

The scrotum is a skin-covered sac b/t the thighs, responsible for providing a cooler temperature for sperm storage. Externally, the raphe serves as a midline of the scrotum. The wall of the scrotum is composed of an external layer of skin, a thin layer of superficial fascia, and a alyer of smooth muscle, the dartos muscle, immediately internal to th efascia.

Describe the structure of the mature sperm cell

The spermatid sheds excess cytoplasm and its nucleus elongates. The acrosome cap forms over the nucleus (contains digestive enzymes that help penetrate the secondary oocyte for fertilization. As the spermatid elongates, a tail (flagellum) forms from the organized microdtubules. The tail is attached to a midpiece, or neck region, that contains mitochondria and a centriole, which provide energy to move the tail.

Describe the location of the uterus in the body. Describe the four anatomical regions of the uterus.

The uterus is a hollow, pear-shaped, thick-walled muscular organ within the pelvic cavity. It has lumen that conects to the uterine tubes superiolaterally and to the vagina inferiorly. It is angled anterosuperiorly across the superior surface of the urinary bladder (a position referred to as anteverted). The four anatomical regions of the uterus are: - Fundus (the broad, curved superior region b/t the uterine tubes.) - Body (the middle region, the major part of the organ, composed of a thick wall of smooth muscle) - Isthmus (the narrow, constricted inferior portion of the body, superior to the cervix) - Cervix (the narrow, inferiormost portion that projects into the vagina)

State the function of the uterine tube

Uterine tubes (aka: fallopian tubes or oviducts) extend laterally from both sides of the uterus toward the ovaries. They function to transport the ovulated oocyte to the uterus, and are the site of fertilization.

Name the three phases of the ovarian cycle & describe the major event in each phase

- Follicular phase: Occurs during days 1-13 of a 28-day cycle. At the beginning, FSH and LH stimulate up to 20 primordial follicles to mature into primary follicles. The follicular cells reelse the hormone inhibin, which inhibits further FSH production, preventing excessive follicle development and allowing primary follicles to mature. A few primary follicles mature. (Those that do not undergo atresia) Typically only one folicle matures. The mature follicle, LH stimulates the volume of fluid to increase and teh oocyte is forced to one side of the follicle, and is surrounded by cumulus oophorus. As the secondary follicle matures, its primary oocye finishes meiosis I and two cells form. One cell rexices minimal cytoplams and forms a polar body (a nonfunctional cell that later regresses). The other receives the bulk of cytoplasm and becomes the secondary oocyte, Secondary oocyte is halted in metaphase II. (It only completes meiosis II if fertilized by a sparm. If not, it breaks down and regresses. - Ovulation phase: Occurs on Day 14 of a regular cycle, and is defined as the release of the secondary oocyte from a mature follicle. completion of meiosis II only if fertilization occurs. At the time of ovulation, follicle cells increase rate of fluid secretion, forming a larger antrum, causing the rupture of the thin edge of the follicle, expelling the secondary oocyte. - Luteal phase: Occurs during days 15-28, when the reamining follicle cells become the corpus luteum. The corpus luteum is essentially a temporary endocrine gland, secreting progesterone and estrgen to stabalize and build up the uterine lining. The corpus luteum has a lifespan of approx 10-13 days if the secondary oocyte is not fertilized. After it regresses, levels of progesterone and estrogen drop, cuasing the lining of the uterus to be shed (menstruation).

Name the four segments of the uterine tube, and identify the segment where fertilization occurs

- Infundibulum: the free, funnel-shaped lateral margin of the uterine tube. Has fimraiae that envelop the ovary only at the tiem of ovluation. - Ampulla: exapnded region medial to the infundibullum. Fertilization of the oocyte occurs here uusally. - Isthmus: constricted region that extends medially from the ampulla toward the lateral wall of the uterus. Forms 1/3 of the length of the uterine tube. - Uterine part: extends medially from teh isthus and penetrates the wall of the uterus.

State the main functions of the vagina

- Is the copulatory organ of the female - Servces as the passwageway for menstruation - Serves as the passageway for baby during childbirth.

