how does the presence of a Y chromosome result in a male?
sex-determining region Y gene (SRY) is present on the short arm of the Y chromosome and ecodes for a protein called the Testis Determining Factor (TDF). This protein induces the formation of the testes
primary sex structures
ovaries, testes
development of secondary sex structures depends on
presence or absence of the hormone testosterone
androgens
testes secrete androgens and make male structures; ovaries can't secrete androgens resulting in female structures
wolffian ducts
up unti the 7th week of development, embryos of each sex posses wolffian ducts (form internal male structures
mullerian ducts
up unti the 7th week of development, embryos of each sex posses mullerian ducts (form internal female structures)
mullerian inhibiting factor
causes regression of the mullerian ducts; females become females because of lack of mullerian inhibiting factor and testosterone
human chorionic gonadotropin
hormone released by the placenta; stimulates early testicular secretion of testosterone which induces develpment of the wolffian ducts into the male reproductive tract (epididymis, ductus deferens, ejaculatory duct, and seminal vesicles)
male reproductive tract
epididymis, ductus deferens, ejaculatory duct, and seminal vesicles
female reproductive tract
oviducts, uterus, and vagina
external reproductive structures requre
dihydtrotestosterone or DHT
genitalia are mostly formed after how many weeks
16
differentiation of the male and female brain also depends on the presence or absence of what
testosterone
differences in male and female brain
size of hypothalamic nuclei, cyclic release of gonadotropin, and sexual behavior
how long does puberty last
3-5 years
menstruation started in 1840 at what age
17
sebaceous glands
stimulated to secreted oil (acne) during puberty
progesterone
female hormone related to menstruation period
precocious puberty
early puberty; early development of secondary sex characteristics; caused by abnormal exposure of immature females to estrogen or males to androgens; often caused by tumors of the gonads or adrenal glands
delayed puberty
menarche has failed to occur by age 17, testes failed to develop by age 20
spermatogenesis works best in what temp
colder
testes are divided into
testicular lobules (250 compartments)
Each lobule in the teste contains
a coiled seminiferous tubule and interstitial cells (Leydig cells)
function of seminiferous tubules
produce sperm; they also contain Sertoli cells which play a role in nurturing the sperm cells
function of Leydig cells
produce testosterone; are located outside of the seminiferous tubules
epididymis
small coiled tube which measures about 20 feet, lies along the top and side of the testes; site of maturation of sperm
capacitation
sperm's capacity to fertilize is enhanced by exposure to secretions of the female reproductive tract; the ductus epididymis also secretes "sperm forward-mobility protein," which causes a movement pattern of the sperm
vas deferens (ductus deferens)
tubes that carry sperm from the epididmis up into the abdominal cavity to the ejaculatory duct near the bladder; at the end of the vas deferens is an expanded region called the "ampulla" which serves as a reservoir for sperm
vasectomy
a small incision is made in the scrotum, the vas deferens is tied in two places and the segments between the ties are removed
Ejaculatory ducts
carry sperm from vas deferens to urethra
urethra
tube extending from the urinary bladder through the flor of the pelvic cavity and then through the penis; carries urine from bladder and sperm from ejaculatory duct
male sex accessory organs
seminal vesicles, prostate gland, bulbourethral glands; these glands secrete seminal plasma which mixes with the sperm to form semen or seminal fluid
seminal vesicles
secrete seminal plasma (more than half of total semen volume); fluid contains fructose to give energy to sperm; fluid also contains prostaglandins which stimulate contraction of the male and female reproductive tracts which helps in sperm transport
prostate gland
lies below the bladder and is doughnut shaped; urethra pases through the small hole in the center; secretes alkaline fluid (13-33% of volume) that helps protect the sperm from the acidic environment of the male urethra and female vagina
bulbourethral glands
secrete alkaline fluid, which acts as a lubricant
male fertility
depends on quantity and quality of sperm; 2-6 ml, 20 million sperm/ml, 60% normal shape
number of sperm produced daily
200 million/day
sperm live how long
3-4 days
sperm count per ejaculation
40 million to 250 million; below 20 million may mean infertility problems
how many sperm enter fallopian tube
100-100,000
how many sperm make it to the egg
few hundred
zygote
fertilized egg
what happens to dead sperm in female
phagocytized by leukocytes
infertility is due to whom
50% man 50% woman
structure of sperm
head (contains nucleus with 23 chromosomes), acrosome (enzyme filled vesicle), tail (for movement), midpiece (contains a large number of mitochondria)
uterus
pear shaped organ situated in the pelvic cavity above the urinary bladder and in front of rectum- 3 inches long, 2 wide, 1 thick; larger in multiparous women
