Lecture Exam: Reproductive System Flashcards
biparental
offspring receive genes from two parents so not identical to each other each produces games (sex cells) combining in a zygote (fertilized egg).
necessary for gametes
Gamete motility is necessary to achieve contact (small motile) and nutrients for developing embryo (large and heavy)
male reproductive system serves to
Males have a copulatory organ (penis) for introducing their gametes into the female reproductive tract
female reproductive system produces
Female reproductive system produces eggs, receives sperm, provides for gametes’ union, harbors fetus, and nourishes offspring. Sheleterd internal environment for development and nutrition of egg
Females have a copulatory organ (vagina) for receiving the sperm
primary sex organs
gonads produce gametes
secondary sex organs
endocrine help w/ reproduction
where are genitalia located?
im male Most are external genitalia except for accessory glands.
female most is internal in perineum located in pelvic cavity
secondary sex characteristics for both sexes
features that distinguish the sexes and influence mate attraction ex.
Develop at puberty
Both sexes- Pubic and axillary hair and their associated scent glands, and the pitch of the voice
secondary sex characteristic for male
Facial hair, coarse and visible hair on the torso and limbs, relatively muscular physique. Secondary sex organs: ducts, glands, and penis
secondary sex characteristic for female
Distribution of body fat, breast enlargement, and relatively hairless appearance of the skin secondary sex organs: uterine tubes, uterus, and vagina
sexually differentiation occurs and how does this happen
fetus is sexually undifferentiated at first until 5-6 weeks
Gonads begin to develop as gonadal ridges w/ two ducts: mesonephric duct (serves mesonephros) developing into reproductive tract in males not females, and paramesonephric duct degenerates in males reproductive tract in females. Estrogen levels always high during pregnancy, development of female results from absence of androgen and mulleran-inhibitting factor .
what gene is found only in males? what does it do?
SRY gene (sex-determining region of Y chromosome)
SRY codes for a protein, testis-determining factor (TDF), that initiates development of testes
Testes begin to secrete testosterone at 8 to 9 weeks
Stimulates mesonephric ducts to develop into male tracts
At same time, the testes secrete müllerian-inhibiting factor causing degeneration of the paramesonephric ducts
development of external genitalia
homologous development among both sexes from same embryonic structures. genital tubercle becomes the (head and glands) penis and clitoris glans, male and female respectively; urogenital folds enclose urethra, as well as labia minora; urogenital folds become the scrotum and labia majora, fully distinguishable by 12 weeks.
descent of the testis
Both sexes gonads develop high in the gonadal cavity near kidneys migrate into pelvic cavity (ovaries and scrotum).
steps of descent of organs: Gubernaculum,
connective tissue cord anchors gonads to floor of abdominopelvic cavity passing between the male internal and external abdominal oblique muscles into scrotal swelling
steps of descent of organs:peritoneum
Peritoneum develops fold extending into scrotum as vaginal process independent of gubernaculum.
steps of descent of organs: inguinal canal
Inguinal canal- gubernaculum and vaginal process create path of low resistance through groin, anterior to pubic symphysis, most common site for herniation in men.
steps of descent of organs: testes
Testes descend beginning week 6-8. Superior part of embryonic gonad degenerates w/ inferior part migrating downward guided by gubernaculum. Seventh month testes pass through inguinal canal into scrotum accompanied by testicular arteries, veins, nerves, lymph vessels, spermatic duct, and internal oblique muscle.
steps of descent of organs:vaginal proces
Vaginal process separated from peritoneal cavity becoming sac
steps of descent of organs: tunica vaginalis
Tunica vaginalis- enfolding anterior and lateral sides of testis protecting from abrasion against scrotum w/ movements of body
steps of descent of organs: cryptorchidism
Cryptorchidism- 3% of boys undescended testes that descend w/in first year of infancy, if not corrected w/ testosterone or surgery; uncorrected leads to sterility and testicular cancer
steps of descent of organs: ovaries
Ovaries descend to lesser extent, gubernaculum (becoming ligaments for support) extends from inferior pole of ovary to labioscrotal fold lodge inferior to brim
Reproductive system remains dormant
for several years after birth 10-12 years in boys, 8-10 in females, surge of pituitary gonadotropins awakens puberty
Testes secrete testosterone
in first trimester of fetal development as high as midpuberty then become dormant during infancy and childhood. As hypothalamus matures in late childhood begins to secrete (GnRH) to anterior pituitary to release FSH and LH need both for sperm production, which act on gonads rest regulated by these three throughout hormone.
