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Reproductive System
Nursing (RLE70)
Capitol University
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The Reproductive System
● Gonads—primary sex organs ○ Testes in males ○ Ovaries in females ● Gonads produce gametes (sex cells) and secrete hormones ○ Sperm—male gametes ○ Ova (eggs)—female gametes ● Remaining structures are accessory reproductive organs ● Reproductive systems ○ Produce offspring via gametes ○ Sperm and egg fuse to form a zygote ○ Female uterus houses the embryo, and later the fetus, until birth
Male Reproductive 01.
Anatomy of the Male Reproductive System
● Testes ● Duct system ○ Epididymis ○ Ductus (vas) deferens ○ Urethra ● Accessory organs ○ Seminal glands (vesicles) ○ Prostate ○ Bulbourethral glands ● External genitalia ○ Penis ○ Scrotum
Testes
● Each testis is connected to the trunk via the spermatic cord, which houses: ○ Blood vessels ○ Nerves ○ Ductus deferens ● Coverings of the testes ○ Tunica albuginea—capsule that surrounds each testis ○ Septa—extensions of the capsule that extend into the testis and divide it into lobules ● Each lobule contains one to four seminiferous tubules ○ Tightly coiled structures ○ Function as sperm-forming factories ○ Empty sperm into the rete testis ● Sperm travels from the rete testis to the epididymis ● Interstitial cells in the seminiferous tubules produce androgens such as testosterone
Duct System
● The duct system transports sperm from the body and includes: ○ Epididymis ○ Ductus deferens ○ Urethra
● Epididymis ○ Highly convoluted tube 6 meters (20 ft) long ○ Found along the posterior lateral side of the testis ○ First part of the male duct system ○ Temporary storage site for immature sperm ○ Sperm mature as they journey through the epididymis ○ During ejaculation, sperm are propelled to the ductus deferens
● Ductus (vas) deferens ○ Runs from the epididymis via the spermatic cord through the inguinal canal and arches over the urinary bladder ■ Ampulla—end of the ductus deferens, which empties into the ejaculatory duct ■ Ejaculatory duct—passes through the prostate to merge with the urethra ○ Moves sperm by peristalsis into the urethra ○ Ejaculation—smooth muscle in the walls of the ductus deferens create peristaltic waves to squeeze sperm forward ○ Vasectomy—cutting of the ductus deferens prevents transportation of sperm (form of birth control) ■ Promotes sterility ■ Male retains secondary sex characteristics
● Urethra ○ Extends from the base of the urinary bladder to the tip of the penis ○ Carries both urine and sperm ○ Sperm enters from the ejaculatory duct
● Urethra regions
- Prostatic urethra—surrounded by prostate gland
- Membranous urethra—prostatic urethra to penis
- Spongy (penile) urethra—runs the length of the penis to the external urethral orifice ● Ejaculation causes the internal urethra sphincter to close ○ Prevents urine from passing into the urethra ○ Prevents sperm from entering the urinary bladder
Accessory Glands and Semen
● Seminal vesicles ● Prostate
● Bulbourethral glands
● Seminal vesicles
○ Located at the base of the bladder ○ Produce a thick, yellowish secretion (60% of semen) that contains: ■ Fructose (sugar) ■ Vitamin C ■ Prostaglandins ■ Other substances that nourish and activate sperm ○ Duct of each seminal vesicle joins that of the ductus deferens on each side to form the ejaculatory duct
● Prostate
○ Encircles the upper (prostatic) part of the urethra ○ Secretes a milky fluid ■ Helps to activate sperm ■ Fluid enters the urethra through several small ducts
● Bulbourethral glands ○ Pea-sized glands inferior to the prostate ○ Produce a thick, clear mucus ■ Mucus cleanses the spongy (penile) urethra of acidic urine prior to ejaculation ■ Mucus serves as a lubricant during sexual intercourse
● Semen
○ Milky white mixture of sperm and accessory gland secretions ○ Components of accessory gland secretions ■ Liquid portion acts as a transport medium to dilute sperm ■ Sperm are streamlined cellular “tadpoles” ■ Fructose provides energy for sperm cells ■ Alkalinity of semen helps neutralize the acidic environment of vagina ■ Semen inhibits bacteria
External Genitalia
● Scrotum ● Penis
● Scrotum
○ Divided sac of skin outside the abdomen that houses the testes ○ Viable sperm cannot be produced at normal body temperature ○ Maintains testes at 3°C lower than normal body temperature
● Penis
