Chpt 25: THE REPRODUCTIVE SYSTEMS AND DEVELOPMENT
*Describe the physiologic mechanisms that produce erection, ejaculation, and return the penis to its flaccid state.
- Erection: Parasympathetic stimulation (sacral region of spinal cord) causes: 1. Relax smooth muscles in arterioles supplying erectile tissue; blood vessels dilate increasing blood supply 2. Smooth muscle in erectile tissue relax widening blood sinuses; also compresses veins draining penis to sustain erection - Ejaculation: Release of semen; Sympathetic reflex (lumbar portion of spinal cord) 1. Sphincter at base of urinary bladder closes 2. Peristaltic contractions in epididymis, ductus deferens, seminal vesicles, ejaculatory ducts, & prostate propel semen -Once sexual stimulation of the penis has ended, the arterioles supplying the erectile tissue of the penis constrict and the smooth muscle within erectile tissue contracts, making the blood sinuses smaller. This relieves pressure on the veins supplying the penis and allows the blood to drain through them. Consequently, the penis returns to its flaccid (relaxed) state.
State how men can minimize the risk of prostate cancer or testicular cancer, and women can minimize the risk of breast cancer or cervical cancer.
- Prostate cancer Screening: level of PSA (prostate-specific antigen), produced by epithelial cells; for males over 40 digital rectal exam -Testicular cancer Screening: monthly self-exam to feel for mass in testes -BREAST CANCER Decreased risk: having children, breastfeeding, being physically active -CERVICAL CANCER Yearly pap smears (+ HPV testing)
*• Describing semen including its composition, structures that produce it, and its functions
- Sperm - Seminal fluid: +Seminal vesicles -Alkaline fluid: neutralize acidity of urethra & female reprod. Tract -Fructose - sperm ATP production -Prostate +Citric acid - ATP production +Proteolytic enzymes - break down clotting proteins from seminal vesicles -Bulbourethral glands +Alkaline fluid- neutralizes acid from urine in urethra mixture of sperm and seminal fluid, a liquid that consists of the secretions of the seminiferous tubules, seminal vesicles, prostate, and bulbourethral glands. Seminal fluid provides sperm with a transportation medium, nutrients, and protection from the hostile acidic environment of the male's urethra and the female's vagina.
- Describing the sequence of passageways through which sperm pass from the time they leave the testes until they exit the male body
- sertoli cells-lumen of seminiferous - straigth tubules-ductus epididymis - ductus deferens - EJACULATORY DUCTS - urethra - external urethral
*• Describing the events in spermatogenesis
1) During mitotic division, some stem cell Spermatogonia (2n) migrate away from the basement membrane of a seminiferous tubule, pass through the blood-testis barrier, and differentiate intoPrimary Spermatocytes (2n) 2) 1 Primary Spermatocyte (2n) undergoes Meiosis I to become 2 Secondary Spermatocytes(2n, but with two matching chromatids) 3) The 2 Secondary Spermatocytes (2n) undergo Meiosis II to become 4 Spermatids (n) 4) The 4 Spermatids (n) undergo spermiogenesis to become 4 sperm cells (spermatozoa) after gaining an acrosome, flagellum, and undergoing nucleus elongation) 5) Sperm cells are pushed into the lumen of the seminiferous tubule
*Summarize the male accessory sex glands by: • Stating the functions of the secretions by each accessory sex gland NPCHL
1. Neutralize acid in the male urethra and the female reproductive tract. 2. Provide fructose for ATP production by sperm. 3. Contribute to sperm motility and viability. 4. Help semen coagulate after ejaculation and subsequently break down the clot. 5. Lubricate the lining of the urethra and the tip of the penis during sexual intercourse
• Describing the average number of sperm in a milliliter of semen and why this huge number is required for fertilization
2.5-5mL large number of sperm required for successful fertilization because only tiny fraction reaches secondary oocyte
State the effect of the acidic environment of the vagina on microbial growth and sperm
ACIDIC ENVIRONMENT RETARDS MICROBIAL GROWTH, but also is harmful to sperm • Alkaline components of semen (FROM SEMINAL VESICLES) RAISE THE PH AND INCREASE SPERM VIABILITY
and state if a vasectomy interferes with testosterone production or libido
Because the blood vessels are not cut, testosterone levels in the blood remain normal, so vasectomy has no effect on sexual desire, performance, and ejaculation.
define pregnancy
Begins with fertilization and is a time when the fertilized egg undergoes IMPLANTATION, embryonic and fetal development, and birth.
