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55 Cards in this Set
- Front
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Spermatogenesis (sperm formation) |
-Takes 65-75 days -Occurs in seminiferous tubules Primordial germ cells > spermatagonia stem cells > primary spermatocytes (2n) > meisos I creates 2 secondary spermatocytes > meisos II creates 4 spermatids > spermiogenesis is the creation of actual sperm cells (spermatozoa) with the signature elongated, slender shape |
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Spermatozoa characteristics |
-300 million complete the process every day -Sperm head: consists of nucleus with 23 condensed chromosomes surrounded by an acrosome filled with enzymes that help sperm penetrate a secondary oocyte. -Sperm tail: Contains neck, middle piece, principal piece and end piece. Middle piece contains mitochondria that provide ATP for locomotion. |
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Hormones involved in spermatogenesis |
During puberty, hypothalamus increases secretion of GnRH, in turn causing anterior pituitary gland to secrete follicle-stimulating hormone and luteinizing hormone. -Luteinizing hormone stimulates Leydig cells to secrete testosterone. LH directly stimulates final steps of spermatogenesis. LH is inhibited by testosterone. -Follicle-stimulating hormone is stimulated by GnRH and indirectly stimulates spermatogenesis via Sertoli cells. It is inhibited by inhibin. |
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Prenatal testosterone |
Testicular descent and development of male external genitals. |
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Dihydrotestosterone |
Byproduct of testosterone that has to do with secondary male sex characteristics. |
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Sperm pathway |
Out of seminiferous tubules 1. Straight tubules (still in testis) 2. Rete testis (still in testis) 3. Efferent ducts (still in testis) 4. Epididymis (site of sperm maturation -- gain motility, ability to fertilize. Can be stored here for several months) 5. Ductus deferens (vas deferens) 18 inches long 6. Ejaculatory ducts 7. Urethra (prostatic region, intermediate (membranous) region, spongy region) |
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Semen |
Mixture of sperm and seminal fluid. Typically 2.5-5 mL of semen ejaculated, with 50-150 million sperm per mL -Below 20 million/mL is when male is likely to become infertile. -Most of seminal fluid is acquired via male accessory sex glands: seminal vesicle, prostate, bulbourethral gland. |
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Seminal vesicle |
Secretes viscous, alkaline fluid mainly during ejaculation which makes up 60% of total semen volume. Alkalinity neutralized the acidic environment of male urethra and female vagina. Also contains fructose (energy) and prostaglandins (smooth muscle contraction) |
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Prostate |
Chestnut-sized gland that secretes 25% of the semen volume. It's a milky, slightly acidic solution containing citric acid for energy and lots of other enzymes. |
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Bulbourethral (Cowper's) glands |
Pea-sized glands inferior to prostate, also produces alkaline mucous to protect sperm in male urethra and lubricate the urethra to limit damage during ejaculation |
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Spermatic cord |
Supportive structure that ascends out of scrotum and passes through the inguinal canal. Consists of ductus deferens, testicular artery, veins that drain testes and carry testosterone, autonomic nerves, lymphatic vessels, and the cremaster muscle. |
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Scrotum |
Supporting structure for the testes. The dartos muscle sits at the bottom of the scrotum and separates the two testis. The cremaster muscle runs down as an extension of the internal oblique muscle. The scrotum needs to be 2-3 degrees celsius cooler than the internal body temperature to produce sperm. Thus its external structure and why it shrivels and gets closer to body in cold weather. |
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Inguinal canal |
The spermatic cord and the ilioinguinal nerve (sensory for skin in area) pass through the inguinal canal |
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Penis |
Contains the urethra and is a passageway for the ejaculation of semen and for urine excretion. Consists of body, glans penis (tip) and root (base). It is supported by the fundiform ligament and the suspensory ligament. |
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Penis tissue |
Erectile tissue is surrounded by tunica albuginea. Two large masses of corpus cavernosa and one smaller mass of corpus spongiosum (which contains spongy urethra) |
