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Bio: chapter 13: Reproductive systems

Terms in this set (154)

Scrotum
important for temperature regulation; relaxation of the scrotum facilitates cooling of the testes.
Role of testes
1) synthesis of sperm 2) secretion of male sex hormones (androgens)
Site of spermatogenesis
seminiferous tubules
Sustentacular cells
aka Sertoli cells, form the walls of seminiferous tubules; protect and nurture developing sperm, both physically and chemically.
Interstitial cells
cells found in testicular interstitial (tissue between seminiferous tubules); responsible for androgen synthesis
Epididymis
where seminiferous tubules empty; its a long coiled tube located on the posterior of each testicle;
Ductus Deferens
where each epididymis empties; next urethra
Where does inguinal canal joins the seminal vesicle duct and to form what?
ejaculatory duct; in the back of urinary bladder
Seminal vesicles
pair of glands on the posterior surface of the bladder; secrete 60% of total volume of semen into ejaculatory duct; secrete mostly fructose
semen
highly nourishing fluid for sperm, produced by 3 separate glands - seminal vesicle, prostate, bulbourethral gladns
Accesosrry glands
seminal vesicle, prostate, bulbourethral gladns; all produce semen
Prostate gland
fructose and coagulant; nourishment and allows semen to coagulate after ejaculation; 35% of ejaculate volume
Bulbourethral glands
thick, alkaline mucus ;to lubricate urethra and neutralize acids in male urethra and in female vagina; 3%
Testes
sperm; male gamete - 2%
Erectile tissue
allows erection; specialized tissue; composed of mofidifed veins and capillaries surrounded by a CT sheath; 3 parts: corpora cavernous, corpora spongiuosum
Arousal in male sexual act
depends on parasympathetic nervous input: erection and lubrication stages
Erection
involves dilation of arteries supplying erectile tissue; causes swelling and obstructs venous outflow; allows it to become pressurized
Lubrication
occurs as a parasympathetic reaction, bulbourethral glands secrete viscous mucous fluid which serves as a lubricant
Orgasm
sympathetic system: 2 stages - emission and ejaculation;
emission
propulsion of sperm from ductus deferens and semen from accessory glands to urethra by contractions of smooth muscle
Ejaculation
semen is propelled out of the urethra by rhythmic contractions of muscles surrounding the base of penis; reflex reaction caused by presence of semen;
Resolution
return to normal state; sympathetic system controlled; caused by constriction of erectile arteries; results in decreased blood flow to tissue, usually 2-3 minutes;
Spermatozoa
gametes produced by male; aka sperm;
Gametes female
ova, eggs;
Syngamy
fusion of the sperm and egg; results in zygote
Egg - zygote and sperm - zygote contrinution
egg - everything else in zygote, sperm - just haploid genome
When does spermatogenesis begin?
begins at puberty and occurs throughout adult life;
immature sperm vs mature sperm location
mature sperm in the lumen of seminiferous tubules; immature sperm - outer wall of the tubule;
Germ cells
cells that give rise to spermatogonia in males and oogonia in females.
Mitosis males
happens in seminiferous tubules; ends with spermatids in seminiferous tubules, which become spermatozoa.
Maturation of spermatozoa
in epididymis; first incapable of motility, a few days later - enter ductus deferens and move;
What allows sperm to conserve energy and remain fertile during storage in ductus deferens for as long as a month?
very low metabolic activity rate
meiosis leads to how many sperms?
4
Head of the sperm
contains haploid nucleus, the acrosome, and flagellum that forms a tail
neck of the sperm
at the base of the tail; contains mitochondria;
Where do mitos in the neck get energy?
from fructose in seminal vesicles and from vaginal secretions
Acrosome
compartment of head of sperm that contains hydrolytic enzymes required for penetration of ovums layers
Bindin
protein on the sperms surface that attaches to receptors on the zone pellucida surrounding the ovum
Flaggelum doesnt form until what stage?