Explain the mechanisms that move the oocyte into the uterine tube and then onward to the uterus
Ciliated epithelial cells lining tube and peristaltic contractions of smooth muscle transport secondary oocyte or zygote (after fertilization) through the tube and into the uterus for implantation
State the functions of middle piece
Contain mitochondria----> supplies the energy needed for sperm locomotion and metabolism.
• Stating when ovulation usually occurs in a 28-day ovarian cycle
Day 14
• Defining the fetus
Developing human from week 9 until birth.
*production sites and pregnancy-related functions of human chorionic gonadotropin, progesterone, estrogens, and relaxin
During the first 3-4 mos. of pregnancy, the corpus luteum continues to secrete progesterone and estrogens, which maintain the lining of the uterus during pregnancy and prepare the mammary glands to secrete milk. the chorion of the placenta secretes hCG into the blood. In turn, hCG stimulates the corpus luteum to continue production of progesterone and estrogens—an activity required to prevent menstruation and for the continued attachment of the embryo and fetus to the lining of the uterus. By the 8th day after fertilization, hCG can be detected in the blood and urine of a pregnant woman. Relaxin: produced by corpus luteum; increases flexibility of the pubic symphysis and dilates the cervix
• Stating the function of the tail of the sperm cell
Enables motility so it can swim to the secondary oocyte
*• Stating production sites and influence of each hormone on the uterine cycle
Estrogen secrete by the ovarian follicles promote the uterine lining development and the development of mature follicle (secondary oocyte) Progesterone promotes the development of the uterine and maintain the lining if pregnancy occurs. Progesterone works with the estrogens to prepare the endometrium for implantation also prepare the mammary glands for milk production
*Summarize the female reproductive cycle by: • Stating production sites and influence of each hormone on the ovarian cycle
FSH produced in AP initiate the growth of ovarian follicles and stimulate the follicle (ovum) development LH help complete the development of the follicle and stimulate the ovulation and the formation of corpus luteum.
*Summarize fetal development by: • Describing the placenta
Formed from the chorion (fetal) and decidua basalis (mother), serves the purpose for exchange of respiratory gases and nutrients and wastes between the mother and the fetus
• Distinguish between fraternal and identical twins
Fraternal twins result from independent release of two secondary oocyte and subsequence fertelization of each by different spermed they have the same age but genetically dissimilar, Identical twins developed from a single ferterlized Ovum ,have exactly the same genetic material and are always the same sex
- Describing the role of the epididymis and ductus deferens in ejaculation
Functionally, the ductus deferens conveys sperm during sexual arousal from the epididymis toward the urethra BY PERISTALTIC CONTRACTIONS OF ITS MUSCULARIS. Like the epididymis, the ductus deferens can store sperm for several months.
explain the mechanism in preventing fertilization of the rhythm method
Having unprotected sex only on infertile days of the menstrual cycle. Requires knowledge of the length of the woman's menstrual cycles and the current progression in the cycle.
*• Stating the fate of the corpus luteum if the secondary oocyte is not fertilized and if it is fertilized
If the oocyte is not fertilized, the corpus luteum has a life span of only two weeks. Then, it degenerates into a corpus albicans, which does not secrete ovarian hormones. If the secondary oocyte is fertilized and begins to divide, the corpus luteum persists past its normal two-week life span. It is "rescued" from degeneration by human chorionic gonadotropin (hcg).
*Summarize male reproductive physiology by: • Describing hormonal control of spermatogenesis including the production site and influence of each hormone
In puberty, hypothalamus incr secretion of GnRH. GnRH stimulate anterior pituitary to inc secretion of LH and FSH. LH stimulates leydig cells(located seminiferous tubules) to secrete testosterone. Negative Feedback: testosterone suppress secretion LH from anterior pituitary and GnRH from hypothalamus. In prostate, testosterone converted to androgen(DHT) FSH acts indirectly to stimulate spermatogenesis. FSH and testosterone act syngergistically on sertoli cells to stimulate ABP into lumen of seminiferous tubules Once adequate lvl sperm cell produced, sertoli cells release inhibin , which inhibits FSH by anterior pituitary If spermatogenesis is slow, less inhibin released which permits more FSH secretion
• Stating testosterone's influence on libido in both men and women
Increasing testosterone can increase libido in both men and women
*explain the mechanism in preventing fertilization of tubal ligation
Known as having your "tubes tied"; the uterine tubes are either clamped or severed and sealed to prevent the eggs from reaching the uterus for fertilization.