Name the three phases of the uterine cycle & Describe the major events that occur in each phase

- Menstrual phase: Approx days 1-5 of the cycle. Marked by sloughing of the functional layer of the endometrium. - proliferative phase: spans days 6-14; is the initial development of the new functional layer of the endometrium, overlapping the time of follicle growthj and estrogen secretion by the ovary. - secretory phase: Aprpox days 15-28. Marked by increased vascularization and development of uterine glands in response to progesterone secretion from teh corpus luteum.

Name the three major accessory glands of the male reproductive system

- Seminal vesicles - Prostate Gland - Bulbourethral glands

Describe the specific function of each gland and substances produced by each gland that contribute to semen formation

- Seminal vesicles: secrete a viscous, whiteish-yellow, alkaline fluid containing fructose and prostaglandins. Fuctose nourishes th sperm as they travel through the female reporductive tract. Prostaglandins arpromote widening and slight dilation fo the external os of teh cervix, which facilitiates sperm entry into the uterus. - Prostate Gland: secretes a slighlty milky fluid that is weakly acidic and rich in citric acid, seminalplasmin, and prostate-specfiic antigen (PSA). The citric acid is for sperm health, the seminalplasmin is an antibiotic that combats urinary tract infections in teh male, and the pSA acts as an enzyme to help liquify semen following ejaculation. - Bulbourethral glands: Produces a clear, viscous mucin that forms mucus. It coats and lubricates the urethra for the passage of sperm during intercourse.

Describe the function of the following components of the male duct system: - epididymis - ductus deferens - ejaculatory duct - prostatic urethra - membranous urethra - spongy urethra

- epididymis: stores sperm until they are fuly mature and capable of being motile. - ductus deferens: where sperm are transported (via contraction of the muscularis) to the penis. - ejaculatory duct: b/t 1-2 cm long; pseudostratified ciliated columnar epithelium. Conducts sperm from teh ductus deferens and a component of seminal fluid toward the urethra. - prostatic urethra: Extends from the bladder through teh prostate gland. The ejaculatory duct opens into the prostatic urethra, which transports sperm to the membranous urethra. - membranous urethra: Conducts sperm to hte spongy urethra - spongy urethra

Describe the microscopic structures of the ovary, including: - primordial follicle - secondary follicle - mature (tertiary) follicle - corpus luteum - corpus albicans

- primordial follicle: most primitive type of ovarian follicle; consists of a primary oocyte surrounded by single layer of flattened follicle cells. A primary follicle is arrested in the first meiotic prophase (Prophase I). Approx 1.5M of these present in both ovaries at birth. - primary follicle: forms from a maturing primordial follicle; consists of a primary oocyte surrounded by 1+ layers of cuboidal follicular cells, caleld granulosa cells. Ea primary follicle secretes estrogen - secondary follicle: forms from a primary follicle; contains a primary oocyte, many layers of granulosa cells, and a fluid-filled space called antrum. (Oocyte is pushed to one side of the folicle, where it is surrounded by a cluser of cells termed the cumulus oophorus. - mature (tertiary) follicle: forms from a secondary follicle; contains a secondary oocyte (surrouned by zone pellucide and coronoa radiata), numerous granulosa cells, adn a large crescent-shaped antrum. A secondary oocyte has completed meiosis I and is arrested in second meiotic metaphase. (Typically, only one mature follicle forms each month) - corpus luteum: When a mature follicle ruptures and expels its oocyte, remants turn into a yellowish strucutre called the corpus luteum, which secretes progesterone and estrogen, which stimulate and support buildup of uterine lining in preparation for implantation. - corpus albicans: If the corpus lutem undergoes regression, it turns into a white connective tissue scar called the corpus albicans, which is typically resorbed.

Describe how the scrotum regulates the temperature of the testes

- the venous plexus pre-cools arterial blood prior to it reaching the testes. - when exposed to elevated temps, the dartos muscle relaxes, which unwrinkles the skin of the scrotum and allows the testes to move inferiorly further away from the body, cooling them. Simultaneously, the cremaster muscle realxes to allow the testtes to move away from the body.