○ Male organ of copulation that delivers sperm into the female reproductive tract ○ Regions of the penis ■ Shaft ■ Glans penis (enlarged tip) ■ Prepuce (foreskin) ● Folded cuff of skin around proximal end ● Often removed by circumcision ○ Internally there are three areas of spongy erectile tissue around the urethra ○ Erections occur when this erectile tissue fills with blood during sexual
excitement ■ Serves as male organ of copulation
Male Reproductive Functions
● Chief roles of the male in the reproductive process ○ Produce sperm ○ Produce a hormone, testosterone
Spermatogenesis
● Sperm production ○ Begins at puberty and continues throughout life ○ Millions of sperm are made every day ● Sperm are formed in the seminiferous tubules of the testis ○ Spermatogonia (primitive stem cells) begin the process by dividing rapidly ○ During puberty, follicle-stimulating hormone (FSH) is secreted in increasing amounts ● Each division of a spermatogonium stem cell produces: ○ Type A daughter cell, a stem cell, that continues the stem cell population ○ Type B daughter cell, which becomes a primary spermatocyte, destined to undergo meiosis and form four sperm
● Meiosis ○ Special type of nuclear division that differs from mitosis ○ Occurs in the gonads ○ Includes two successive divisions of the nucleus (meiosis I and II ○ Results in four daughter cells (gametes)
● Gametes are spermatids with 23 chromosomes ○ 23 chromosomes are half the usual 46 found in other body cells ○ 23 is known as the haploid number (n)—half the genetic material as other body cells ● Union of a sperm (23 chromosomes, n) with an egg (23 chromosomes, n) creates a zygote (2n, or 46 chromosomes)
● Spermiogenesis ○ Spermatids are nonmotile and not functional as sperm ○ A streamlining process is needed to strip excess cytoplasm from a spermatid and modify it into a sperm
○ A sperm has three regions: head, midpiece, tail ○ Acrosome sits anterior to the sperm head (nucleus) ○ The entire process of spermatogenesis, including spermiogenesis, takes 64 to 72 days
○ Size and shape of a pear, in a woman who has never been pregnant ○ Receives, retains, nourishes a fertilized egg
● Uterine support ○ Broad ligament suspends the uterus in the pelvis ○ Round ligament anchors the uterus anteriorly ○ Uterosacral ligament anchors the uterus posteriorly
● Regions of the uterus ○ Body—main portion ○ Fundus—superior rounded region above where uterine tube enters ○ Cervix—narrow outlet that protrudes into the vagina
● Layers of the uterus
○ Endometrium ■ Inner layer (mucosa) ■ Site of implantation of a fertilized egg ■ Sloughs off if no pregnancy occurs (menstruation or menses) ○ Myometrium is the middle layer of smooth muscle that contracts during labor ○ Perimetrium (visceral peritoneum) is the outermost serous layer of the uterus
● Vagina (birth canal)
○ Passageway that extends from cervix to exterior of body and is located between urinary bladder and rectum ○ Serves as the canal that allows a baby or menstrual flow to leave the body ○ Female organ of copulation ○ Receives the penis during sexual intercourse ○ Hymen—partially closes the vagina until it is ruptured
External Genitalia and Female Perineum
● The female external genitalia, or vulva, includes: ○ Mons pubis ○ Labia ○ Clitoris ○ Urethral orifice ○ Vaginal orifice ○ Greater vestibular glands
External Genitalia and Female Perineum
● Mons pubis ○ Fatty area overlying the pubic symphysis ○ Covered with pubic hair after puberty
● Labia—skin folds ○ Labia majora ■ Hair-covered skin folds ■ Enclose the labia minora ■ Also encloses the vestibule ○ Labia minora—delicate, hair-free folds of skin
● Clitoris ○ Contains erectile tissue ○ Corresponds to the male penis ○ The clitoris is similar to the penis in that it is: ■ Hooded by a prepuce ■ Composed of sensitive erectile tissue ■ Swollen with blood during sexual excitement ○ The clitoris lacks a reproductive duct
● Vestibule ○ Enclosed by labia majora ○ Contains external openings of the urethra and vagina
● Greater vestibular glands ○ One is found on each side of the vagina ○ Secretions lubricate vagina during intercourse
● Perineum ○ Diamond-shaped region between the anterior ends of the labial folds, anus posteriorly, and ischial tuberosities laterally
Female Reproductive Functions and Cycles
● The total supply of eggs is determined by the time a female is born ● Ability to release eggs begins at puberty with the onset of the menstrual cycle ● Reproductive ability ends at menopause (in female’s fifties)
Oogenesis and the Ovarian Cycle