State the location and function of Leydig cells.
Legdig cell are located between the seminiferous tubules of the testes. Their function is they produce TESTOSTERONE.
*• Describing ovulation
MATURE FOLLICLE RUPTURES THROUGH OVARIAN WALL, RELEASING THE SECONDARY OOCYTE INTO THE PELVIC CAVITY • Gradual increase in estrogen levels starts to have a positive feedback effect on GnRH and LH secretion. • Surge in LH causes rupture of mature follicle and expulsion of secondary oocyte. • Ovulated secondary oocyte is surrounded by cells of corona radiata (inner layer of follicular cells). • Ovulated oocyte is swept into uterine tube by cilia on fimbriae of infundibulum. 1) A high blood level of estrogens stimulates the hypothalamus to release more GnRH. It also directly stimulates the anterior pituitary to secrete LH. 2) GnRH stimulates the anterior pituitary to secrete FSH and even more LH. 3) The resulting surge of LH causes rupture of the mature follicle and expulsion of a secondary oocyte. The ovulated oocyte and its corona radiata are usually swept into the uterine tube.
• Stating the male secondary sex characteristics
MUSCULAR AND SKELETAL GROWTH result to wide shoulder and narrow hips, PUBIS, AXILLARY, FACIAL AND CHEST HAIR, thickening of the skin, deepening of the voice and INCREASE OIL GLAND SECRETION.
State the uterine tissue layer involved in labor and childbirth and the muscle tissue type composing that layer
MYOMETRIUM (middle layer)-----> composed of 3 layers of smooth muscle fibers ----> involved in labor and delivery.
• Defining meiosis and explain why gametes must form by meiosis rather than mitosis (See textbook Chapter 3.)
Meiosis produces gametes with 23 chromosomes ( so in fertilization they fuse to create zygote with 46 chromosomes, the ideal number) while mitosis cannot achieve this.
*Describe follicular development
PUBERTY: ~400,000 primary oocytes remain. Each month LH and FSH cause a few primordial follicles containing primary oocytes to develop. • First: primordial follicle --> primary follicle (granolosa cells form) • Then: Primary follicle --> secondary follicle (antrum and capsule form) • A single primary oocyte in a secondary follicle will become dominant and develop into a large mature Graafian follicle, and complete meiosis I (becomes a secondary oocyte- haploid; n) just prior to ovulation • Completion of meiosis I produces a secondary oocyte and 1st polar body (unequal cytoplasm distribution) • Ovulated as secondary oocyte (haploid; n) and corona radiata (innermost layer of granulosa cells) Meiosis II - only if penetrated by sperm in uterine tube Yields an ovum and a second polar body Fusion of nuclei = fertilization, forms diploid zygote
*Define labor, state its other name, and state the influence of oxytocin on labor
Partuition= process by which the fetus is expelled from the uterus through the vagina.Oxytocin stimulates uterine contractions and relaxin from the placenta assists by increasing the flexibility of the pubic symphysis and helping dilate the uterine cervix.
Define sexually transmitted disease and name the developed country where STDs are rising to near-epidemic proportions (the exam will not ask about specific STDs, but do read this important information).
STDs are diseases that spread through sexual contacts.In the United States,STDs have been rising to near-epidemic proportions; they currently affect more than 65 million people!!!!!!!
explain how vasectomies can prevent fertilization
Since the ductus deferens are ligated the sperms are unable to exit the persons body to reach an oocyte so prevents fertilization.
*Describe oogenesis
The formation of gametes in the ovaries.
*• Describing implantation
The insertion of a tissue or a part into the body. The attachment of the blastocyst to the stratum basalis of the endometrium about 6 days after fertilization.
Summarize fertilization: • Describing fertilization
The process that results in the union of a male gamete with a female gamete.
define fertilization
The process that results in the union of a male gamete with a female gamete.
*• Explaining the influence of human chorionic gonadotropin and its use in detecting pregnancy
This hormone is produced by the chorion of the embryo beginning about eight days after fertilization. Like LH, hCG stimulates the secretory activity of the corpus luteum. The presence of hCG in maternal blood or urine is an indicator of pregnancy and is the hormone detected by home pregnancy tests.
Describe ectopic pregnancy
This occurs when a fertilized egg attaches itself somewhere besides the lining of the uterus.