Spermatid stage
Flagellar movement in prokaryotes
rotation of basal structure embedded in membrane
Testesterone
plays essential role of stimulating division of spermatogonia
LH
stimulates interstitial cells to secrete testesterone;
FSH
stimulates sustenacular cells;
Inhibin
secreted by sustenacular cells and granulose cells; its role is to inhibit FSH release
GnRH
GnRH is a hormone produced in the hypothalamus region of the brain. GnRH moves through the bloodstream to the pituitary gland. There, it binds to certain receptors. Those receptors signal the pituitary gland to create two more hormones: LH and follicle-stimulating hormone (FSH); this is the hormone that gets released via portal system
Do testesterone, estrogen, progesterone, inhibit exert feedback inhibition upon anterior pituitary?
Yes and onto brain
Wolffian ducts
early embryos whether female or male have undifferentiated gonads that can develop into male internal genitalia
in absence of Y chromosome what happens?
Mullerian ducts develop by default + female external by default - but not from mullein ducts
Presence of Y chromosome what happens?
causes male internal and external fenitalia to develop by producing testestrone and Mullerian Inhbiting factor (MIF)
Testes arise when
7th week of gestation
Week 9 of males
testes are formed, interstitial cells supply testesterone
dihydrotestesterone
what testesterone gets converted into
if an XY genotype fails to secrete testosterone, will it have testes or ovaries?
Testes (page 472)
Mullerian ducts
that can further become female genitalia
Analogous structures in females and males organs
uterine tubes and ductus deferens
Homologous organs
testes and ovaries because they are developed from same structure
what are lubrication organs in males and females
bulbourethral glands and greater vestibular galdns
adnrogens
hormones involved in development and maintenance of male characteristics
estrogens
hormones for maintaining female characteristics
Primary estrogen
estradiol
primary androgen
testesterone which is converted to dihydrotestesterone in target tissues
Testesterone levels and growth
falls after birth until puberty; then increases and remains high for adult life; responsible for maintenance of secondary male characteristics; pubertal growth causes growth but then fusion of epiphyses
Estrogen levels and growth
after birth until puberty - low, at puberty - regulates uterine cycle and development and maintenance of sec female characteristics. causes fusion of epiphyses in females
What controls sex steroid production in puberty and adult life?
hypothalamus and anterior pituitary; GnRH - from hypothalamus stimulates pituitary to release gonadotropins: FSH, LH; controlled by feedback inhibition
FSH stimulates in men/women
Sustenacular cells/ granulose cells to secrete estrogen
LH stimualtes in men/women
interstitiaL cells/ formation of corpus lutes and progesterone secretion
labioscrotal swellings caused by
testesterone become then scrotum; no testesterone - turn into labia major forms
clitoris
structure that gave rise to penis if there was testesterone
what neighbors with vagina in the end?
uterus; upper portion of uterus - cervix
endomterium
innermost lining of uterus; responsible for nourishing embryo and in the absence of pregnancy it is shed once a month;
myometrium
surrounds endometrium; thick muscle wall
uterine tubes
aka fallopian tubes; extend into pelvis on either side; uterus ends into 2 fallopian tubes;
fimbriae
end of each uterine tube; finger-like structures; they brush against ovary
Female sexual act stages
arousal, organs and resolution;
arousal in females
erection and lubrication (like in males), parasympathetic regulation,; clitoris and labia minor become engorged with blood just as in male
Lubrication in females
by greater vestibular glands and vaginal epithelium
orgasm
controlled by sympathetic; muscle contractions, widening of cervix( thought to facilitate movement of sperm)
resolution in females
up to 20-30 minutes
Oogonesis
in ovaries, germ cells divide mitotically to produce large numbers of oogonia; begins prenatally unlike in males, which only in adult males
oogonia arrested at what phase before puberty?
enter the first phase of meiosis and arrest at prophase I ( primary oocytes)
How many oocytes will actually ovulate?