LH effect on male reproduction
- interstitial cell-stimulating hormone stimulating endocrine cells to secrete androgens, testosterone. Promoting sperm production
FSH-effect on male reproduction
stimulates nurse cells of testes to secrete androgen-binding protein binding and accumulating testosterone in seminiferous tubules and epididymis, spermatogenesis
Adolescence in men
period from onset of gonadotropin secretion and reproductive development to when a person attains full adult height
Puberty in men
first few years of adolescence, until the first menstrual period in girls or the first ejaculation of viable sperm in boys. Growth of sex organs: testes, scrotum, ducts and glands. Sperm production by testosterone as well as limb bones elongate rapidly growing taller w/ more muscle mass. Larynx enlarges deepening voice and making thyroid cartilage more prominent, higher RBC count increasing basal metabolic rate and appetite. Testosterone stimulates brain awakening libido converting to estrogen (causing wet dreams). Dehydrin testosterone-develops pubic hair, axillary hair, facial hair, thicker darker skin more sebum, scent glands.
Adulthood in men
testosterone sustains male reproductive tract, sperm production, and helps maintain libido. Inhibin from nurse cells suppresses FSH decreasing sperm production w/out reducing LH and testosterone secretion.
Aging and Sexual Function-
Due to decline in activity and edrogencells, Testosterone secretion declines with age
Peak secretion at 7 mg/day at age 20; declines to one-fifth of that by age 80
Decline in number and activity of interstitial endocrine cells
Male climacteric (andropause)
may occur
A period of declining reproductive function that may be first seen in early 50s
Although sperm counts decline, men can still father children throughout old age
age related drop in testosterone inhibin triggers rise in FSH and LH drive can experience mood changes, hot flashes, and allusions of suffocation
can lead to impotence or erectile dysfunction 20% of men in 60s and 50% in 80s, inability to produce or maintain erection
Spermatogenesis—
process of sperm production in seminiferous tubules
spermatogenesis Involves three principal events
Division and remodeling of large germ cells into small, mobile sperm cells with flagella
Reduction of chromosome number by one-half
Shuffling of genes so each chromosome contains new gene combinations that did not exist in parent
Ensures genetic variation in the offspring
Meiosis
recombines genes and reduces chromosome number, while producing four daughter cells, gametes that are haploid cells that will become sperm and combine w/ egg to produce diploid fertilized egg
Half genetic material reduction division, two cell division one replication of DNA w/ each having four stages.
spermatogenesis: primordial germ cell
Begin as primordial germ cells form in yolk sac, crawl into embryo itself colonizing gonadal ridges becoming stem cells spermatogonia remaining dormant throughout childhood, lying along periphery of seminiferous tubules near basement membrane outside blood testis barrier
spermatogenesis: spermatogonia
Puberty testosterone secretion rises. Spermatogonia divide by mitosis, one daughter cell remains near tubule wall as type A spermatogonium lifetime supply of stem cells, other daughter cell is type B spermatogonia migrating away from wall.
spermatogenesis: primary blood barrier
Type B spermatogonia enlarges becoming primary spermatocyte, protected by nurse cells w/ tight junction dismantled allowing movement through to protected area.
spermatogenesis: primary spermatocyte
Primary spermatocyte undergoes meiosis I, giving rise to two equal size haploid and genetically unique secondary spermatocytes
spermatogenesis: secondary spermatocyte
Secondary spermatocyte undergoes meiosis II dividing into two spermatids four for each spermatogonium then undergoes spermatogenesis differentiating into single spermatozoon sprouting tail and discarding cytoplasm towa.
mature spermatazoon
Head-pear shaped containing nucleus w/ haploid DNA, acrosome (lysosome for egg) and flagella basal body. Tail- three different regions midpiece- contains mitochondria ATP for flagella movement, principa- axoneme supporting fibers most of tail. Endpiece- tip of flagella.
semen
(seminal fluid)—fluid expelled during orgasm.