*• Explaining why only one graafian follicle usually develops during each ovarian cycle
Under the influence of FSH, several primordial follicles develop into primary follicles and then into the secondary follicle. Some of the secondary follicles in the ovaries start to secrete the estrogen and inhibin. By 6 days one secondary follicle outgrows and all others become dominant follicles. Estrogen and inhibin secreted by the dominant follicle decrease the secretion of FSH, which causes other less developed follicles to stop growing and undergo atresia. The only one mature secondary oocyte will go through ovulation.
State the collective name for the female external genitals and know that the labia majora and labia minora protect the vestibule and aid sexual stimulation.
Vulva KNOW: the labia majora and labia minora protect the vestibule and aid sexual stimulation.
• Describing hormonal changes that initiate menstruation if fertilization does not occur
Withdrawal of progesterone and estrogen causes menstruation.
*• Explain how polyspermy is blocked
Within a few seconds, the cell membrane of the oocyte depolarizes, which acts as a fast block to polyspermy—a depolarized oocyte cannot fuse with another sperm cell. Depolarization also triggers exocytosis from the oocyte of molecules that harden the zona pellucida, preventing additional sperm from binding to or penetrating it, events called the slow block to polyspermy.
Describe the vasectomy procedure
a portion of each ductus deferens is removed. An incision is made on either side of the scrotum, the ducts are located and cut, each is tied (ligated) in two places with stitches, and the portion between the ties is removed.
State the functions of the sperm cell's head
contains the nucleus with 23 chromosomes
• Listing the female secondary sex characteristics
distribution of adipose tissue to breast and hips voice pitch, BROAD PELVIS, hair growth on head and body
State the functions of acrosome
filled with enzymes that help sperm cell penetrate secondary oocyte to bring about fertilization
*• Describing sperm penetration
for fertilization to occur, a sperm cell first must penetrate the corona radiata as well as the zona pellucida, the glycoprotein layer between the corona radiata and the oocyte's plasma membrane. The acrosome contains several enzymes. Acrosomal enzymes and strong tail movements help sperm penetrate the corona radiata and come in contact with the zona pellucida. Once the glycoproteins in the zona pellucida binds to the sperm cell's head, triggers acrosomal reaction, and the release of the contents of the acrosome. The acrosomal enzymes digest a path through the zona pellucida as the lashing tail pushes the sperm cell onward. Although many sperm bind to the zona pellucida and release their acrosomal enzymes, only the first sperm cell to penetrate the entire zona pellucida and reach the oocyte's plasma membrane fuses with the oocyte.
Name the male and female gametes and gonads
gonads- testes in males, ovaries in females gametes- sperm cells in males, secondary oocyte in females
• Explaining how the embryo receives nourishment
human embryos receive their nutrients from the endometrium
*• Defining the amnion
it is a thin protective membrane which is developed from the epiblast while the amniotic cavity enlarges.
Summarize spermatogenesis by: • Defining spermatogenesis
where the germ cells in males undergo mitosis, then meiosis which results in spermatids. Those spermatids mature into sperm
*explain the mechanism in preventing fertilization of oral contraceptives
prevent pregnancy mainly by preventing ovulation though a pill (taken orally) containing progestin/estrogen or progestin alone. Progestin inhibits ovulation by suppressing leutenizing hormone (LH) from the anterior pituitary.
Define contraception (see textbook Glossary)
prevention of fertilization/impregnation without destroying fertility
explain the mechanism in preventing fertilization of condoms
prevents deposition of sperm in the female reproductive tract.
Define puberty (see textbook Glossary).
puberty-first few years of adolescence, until the first mentrual period in girls or the first ejaculation of viable sperm in boys
Define lactation.
secretion/ejection of milk by the mammary glands
• Defining libido
sexual desires
explain the mechanism in preventing fertilization of diaphragm
stops most sperm from passing into the cervix and the spermicide kills most sperm that do get by
Define menopause (see textbook Glossary).
termination of menstrual cycle
Summarize embryonic development by: • Defining the embryo
the developing organism from fertilization to the end of the eighth week of development.
Summarize the male reproductive ducts by: - Stating in which male reproductive duct sperm become mature
the epididymis
- Defining sperm maturation
the process by which sperm acquire motility and the ability to penetrate a secondary oocyte.
• Defining the umbilical cord and afterbirth.
the umbilical cord is the connection between the placenta and the embryo(later, the fetus); the afterbirth is the detached placenta from the uterus after pregnancy.
• Stating the function of amniotic fluid
this fluid that fills the amniotic cavity serves as a shock absorber for the fetus, regulates BODY TEMPERATURE, prevents drying out of the fetus, and helps prevent injuries to the fetus from surrounding tissues.