● Oogenesis is the process of producing ova (eggs) in a female ○ Oogonia are female stem cells found in a developing fetus ○ Oogonia undergo mitosis to produce primary oocytes that are surrounded by cells that form primary follicles in the ovary ● Primary oocytes are inactive until puberty ● Follicle-stimulating hormone (FSH) causes some primary follicles to mature each month ● Cyclic monthly changes constitute the ovarian cycle ● Meiosis starts inside maturing follicle ○ First meiotic division produces a larger secondary oocyte and a smaller first polar body ○ A vesicular follicle contains a secondary oocyte (maturation from a primary follicle takes about 14 days) ● Ovulation of a secondary oocyte occurs with the release of luteinizing hormone (LH) ● Secondary oocyte is released and surrounded by a corona radiata ● Meiosis is completed after ovulation only if sperm penetrates the oocyte ○ Ovum is produced ○ Two additional polar bodies are produced ● Once ovum is formed, the 23 chromosomes can be combined with the 23 chromosomes of the sperm to form the fertilized egg (zygote) ● If the secondary oocyte is not penetrated by a sperm, it dies and does not complete meiosis to form an ovum ● Mature follicles that are not ovulated will deteriorate ● Luteinizing hormone (LH) ○ Triggers ovulation ○ Causes the ruptured follicle to transform into a corpus luteum ● Meiosis differences between males and females ○ Males—produces four functional sperm ○ Females—produces one functional ovum and three tiny polar bodies ● Sex cell size and structure differences between sperm and eggs ○ Sperm are tiny, motile, and equipped with nutrients in seminal fluid ○ Egg is large, is nonmotile, and has nutrient reserves to nourish the
embryo until implantation
Hormone Production by the Ovaries
● Estrogens are produced by follicle cells ○ Cause secondary sex characteristics ■ Enlargement of accessory organs of the female reproductive system ■ Development of breasts ■ Appearance of axillary and pubic hair ■ Increase in fat beneath the skin, particularly in hips and breasts ■ Widening and lightening of the pelvis ■ Onset of menses (menstrual cycle) ● Progesterone is produced by the corpus luteum ○ Production continues until LH diminishes in the blood ○ Does not contribute to the appearance of secondary sex characteristics ○ Other major effects ■ Helps maintain pregnancy ■ Prepares the breasts for milk production ○ Placenta is the major source of progesterone by the second month of pregnancy
Uterine (Menstrual) Cycle
● Cyclic changes of the endometrium, about 28 days in length ● Regulated by cyclic production of estrogens and progesterone by the ovaries ● FSH and LH, from the anterior pituitary, regulate the production of estrogens and progesterone by the ovaries ● Ovulation typically occurs about midway through cycle, on day 14 ● Stages of the menstrual cycle ○ Menstrual phase ○ Proliferative stage ○ Secretory stage
● Days 0–4: menstrual phase ○ Functional layer of the endometrium is sloughed off ○ Bleeding occurs for 3 to 5 days ○ By day 4, growing ovarian follicles are producing more estrogen ● Days 5–14: proliferative stage ○ Regeneration of functional layer of the endometrium ■ Endometrium is repaired, thickens, and becomes well vascularized ○ Ovulation occurs in the ovary at the end of this stage ● Days 15–28: secretory phase
○ Levels of progesterone rise and increase the blood supply to the endometrium ○ If implantation does occur: ■ Embryo produces a hormone that causes the corpus luteum to continue producing its hormones ○ If fertilization does not occur: ■ Corpus luteum degenerates as LH blood levels decline ■ Lack of ovarian hormones causes endometrial cells to die and menses to begin on day 28
Mammary Glands
● Present in both sexes, but function only in females ○ Modified sweat glands ● Function is to produce milk to nourish a newborn ● Stimulated by sex hormones (mostly estrogens) to increase in size ● Parts of the mammary gland that form the breast ○ Areola—central pigmented area of the breast ○ Nipple—protruding central area of areola ○ Lobes—internal structures that radiate around nipple ○ Lobules—located within each lobe and contain clusters of alveolar glands ○ Alveolar glands—produce milk when a woman is lactating (producing milk) ○ Lactiferous ducts—connect alveolar glands to nipple ○ Lactiferous sinus—dilated portion where milk accumulates
Mammography
● Mammography is X-ray examination that detects breast cancers too small to feel ● American Cancer Society recommends mammography annually for women between 45 and 54 years old and every 2 years thereafter if the results are normal ● Breast cancer is often signaled by a change in skin texture, puckering, or leakage from the nipple