0.01%
1st meiotic division yields
a large secondary oocyte and a small polar body - containing half the DNA but no cytoplasm or organelles)
2nd meiotic division
occurs only if secondary oocyte is fertilized by a sperm;
Fusion doesn't happen immediately, why?
because must wait for a secondary oocyte to release the second polar body and finish maturing to an ootid and then to an ovum
Follicle
a structure with primary oocyte, granulosa cells - clump of supporting cells
Granulosa cells
assists with maturation of an oocyte; secrete estrogen together with thecal cells during 1st half of menstrual cycle;
Primordial follicle
immature primary oocyte surrounded by a single layer of granulosa cells
zona pellucida
a protective layer of monosaccharides around the oocyte; forms when primordial follicle starts to mature
thecal cells
follicles in ovary are surrounded by; analogous to testicular interstitial cells;
Graafian follicle
one of the few follicles that matures
Corona radiata
layer of granulosa cells surrounding the ovum; after graafian follicle bursts
Corpus luteum
cells remaining in ovary after ovulation form this new structure; secretes estrogen and progesterone like CRAZY --> marks the beginning of secretory phase of uterine cycle
Ovarian cycle
aka menstrual cycle; - events occurring in ovaries; 3 phases: 1)follicular phase 2) ovulatory phase 3) luteal phase
Uterine cycle
events occurring in uterus - shading of old endometrium and preparation of a new endometrium; 28 days; 3 phases: menstruation, proliferative phase, secretory phase
follicular phase
primary follicle matures and secrete estrogen; maturation controlled by FSH from anterior pituitary. lasts 13 days
Ovulatory Phase
secondary oocyte is released from ovary; triggered by surge of LH from anterior pituitary; surge also causes remnants of follicles to become corpus luteum; occurs on 14th day
Luteal phase
begins with full formation of corpus luteum in ovary; structure secretes both estrogen and progesterone; has a lifespan of 2 weeks; average length of cycle is 14 days
menstruation
1st phase of uterine cycle; triggered by degeneration of corpus luteum and subsequent drop in estrogen and progesterone; sharp decrease in those hormones causes bleeding and shedding out; lasts typically about 5 days
Proliferative phase
2nd phase of uterine cycle; estrogen produced by follicle starts new endometrium lining; phase lasts 9 days
secretory phase
3rd phase of uterine cycle; occurs in which estrogen and progesterone produced by corpus luteum further increases development of endometrium; including secretion of glycogen, lipids and others; if pregnancy doesn't occur = degeneration of corpus luteum, decline in secretion of estrogen and progesterone triggers menstruation again; lasts 14 days
drop in estrogen and progesterone induces...
menstruation
hCG hormone
is like LH, but when implantation happened successfully; so secretes estrogen and progesterone
why does endometrial shedding occur?
to decrease estrogen and progesterone levels, which occur as corpus luteum degenerate
why does corpus luteum degenerate?
due to decrease in LH
why does LH decrease
due to feedback inhibition from high levels of estrogen and progesterone by corpus luteum
LH surge means...
OVULATION
chorion
portion of placenta that is derived from zygote; secretes human chorionic gonadotropin, HCG which takes place instead of LH to maintain corpus luteum and high levels of estrogen and progesterone, so menstruation doesnt occue
Sperm capacitation
involves dilution of inhibitory substances present in semen; activated sperm will survive for 2 or more days'
acrosome reaction
how sperm penetrating corona radiate and binding to and penetrating zone pellucida'
acrosomal process
contains actin: elongates toward zona pellucida; has binding, species-specific proteins which binds to receptors in zone pellucida
fast block to polyspermy
depolarization of egg plasma membrane; prevents spermatozoa from fusing with egg cell membrane
slow block to polyspermy
results from Ca2+ influx caused by initial depolarization; aka cortical reaction; 1 - swelling of space between zp and plasma membrane and 2 - hardening of zp
Ca2+ influx also affects
metabolism and protein synthesis, aka egg activation
Embryogensis
1 - cleavage: zygote undergoes many cells divisions to produce a ball of cells called morula - 36 hours after fertilization 2 - blastulation
Blastocyst
consists of ring of cells called trophoblast surrounding cavity and inner cell may adhering to inside of trophoblast at one end of cavity
trophoblast will give rise to
chorion - zygote's concentration to placenta
inner cell mass will give rise to
embryo
How long it takes for a blastocyst to implant?