2 to 5 mL of fluid expelled during ejaculatiom
60% seminal vesicle fluid, 30% prostatic fluid, and 10% sperm and spermatic duct secretions
Normal sperm count 50 to 120 million/mL
Lower than 20 to 25 million/mL: infertility
prostate produces
thin, milky white fluid
Contains calcium, citrate, and phosphate ions
Clotting enzyme
Protein-hydrolyzing enzyme called serine protease (prostate-specific antigen)
seminal vesicle
Seminal vesicles contribute viscous yellowish fluid
Contains fructose and other carbohydrates, citrate, prostaglandins, and protein called proseminogelin. Stickines sof semen promotes fertilization, clotting enzyme activates prosemenogelin to semenogelin entangling sperm sticking to walls of inner vagina and cervix ensuring that semen doesn’t drain out, and can promote uptake of sperm-laden clots of semen into uterus. 20-30 minutes after ejaculation, serine protease of fluid breaks down semenogelin liquefying it.
sperm motility needs?
Sperm motility required to have elevated pH and energy source (sugars from seminal vesicles). Spermatic fluid buffers vagina and seminal acidity raising pH significantly activating sperm. Activated sperm crawl up thin mucosa of vagina and uterus. Prostaglandins of semen thin mucus and cervical canal of female for easier migration into uterus, stimulate peristaltic waves in uterus and uterine tubes helping to spread semen through female reproductive tract.
circulation to penis during arousal
internal iliac artery gives rise to internal pudendal (penile artery), root of penis, dividing into two dorsal branches under skin dorsal surface- supplies most when flaccid innervating skin, fascia, and corpus spongiosum. Deep artery- travels through core of corpus cavernosum giving off helicine arteries penetrating trabeculae emptying into lacunae filling w/ blood becoming erect. Numerous anastomosis between deep and dorsal arteries allowing for full erection throughout.
Innervation to penis during arousal
Richly innervated by sensory and motor nerve fibers w/ glans and foreskin having abundance of tactile, pressure and temperature receptors. Lead by dorsal nerves to internal pudendal lead to sacral spinal cord autonomic somatic impulses from spine to penis induce sympathetic: erection based on thoughts and senses. Parasympathetic: direct stimulation of penis and perineal region
Divided intercourse
(aka coitus,coition,or copulation) into four recognizable phases- excitement plateau orgasm resolution
Excitement phase of intercourse in men
vasocongestion (swelling of genitals w/ blood), myotonia (muscle tension), increase in heart rate, blood pressure, and pulmonary ventilation. Bulbourethral glands secrete fluid during this phase. Initiated by erotic stimuli: sights, sounds, aromas, touch, dreams or thoughts w/ emotions inhibiting. Erection due to parasympathetic triggering of nitric oxide dilating arteries and filling lacunae w/ blood. Vasocongestion (50% larger) erection for entry into vagina.
Plateau: phase of intercourse in men
marked increase in respiratory, heart rate, and blood pressure continued increase vasocongestion and myotonia few minutes before orgasm.
Orgasm phase of intercourse in men
climax short but intense reaction marked by the discharge of semen lasting 3-15 seconds vitals increased. Heart rate increases to 180 beats/min, blood pressure rises, and breathy very elevation.
Ejaculaiton phase of intercourse in men
Ejaculaiton occurs in two stages: emission (sympathetic nervous system stimulates peristalsis propels sperm through ducts as glandular secretions are added) expulsion (semen in urethra activates somatic and sympathetic reflexes stimulating muscle contractions leading to expulsion. Contracts internal urethra sphincters so urine cannot pass during this time. Ejaculation and Orgasm are separate usually occur together but not always.