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Male sexual response |
Parasympathetic initiate and maintain erection. Parasympathetic neurons release nitric oxide which dilates penile arteries. Sympathetic nervous system is necessary for ejaculation. It closes bladder sphincter while semen is being propelled into urethra and peristaltic contractions culminate in release of semen. |
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Ovaries |
Female gonads whose primary role is to produce mature second degree oocytes and release one during each ovarian cycle. Ovaries also secrete the female hormones estrogen, progesterone, inhibin and relaxin. They are held in place by ovarian ligaments and suspensory ligaments. Germinal epithelium covers the surface of the ovary. Ovarian cortex contains ovarian follicles. Ovarian medulla contains blood vessels, lymphatic vessels and nerves. |
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Uterine (fallopian) tubes |
Site of potential fertilization. Uterine tube receives oocyte at infundibulum. Ampulla is the widest part, isthmus is the narrowest part. |
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Uterus |
Pathway through which sperm reach uterine tubes. Pear-shaped organ that is the site of implantation of ovum and site of fetal development. Supported by broad ligaments and uterosacral ligaments. |
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Uterine subdivisions |
Fundus: Dome-shaped superior portion. Body: Central portion with hollow uterine cavity. Cervix: Inferior portion. Cavity consists of internal os and external os. Uterine cavity is above internal os. |
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Uterine wall |
From deep to superficial: endometrium, myometrium, perimetrium. Endometrium: Includes inner stratum functionalis, which is shed during menstruation and stratum basalis which is permanent and gives rise to stratum functionalis. Myonetrium: Middle section. Perimetrium: A part of the visceral peritoneum. |
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Vagina |
A fibromuscular canal lined with mucous membrane that extends from exterior to the cervix. Serves three functions: 1. Receives penis during intercourse 2. Passageway for menstrual flow 3. Forms the lower birth canal |
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Vulva (pudendum) |
Female external genitals. Includes bodies like mons pubis (adipose tissue providing cushioning), labia majora (outer folds), labia minora (inner folds), clitoris (erectile tissue), vestibule (area between folds of labia minora with vaginal orifice, urethral orifice, hymen, glands) bulb of vestibule (internal erectile tissue that becomes engorged with blood during sex and places pressure on penis) |
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Vestibular glands |
Paraurethral (Skene's) glands: Duct openings flank the external urethral orifice. They secrete mucous. Homologous to prostate. Greater vestibular (Bartholin's) glands: Duct openings between hymen and labia minora. They produce lubricating mucous during sexual arousal. Several lesser vestibular glands also exist. |
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Perineum |
Diamond shaped area that includes external genitals and anus in males and females. An imaginary transverse dividing line between the ischial tuberosities creates the urogenital triangle and the anal triangle. |
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Mammary glands |
Within each breast is a mammary gland -- modified sudoriferous gland that produces milk. Each mammary gland contains 15-20 lobes divided into lobules. Each lobule is composed of milk-secreting glands called alveoli. Milk produced in the alveoli move through various ducts before exiting the breast at lactiferous ducts in an apocrine manner. This is an exocrine process. |
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Female sexual response |
Initiation is via the parasympathetic system as nitric oxide dilates erectile tissue (the clitoris). Sexual climax culminates in sympathetic discharge, accompanied by quick cycles of muscle contraction in lower pelvic muscles. |
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Sex organ equivalencies |
Ovaries :: Testes Ovum :: Sperm cell Labia majora :: Scrotum Labia minora :: Spongy urethra Vestibule :: Intermediate urethra Bulb of vestibule :: Corpus spongiosum/bulb of penis Clitoris :: Glans penis/corpus cavernosa Paraurethral glands :: Prostate Greater vestibular glands :: Bulbourethral glands |
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Oogenesis |
Begins in females before they are even born, this in contrast with male spermatogenesis which doesn't begin until puberty. The ovarian cycle does not begin in women until puberty. |
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Follicle |