two main regions of the uterus
corpus or body, uterine isthmus or cervix (neck)
two main components of the wall
endometrium (shed during menstruation) and myometrium (smooth muscle, contraction of the uterine wall results in expulsion of the fetus at birth
fallopian tubes, oviducts, or uterine tubes
serve as ducts for ovaries (diameter of drinking straw); fertilization usually takes place there)
ovaries
among the most vascular organs of the body
ovarian follicles
female germ cells or oocytes are enclosed inside the ovary in tissue sacs called ovarian follicles
how many follicles do newborn girls have
500,000
how many follicles are released through ovulation
400
ovulation
production of mature egg;when there is estrogen present, the immature oocyte will go from a primary, to secondary, to tertiary follicle. the large follicle that develops during the cycle is called a graafian follicle. It is this follicle that breaks ope
secretion
production of female hormones
Estrogen
estradiol, estrone, and estriol; estradiol is the principle estrogen; produced by follicle, corpus luteum, and plaenta, stimulates development of secondary sex structures, promote myometrial contractions, inhibit FSH secretion
progesterone
produced by corpus luteum and placenta; stimulate development of secondary sex structures; inhibits contraction of uterine muscle
average human menstrual cycle length
29.5 days
day 1 of ovarian cycle
menstruation starts, estrogen and progesterone levels are low, FSH stimulates the development of the follicle (the egg inside the follicle), several follicles start to develop-follicle secrete estrogen
day 7 of ovarian cycle
usually only one follicle continues to develop and secrete estrogens; others degenerate; estrogen elvels increase as the folicle grows into a graafian follicle;several days before ovulation, more LH are releases from anterior pituitary
day 14 of ovarian cycle
high levels of LH stimulate ovulation; LH surge occurs 16 hours before ovulation; expulsion of egg from the mature follicle--ovaries usually alternate
indications of ovulation
rise in basal body temperature due to progesterone; slight pain over ovary; vaginal secretory pattern
fertile period length
4-6 days
destiny of follicle cell after ovulation
LH stimulates the transformation of follicle cell into a corpus luteum (yellow body)
cells of corpus luteum secrete
estrogens and progesterone
day 23 of ovarian cycle if pregnancy occurs
the corpus persists; Human chorionic gonadotrophin (HCG) maintains the corpus luteum during pregnancy, which in turn maintains the levels of estrogen and progesterone
HCG
human chorionic gonadotrophin; is detectable in the blood and urine as early as 8-10 days after fertilization so it's used in pregnancy kits; similar to GH and prolactin; has anti-insulin effects to divert glucose from mother to fetus
day 23 of ovarian cycle if no pregnancy
corpus luteum begins to degenerate on about day 23 or 24; with degeneration of the corpus luteum, the levels of estrogens and progesterone drop
day 27 of ovarian cycle (no pregnancy)
low levels of estrogen and progesterone cause ischemia in the endometrium, which initiates the beginning of the next cycle in one to two days
menstrual cycle names
day 1-5 menstrual phase; 6-14 postmenstrual, preovulatory, or follicular phase; day 14 ovulation; day 14-27 premenstrual, postovulatory, or luteal phase; day 27-28 ischemic phase
implantation takes place how many days after fertilization
6-7 days
intrauterin implantation
usually implants in the upper posterior wall of uterus; cervical implantation
extrauterine implantation
rare; called ectopic pregnancy (anywhere outside the uterus); tubal, abdominal, ovarian
pregancy lasts how long
38 weeks (9.5 months)
pre-embryo
first 2 weeks after conception
embryo
3-8 weeks after fertilization; most critical period for damage to occur to baby
how much weight should a pregnant mother gain
25 pounds
during pregnancy, which hormones increase
estrogens, progesterone, HCG (human chorionic gonadotrophin which peaks at 2nd month), Glucocorticoids from the adrenal glands, T3 and T4 from thryoid, parathyroid hormone
change in pituitary during pregnancy
increases in size and activity
change in blood volume and cardiac output during pregnancy
increase
parturition
act of giving birth
factors that increase contractibility of the uterus
increased estrogen levels, secretion of oxytocin from posterior pituitary, formation of prostaglandins in the uterus
labor is divided into three stages
1)cervical dilation-up to 10 cm 2)delivery of the baby 3)delivery of the placenta (afterbirth)
when does menopause start
52
menopause (what happens)
follicle does not develop and therefore LH and FSH remain high and estrogens and progesterone remain low
treatment for menopause
estrogen replacement therapy using premarin; there's recent evidence that ERT might not be so good
benefits of ERT
relieves hot flashes, insomnia, vaginal dryness, mood swings, and heart disease
risks of ERT
increased risk of endometrial and breast cancer, weight gain, and gall bladder disease
tubal ligation
tying off both uterine tubes and thus preventing the transport of sperm or egg through the tubes
mr. charles11