Resolution- body vitals return to normal sympathetic signals constrict internal pudendal artery reducing blood flow to penis becoming soft and flaccid, cardiovascular and respiratory return to normal w/ a refractory period 10 minutes to a few hours following intial impossible for male to maintain another erection.
Female reproductive system in comparison to the male system
The female reproductive system is more complex than the male system because it serves more purposes. Female system is more cyclic, and hormones are secreted in a more complex sequence
puberty begins what hormones involved and what do they do
at age 8 to 10 for most girls in United States
Triggered by rising levels of GnRH which stimulates anterior pituitary to secrete FSH and LH
FSH stimulates ovarian follicles and they begin to secrete estrogen, progesterone, inhibin, and a small amount of androgen
Estrogens are feminizing hormones with widespread effects on the body
Estradiol (most abundant), estriol, and estrone
three stages of puberty
Thelarche, pubarche, menarche,
thelarche
- onset of breast development, sign of onset of puberty, estrogen progesterone, and prolactin trigger the development of ducts and lobules completion of Governed by glucocorticoids growth hormone, adipose and fibrous tissue enlarge breast tissue
Pubarche-
appearance of pubic and axillary hair, sebaceous and axillary glands. androgens from ovaries and adrenal glands stimulate this as well as libido
Menarche-
first menstrual period requires 17% body fat, improved nutrition lowering onset, leptin stimulates gonadotropin secretion if both levels too low then menstrual cycle stops. If started only drops if below 22% body fat. Ovulating regularly year later.
Estradiol in puberty
changes of puberty: metaplasia of vaina, growth of ovaries and secondary sex organs, growth hormones leading to changes in height, widening of pelvis, fat deposition in feminine areas, thickens girls skin thinner softer and warmer than males.
Progesterone in puberty
- acts on uterus during second half of menstrual cycle preparing from possible pregnancy
Estrogen and progesterone- in puberty
suppress FSH and LH secretion by anterior pituitary through negative feedback, inhibin regulates FSH secretion.cyclic in specific sequence.
Climacteric and Menopause-
Females are born w/ 2 million eggs, climacteric when 1000 left Climacteric—midlife change in hormone secretion when 1000 left
Accompanied by menopause
climacteric
cessation of menstruation.
less responsive to gonadotropin secretes less estrogen and progesterone. Uterus, vagina and breastatrophy, intercouse uncomfrotable causing infections more easily, thinner skin, cholesterol rises, increase in cardiovascular disease, bone mass decline, shifting hormones and dilation causing hot flashes. Hormone replacement therapy relieve symptoms (low doses of estrogen and progesterone)
Menopause—
cessation of menstrual cycles- older mother not live long enough to rear infant to survivable age
Usually occurs between ages of 45 and 55
Age of menopause has increased in last century
Menopause considered complete when there has been no menstruation for a year. Evolution says that older mother not live long enough to survivable age
Oogenesis and Sexual Cycle
Reproductive cycle
—sequence of events from fertilization to giving birth and returning to fertility
Sexual cycle what are the two cycles w/in
—events that recur every month when pregnancy does not intervene
Consists of two interrelated cycles controlled by shifting patterns of hormone secretion
Ovarian cycle—events in ovaries
Menstrual cycle—parallel changes in uterus
Oogenesis
—egg production produces haploid gametes by meiosis producing 1 egg per month due to changes in hormone secretion changing histological structure of ovaries in uterus and resulting in monthly menstrual
Embryonic development of ovary-
female germ cells arise from yolk sac colonizing gonadal ridges and differentiate there in the first 5-6 weeks they then differentiate into oogonia multiplying until 5th month reaching 6-7 million in number then are under arrested development until birth. Differentiate into primary oocytes to meiosis I done by birth rest can be called egg or ovum to time of fertilization
atresia
Oocytes undergo atresia process of degeneration so only 2000,000 left by puberty ovulating 480 times, lifetime supply
Egg development resumes
in adolescence, FSH stimulates cohorts to complete meiosis two unequal daughter cells of different size and destinies w/ a lot of cytoplasm needed to keep creating daughter cells of fetus.