Pregnancy and Embryonic Development
● Fetal changes are summarized in
Effects of Pregnancy on the mother
● Pregnancy—period from conception until birth ● Anatomical changes ○ Enlargement of the uterus ○ Accentuated lumbar curvature (lordosis) ○ Relaxation of the pelvic ligaments and pubic symphysis due to production of the hormone relaxin
● Physiological changes ○ Gastrointestinal system ■ Morning sickness is common and is due to elevated progesterone and estrogens ■ Heartburn is common because of organ crowding by the fetus ■ Constipation is caused by declining motility of the digestive tract ○ Urinary system ■ Kidneys have additional burden and produce more urine ■ The uterus compresses the bladder, causing stress incontinence ○ Respiratory system ■ Nasal mucosa becomes congested and swollen ■ Vital capacity and respiratory rate increase ■ Dyspnea (difficult breathing) occurs during later stages of pregnancy ○ Cardiovascular system ■ Blood volume increases by 25% to 40% ■ Blood pressure and pulse increase ■ Varicose veins are common
Childbirth (Parturition)
● Initiation of labor ○ Labor—the series of events that expel the infant from the uterus ■ Rhythmic, expulsive contractions ■ Operates by the positive feedback mechanism ○ False labor—Braxton Hicks contractions are weak, irregular uterine contractions ○ Estrogen levels rise ○ Uterine contractions begin ○ The placenta releases prostaglandins ○ Oxytocin receptors increase in the myometrium ■ Oxytocin is released by the posterior pituitary ○ Combined effects of rising levels of hormones— oxytocin and prostaglandins—initiates contractions and forces the baby deeper into the mother’s pelvis
Stages of Labor
● Stage 1: Dilation stage ○ Cervix becomes dilated ○ Full dilation is 10 centimeters ○ Uterine contractions begin and increase ○ Cervix softens and effaces (thins) ○ The amnion ruptures (“breaking the water”) ○ Longest stage, at 6 to 12 hours
● Stage 2: Expulsion stage ○ Infant passes through the cervix and vagina ○ Can last as long as 2 hours, but typically is 50 minutes in the first birth and 20 minutes in subsequent births ○ Normal delivery is head-first (vertex position) ○ Breech presentation is buttocks-first ● Stage 3: Placental stage ○ Delivery of the placenta ○ Usually accomplished within 15 minutes after birth of infant ○ Afterbirth—placenta and attached fetal membranes ○ All placental fragments should be removed to avoid postpartum bleeding
Developmental Aspects of the Reproductive System
● Gender is determined at fertilization ○ Males have XY sex chromosomes ○ Females have XX sex chromosomes ● Reproductive system structures of males and females are identical during early development (indifferent stage) ● Gonads do not begin to form until the eighth week ● The presence or absence of testosterone determines whether male or female accessory reproductive organs will form ● The reproductive system is inactive during childhood ● Reproductive system organs do not function for childbearing until puberty ● Puberty usually begins between ages 10 and 15 ● Puberty
○ Males ■ Enlargement of testes and scrotum signals onset of puberty (often around age 13) ○ Females ■ Budding breasts signal puberty (often around age 11) ■ Menarche—first menstrual period (usually occurs about 2 years later) ● Menopause—a whole year has passed without menstruation ○ Ovaries stop functioning as endocrine organs ○ Childbearing ability ends ○ Hot flashes and mood changes may occur ● There is a no equivalent of menopause in males, but there is a steady decline in testosterone
A Closer Look: Contraception
● Contraception—birth control ● Birth control pill—most-used contraceptive ○ Relatively constant supply of ovarian hormones from pill is similar to pregnancy ○ Ovarian follicles do not mature, ovulation ceases, menstrual flow is reduced ● Morning-after pill (MAP) or emergency contraceptive pill (EC) ○ Taken within 3 days of unprotected intercourse ○ Disrupts normal hormonal signals to the point that fertilization is prevented ● Sterilization techniques ○ Tubal ligation (females)—cut or cauterize uterine tubes ○ Vasectomy (males)—cut or cauterize the ductus deferens ● Barrier methods ○ Diaphragms ○ Condoms ● Abstinence ○ Only birth control method that is 100% effective
Reproductive System
Course: Nursing (RLE70)
University: Capitol University
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