A gamete plus the cluster of cells surrounding it. While a gamete undergoes oogenesis, the entire follicle is also undergoing changes, a process known as follicular development. Follicles don't just house gametes, they are the source for estrogen and progesterone. |
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Oogenesis during fetal period |
During early fetal development, primordial germ cells migrate from the yolk sac to the ovaries where they differentiate into oogonia. Oogonia are diploid stem cells that divide mitotically to produce millions of themselves. Most degenerate prior to birth (known as atresia) though some develop into primary oocytes that enter prophase of meiosis I during fetal development but do not complete that phase until after puberty. During this phase a single layer of follicular cells surround the oocyte. At birth a baby has 200K to 1M primary oocytes per ovary. |
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Oogenesis at puberty |
Ovarian cycle begins. LH and FSH stimulate several primordial follicles to develop further. A few will develop into primary follicles. This primary follicle has granulosa cells that surround primary oocyte. There is also a glycoprotein layer known as the zona pellucida between the primary oocyte and the granulosa cells. There is a stromal cell layer consisting of theca folliculi. |
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Oogenesis develops into secondary follicles |
Secondary follicles still have primary oocytes. There are now two types of theca, a vascularized interna and a stromal/collagen layer externa layer. Granulosa cells begin secreting follicular fluid creating a cavity known as an antrum. Innermost layer of granulosa cells attaches to zona pellucida to form corona radiata. |
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Oogenesis develops into one secondary follicle |
One secondary follicle emerges as the dominant follicle, which continues to grow and turns into mature follicle. It is inside this mature follicle that the primary oocyte completes meiosis I, yielding two haploid cells. One haploid cells is larger, becoming the secondary oocyte, and the other is known as the first polar body. The secondary oocyte begins meiosis II, but stops at metaphase. |
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Ovulation |
Soon after the secondary oocyte stops during metaphase II, the mature follicle ruptures and releases the secondary oocyte. It is swept into fallopian tube for potential fertilization. If the oocyte is fertilized, it will complete meiosis II. Upon completion of meiosis II, there is a resulting ovum and a second polar body. The nuclei of the sperm and ovum then fuse, yielding a diploid zygote. |
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Ovarian cycle |
The production/release of the secondary oocyte |
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Uterine/menstrual cycle |
Preparation of the uterine lining to receive a fertilized ovum. |
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Female reproductive cycle |
Encompasses both the ovarian and uterine cycles, plus the hormonal changes that regulate them, and the related cyclical changes in the breasts and cervix. |
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Hormonal regulation of the female reproductive cycle (GnRH > FSH/LH) |
Hypothalamus secretes GnRH, which controls the ovarian and uterine cycles. This stimulates the release of LH and FSH from the anterior pituitary gland. Together they stimulate the follicles to secrete estrogen. FSH initiates follicle growth. LH further develops follicle and a surge at mid-cycle triggers ovulation. This also promotes formation of the corpus luteum, the remnant of the mature follicle and the key producer of progesterone, inhibin and relaxin. |
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Hormonal regulation of the female reproductive cycle (Estrogen) |
Estrogens secreted by follicles have several key effects: 1. Help develop reproductive structures, secondary sex characteristics, and breasts 2. Increase protein anabolism 3. Lower blood cholesterol 4. Levels of estrogen dictate the release of GnRH (and FSH/LH) |
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Hormonal regulation of the female reproductive cycle (Progesterone) |
Secreted by cells of the corpus luteum, it is the principle hormone responsible for the maturation of the uterine lining (endometrium), as well as an important player in stimulating breast development. Levels of progesterone influence GnRH and LH via negative feedback. |
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Hormonal regulation of the female reproductive cycle (Relaxin/Inhibin) |
Relaxin: Released by the corpus luteum, it relaxes the myometrium during pregnancy and the pubic symphysis at the end of pregnancy. Inhibin: Released by granulosa cells of growing follicles as well as by the corpus luteum, it inhibits the secretion of FSH (and LH a little). |