a week after fertilization
What does trophoblast secrete?
proteases that lyse endometrial cells; also allows inner cells mass to absorb nutrients
placenta
organ which is specialized to exchange nutrients, gases and even antibodies between maternal and embryonic bloodstreams; takes about 3 months to develop
after 6 months of pregnancy no corpus luteum needed, why?
because placenta secretes enough esterogen and progesterone for maintennace
placental villi
chorionic projections extending into endometrium into which fetal capillaries grow;surroundign villi are sinuses with maternal blood
what is derived from inner cell mass
amnion, yolk sac, allantois
amnion
surrounds fluid filled cavity which contains developing embryo
yolk sac in mammals vs reptiles and birds
mammals dont store yolk; it is the first site of red blood synthesis in embryo
allantois
develops from embryonic gut and forms blood vessels of umbilical cord which traposrt blood between embryo and placenta
Gastrulation
when 3 primary germ layers become distinct )ecto, meso , endoderm; happens only in inner cell mass
Archenteron
primitive gut, cavity where you "fist will be"
blastopore
""opening where you wrist will be"
gastrula
whole structure
human vs primitive organism
gastrula develops from a double layer of cells called embryonic disc instead of spherical gastrula
Ectoderm
entire nervous system; pituitary gland, adrenal medulla, cornea, lens, epidermis of skin and derivatives (hair, nails, sweat gland, sensory receptors), nasal oral anal epithelium
mesoderm
All muscle, bone, Ct, entire cardiovascular and lymphatic system, includign blood, urogenital organs (kidneys, ureters, grans, reproductive organs,) dermis of skin
Endoderm2
GI tract epithelium except mouth and anus, GI glands (liver, pancreas,,) Respiratory epithelium Epithelial lining go urogenital organs and ducts, urinary bladder
WHen does neurulation begin?
when ectoderm portion differentiates intro neural plate
neural crest cells
at teh edges of the neural plate; edges then thicken and make neural folds --> tubes
neural crest destiny
separates from neural tube and overlying ectoderm and migrates to different parts of embryo to differentiate into variety of cell types, including melanocytes, glial cells, adrenal medulla, and some peripheral neurons, and facial CT
How does neural tube form?
underlying notochord give sintructions <<<< vertebral column forms
organogenesis
by end of 8 weeks
During which trimester is fetus more sensitive to radiation and toxins?
first trimester, because organs forms
embryonic stem cells are th only
pluripotent cells that have been found; they are isolated inform inner cell mass of blastocyst
Every cell has the same genome
true
the only exception to every cell has the same genome
T cells and B cells, that undergo DNA! rearrangements to attain antigen specificity; and gametes
Totipotent
Can generate trophoblast and inner cell mass ;ex: zygote, morula
Rluripotent
can differentiate into any of the 3 types of primary germ layers; can generate all adult cells; ex: inner mass cells of blastocyst; IPS cells
Multipotent
can produce many but not all cell types; more differentiated than pluripotent, often tissue specific; ex - 3 primary germ layers, adult stem cells
Dedifferentiation
some cells cna go back and become less specialized: ex: IPS cells, cancer cells
II trimester
continue to develop organs, fetus - 0.6 kg
III trimester
rapid fetal growth, deposition of adipose tissue, organs functional; 1-2 months early - has good survival chances
high progesterone causes contraction
to stop
excitability in uterine muscles increases with
ration of estrogen to progesterone, oxytocin, mech stretching of uterus and cervix
cervix pressure --> contractions
through increased oxytocin
2 labor stages
1- dilation of cervix, 2 - birth 3 - expulsion of placenta
prolactin
inhivited by estrogen and progesteron ;oxytocin also released during suckling
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