Secondary oocytes
products of meiosis proceed as far as metaphase two, arrests until ovulation if not fertilized die and doesn’t finish meiosis completes, if fertilization occurs casts off a polar body, uniting w/ sperm.
Ovarian Follicles- Folliculogenesis–
development of follicle around egg undergoing oogenesis.
Primordial follicles-
primary oocyte in early meiosis surrounded by single layer of squamous follicular cells and basement membrane separated from ovary in ovarian cortex. 13-50 years to develop. 90-95% primordial in adult.
Recruitment primordial follicle
activation awakens 2 dozen primordial follicles each month for a 290 day maturity
Primary follicles-
140 days into cycle larger secondary oocyte than predecessor and follicular cells are simple cuboidal their development is done by recruiting primordial follicles ot become primary.
Secondary follicles-
170 days, oocyte larger multiple layers of cells,
Tertiary follicles
60 days before ovulation, pools enlarge and emerge entrance to form follicles. Mature 20 days before ovulation w/ one becoming follicle destined to ovulate rest die or degenerate. One ovulate captures and holds FSH to ovulate 5 days before ovulation become preovulatory follicle.
Sexual Cycle
- 28 days, hormones of hypothalamus regulate pituitary gland, pituitary regulate ovaries, which in turn regulating uterus. Ovaries exert feedback control of brain.
Sexual cycle begins
Cycle begins two weeks w/in the follicular phase. beginning w/ 3-5 days of menstruation discharge of blood and endometrial tissue. Preovulatory phase- end of menstruation until ovulation. Uterus replaces lost tissue by mitsis, w/ tertiary follicles grow until dominant follicle ovulates around day 14. Remainder of follicle becomes corpus luteum.
FSH stimulates
growth of follicles in cohort particularly dominant to secrete estradiol, which causes it to upregulate receptors w/ rich blood supply becoming preovulatory follicle rest degenerate because estradiol inhibits GnRH decreasing FSH that is picked up more often by dominant.
Ovulation
-day 14 rupture of mature follicle and release of egg and cells surrounding it, estradiol stimulates surge of LH (inducing primary oocyte complete meiosis, follicular fluid swells dramatically, macrophages & enzymes weaken follicular wall releasing egg) and FSH by anterior pituitary, lasting 2-3 minutes. Egg swept up by ciliary currents into uterine tube catches oocyte swelling w/ edema, fimbria grab ovary in synchrony w/ womens heartbeat, cilia create gentle currents in peritoneal fluid, if not caught and fertilized can create ectopic pregnancy
Ovarian Cycle
- reflects what happens in ovaries w/ their relations to hypothalamus and pituitary
Luteal phase (postovulatory)
- corpus luteum stimulates endometrial secretion making it thicker, last two days if not fertilized starts over. (phase—day 15 to day 28, from just after ovulation to onset of menstruation
High levels of estradiol and progesterone, along with inhibin from the corpus luteum, have a negative feedback effect on the pituitary
Corpus luteum begins process of involution (shrinkage)
Ovulation occurs in one ovary per cycle with the two ovaries usually alternating from month to month
Ovulated oocyte began ripening 290 days earlier and began development before birth
Follicle ruptures and collapses bleeding into antrum, clotted blood absorbed
Granulosum and cells surrounding fill antrum there are dense beds of capillaires growing surrounding
Ovulated follicle corpus luteum transformation of ruptured follicle regulated by LH, stimulates grow and secrete rising estradiol and progesterone (crucial roll for preparing for possibility of pregnancy). secretion of FSH and LH decline throughout cycle.
Corpus luteum involution shrinkage 22-26, what was corpus luteum becomes small scar w/ diminishing ovarian steroid secretion FSH levels rise and new follicle starts to develop. Ovulation- One ovary per cycle alternating, oocytes began ripening 290 earlier.
Menstrual cycle
—consists of a buildup of endometrium during most of the sexual cycle, followed by its breakdown and vaginal discharge
Divided into four phases:
proliferative phase,secretory phase,premenstrual phase,and menstrual phase