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Phases of reproductive cycle |
Menstrual phase (day 1-5) Preovulatory phase (day 6-13) Ovulation (Day 14) Postovulatory phase (15-28) |
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Menstrual phase (1-5) |
Ovaries: FSH causes primordial follicles to become primary follicles and then secondary follicles. Uterus: Menstrual flow of 50-150 mL of blood, tissue, fluid, mucous and epithelial cells from endometrium. Declining levels of progesterone and estrogen stimulate prostaglandin release, which causes uterine spiral arteries to constrict resulting in stratum functionalis layer sloughing off |
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Preovulatory phase (6-13) |
Ovaries: Dominant follicle emerges and secretes estrogen and inhibin, which decreases FSH secretion, causing other follicles to degenerate. Dominant follicle becomes mature follicle. Uterus: Estrogens from growing follicle stimulate repair and growth of endometrium, causing it to double in thickness (4-10 mm) |
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Ovulation (14) |
LH surges, causing mature follicle to rupture and release secondary oocyte. This LH surge is due to gradual estrogen surge during preovulatory phase. Fun fact: Low to moderate levels of estrogen inhibit GnRH and LH, but high amounts of estrogen stimulate their release. |
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Postovulatory phase (15-28) |
Ovaries: Ruptured mature follicle becomes corpus luteum. If fertilization did not occur, corpus luteum degenerates after these 2 weeks. If fertilization does occur, the corpus luteum is "rescued" from degeneration by human chorionic gonadotropin (hCG) produced by the chorion (a membrane surrounding the fetus). Uterus: Progesterone and estrogen from corpus luteum cause growth of endometrial glands, endometrial vascularization and thickening (12-18 mm). Without fertilization, progesterone and estrogen levels fall and reproductive cycle begins again. |
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Hormone levels during female reproductive cycle |
FSH: Highest during menstruation as next follicle is being stimulated. Drops to low levels then gets small boost pre-ovulation Estrogens: Steadily rises during menstruation and preovulatory phase, and peaks around day 12, initiating a surge in LH that results in ovulation. LH: Surges at Day 12-14 due to gradual rise in estrogen Progesterone: Gradual rise and fall from ovulation through postovulatory phase. |
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Ovarian cycle |
Menstruation (1-5) Proliferative phase (6-13) (secondary follicle proliferates) Secretory phase (15-28) (corpus luteum secretes) |
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Birth control |
Abstinence > surgical sterilization > hormonal methods > male condom > other barrier methods > periodic abstinence > spermicides |
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Development of the reproductive system |
-Gonads develop from the mesoderm, and differentiation occurs by 7th week of fetal development -Male reproductive system develops from Wolffian ducts -Female reproductive system develops from Mullerian ducts -External genitals remain undifferentiated until 8th week. If DHT (dihydrotestosterone) is present, then it's male. If not it's female. |
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Aging and the female reproductive system |
In females, the reproductive cycle is active from menarche (puberty ~12/13) through menopause. As women get over 40, ovaries become less responsive to anterior pituitary hormones, leading to decrease in estrogen and progesterone, thus follicles do not undergo normal development. |
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Aging in the male reproductive system |
Men retain reproductive function through their 80s and 90s. Decreasing levels of testosterone do decrease muscle strength, sexual desire, viable sperm. Prostate disorders become increasingly likely. |
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Reproductive disorders (male) |
Benign prostatic hyperplasia: Enlargement of prostate gland, occurs in most men over 60. Inability to completely empty bladder. Impotence: Inability to maintain erection long enough for intercourse Infertility: Less than 20 million sperm per mL or as a couple one year of unprotected sex without pregnancy. |
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Reproductive disorders (female) |
Amenorrhea: The absence of menstruation Dysmenorrhea: Unusual menstrual discomfort usually due to excess prostaglandin secretion Disfunctional uterine bleeding: Uterine bleeding in the absence of disease (generally due to hormone imbalance) PMS: Mild distress near the end of postovulatory phase |
